westslope Posted September 8, 2012 Share Posted September 8, 2012 Something electrical is not right. The other day I measured just over 10 volts on the battery. But I was able to charge it back up with a 2 Amp trickle charger. An AVR test suggests that amperage, voltage and resistance are fine. The battery tests fine. Alternator puts out 70 amps. The starter demands 400 AMPs which is a little high. So the mechanic suggests I test for an internal short in the battery by unhooking the negative terminal and leaving it overnight. I did that. The voltage dropped over a day and half to 12.57 volts from 12.6 volts. Is that fast enough to constitute a battery short? Link to comment Share on other sites More sharing options...
unccpathfinder Posted September 8, 2012 Share Posted September 8, 2012 I'm no electrician but id say That's fine...I mean .3v over a night isn't bad? Maybe just try to Google around Link to comment Share on other sites More sharing options...
Tungsten Posted September 9, 2012 Share Posted September 9, 2012 (edited) Just seems like the battery may be on its way out. They will eventually fail if you don't maintenance the electrolyte levels. See sulfation in the FSM or Google it. Edited September 9, 2012 by Tungsten Link to comment Share on other sites More sharing options...
westslope Posted September 12, 2012 Author Share Posted September 12, 2012 I'm no electrician but id say That's fine...I mean .3v over a night isn't bad? Maybe just try to Google around I didn't find anything googling around. But so far I observe 0.02 volt drops over 24 hours when the battery negative terminal is disconnected and 0.03 volt drops over 24 hours when the battery negative terminal is connected. Over 20 days, the measured voltage would drop by 0.4 or 0.6 volts. The battery measures 12.6 to 13+ volts immediately after it is shut off following a trip. I will continue to regularly measure the voltage. For now the 'problem' is intermittent. Perhaps I should just go ahead and replace all the battery cabling. (It looks fine.) Link to comment Share on other sites More sharing options...
Precise1 Posted September 14, 2012 Share Posted September 14, 2012 Honestly, when you are talking voltage drop , 20 millivolts could be explained by temperature alone. I think you are over analizing the drop over 20 days, and even that much drop would still start the vehicle fine. Go have it load tested and see what the amperage is. Have you checked all the connections, including ground at the chassis and motor? How many volts does the battery drop down to when you crank it? I have had batteries slowly die and catastrophocally fail (6 volts after 2 mile drive and 8 hour rest), but your symptoms don't seem to match either... B Link to comment Share on other sites More sharing options...
westslope Posted September 15, 2012 Author Share Posted September 15, 2012 Precise1: You misunderstand. I understand perfectly well that the measured voltage drop is insignificant. Already load-tested. But I'm going to get myself a small amp-meter to measure the amp draw. Link to comment Share on other sites More sharing options...
Tungsten Posted September 15, 2012 Share Posted September 15, 2012 How long does it usually take to charge the battery from 10 volts with a 2 amp trickle charger? Link to comment Share on other sites More sharing options...
Precise1 Posted September 15, 2012 Share Posted September 15, 2012 Precise1: You misunderstand. I understand perfectly well that the measured voltage drop is insignificant. Already load-tested. But I'm going to get myself a small amp-meter to measure the amp draw. Ok, you are right, I misunderstood. B Link to comment Share on other sites More sharing options...
adamzan Posted September 15, 2012 Share Posted September 15, 2012 (edited) How long does it usually take to charge the battery from 10 volts with a 2 amp trickle charger? I leave my automatic charger set on 2 amp, and if I put it on at say noon, it will say full charge the next morning. Takes a while. I was always told that it is better to trickle charge a battery than just boost the car and let the alternator do it. Edited September 15, 2012 by adamzan 1 Link to comment Share on other sites More sharing options...
ahardb0dy Posted September 16, 2012 Share Posted September 16, 2012 You said the other day you measured the battery voltage and it was just over 10 volts. Than you said you monitored the voltage and it dropped from 12.6 to 12.57. So did the truck sit for a while with out being run when you first tested it and got over 10 volts? If you disconnected the negative cable and when you tested it again it was at 12.57 from 12.6 volts is that what it normally is after sitting for a while? I doubt you have anything that is really drawing power when the truck is not running, other than the clock and possibly the memory for presets on the radio, you said when the negative was connected and the truck sat it still only dropped 0.01 volts compared to when the negative was disconnected. If the truck starts fine every time I would not worry about it, I mean your talking very low voltage drop. I think most battery voltage drops to around 12.5 when the engine is shut off and I think the drop from the running voltage (say 14) to the not running voltage at the battery will drop faster as soon as the engine is turned off but I do not think it will continue to drop at the same rate over time. I don't think an amp gauge is going to reveal much unless it is digital and if your still talking about a tenth or hundredth of a volt I still think it is so small it would not be worth worrying about. Link to comment Share on other sites More sharing options...
Tungsten Posted September 16, 2012 Share Posted September 16, 2012 I leave my automatic charger set on 2 amp, and if I put it on at say noon, it will say full charge the next morning. Takes a while. I was always told that it is better to trickle charge a battery than just boost the car and let the alternator do it. Yeah it should take a while. This was a question for the OP. That's pretty much how you are supposed to charge the battery from dead. If the trickle charger charges it too quickly then the battery has gone bad. Link to comment Share on other sites More sharing options...
westslope Posted September 16, 2012 Author Share Posted September 16, 2012 [Re: how long to charge from 10 volts reading? (i.e., flat).....]I leave my automatic charger set on 2 amp, and if I put it on at say noon, it will say full charge the next morning. Takes a while. I was always told that it is better to trickle charge a battery than just boost the car and let the alternator do it. That sounds about right. An empty deep cycle group 24 or group 27 battery could take in excess of 30 hours to fully charge. A trickle charge is always preferable. Link to comment Share on other sites More sharing options...
westslope Posted September 16, 2012 Author Share Posted September 16, 2012 I found this post in Similar Topics that I missed earlier: Which Optima Battery? I read some good experiences with Optima batteries. MYPATH1's post here caught my attention. I paste a couple of entries: Yellow Top is a Deep cycle battery, Not moderate, full deep cycle. Deep cycles feature lower CCA ratings than same other batteries of the BCI group. But they do like repeated full drains, and typically are not as well adapted to constant charging like car applications (shortens their life not being able to drain) In the last 2 years optima has improved their deep cycles for use with constant charging applications so they last about as long as a starting battery. Also Pathy's start fine with low CCA's so if you wanna run a deep cycle for your stereo, winch or simply because you forget to turn your lights off allot then go ahead and do so. Link to comment Share on other sites More sharing options...
westslope Posted September 21, 2012 Author Share Posted September 21, 2012 Update: I bought a cheap multimeter that allows me to measure current flow. I unhooked the positive terminal clamp and connected the positive terminal clamp to the positive battery terminal with the multimeter. The draw is 0.2 mA 0.2 milliamps isn't much. Ghost amp draws are not the problem. Good to know. Link to comment Share on other sites More sharing options...
Tungsten Posted September 22, 2012 Share Posted September 22, 2012 The 0.2 mA could be what the multimeter is drawing. Looks fine to me. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now