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Old 03-04-2015, 08:52 AM   #1
len poleshaj's Avatar
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Battery issues continue

I just popped good sized $'s for new Interstate 31's again. Put them in the coach,charged them 24 hours using a Progressive Dynamics 9260. This morning the voltage was showing 12.7 volts. I ran the furnace for one cycle of about 12 minutes. After a 30 minute rest period the batteries are showing 12.3 volts.Shouldn't they still be in the full range? Normal? I hope not. What is going on?

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Old 03-04-2015, 09:05 AM   #2
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Hi len poleshaj,
This could be the result of several things. Take all readings directly from the batteries, not the monitor.
1. Charge the batteries for a couple of days to ensure a full charge. New batteries may need more than the charge period you allowed.
2. Check the new batteries with a load tester. It would not be the first time a "new" battery was not perfect when sold.
3. There may be a draw on the batteries. check the positive cable from the batteries to the coach for parasite draws.

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Old 03-04-2015, 09:11 AM   #3
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Another point: The capacity of a new battery will increase after several recharges.

See understanding batteries post
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Old 03-04-2015, 09:15 AM   #4
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Prime suspect might be the charger. If the 12.7 volts was with the charger connected and running, then the charger is faulty.

Best check voltages with a digital multimeter so you know for sure what the voltages are.

Normal furnace running for 10 minutes should take about 1 Ah out of the batteries so any voltage drop should be negligible.

A new battery should be delivered close to fully charged so any competent charger, especially a three-stage charger, should be easily able to get the batteries close to fully charged in 24 hours
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Old 03-04-2015, 09:18 AM   #5
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It's a little difficult to troubleshoot chemistry remotely... But here we go. Where did you measure 12.7 volts? Was the converter disconnected at that time? If it was still connected, you should have read approx 13.8v at the battery. Did you disconnect the negative terminal when you measured 12.3v?How much current does your furnace draw? Do you have an inverter connected? Did you check the water level and specific gravity of each cell for the new battery? They will often perform better after a few cycles

You mentioned "again" in the first sentence, are you replacing batteries often?
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Old 03-04-2015, 09:58 AM   #6
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You say "New 31s". If you have two in parallel, they have to be connected properly to effectively share load.

If you did not trip the PD to bulk charge for a second time, pretty good bet that the batteries were not at full density. This also counts on their being connected correctly.

I did a lot of electrical work on boats before the depression and fought this battle all the time.

A lifelong waterman and his bride going dry places for as long as the fuel money lasts.
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Old 03-04-2015, 10:28 AM   #7
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Thanks to all that have thus far responded. I had the same issues a few days ago with brand new Interstates, fought the problem for four days. Returned the batteries for an exchange. Requested the dealer recharge the set overnight prior to my picking them up. Installed them, charged them some more overnight and them some. Digital measurements were taken with shore power on and off. Charger IS working. Also took all loads off using the salesman switch. Every thing checks right except after cycling the batteries with the furnace blower. A clamp amp gauge even confirms 7-8 amp draw when furnace ran.
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Old 03-04-2015, 10:36 AM   #8
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FWIW A steadily running thread is that the salesman switch seldom turns everything off.

The only safe assumption is that you cannot assume anything. I'd run the batts down and recharge them once or twice and see what happened. If you do it then you know it is done. Check with a DVM at the battery posts.

When it under heavy charge I would be inclined to measure between the post and clamp. Drop is worst at the highest current. That connection should not have much drop.
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Old 03-04-2015, 10:39 AM   #9
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Yes I did rest the pendant controller on the PD for the boost.
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Old 03-04-2015, 01:28 PM   #10
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Didn't see it posted so.... are these deep cycle batteries? Not marine/RV batteries, they are different.
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Old 03-04-2015, 02:30 PM   #11
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All terminals are clean and tight throughout the power system? Chances that 2 sets of batteries are weak is pretty slim. Did you measure the current load with a clamp on ammeter? Are these deep cycle batteries or marine batteries? If they have a CCA rating and caps then they are hybrids.
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Old 03-04-2015, 04:33 PM   #12
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Just had the same problem with a new set of Trojans they would charge up but not hold one all digital checkers showed good but the trusty hydrometer showed 2 weak separated the battery's and charged each individually to full charge and that did the trick all is well now
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Old 03-04-2015, 07:22 PM   #13
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Yes, This was the second set of Interstates, I charged the first set for about 3 days using the three stage charger. The boost would show the DVM 14.4 volts at the opposing posts of the set. Eventually it would drop to 13.6 volts. They would deliver about 3 hours of furnace use at cycles of about 9 minutes on and 20-25 minutes off. At the end of the 3 hours the voltage was 12.1-12.2. I recharged them 12 or so hours,let them rest for 2 hours and the took a Specific Gravity test.. Two cells were very weak and the rest were so so on both batteries. That is when I gave up and forced the distributor replace both. He too got weak SG readings but still was not happy to replace them. I am in the process giving them 14.4 volt charges till the batteries get slightly warm and drop the charge to 13.6. I will drop the shore power tonight and try to survive tonights 40* weather. Unfortunately they are RV/Marine. Claim to deliver 130AH. No Trojan dealers nearby and even Napa could not come up with Group 31 deep cycles. I am being forced to work with what I can get. Leaving Calif toward the So.Rim in Arizona in two days. I need some night time battery strength!!!!
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Old 03-05-2015, 05:16 AM   #14
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After running the furnace for a full cycle (Without shore power) should the batteries still be FULL... (or for that matter the propane tank).

NO, they should not, you burned electricity running the blower, and many other things as well (Stuff that is always on like the control board for stuff like the fridge) and of course you burned propane.

So both the batteries and the propane tank will no longer be full.

Also, several other good comments above about new batteries and where you take measurements and such.

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