Solar The Solar Panel Thread

[Boots in Action]

Hi @Boots in Action,
what model Setec do you have? Only the mkIII has the manual battery isolate switch incorporated. If you have an earlier Setec AND a battery isolate switch than it is wired differently and probably only directly disconnects the battery.

cheers
Mike

Hi Mike @mikerezny , I have a Setec ST 20 - 111 (20 amp version). However, I think my Daughter's 2010 Discovery has Setec ST 20 - 11, but will have to check. Can try to do same tests later in week, but did not notice anything different to mine when installing Powertech Solar controller with Load through controller terminals - but did not really check. However, there was a separate battery switch in the circuit.

Brilliant!!! Thanks for this. I can now take advantage running two panels in parallel mode roof+folding panels(occasionally).Problem solved

Well now that you are organised @Eddii , I have had another go at the connections and circuit. This time I have just done tests and observations and will let some really smart "Tech Head" work out the circuit in full. See new post and connection diagram. Will take a while for me to go through notes and put into words. Glad you have made some progress. Is the "Treasurer of Home Affairs" going to approve of your expenditure???

 

[Boots in Action]

Hi @Boots in Action,
what model Setec do you have? Only the mkIII has the manual battery isolate switch incorporated. If you have an earlier Setec AND a battery isolate switch than it is wired differently and probably only directly disconnects the battery.

cheers
Mike

Hi there @mikerezny , @G Daddy , @Bellbirdweb and @Eddii , here is the updated amended diagram of how I have connected up my MPPT controller to the Setec so that everything works. The following tests and observations were made today to understand exactly how this all comes together. 4 separate tests were conducted each one with battery switch ON and OFF and also WITH and WITHOUT a load applied. 16 tests in all!!

First test "A" - no external power connected - Internal battery only.
WITH BATTERY SWITCH ON: NO Load: Controller working and all displays as normal: battery voltage, 0 amps in, 0 amps out, PV voltage and PV current 0, no load and Setec connected.
With Load ON (lights etc): Controller showing as above but with load in AMPs displayed. Setec on and operational.

WITH BATTERY SWITCH OFF: NO Load: All accessories off including radio memory function, Setec off. Note controller still operating as per NO Load test above with normal displays.
WITH BATTERY SWITCH OFF: Load ON: All accessories off incl radio memory function, Setec off. Controller still operating as per No load test above.

2ND TEST "B" - 240 volt power connected to van (and SETEC)
WITH BATTERY SWITCH ON: NO Load: Setec charging to max voltage of 14.0 volts. Controller functioning as per same test in "A". Only difference was it was showing higher battery voltage caused by Setec charging. Not showing current into battery.
With Load ON: All accessories working. Controller detected battery voltage drop because of LOAD applied. Otherwise Controller as above. Load not displayed.

WITH BATTERY SWITCH OFF: No LOAD: Setec off, but no change to Controller displays . Note in this test, the SETEC is STILL charging but only at 0.8A. Noted that battery voltage rose slightly to 14.1 volts in this mode. Dropped back to float voltage of 13.7 volts as per Setec specs when battery switch "ON' again.

3RD Test "C" - External charging by Multi stage "Smart Charger" from Anderson plug at side of van and wires connected directly across battery terminals. No other power to van .

WITH BATTERY SWITCH ON: No LOAD: Setec on, and Controller in operation showing battery voltage to 14.7 volts (correct for AGM) and as per specs of charger. No load or amps in shown on controller.
With Load ON: Setec on, all accessories On and working, controller showing Load IN AMPS and amps in, and battery voltage, plus zero for PV voltage and amps.

WITH BATTERY SWITCH OFF: No Load: Setec off, all accessories off. Controller showing no load or amps in, but charging voltage still at 14.7 volts before dropping back to 13.8 volts (float voltage) as per specs for charger.
With Load ON: Setec off, all accessories off, controller showing No Load or amps in/out, but voltage and other displays as per above.

4Th Test "D" - solar panel connected (only 1 X 180w) - no other power connected to van.
WITH BATTERY SWITCH ON: No load: Setec on, controller showing full details of 8.4 amps in, no load, PV voltage at 18.6 volts and battery charge voltage of 14.6 volts (user adjustable setting correct as set) and continuous logging of electrical system operating.
With Load ON: Setec on, all accessories working, controller showing load of 3.6amps, PV voltage of 16.1 volts, 5.8amps charge to battery and battery voltage of 14.1 volts. All electrical logging in operation.

WITH BATTERY SWITCH OFF: No load: Setec off, all accessories off, controller showing no load, but PV voltage up to 18.6 volts, charge rate of 5.8 amps and battery charge voltage at max setting of 14.6 volts (correct as set by user and adjustable) before dropping to 13.8 volts (float setting - also adjustable and correct for setting made).
With Load On: Setec off, all accessories off, controller showing no load, but still showing PV voltage at 18.6 volts,5.8 amps into battery at battery charge voltage of 14.6 volts and then 13.8 volts (float) as per user adjustable settings made by me.

I think I have covered most of the combinations possible, but if I have missed one or you want me to double check any info, I am happy to do test again for any member to clarify this very successful setup for me.
And here is the simplest way I could explain the connections I have made. Could not take photo as too many wires in the way. However, the diagram is exactly as the Setec distribution area looks and the terminals are as marked on all the connections. Hope this helps. NO FLAMES, NO SMOKE AND NO MIRRORS EITHER.

 

[Eddii]

Hi Mike @mikerezny , I have a Setec ST 20 - 111 (20 amp version). However, I think my Daughter's 2010 Discovery has Setec ST 20 - 11, but will have to check. Can try to do same tests later in week, but did not notice anything different to mine when installing Powertech Solar controller with Load through controller terminals - but did not really check. However, there was a separate battery switch in the circuit.



Well now that you are organised @Eddii , I have had another go at the connections and circuit. This time I have just done tests and observations and will let some really smart "Tech Head" work out the circuit in full. See new post and connection diagram. Will take a while for me to go through notes and put into words. Glad you have made some progress. Is the "Treasurer of Home Affairs" going to approve of your expenditure???

@Boots in Action I shall ask the "minister of finance" after our holidays. I already spent enough money prior to our trip. Diesel Heater was the biggest expenditure for this trip. I shall find a way to justify the next project

Thanks for the diagram, makes much sense now

 

[Boots in Action]

I didn’t get a chance to see you original diagram @Boots in Action so now I’m really interested in seeing your revised version.

Based on @mikerezny’s comment above about losing the battery isolate switch on the STIII and having a drifter, I’m keen to have a look and see if it’s something applicable to my setup or not.

Hi @Bellbirdweb , it would appear that the comment by @mikerezny about losing the normal use of the Battery Isolation Switch seems to be unfounded. Based on the results of my testing under all 4 conditions, it appears that the switch controls the Setec relay and not only disconnects the power to the Setec, but also interrupts the load distribution circuit as well. As my connection of the MPPT controller is across the battery terminals and NOT through the Setec switching, it is able to continue operating independently without the Setec. When the Battery Isolation switch is closed, the load circuit is picked up by the Controller. If my limited understanding is correct, then the MPPT controller will operate the LVD long before the Setec does. What are your thoughts??
Note to those with sophisticated Drifter Panels:: This setup may or may not be suitable for you. More advice needed from "Tech Heads" with Drifter panels themselves. Definitely the way to go if proven to protect your battery/ies.

 

[Boots in Action]

Brilliant!!! Thanks for this. I can now take advantage running two panels in parallel mode roof+folding panels(occasionally).Problem solved

Hi @Eddii , just in case you were wondering about charge voltages for the different types of batteries (the Setec does not do the complete charge job for AGMs in my opinion) I found this little gem on my computer regarding advantages/disadvantages of various terminal charge voltages. Have a read and see what one is up against. It seems that temperature has a huge bearing on what voltages should be set (on user adjustable types) like the MPPT controller you are thinking about??) As has been said on this forum, it is best to go by the manufacturers' specs which are set out on the side of the battery - Gel or AGM. The controller you and I have discussed HAS a remote temp sensor which you can tape to the battery for very accurate temps whilst charging. Otherwise, you have to rely on the ambient temp sensor in the controller itself which could be way different.

Courtesy of Cadex

During the constant-current charge, the battery charges to 70 percent in 5–8 hours; the remaining 30 percent is filled with the slower topping charge that lasts another 7–10 hours. The topping charge is essential for the well-being of the battery and can be compared to a little rest after a good meal. If deprived, the battery will eventually lose the ability to accept a full charge and the performance will decrease due to sulfation. The float charge in the third stage maintains the battery at full charge.

The switch from Stage 1 to 2 occurs seamlessly and happens when the battery reaches the set voltage limit. The current begins to drop as the battery starts to saturate, and full charge is reached when the current decreases to the three percent level of the rated current. A battery with high leakage may never attain this low saturation current, and a plateau timer takes over to initialize the charge termination.

The correct setting of the charge voltage is critical and ranges from 2.30 to 2.45V per cell. Setting the voltage threshold is a compromise, and battery experts refer to this as “dancing on the head of a needle.” On one hand, the battery wants to be fully charged to get maximum capacity and avoid sulfation on the negative plate; on the other hand, an over-saturated condition causes grid corrosion on the positive plate and induces gassing.

To make “dancing on the head of a needle” more difficult, the battery voltage shifts with temperature. Warmer surroundings require slightly lower voltage thresholds and a cold ambient prefers a higher level. Chargers exposed to temperature fluctuations should include temperature sensors to adjust the charge voltage for optimum charge efficiency. If this is not possible, it is better to choose a lower voltage for safety reasons. Table 4-5 compares the advantages and limitations of various peak voltage settings.

​

Site for reference as below:
http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

 

[Jared Dunne]

Did a quick search with some confusion.

After solar installations, how has everyone found the new weight of their roof when popping it up?
I specifically have a expanda 17ft with 2x 200w panels. Approximately 30kg more weight. I have them placed as Central a possible. And am quite surprised at how much harder it is to open?

I'm fairly sure the roof struts suppress the closing weights, not assist in opening? It is simply a matter of hitting the gym and dealing with it

 

[Glen Bundesen]

I had 2 panels on a pop top expander with roof top air con, and even after replacing the gas struts with stronger ones found it too heavy - did have shoulder issues prior! Ended up selling it because of the effort to lift the the roof. Tried lowering it both ends at the same time, but still had issues with it not sitting evenly.

 

[Boots in Action]

For you to think about - what happens at caravan parks when a van is connected to 240 volt power and there are solar panels on roof and a solar controller is in operation??? Because the Setec maxes out at 14.00 volts and most solar controllers (even the cheap ones too) usually put out 14.4 volts or more, the recommended charge for Gel battery is 14.2 to 14.4 volts (as on the side of the Ritar Gel), and my AGM wants 14.4 to 14.7 volts, I believe the solar controller would take precedence in charging. What are your educated "Tech Head' ideas on that???? The mind boggles and does my head in too!!!

 

[Boots in Action]

Hi @mikerezny , @Duncanblake36 , @Drover , I had a chance recently at a caravan park to do proper field tests to see what really happens when connected to the 240v grid and still having solar panel/s on roof operating. Given 2011 Jayco Journey, a new 130 AH AGM, Setec ST20 Series II (14.0v charge voltage limit and 13.6 float) , 80w solar roof panel, and a PowerTech 30A PWM solar controller with user adjustable charge settings made at 14.7v terminal charge voltage and 13.8v float charge.

During the evening when no solar charge possible, voltage on solar controller was approx 12.8 volts when electrical system under light to moderate loads - lights, television, I-pad charging etc. High 240 volt loads like electric jug or toaster did not appear to cause much change. During the day time when sun was shining, voltage was always approx 14.7 with a small charge current from the solar of 0.3A to 0.75A and a daily ah input total of approx 2.5ah. This would tend to prove to me that the solar controller voltage setting over-rides the lower Setec setting in all cases. It would seem from these results that the Setec charges fast and furious to carry the load until the voltage reaches 14.0 , then goes into neutral, but fails to get the voltage high enough to FULLY charge the AGM to 14.7 volts. It appears this is left to the smaller solar panel to try to get the battery voltage up to the setting on the solar controller, even if slowly.

Now this could have significant effects on those with considerable solar generation on the roof as the terminal charging voltage for batteries will be decided by the solar controller setting and NOT the 240 volt charger setting. Most solar controllers, even the cheap ones with factory set fixed charge voltage settings, are around 14.4 volts, so this helps "top up" the voltage to all those batteries that would otherwise be undercharged by the Setec or other type charger. Note that on the side of most batteries are the recommended charge voltages for "stand by use" and "cycle use". The Ritar Gel battery in a lot of Jayco vans shows charge voltage recommended at 14.2 to 14.4 volts so solar charging would help "top up" these batteries to full charge, and get AGMs closer to their peak charge voltage.

Incidentally, in my Penguin with the later Setec ST20 Series III, battery voltage remained at 13.3 volts all the time regardless of load, day or night. I remember that @mikerezny or someone else on this forum said that the later model Setec can be a power source for 12 volts as well as a charging source for battery, something the earlier model was not able to do as it was only a charge source and current was directed to the 12 volt system to keep battery charged??

Note: All voltages were taken from fixed voltmeter display from the Powertech solar controller in Journey, and from fixed voltmeter in electrical circuit in my van, backed up by readings available on my MPPT controller although NO panels deployed!!

 

[Drover]

While I don't have a Setek on the rare occasion I plug into 240 and actually use my charger I just turn the solar off , most times I'll just use 240 for fridge, HWS and kettle and the solar looks after the batteries, my charging system units are individual just turn on what you want. I find my panels/regulator bring my batteries up to speed, plug in the 240 charger and it switches to trickle almost straight away.

 

[mikerezny]

Incidentally, in my Penguin with the later Setec ST20 Series III, battery voltage remained at 13.3 volts all the time regardless of load, day or night. I remember that @mikerezny or someone else on this forum said that the later model Setec can be a power source for 12 volts as well as a charging source for battery, something the earlier model was not able to do as it was only a charge source and current was directed to the 12 volt system to keep battery charged??

Hi @Boots in Action,
actually, I believe it is quite the opposite with both the series II and series III Setec units behaving identically. The only noticeable differences being that the series III has more load fuses AND has a set of terminals providing the function to connect / disconnect the battery by adding an externally mounted switch.

Both can be a 12V power supply powering the vans 12V lights and sockets without requiring a battery to be fitted. If a battery is fitted, it also functions as a battery charger. Other features common to both are Low Voltage disconnect (set too low, as you know), low voltage reconnect, and a feature that limits the charge current if the battery voltage is too low. This prevents large damaging charge currents from flowing into a flat battery.

Both also provide an aux input for charging the battery from an external 12V source. This is commonly connected to the tug alternator to give the van battery some charge whilst driving. I am unsure what the charge current is. Some people are adamant it is only a 0.8A trickle charge. The manual is not clear on this point. I need to get my clamp meter out and make a measurement early in the morning when the tug is connected. The aux input has an isolating diode to prevent current flowing from the van battery back to the car. Particularly important when cranking since quite large currents could flow from the van to support the tug battery.

Regardless of what some people might state, a good multistage 240V charger IS NOT a direct replacement for the Setec. A battery charger is not designed provide a 12V power supply for the van if the battery is not present. It does not have a number of load fuses to protect in the event of short circuits in the wiring. It has no LVD or LVR function to protect the battery from being completely drained. Also, it is not clear to me if a charger will maintain the battery correctly IF there is a load on the battery as well. They are designed to be put across an unloaded battery where the charger is in complete control of the battery voltages and currents.

cheers
Mike

 

[Bellbirdweb]

I run my system exactly that way all the time.

The solar is connected directly to the batteries via the Eperver MPPT controller, and reliably charges up to 14.4v (I have Gel and not AGM batteries) when in the sun.

If I'm at a van park, I will have the 240v plugged in, and the solar will continue to charge regadless of the fact that the setec is also charging.

Obviously at night, the setec is doing all the work but never goes above 14.2v at max charge (which is not normally achieved when we are using the van as we are drawing from the system at the same time)

The 2 systems appear to operate together without any issues.

 

[Boots in Action]

Hi @Boots in Action,
actually, I believe it is quite the opposite with both the series II and series III Setec units behaving identically. The only noticeable differences being that the series III has more load fuses AND has a set of terminals providing the function to connect / disconnect the battery by adding an externally mounted switch.

Both can be a 12V power supply powering the vans 12V lights and sockets without requiring a battery to be fitted. If a battery is fitted, it also functions as a battery charger. Other features common to both are Low Voltage disconnect (set too low, as you know), low voltage reconnect, and a feature that limits the charge current if the battery voltage is too low. This prevents large damaging charge currents from flowing into a flat battery.

Both also provide an aux input for charging the battery from an external 12V source. This is commonly connected to the tug alternator to give the van battery some charge whilst driving. I am unsure what the charge current is. Some people are adamant it is only a 0.8A trickle charge. The manual is not clear on this point. I need to get my clamp meter out and make a measurement early in the morning when the tug is connected. The aux input has an isolating diode to prevent current flowing from the van battery back to the car. Particularly important when cranking since quite large currents could flow from the van to support the tug battery.

Regardless of what some people might state, a good multistage 240V charger IS NOT a direct replacement for the Setec. A battery charger is not designed provide a 12V power supply for the van if the battery is not present. It does not have a number of load fuses to protect in the event of short circuits in the wiring. It has no LVD or LVR function to protect the battery from being completely drained. Also, it is not clear to me if a charger will maintain the battery correctly IF there is a load on the battery as well. They are designed to be put across an unloaded battery where the charger is in complete control of the battery voltages and currents.

cheers
Mike

Thanks @mikerezny for tidying up the difference between the Series II and III Setec. I must have given you the wrong impression as I was always talking about using a "smart" charger to recharge a discharged battery IN THE VAN - not trying to use the power supply of the charger as a primary source of power for all the accessories (12 volt type anyway). I agree with you TOTALLY on all the points you have raised, especially the last paragraph . I too do not know how much current (amps) would be accepted into the van battery when hooked up to the tug. I guess this current would be controlled (voltage wise) by the Setec controller. Unlikely to be an issue with only limited voltage getting to battery and probably only JUST "float" anyway!! Must try it for myself when next out and about. That was one of the reasons I upgraded the wiring from the tug to the van recently to maximize the current that the van battery would accept whilst driving without going to a BC to DC hook up.

 

[Drover]

I don't even have a tug to van charging system, am I missing out something here...???????

 

[Boots in Action]

Hi @Boots in Action,
actually, I believe it is quite the opposite with both the series II and series III Setec units behaving identically. The only noticeable differences being that the series III has more load fuses AND has a set of terminals providing the function to connect / disconnect the battery by adding an externally mounted switch.

Both can be a 12V power supply powering the vans 12V lights and sockets without requiring a battery to be fitted. If a battery is fitted, it also functions as a battery charger. Other features common to both are Low Voltage disconnect (set too low, as you know), low voltage reconnect, and a feature that limits the charge current if the battery voltage is too low. This prevents large damaging charge currents from flowing into a flat battery.

Both also provide an aux input for charging the battery from an external 12V source. This is commonly connected to the tug alternator to give the van battery some charge whilst driving. I am unsure what the charge current is. Some people are adamant it is only a 0.8A trickle charge. The manual is not clear on this point. I need to get my clamp meter out and make a measurement early in the morning when the tug is connected. The aux input has an isolating diode to prevent current flowing from the van battery back to the car. Particularly important when cranking since quite large currents could flow from the van to support the tug battery.

Regardless of what some people might state, a good multistage 240V charger IS NOT a direct replacement for the Setec. A battery charger is not designed provide a 12V power supply for the van if the battery is not present. It does not have a number of load fuses to protect in the event of short circuits in the wiring. It has no LVD or LVR function to protect the battery from being completely drained. Also, it is not clear to me if a charger will maintain the battery correctly IF there is a load on the battery as well. They are designed to be put across an unloaded battery where the charger is in complete control of the battery voltages and currents.

cheers
Mike

Hi again Mike @mikerezny , just read your last post again and have to disagree with you on the last two sentences regarding chargers maintaining battery properly when connected and a load placed across the terminals. Car alternators are doing this all the time as are our solar chargers. The controllers continue to adjust current and voltage to suit various loads and always are attempting to do what they are supposed to do - charge or maintain charge for maximum energy in/into battery. Regards from a fellow "Tech Head".

 

[Drover]

Damn, I have to agree with the above post.....whats the world coming too........................ @Drover and @Boots in Action nodding in agreement, I'm outa here....

 

[mikerezny]

Hi again Mike @mikerezny , just read your last post again and have to disagree with you on the last two sentences regarding chargers maintaining battery properly when connected and a load placed across the terminals. Car alternators are doing this all the time as are our solar chargers. The controllers continue to adjust current and voltage to suit various loads and always are attempting to do what they are supposed to do - charge or maintain charge for maximum energy in/into battery. Regards from a fellow "Tech Head".

Hi @Boots in Action,
as we both know, a simple car alternator IS NOT a multi-stage battery charger. Further, later model cars have a more sophisticated power management system incorporating shunts to measure various currents and possibly a thermometer to measure ambient temperature.

Sophisticated multi-stage chargers measure current drop-off during bulk charging to determine when to shift to a different stage. This is going to be problematic when a load is switched on and off. Granted, if the charger is only interested in battery voltage, then the charger will vary the current to maintain the correct voltage. BUT that is not the issue, the issue is how to determine from the current profile, when the charger should shift to a dufferent stage. This cannot be done if the current profile includes currents drawn from loads.

Here is my understanding using a simple example. Smart charger is in bulk charge stage and has examined battery voltage and current profile and is about to shift to absorption stage to put in the remaining 15% of capacity to reach full charge. Someone switches on an inverter to boil a jug. Battery voltage suddenly drops substantially. Smart charger is going to be confused. Does it go back into maximum bulk charge?

My point is that in the presence of a varying load it is difficult for any sophisticated multi-stage charger to do its job properly. At best, it will probably only do an ok job. To get the best from these chargers, I would have it regularly connected to a battery not under load as often as is practical

In my simple setup, I run off grid all the time. The battery is charged either by a small solar panel when we are camped or from the tug when we are driving. The only purpose at this point is to recover the power we used during camping. Once home, I set up the solar panel once a week for a day and let the solar regulator do its job properly without any load. It bulk charges for a while and then drops down to float. I leave it on float for several hours to fully charge the battery. My regulator is only a three-stage. But the third, enhanced mode, at 14.8V, is only activated on a cycle of 15 minutes every 24 hours. I have never had it connected long enough for this to happen. This regulator does not have absorption stage.

There are most interesting discussions on this and I do quite enjoy them. They contribute a lot to our collective knowledge. Regardless of the technology. There are four necessary requirements, which we all seem to have:
1: a good multimeter and the ability to use it
2: a good understanding of the basics of our systems
3: the ability to absorb information from a variety of sources and apply it to our specific systems
4: respect for each others opinions and being able to have a discussion without it turning into a s&^%*^*^8t fight.

I got confused in the above using float when I really meant absorption:

• In an automatic 3 stage charger typically you get Bulk, Absorbtion & Float phases.
• Bulk charging puts in the rated maximum current while maintinaing a constant voltage.
• Absorbtion charging then "tops up" the battery to 100% with a constant (elevated) voltage while monitoring the reducing current.
• When the battery is fully charged Float Mode is a reduced voltage which avoids overcharging the battery but just maintains the battery in a non-sulphating state. Some chargers periodically also "trickle" or pulse current into the battery to counter self-discharge.

cheers
Mike

 

[Duncanblake36]

FYI. Here is what the setec charger looks like when charging off 240v.
I ran a lead from the toilet block while camping as my batteries were stuffed.

All fixed now. My setup is all solar and tug charging goes through a Ctek d250s. The setek charges the batteries when on 240v.

 

[Boots in Action]

Hi @Boots in Action,
as we both know, a simple car alternator IS NOT a multi-stage battery charger. Further, later model cars have a more sophisticated power management system incorporating shunts to measure various currents and possibly a thermometer to measure ambient temperature.

Sophisticated multi-stage chargers measure current drop-off during bulk charging to determine when to shift to a different stage. This is going to be problematic when a load is switched on and off. Granted, if the charger is only interested in battery voltage, then the charger will vary the current to maintain the correct voltage. BUT that is not the issue, the issue is how to determine from the current profile, when the charger should shift to a dufferent stage. This cannot be done if the current profile includes currents drawn from loads.

Here is my understanding using a simple example. Smart charger is in bulk charge stage and has examined battery voltage and current profile and is about to shift to absorption stage to put in the remaining 15% of capacity to reach full charge. Someone switches on an inverter to boil a jug. Battery voltage suddenly drops substantially. Smart charger is going to be confused. Does it go back into maximum bulk charge?

My point is that in the presence of a varying load it is difficult for any sophisticated multi-stage charger to do its job properly. At best, it will probably only do an ok job. To get the best from these chargers, I would have it regularly connected to a battery not under load as often as is practical

In my simple setup, I run off grid all the time. The battery is charged either by a small solar panel when we are camped or from the tug when we are driving. The only purpose at this point is to recover the power we used during camping. Once home, I set up the solar panel once a week for a day and let the solar regulator do its job properly without any load. It bulk charges for a while and then drops down to float. I leave it on float for several hours to fully charge the battery. My regulator is only a three-stage. But the third, enhanced mode, at 14.8V, is only activated on a cycle of 15 minutes every 24 hours. I have never had it connected long enough for this to happen. This regulator does not have absorption stage.

There are most interesting discussions on this and I do quite enjoy them. They contribute a lot to our collective knowledge. Regardless of the technology. There are four necessary requirements, which we all seem to have:
1: a good multimeter and the ability to use it
2: a good understanding of the basics of our systems
3: the ability to absorb information from a variety of sources and apply it to our specific systems
4: respect for each others opinions and being able to have a discussion without it turning into a s&^%*^*^8t fight.

I got confused in the above using float when I really meant absorption:

• In an automatic 3 stage charger typically you get Bulk, Absorbtion & Float phases.
• Bulk charging puts in the rated maximum current while maintinaing a constant voltage.
• Absorbtion charging then "tops up" the battery to 100% with a constant (elevated) voltage while monitoring the reducing current.
• When the battery is fully charged Float Mode is a reduced voltage which avoids overcharging the battery but just maintains the battery in a non-sulphating state. Some chargers periodically also "trickle" or pulse current into the battery to counter self-discharge.

cheers
Mike

Yes @mikerezny , you do bring up some points, but I beg to differ on some items. I was really full of answers about a missed stage until I read the last paragraph. Whilst understanding and respecting your opinion on this forum, perhaps you can follow my thinking. Ain't it great for all you "spectator" members" on this forum seeing two "Tech Heads" debating about an electrical subject WITHOUT malice???

PARA 1. I partially agree. Alternators are not multi stage chargers, but they do have the ability to charge to a pre-set voltage before switching to a pre-set float or maintain voltage. However, if a large load is applied to electrical system like headlights, fan etc, battery voltage drops and this drop is sensed by electrics in alternator and changes the charging algorithm to suit. This will cause alternator to change from FLOAT (or maintain) category to CHARGE to make up energy loss (in battery) or carry more load. Besides being able to do this, temperature sensitive resistors and thermistors adjust charging voltage to prevent alternator applying too higher voltage to battery causing possible damage to battery at ambient under bonnet temperature. Heat kills batteries, especially if charged at too high voltage that is not temperature adjusted. Multi stage no, but variable voltage and current control yes. 2 stage - at least bulk and float.

PARAS 2, 3 and 4. Sophisticated multi stage chargers in my understanding have several stages but we shall just talk about a simple 3 stage one to start with. First stage is BULK where the charger puts in the maximum amperage it is capable of/rated at to start with, and voltage as per charger setting. As this continues at max current, battery voltage increases as incoming current puts more energy into battery, until the max pre-set charge voltage is reached and held for a short time (depending on algorithm) . At that point, charging changes to ABSORB where the pre-set max charge voltage is maintained but CURRENT is gradually reduced until it reaches a pre-set low current level of less than 1 amp. The battery at this stage is FULLY CHARGED and battery has ABSORBED all the energy of which it is capable. The charger then changes to FLOAT and tries to maintain/keep the energy stored in battery at that time. It can do this indefinitely , just sending a short pulse of current into battery as needed to replace any self discharge. This FLOAT stage does NOT charge up a battery, all it does is maintain the status quo!! In my MPPT solar controller, these stages apply to the user adjustable preset charge voltage and float voltages. In the FLOAT mode, the controller replaces any current used by accessories for the next two hours cumulatively. It then switches to BULK charge again, then to ABSORB before returning to FLOAT. However, should a large current draw occur and/or voltage drops below a set value in controller, the controller automatically switches to BULK and the process starts again! The technical "smarts" in the MPPT controller seem to be able to overcome any changes in battery voltage or current draw and adjust quickly and automatically too , all the time aiming to carry the load AND get battery to FULL charge and into FLOAT mode as quickly as possible. That should handle most of the points in paras 2, 3 and 4. It certainly would be easier for a controller to have time charging a battery if there are no loads or varying loads, but that is not always possible especially if off grid and having to use the electrical system.

Para 5. This is where we both differ, not only on the need for charging , but on the type and operation of the solar controller. Mike puts his van battery on charge when he gets home using his solar. This is definitely better than the SETEC even if charging is a lot slower. Mike's solar controller probably has a max charge voltage of 14.4 volts and just goes from BULK (flat out!) to float which is all an PWM controller can do. When the PWM controller has the battery at the preset (fixed??) max battery charge voltage, it then pulses a current to maintain a preset (fixed?) float voltage (switching on and off) to overcome self discharge. Mike has a "special" feature that I was unaware of where the controller gives a sharp high voltage boost of 14.8 volts for only 15 minutes every 24 hours. This is above the normal charge voltage recommended for GEL batteries of 14.2 to 14.4 volts, and I believe it is just to make sure that there is no major difference between each of the 6 cells - a type of battery equalization charge.
Whilst Mike is very frugal with his power usage (approx 2 to 4 ah per day) and sees only a need to replace what he uses, I must admit that I may be extravagant with power use, using 32 to 36ah per day and so my priority is to get battery (I only have one 120ah AGM) to a FULL and FLOAT stage as much and as soon as possible. As I have 380 watts of portable solar power and a very efficient MPPT controller, this is quite achievable. The stages of my MPPT controller consist of " MPPT charging", "absorb", "float" and "boost" which is really "bulk" when the battery is in "float" setting and needs charging (timed out after 2 hours of small discharges or when voltage drops below a fixed setting in controller. I do not use my solar to recharge battery on return home as it is easier to use my 'Smart" 7 stage 15A charger which charges AGM to 14.7 volts. Like Mike, I leave van battery on charge until "float" stage has been achieved for several hours or overnight. Battery voltage after disconnection of charger is always 13.0 volts and remains at that level for at least two weeks if no usage.

So there you have it Members. I believe I have met ALL Mike's points 1,2 3 and 4 at the end of his post and no ##@*&^?! fight. Shake hands Mike. A great "TECH HEAD" too. Thank you all for your attention. You can now applaud or Boo as you see fit!!!

 

[Drover]

I was put onto this site last week by someone on here in regard to another subject and came across this section which I thought would be of interest to the you both @Boots in Action and @mikerezny ............... the author I've found to be pretty good as Ive read some of his books and to a non techo find them easy to understand while being a good source of info that has been field tested not just bench.

https://www.gorv.com.au/10-rv-solar-myths/