Electrical Why your Tug will not fully charge your van battery

Boots in Action

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Mar 13, 2017
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Ferny Grove, Queensland
There has been several posts on this forum of members complaining that their van battery/ies are not getting enough charge from the vehicle when travelling, even though they may be driving for several hours between spots. The changing technology of vehicle charging alternators and the different battery chemistry and charge requirements has made this a minefield for today's camper traveller. I note that some members have gone to the expense of purchasing BC to DC chargers to overcome some of these problems, but there are probably quite a few who are ignorant of what is happening to their electrical system and why some are not getting the maximum out of their very expensive AGM or Gel batteries.
Attached are two pages of important information on what is happening in the auto industry and why one should at least be aware of a potential problem. Fortunately, my 2011 RC Colorado does not seem to be in the list of vehicles that are affected, but there are plenty of others on this forum that should be interested in these write-ups.
 

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jazzeddie1234

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May 19, 2016
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I have searched and searched for non 3rd party (ie car manufacturer) info on the charging profile of a smart alternator without success. I suggest the full charge of a second or tug battery from any type of alternator is limited... by time. A typical battery at 50% charge will require maybe 5 to 10 hours and I never drive that much!
I would love to hear from someone other than a salesperson who has actually profiled the cranking battery from say 50% to full charge with a smart alternator
 

BaxnRach

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Apr 5, 2013
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Cobram Vic
Anyone with an Everest, PX Ranger or BT50 can have their alternator set to the correct output, with a program called forscan and an OBD adapter.
If anyone wants help with this in northern Vic I have the hardware and software to assist.
Cheers.
Bax.
 

Drover

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Nov 7, 2013
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@jazzeddie1234 , as stated easier and less hassle to just get the ECU set to accommodate it but better still fitting a Ctek D250S dc- DC charger is going to ensure the aux gets charged and you can vary the 12v supply with solar/alternator or other source....have mates that have gone down other paths and just had problems later with battery/alternator failures etc and have ended up with the DC- DC charger fitted in less time and no problems later.
 

jazzeddie1234

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May 19, 2016
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Fair enough, I'm fitting a dc dc unit at the moment but only because I'm changing the second battery from flooded to agm. My agm can only deal with about 10amps (ah / 10) charge so will be looking to solar to do most of the heavy lifting as I don't drive that much.
On the subject of changing the smart alternator - some new utes specify the new cranking batteries that can take a much higher bulk voltage. I wonder if disabling the smarts in the ecu will allow the cranking battery to get it's proper charge?
 

Boots in Action

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Mar 13, 2017
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Ferny Grove, Queensland
Fair enough, I'm fitting a dc dc unit at the moment but only because I'm changing the second battery from flooded to agm. My agm can only deal with about 10amps (ah / 10) charge so will be looking to solar to do most of the heavy lifting as I don't drive that much.
On the subject of changing the smart alternator - some new utes specify the new cranking batteries that can take a much higher bulk voltage. I wonder if disabling the smarts in the ecu will allow the cranking battery to get it's proper charge?

Hello @jazzeddie1234 , the old adage of maximum charging rate for a FLOODED battery was no more than 10% of rated amp hour capacity ie if FLOODED battery has 100ah capacity, then the max recommended charge rate would be 10 amps. This prevented over gassing and over-heating. However, with modern Gel and AGM batteries with higher quality pure lead plates, there is less resistance in battery and so no real heat in high charging. In fact, with a 130ah AGM, it can easily handle a charge rate of 30 amps (or more) without any problem and without heating up. A gel battery is not quite as robust and could handle approx 20 amps. But remember, Gel only likes a charging voltage of 14.2 to 14.4, whilst an AGM needs slightly higher charge voltage of 14.4 to 14.7 volts to achieve FULL energy capacity at 25 C. Always check the side of battery for recommended rates for "cyclic usage rate" not "standby usage rate" for best results.
The higher bulk charge voltage for a cranking battery is to FULLY charge up a "calcium" type battery. This is as high as 15.6 volts, a level not achievable normally with auto alternators. The "smart" auto alternator is only interested in varying voltages from around 14.0 volts to as low as 12.6 volts, all to save fuel by turning the alternator "off charge" when not needed. The best way to keep your "calcium" battery in top condition is to connect same up to a "smart" charger every few months or so to maintain its ability to hold a full capacity charge. This was explained to me by an Royal Automobile Club tech when replacing my old 4WD vehicle battery which was a "calcium" type, with a new one of the same type.
Use of a "smart" charger of 15 amps or more will push plenty of charge into your AGM and at the correct voltage, even if your alternator cannot. However, your BC to DC charger can do all these things if correct settings are made.
 

jazzeddie1234

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May 19, 2016
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Thanks, my original response was that there is very little technical literature available about the smart charging profiles of modern alternators (well the car cpu in reality) and the only snippets I can find mention battery life and performance. As to charging and cycling any battery I like to read the spec sheets to try and understand how to get the best out of them - eats into the holiday/drinking budget otherwise!
 

Drover

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Nov 7, 2013
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The biggest problem is none have the same set up, so what's good for one may not be OK on another, far easier to leave alone as I said above, lots of manufacturers only have online workshop manuals so makes assessing things hard......oh and putting a AGM under the bonnet is not a good idea whatever the spurts say...