Uneven battery charge on 24V
- Thread starter AlexD
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Sounds like the passenger side battery is toast... that or some dodgy wiring in your hj, since the batteries should be wired parallel which means they should balance themselves...
Are you drawing 12V loads from the passenger side battery? If so, you'll potentially kill both.
Either the battery are toast or you have something hooked up between the two batteries drawing 12V.
You may need a active batteri equaliser like this http://www.antares.co.uk/microactive-battery-equaliser.html
You may need a active batteri equaliser like this http://www.antares.co.uk/microactive-battery-equaliser.html
- Thread starter
- #5
All food for thought. I'm pretty sure the battery is ok, certainly to the point of holding the charge that it is given, I've also tried swapping batteries recently but with difference. Dodgy wiring is my first thought but I don't really enjoy trying to chase down that kind of problem, so I thought I'd try and eliminate other possibilities first.
There's 24V to 12V converter in the car (PO mod) so I didn't think there would be a 12V load but I haven't looked into it. That's something to check. I like the battery equaliser, nifty.
There's 24V to 12V converter in the car (PO mod) so I didn't think there would be a 12V load but I haven't looked into it. That's something to check. I like the battery equaliser, nifty.
The batteries aren't wired in parallel like blis mentions. They're in series.
Are the batteries (brand and capacity) identical?
I don't think it's dodgy wiring. The thing is, you're measuring close to the normal "total" voltage across both batteries. 14.x + 12.x comes very close to 27V, which is normal alternator output voltage range (have you increased the alternator output voltage at all?). Maybe check the cable that connects the driver's side negative terminal to the passenger side positive. Use jumper cables between these terminals and see by how much the lower voltage rises by. If low voltage rises to 14.x, then cable connecting the batteries is suspect, but I'd also suspect then that PO has played around with increasing alternator output voltage.
Are the batteries (brand and capacity) identical?
I don't think it's dodgy wiring. The thing is, you're measuring close to the normal "total" voltage across both batteries. 14.x + 12.x comes very close to 27V, which is normal alternator output voltage range (have you increased the alternator output voltage at all?). Maybe check the cable that connects the driver's side negative terminal to the passenger side positive. Use jumper cables between these terminals and see by how much the lower voltage rises by. If low voltage rises to 14.x, then cable connecting the batteries is suspect, but I'd also suspect then that PO has played around with increasing alternator output voltage.
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Sorry about that, shouldnt write anything in the morning... I meant in SERIES as you corrected me...
- Thread starter
- #8
daboheme, I like your way of troubleshooting the connecting wire, it's certainly the first wire I wanted to check but wasn't sure how. The batteries aren't exactly the same but they are the same CCA and Ah ratings though I don't suppose that necessarily means they have the same internal resistance. How would an increased alternator output affect the system asymetrially?
If you've got an excessive voltage drop on a connecting cable such as the one connecting the negative terminal of drivers side to positive of passenger side. Or bad ground from negative of passenger side to body. Not too many ohms of resistance is required to cause a volt drop if 30 amps is travelling through it. You should be able to isolate this using the jumper cables.
If alternator voltage wasn't increased and cable is dodgy, you shouldn't measured an increased voltage on one side to more than 14V. All you'd find is an excessive volt drop somewhere.
If alternator voltage wasn't increased and cable is dodgy, you shouldn't measured an increased voltage on one side to more than 14V. All you'd find is an excessive volt drop somewhere.
Glad to help if it worked, but I've been thinking about this a bit more, and I think that the volt drop of a dodgy cable should be split between the batteries if they are identical. You shouldn't see the imbalance. There might still be a battery issue.
The drivers side is the one that will fail! It is being overcharge due to a unequal draw on the passenger side battery.
Alternator output 27 to 28V, you have one battery down on voltage, for exemple 11.5v and 13.5v. When the alternator charge it outputs 28V, so you are charging one battery to 12.5v and the other to 14.5V, 14.5V is too high, the battery will fail. You check the voltage while the truck was idling. and got about 26v output. But when you drive and the rpm exceed 1200-1500rpm the voltage output goes to 27.5-28. and the voltage to that drivers side abttery up to 14.5 -15V
find you unequal draw, fix it (like in, do not use 12V from one battery) then replace both battery and be happy forever!
If you cannot afford new battery, fix your 12V draw and swap the battery sides and hope for the best.
Alternator output 27 to 28V, you have one battery down on voltage, for exemple 11.5v and 13.5v. When the alternator charge it outputs 28V, so you are charging one battery to 12.5v and the other to 14.5V, 14.5V is too high, the battery will fail. You check the voltage while the truck was idling. and got about 26v output. But when you drive and the rpm exceed 1200-1500rpm the voltage output goes to 27.5-28. and the voltage to that drivers side abttery up to 14.5 -15V
find you unequal draw, fix it (like in, do not use 12V from one battery) then replace both battery and be happy forever!
If you cannot afford new battery, fix your 12V draw and swap the battery sides and hope for the best.
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I had this problem in the beginning as the PO had wired the radio to one battery only. What I did was remove the batteries and charged them each for about a week on a desulpator type charger like the Battery Tender. You can actually charge both batteries at the same time, by joining them in parallel. In fact, its probably best to charge them both at the same time, as the charger would equalize them.
After they were both showing an equal charge, then installed them into the battery bays and they work really good now.
To help the weak alternator charge the batteries better, I made a new ground cable as well as a new interconnect cable (is there a better word?) out of really large gauge welding cable. I crimped the ends myself by cutting a nut into half and then using a vise to crimp the copper connector on. I then used the paint-on insulation to fill up the voids, and topped of with the non-adhesive electrical tape.
My batteries are in really good shape and are always the same voltage now!
After they were both showing an equal charge, then installed them into the battery bays and they work really good now.
To help the weak alternator charge the batteries better, I made a new ground cable as well as a new interconnect cable (is there a better word?) out of really large gauge welding cable. I crimped the ends myself by cutting a nut into half and then using a vise to crimp the copper connector on. I then used the paint-on insulation to fill up the voids, and topped of with the non-adhesive electrical tape.
My batteries are in really good shape and are always the same voltage now!
I used this to solve the same problem.
http://www.altestore.com/store/DC-t...-1224-20A-1224V-DC-DC-UpDown-Converter/p1284/
Check around as there are better prices. But I haven't had battery issues for years since I installed this system. There is also a great writeup from "Stone" I believe on here regarding the system and proper wiring.
http://www.altestore.com/store/DC-t...-1224-20A-1224V-DC-DC-UpDown-Converter/p1284/
Check around as there are better prices. But I haven't had battery issues for years since I installed this system. There is also a great writeup from "Stone" I believe on here regarding the system and proper wiring.
bj40green
Tssss, tssss
Use a smart charger like this one: http://www.amazon.com/exec/obidos/asin/b000ejti4g/buyonsalenow-20
This charger "thinks" and regulates the current/voltage for optimum reconditioning. I used this charger several times and my battery is in top notch condition.
Rudi
This charger "thinks" and regulates the current/voltage for optimum reconditioning. I used this charger several times and my battery is in top notch condition.
Rudi
