Forum Discussion

Naio's avatar
Naio
Explorer II
Jun 25, 2016

Battery troubleshooting help, please?

This regards one of my elderly 90aH gel cells in my shave ice machine. Though old, they have been performing awesomely. Possibly until now?

There are 2 12v batteries running a 24v motor. I'll call the batteries A and B.

I usually charge them with a 24 charger, but those chargers die often and then I sub a 12v until I get another 24v. I have been doing this for 9 years, have great battery life. The charging setup is not the problem.

Battery A had an incident with a 12v charger, though, about a month ago. The charger's clips were large, and the only way to get them on the terminals was to cross the handles. After 9 years doing this with no incident, I guess there must have been a gap in insulation bec a small fire started, melted off one of the handles. Luckily I was right there and smelled it. I have been worried about this battery ever since, but it seems fine. In fact, my problem today is with the other battery, but I am trying to give you all any info that could be relevant.

I also mentioned the other day that my 'smart' charger continues to charge at diminishing amperage after it indicates 'done'. Now that I know this, I leave it on until it gets down to about half an amp. ('Done' is about 2 amps.)

Today's problem: I charged both batteries to half an amp last night before bed. This morning, A reads 12.92v (they are usually 13.13 or so when full) and B reads 12.30. Yipes!

B has the following wires connected to it. All connections are tight, wires have no cracks or wear in housing.

Positive terminal:
- Cable to battery A negative terminal
- Cable to an Anderson connector (unused)

Negative terminal:
- Cable to controller
- Cable to Anderson connector (unused)
- Small wire to socket for 24v charger
- Small wire to solenoid to start motor

...and nothing else.

While charging right now (5.5amps from a 10a charger), the wires to solenoid and unused charger plug both read about 0.5 amps. Is that normal? Or within the margin of error of my cheap ammeter?

Can a solenoid go bad in such a way as to drain the battery?

When charged, I will put a small 12v load on the battery to see what voltage it has reached. Maybe it's sulfated?

Battery A also seems to have lost more overnight than it should, though not as bad as B.

Any ideas are welcome!
  • Naio's avatar
    Naio
    Explorer II
    Jun 26, 2016
    Oh, by the by, I think my batteries are really 90aH for the pair, 45 each.

    Their labels are worn and my memory is terrible. But by measuring their dimensions this is my guess.

    Battery A seems to be weird in the opposite direction. At 12.61v, I hooked it to the charger. 10 minutes later, ammeter says half an amp. Like Goldilocks, I think this one is slurping too SMALL a serving of juice.

    I've been calling around for replacement batteries and prices, but I'd still like to understand what I am seeing here.
  • landyacht318's avatar
    landyacht318
    Explorer
    Jun 26, 2016
    When a battery voltage is raised to 14.X volts, and the amps taper to small numbers quickly while still being held at 14.x volts, either the battery is fully charged or very close to it, or it is very sulfated, or both.

    Now if the charging source drops to a lower voltage, well it requires less amperage to hold the battery at a lower voltage.

    Restarting a smart charger over and over on a nearly fully charged battery is going to be confusing to both human and charger.

    Put a fairly significant load on the battery, wait for voltage to drop to 12.6 or less, then restart charger, then quickly remove load. This will allow the 'Smart' charger to at least seek 14.x volts.

    How long it holds 14.x volts is an issue, as many smart chargers hold it for only 2 hours, and 4 is usually needed on a deeply cycled battery.

    I have a 40 amp charging source, Apply this to my 90 AH battery depleted 18AH to 72AH is exactly 80% charged.

    I have never applied this 40 amp charging source and been able to get amps to taper to less than 0.4a at 14.4 to 14.7v, in less than 3.5 hours from 80% charged.

    But but but... its a 40 amp charging source and only needed to replace 18 AH. LEad acid batteries..... wasting amps and charge time and losing capacity, since day one.
  • time2roll's avatar
    time2roll
    Nomad
    Jun 26, 2016
    For testing... charge the battery to full and then disconnect overnight.
    Compare in the morning again.

    Divide and conquer. Anything connected and you don't know the issue.
  • MEXICOWANDERER's avatar
    MEXICOWANDERER
    Explorer
    Jun 26, 2016
    22F and 22NF sounds suspiciously close to what you have. Google BCI GR 22 BATTERY DIMENSIONS and check against your batteries.
  • Naio's avatar
    Naio
    Explorer II
    Jun 26, 2016
    Well, now, based on this morning's numbers, I am wondering if I do not have a battery problem but instead have a charger problem, or an electrical drain problem.

    Normally I would test one charger against another, but I am down to one right now. Maybe I can fix another.

    Battery A reads 12.6 at rest (that's the one that went down to half an amp draw suspiciously quickly last night), and battery B is 12.83. (I did not check its final amp draw; I just charged it till I went to bed. After the fire I am afraid to plug in overnight.)

    12.6 is about where A was before charging, last night. So... why did it not draw the amps?

    12.83 seems reasonable for B given that it was not done charging.

    Landy's discussion of charger output voltage is relevant. I don't pay a lot of attention to mine, bec it is not adjustable. But his post made me realise i never see numbers starting with 14. I checked just now, and it is putting out 13.40. That's don't seem right. Yeah, looking up the specs, it is supposed to be 14.4.

    I think my next steps are to borrow my neighbor's Fluke to confirm output voltage, and borrow or fix another charger to see what it does. Unless y'all have better ideas?
  • Naio's avatar
    Naio
    Explorer II
    Jun 26, 2016
    @Mex: My batteries are only 7.25" tall, not counting the posts. Looking at this chart, that seems like 97R or 59. Am I supposed to be measuring the posts?

    I got them used, had no idea they were an unusual size. But now I do not know what I have.
  • landyacht318's avatar
    landyacht318
    Explorer
    Jun 26, 2016
    Guessing what the smart charger is trying to do at the moment can drive a person insane.

    generally if the battery is fully charged, not much current will be required to reach absorption voltage, the charger 'should' be able to sense this low current to hold ABsv requirement, hold it only so long and then drop to float voltage.

    I got so sick of My schumacher, and trying to guess what the Eff it was attempting to do, I pestered this forum until mex brough up the possibilities of an adjustable power switching power supply.

    Now I know what voltage the charging source seeks, i determine how long it is to be held, and I have the tools and experience to tell me how long it is to be held, and can basically fairly accurately geustimate a state of charge based on how many amps the battery is accepting at the voltage at the battery terminals.

    When I bust out the Schumacher now, with these measuring tools and experience, well Sometimes i want to swing the Schumacher around by its power cord round and round with increasing speed until it meets an object which can't move.

    Actually it is OK, when I use the AGM setting as it will not goto 16.4 volts, and it will hold mid 14v for longer than it will on the regular to deep cycle settings, and it floats at 13.6v and works OK as a power supply in float as long as the loads are not huge and switched on and off.

    But the bell and whistle 8 stage chargers with included neck massager, who knows what the EFF they are trying to do at any given point on any given battery at any state of charge.
  • Naio's avatar
    Naio
    Explorer II
    Jun 26, 2016
    WTF is right. I checked battery A after half an hour or so on the charger and it was pulling 5amps. At the same or better SOC that it pulled half an amp last night!

    Still only 13.40v charger output tho.
  • landyacht318's avatar
    landyacht318
    Explorer
    Jun 26, 2016
    Something is certainly amiss. Your Ammeter.... Describe. How are its internal batteries?

    My clampmeter is not worth its weight in feces when the aaa batteries inside fall to below 1.28 volts. It will not read resistance at all, voltage is off by 20% or more, and amperage off by 75% or more.

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