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Another battery question

August 25, 2018, 08:30:36 pm

To make a long story short, I went to start the coach this morning. Dead batteries.   Pulled them out and brought them home to put on the charger. The starter battery started charging at 12.2v around 10 this morning. It is now 7:30 and the charger has continued to rise to now charging at 14.2 volts. Is this normal? If so, why the gradual rise. Before it charged most batteries starting around 14 volts and then dropping. It also seems like an unusual long time for charging. Any comments, suggestions?

Thanks,
Larry

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Re: Another battery question

Reply #1 – August 25, 2018, 08:43:27 pm

Batteries were flat. Pretty normal for an initial slow chargin rate and then higher as they start to take a charge. Keep an eye on it and if it's not normal after a while, separate the batteries and check voltage at each battery.

Pierce

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Re: Another battery question

Reply #2 – August 25, 2018, 08:55:21 pm

Ours  (Optima & Lifeline) are sitting at 13.5 right now and our True Charge 40 is at idle, showing 'ready', which means it has no reason to put the screws to the two banks. Any time both banks get down into the medium 12s  (once a month, or so) ,it will go to full charging mode (into the 14s) for a half day, then back to 'rest/trickle'. 

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Re: Another battery question

Reply #3 – August 25, 2018, 09:58:40 pm

Larry,

What amp charger and what size battery bank was it charging.  When in doubt, look at the math to see if this is normal or there is a problem.

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Re: Another battery question

Reply #4 – August 25, 2018, 11:14:36 pm

Brett, it is a 25 amp smart charger. The battery is an 8D AGM. I just disconnnected for the night. It has been charging for 12 hrs now, and the leads are warm. Don't want to take a chance on something overloading while sleeping. I checked the battery poles, reading 12.4 volts. I will let them settle for the night and go from there.

Larry

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Re: Another battery question

Reply #5 – August 25, 2018, 11:32:12 pm

12.4 volts is about three quarters charged but the voltage will slowly drop for about six hours after charging. Look for 12.2 or so in the morning.

Pierce

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Re: Another battery question

Reply #6 – August 26, 2018, 07:24:53 am

Pierce, just checked and was very surprised. After being disconnected for 8 hrs the reading was 13.2 volts across the battery terminals. Have put the charger back on, showing 14.4 volts. I'll let it finish up, then work on the house batteries.

Larry

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Re: Another battery question

Reply #7 – August 26, 2018, 08:06:40 am

Larry,

Something is fishy.  9 hours ago (last evening) you disconnected the charger, and the batteries showed 12.4 volts.  This morning, you check them and they show 13.2 volts.  That is pretty amazing...

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Re: Another battery question

Reply #8 – August 26, 2018, 08:40:18 am

Can't explain it, unless my reading was skewed by sleepy eyes I expected the numbers to drop a couple of tenths.

Larry

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Re: Another battery question

Reply #9 – August 26, 2018, 10:20:49 am

Probably was 13.4 last night.

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Re: Another battery question

Reply #10 – August 26, 2018, 02:45:35 pm

Most batteries run way down for long term need replacing.  Cycle like and  voltage drop suffer greatly if damaged

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