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Old 11-23-2020, 04:04 PM   #1
Join Date: Nov 2019
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Battery charging issue (not so much newby as battery idiot)

I'm sure this issue is beaten to death, but I am still stymied. I have a Go Power IC2000 inverter charger. I have 4 Interstate GC2-ECL-UTL golf cart batteries. (225 amp hour 6 volt wired for 12 volt.)

Both were installed last april, and I have been using them since.

Having parked the coach at my office this past weekend for some work I plugged it in and left the charger on all weekend. This morning the charger remote indicated .2 amps charge rate and 12.7 to 13.1 v( both these numbers are continually moving as loads and charge rate change slightly).

Removed the batteries for cleaning and inspection. Found them a bit dirty, a VERY small amount of dampness on the top near the caps from venting a bit of acid (VERY little,, less than a square inch of wet around one or 2 caps). Cleaned case and connections which were in great shape.

Checked the batteries and found voltages were from 6.43 to 6.45 on each battery (only a .02 v difference from highest to lowest). This seemed excellent to me. (although maybe too low? at least balanced)

Check Specific Gravity and found 1.150 on almost all cells (all within 0.02 which is great from a balance standpoint) but this seems very low to me. I have already ordered a new Hydrometer in case that is the issue.

So I cleaned them up, and connected them again. Charger came on at 40 amps and immediately started backing down until, after less than 30 seconds, the charge rate was down to 0.2 amps again, voltage floating between 12.7 and 13.1 as per the display.

I should note I was concerned about some other problem on the coach causing issues so I disconnected the coach from the charger and batteries and ran JUST the charger connected to JUST the batteries. No change.

Seems like the IC2000 is stopping charging before reaching full charge. I have looked through the settings and double checked that it is programed for flooded batteries.

I am pretty savvy when it comes to electricity, but lead acid batteries can be a mystery to me. Seems like they are mostly black magic anyway! ;-)

Anyone seen this?
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Old 11-23-2020, 11:55 PM   #2
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Fully charged, 100%, for a lead acid battery is 12.7 volt (6.35).

Doesn't sound like you have anything to worry about. Float charging these days is often a pulsing voltage so your meter might not read it correctly.

You measured the spec gravity, that's good enough to go on.
'02 Winnebago Journey DL, DSDP, 36' of fun.

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Old 11-24-2020, 12:52 AM   #3
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Turn OFF Batteries/ chargers/ Loads and let sit for 30-minutes, (to allow charger FALSE HIGH surface charge VOLTAGE to dissipate) then read the x4 batteries voltage? If water levels OK on all cells, and voltage proper, you are good... BUT YES, IT ONLY TAKES A VERY, VERY SLIGHT CORROSION TO STOP A BATTERY FROM CHARGING OVER ABOUT 75% (LUCK to ya) https://www.bing.com/images/search?q...mageBasicHover
(TerryH.) 2000-GS Conquest Limited 6266 Class-C 99-E450SD V10
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Old 11-24-2020, 12:56 AM   #4
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NOTE: from chart, if 6.37vdc= 100& CHARGED, then your readings of 6.43-6.45 were the FALSE HIGHSURFACE CHARGE that you need to allow to dissipate.
(TerryH.) 2000-GS Conquest Limited 6266 Class-C 99-E450SD V10
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Old 11-24-2020, 07:32 AM   #5
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The specific gravity does sound a bit low. Hard to say about the voltage, as the surface charge was clouding the actual SOC voltage.

So is the concern that these are being undercharged? Since these are pretty new batteries I would expect they're capable of 100% or more of their rated capacity. You could do a capacity test and see if indeed you have 100% or some other amount. I don't think I've seen a float charger toggle from float to off before (13.1/12.7) but perhaps with that unit it's expected. Something to research anyway. I've communicated with a couple of converter manufacturers about the particular default charge profile setpoints they use and I believe they all err on the conservative side, so that's what you may be seeing here too.

You didn't mention what the temperature of the batteries were, which will affect all battery parameters - voltage, SG and delivered capacity. "Better" hydrometers have a thermometer so you can know what the temperature of the electrolyte is and make appropriate measurement corrections.

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Old 11-24-2020, 07:41 AM   #6
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If you have a battery temp sensor, see if its sending the correct data, or disconnect it and see if the float voltage climbs up a bit.

Without it connected, it should default to 77F battery temps.
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Old 11-24-2020, 09:24 AM   #7
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Agree with the others - everything looks fine except that SG value, which is low. Could be a faulty gauge, or could be your sampling technique is off a bit. Sometimes it's hard to get a good electrolyte sample into the gauge so that it can read accurately. An SG of 1.150 indicates about 25% charge, but that is inconsistent with your other readings.

At full charge, each cell should read about 1.265 (@ 80 F). The variation with temperature isn't big (about 0.004 per 10 degrees), so anything in the vicinity of 1.250-1.270 is OK.

Carefully re-do the SG measurement with the charger off and no load on the batteries and see what you get.
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Old 11-24-2020, 09:48 AM   #8
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Originally Posted by AirBossdavid View Post
Charger came on at 40 amps and immediately started backing down until, after less than 30 seconds, the charge rate was down to 0.2 amps again, voltage floating between 12.7 and 13.1 as per the display.

I would suggest that after only 30 seconds that the charger should be in BULK or at most ABSORPTION mode. That should be closer to 14 VDC.

No first hand knowledge of your inverter/charger, but please confirm that it IS properly programmed.
Brett Wolfe
Ex: 2003 Alpine 38FDDS. Ex: 1997 Safari Sahara. Ex: 1993 Foretravel U240
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Old 11-24-2020, 04:18 PM   #9
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Update. Thanks for the info

Update on this.
As usual thanks very much for the thoughtful answers. This is a great forum.
The IC2000 is preprogrammed with very conservative voltages. I spoke to Interstate and they tell me the correct voltages for this model of battery are;
Bulk charge 14.46V
Absorption 15.2 V for 2 hours
Float 13.4 V
Equalization 15.6 V for 2 hours

I have reprogrammed the charger/inverter to reflect these settings. Fortunately the IC2000 has the ability to custom program all these parameters.

Specific gravity I should be seeing fully charged is 1.285 according to Interstate. I have them out of the RV now and charging in my shop overnight. In the morning I will disconnect. let sit for 45 mins then re-check SG and Voltage. I will use that data as baseline for some testing in the spring once in use with the RV again.
Temp is mid teens Deg C in my garage.

Learned a great deal about Lead acid batteries in the past 2 days. Hopefully I will be a more knowledgeable user next year!
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