Hi guys, can someone in the know recommend the right dc-dc charger..800w of solar and 150ah lithium battery..maybe 2 down the track! I haven't connected the solar yet.. not sure if i should connect in series or parallel! Only want to do this once! Thanks guys. Im appreciating all your input so far!
18' Series Dcdc charger.
- Thread starter Linc
- Start date
Do you mean a Solar Controller or Regulator which converts your solar supply to 12v to charge your batteries ????
if all your panels are identical then I would go in series then the wattage is just added together with 12v output but if you go parallel then the wattage is just added together but you will have 24v output, .... distance isn't a problem so you don't need powerline size cabling.
Booties and/or Mike will be sure to give you the techo reasoning..........
With 800w solar and a 150ah lithium I wouldn't even bother about wiring the tug to supply 12v to van for anything other than fridge, just be a waste of money, the solar would do a far better job...........Big Mal has 250w and 210ah and hasn't even got the capability to charge from tug.
if all your panels are identical then I would go in series then the wattage is just added together with 12v output but if you go parallel then the wattage is just added together but you will have 24v output, .... distance isn't a problem so you don't need powerline size cabling.
Booties and/or Mike will be sure to give you the techo reasoning..........
With 800w solar and a 150ah lithium I wouldn't even bother about wiring the tug to supply 12v to van for anything other than fridge, just be a waste of money, the solar would do a far better job...........Big Mal has 250w and 210ah and hasn't even got the capability to charge from tug.
Hi,
the term DC-DC charger usually mean a device hooked up to ensure that an alternator in a car will correctly maintain an auxiliary battery in the back of the car or a van battery. It overcomes the low voltage of a smart alternator and the voltage drop on long runs of cable from the car back to the battery.
The device used to connect between solar panels and batteries is called a solar regulator or controller. There is also the term BC-DC charger which is similar but subtely different. Since I haven't a need for one, I have never bothered to understand the differences.
Also, many devices provide more than one feature so it becomes confusing. Some also provide charging from 240V as well.
These are more commonly grouped together and called Battery Management Systems (BMS).
I have no experience with what I call DC-DC chargers. But since your post seems related to batteries and solar panels, the following is some information on solar regulators or solar controllers.
Regardless of whether you wire the panels in series or parallel the panels will deliver the same wattage.
If you wire the panels in parallel, you will get same voltage as a single panel but double the current.
If you put the panel in series you will get the same current as a single panel but double the voltage. You can use either a PWM or a MPPT solar controller
In parallel, since you hav twice the current, the wiring down to the controller will have to take twice the current and thus will need to be much heavier.
In series, you HAVE to have a MPPT solar controller to convert the higher voltage down to the battery voltage.
With multiple panels you have to consider the issue where one panel is in the sun whilst the other is in the shade.
With parallel panels, Diodes are placed in series with each panel to prevent a panel in the shade from becoming a load on the panel in the sun. These are called Blocking diodes.
With panels in series, a diode is wired across each panel so that it is bypassed when the panel is in the shade. Naturally enough, they are called Bypass diodes.
"In the shade" can also mean, the panel is on the roof and covered with a big splash of animal poo.
MPPT controllers are more efficient than PWM controllers but they are more expensive.
For the size and cost of the panels you are considering, it would be worth investing in an MPPT controller.
You will need to read the specifications for any controller to ensure it will handle the maximum current and maximum voltage that the panels can generate. In good sunlight and cool temperatures, a panel can easily produce 20% more current than the Maximum Power current of the panel. (Ipm).
Further, the solar controller will have to support your lithium batteries.
take care
Mike
the term DC-DC charger usually mean a device hooked up to ensure that an alternator in a car will correctly maintain an auxiliary battery in the back of the car or a van battery. It overcomes the low voltage of a smart alternator and the voltage drop on long runs of cable from the car back to the battery.
The device used to connect between solar panels and batteries is called a solar regulator or controller. There is also the term BC-DC charger which is similar but subtely different. Since I haven't a need for one, I have never bothered to understand the differences.
Also, many devices provide more than one feature so it becomes confusing. Some also provide charging from 240V as well.
These are more commonly grouped together and called Battery Management Systems (BMS).
I have no experience with what I call DC-DC chargers. But since your post seems related to batteries and solar panels, the following is some information on solar regulators or solar controllers.
Regardless of whether you wire the panels in series or parallel the panels will deliver the same wattage.
If you wire the panels in parallel, you will get same voltage as a single panel but double the current.
If you put the panel in series you will get the same current as a single panel but double the voltage. You can use either a PWM or a MPPT solar controller
In parallel, since you hav twice the current, the wiring down to the controller will have to take twice the current and thus will need to be much heavier.
In series, you HAVE to have a MPPT solar controller to convert the higher voltage down to the battery voltage.
With multiple panels you have to consider the issue where one panel is in the sun whilst the other is in the shade.
With parallel panels, Diodes are placed in series with each panel to prevent a panel in the shade from becoming a load on the panel in the sun. These are called Blocking diodes.
With panels in series, a diode is wired across each panel so that it is bypassed when the panel is in the shade. Naturally enough, they are called Bypass diodes.
"In the shade" can also mean, the panel is on the roof and covered with a big splash of animal poo.
MPPT controllers are more efficient than PWM controllers but they are more expensive.
For the size and cost of the panels you are considering, it would be worth investing in an MPPT controller.
You will need to read the specifications for any controller to ensure it will handle the maximum current and maximum voltage that the panels can generate. In good sunlight and cool temperatures, a panel can easily produce 20% more current than the Maximum Power current of the panel. (Ipm).
Further, the solar controller will have to support your lithium batteries.
take care
Mike
Whoops @Drover !! If connected in SERIES, AMPERAGE is as per the lowest output of any panel, AND VOLTAGE is added together. IE. 4 X 200w panels in SERIES will give you (in theory) approx 11A at 72 volts (necessary to use only an MPPT controller to charge a 12 volt bank). Any good MPPT controller that can handle up to 100v would be okay and suggest at least a 40A unit, but better with a 50A unit as output could reach that much. 8A at 65V amounts to 520w and input into a battery which is at 12.4v , will be capable of charging the battery/ies at nearly 42A disregarding losses which would be small!!
If connecting 4 X 200w panels in PARALLEL, VOLTAGE remains the same at 18 volts and AMPS is the total of all 4 panels (44A) under perfect conditions. Also note that a PWM controller limits the panel voltage down to the battery voltage and excess voltage (18v down to only 12.4v) is just wasted!! The MPPT controller converts this excess voltage into extra current and is not wasted.
The advantages of SERIES over PARALLEL is explained in the attached. @Crusty181 has 3 panels in SERIES as do I.
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Thanks guys. I thought i needed a dcdc charger as well for the solar just because i have a lithium battery, but realise now the right solar controller with produce thd correct voltage etc..for my battery. By the way i have 2 x 300w and a 200w semi flexible solar panels. Im thinking now that i have 2 options. Run them in parallel or ditch the 200w and run them in series. The reason i got so much solar is that i plan to park in the shade on hot days! Also they cost and weigh next to nothing..well..compared with my battery anyway! Thanks for your input guys..I'm learning !
I too will be installing my 3 or 4 panels in series. Less cables needed, and can be run in smaller gauge cable aswell.
Thanks Booties, I knew that, must have been a bit dyslexic with the typing is all I can think about, weird, anyway all corrected................
I find this gives a nice clear explanation not hindered by waffle, plus good pictures ....https://itechworld.com.au/blogs/learn/can-i-mix-different-size-solar-panels
I find this gives a nice clear explanation not hindered by waffle, plus good pictures ....https://itechworld.com.au/blogs/learn/can-i-mix-different-size-solar-panels
Careful about "semi flexible or flexible panels" @Linc . There have been many failures with that type with members on this forum. Also, there is a site giving details of the possible problems incurred by campers in the USA too. I will see if I can find the posts from a member who tried twice with flexible panels and had two disasters. They do reduce the weight but are nowhere near as reliable as the fixed glass type with the proper air gap to reduce the heat on panels on roof of van.
The flexi panels are terrible. They'll leave burn in marks on your roof, and are incredibly inefficient. As said above, many a RV user in America has seen some catch on fire over the years.
Hi @Linc and @Brente1982 , I went back over a lot of posts and found that it was @Moto Mech from Tasmania who had a lot of ill experiences with flexible panels which he had on the roof of his van. Problems involved drop off in output, early failure of panels, "burn through" from cells and others. After his second try with newer flexi panels, gave them away completely as still had similar problems in short time. I think he then changed to fixed glass panels. Still looking for pictures he posted for "burn through" on a couple of panels. He would be a good member to give you his experiences and suggestions.
If I preaching to the converted, ignore the following. Solar is a system which only loves full sun, there no real compromise there. Its not really a system suitable to plan to hide it in the shade. Your 600w array has the potential to harvest a substantial amount of energy when catching full sun, but also tank horribly in the shade; shade will hammer your solar output mercilessly. If your plan is to only harvest that of a small single panel located in sunlight, with your large shaded system you'll get your wish. If you're hoping to only loose a percentage of you 600w, and maybe still get a healthy output you won't. Shade is death to consumer solar panels, and shade will strangle the bejesus out of your 600w. On a clear otherwise beautiful sunny day, one single cell of our fixed 150w panel was shaded by leaves (the rest in full sun) and that was enough to all but knock out the panel output completely.
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Hey @Linc, still not able to find previous posts on failures of flexible panels, but did find the following link for your info. It might make you think again about semi or flexible solar panels. Tread your own path!!!
https://www.flexible-solar-panel.com/flexible-solar-panel-review/
Hello @Crusty181 and @Linc , I have often spoken about the problems of heat build up behind roof mounted (and portable panels too!!), and today while surfing the net came across the following attached link. @Linc , this is particularly important for you as the flexible solar panels are really rubbished. @Crusty181 was thinking about something like this in reducing the weight of any panels he was going to place on the roof of his van. Yes @Crusty181 , I went back over our posts a long time ago! However, after looking at all the options, you decided to go with the glass framed solar panels on the roof of your van and with a good air gap to reduce heating of the panels. Thank goodness you did. So it seems that my research was correct and is confirmed by the link.
Hope this is of interest to all with solar panels and the effect heat has on the solar cells, whether flexible or fixed glass.
Just search Moto Mech, you’ll find my old posts
I have questions regarding DC2DC Chargers
I have two 200w solar panels on the roof of our Jayco which are currently wired up using a PWM controller.
I have a Projecta 25A DC2DC charger which has an inbuilt MPPT solar controller which I would like to use instead of the PWM
1) Can I use it by only connecting the solar panels to the solar input of the Projecta and the aux battery cable from the Projecta to the van battery, or do I have to have the alternator-in lead connected somewhere ?
2) If I have to have the alternator lead connected, can I connect it to the exiting Setec unit in the van?
I assume I will not need the ignition wire from the Projecta, connected to anything??
This may have been covered but I can't see it anywhere.
Thanks
I have two 200w solar panels on the roof of our Jayco which are currently wired up using a PWM controller.
I have a Projecta 25A DC2DC charger which has an inbuilt MPPT solar controller which I would like to use instead of the PWM
1) Can I use it by only connecting the solar panels to the solar input of the Projecta and the aux battery cable from the Projecta to the van battery, or do I have to have the alternator-in lead connected somewhere ?
2) If I have to have the alternator lead connected, can I connect it to the exiting Setec unit in the van?
I assume I will not need the ignition wire from the Projecta, connected to anything??
This may have been covered but I can't see it anywhere.
Thanks
I would think the short answer is yes, but youll just need to ensure the voltage and amperage of the Projecta are capable of handling the output of the 2 x 200 watt panels, 50v in the case of series connection and 20amps in the case of parallel connection, although you'll get greater benefit from series with a mppt controller.
Yes.....................
I would fit the Projecta in the van, run the 12v from the tug to the Projecta, disconnect the 12v into the Setek at the Setek if its the early models......... Disconnect the solar input and battery connections into your PWM unit and couple them up to the Projecta, with appropriate fuses in place....
Solar panels would have to be wired up in Parallel though as the Projecta only has a 28v DC input and 385w max.......thats going off the IDC 25 spec sheet...................... should only have to hook up the ignition wire if your tug has a smart alternator and your getting charge from tug while driving.................leave the battery connection to the Setek but disable the 12v input to the Setek, that way you will have 12v supply to lights and stuff and the Projecta will charge your battery and they should all live happy together, even if plugged into 240v the Setek will provide a charge to the battery but the Projecta shouldn't be bothered at all by it until the battery is nearly charged...................
I would fit the Projecta in the van, run the 12v from the tug to the Projecta, disconnect the 12v into the Setek at the Setek if its the early models......... Disconnect the solar input and battery connections into your PWM unit and couple them up to the Projecta, with appropriate fuses in place....
Solar panels would have to be wired up in Parallel though as the Projecta only has a 28v DC input and 385w max.......thats going off the IDC 25 spec sheet...................... should only have to hook up the ignition wire if your tug has a smart alternator and your getting charge from tug while driving.................leave the battery connection to the Setek but disable the 12v input to the Setek, that way you will have 12v supply to lights and stuff and the Projecta will charge your battery and they should all live happy together, even if plugged into 240v the Setek will provide a charge to the battery but the Projecta shouldn't be bothered at all by it until the battery is nearly charged...................
At the moment there is no 12v from the tug. Could I connect the 12v out from the Setec (to the battery) to the alternator wire on the Projecta. ?
That should mean the battery is still getting charged from the Setec when it is plugged into shore power ???
leave the battery connection to the Setek but disable the 12v input to the Setek, ?? I don't follow this bit ??
That should mean the battery is still getting charged from the Setec when it is plugged into shore power ???
leave the battery connection to the Setek but disable the 12v input to the Setek, ?? I don't follow this bit ??