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Old 03-11-2016, 06:42   #16
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Re: Baffled - battery charge rate all of a sudden cut in half??

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If the shunt measuring battery current is installed such that it measures battery charge and discharge current (amp counting type) then if a load is present that will display on the amp meter as less charging current. It all depends on where the current measurement is done. The charger may be outputting the same current but the current used by house loads will be subtracted from the displayed charging current.

When things change by exactly half then I look for "simple" explanations like something could be wrong with the shunt or sampling wires.
I am not 100% certain, but I am pretty sure the charge display is net of load. Our load during the day can very from -7 to 3 because we also have about 300w of solar, and our generator has plenty of excess capacity to cover additional loads. So when the display shows a charge of 55 amps, the generator could be putting out anywhere from roughly 52 to 62amps. About 10 amps more if we charge at night.

Regardless of what we have running or what time of day we charge using the generator, it always showed 55amps+- charge on early bulk stage. ....until a few days ago!
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Old 03-11-2016, 08:35   #17
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Re: Baffled - battery charge rate all of a sudden cut in half??

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Even prior to the drop, the charge rate when on generator, ever changed, regardless of what load we had on the batteries.
What Dan said, but your statement here changes that
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Old 03-11-2016, 08:49   #18
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Re: Baffled - battery charge rate all of a sudden cut in half??

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I am not 100% certain, but I am pretty sure the charge display is net of load. Our load during the day can very from -7 to 3 because we also have about 300w of solar, and our generator has plenty of excess capacity to cover additional loads. So when the display shows a charge of 55 amps, the generator could be putting out anywhere from roughly 52 to 62amps. About 10 amps more if we charge at night.

Regardless of what we have running or what time of day we charge using the generator, it always showed 55amps+- charge on early bulk stage. ....until a few days ago!
So if you think 55A is the bulk acceptance rate of your battery bank (55/345 = 0.16C) and now the acceptance rate is 1/2 of that it could mean 1/2 of your battery bank is no longer connected. Do you have individual fuses on each set of parallel batteries? If so, check them to be sure you don't have a blown fuse.

If the batteries are flooded and have inspection caps check the specific gravity of each cell to see if there are any discharged cells. I doubt a shorted cell could explain what you see but an open cell could explain it.

Disconnect all parallel connections and measure the voltage of each set of series batteries to see if the no-load voltage of one set is drastically different than the others.
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Old 03-11-2016, 08:51   #19
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Re: Baffled - battery charge rate all of a sudden cut in half??

If the charger is temperature compensated and the batteries get hot, it will reduce the charge rate.
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Old 03-11-2016, 09:21   #20
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Re: Baffled - battery charge rate all of a sudden cut in half??

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So if you think 55A is the bulk acceptance rate of your battery bank (55/345 = 0.16C) and now the acceptance rate is 1/2 of that it could mean 1/2 of your battery bank is no longer connected. Do you have individual fuses on each set of parallel batteries? If so, check them to be sure you don't have a blown fuse.

If the batteries are flooded and have inspection caps check the specific gravity of each cell to see if there are any discharged cells. I doubt a shorted cell could explain what you see but an open cell could explain it.

Disconnect all parallel connections and measure the voltage of each set of series batteries to see if the no-load voltage of one set is drastically different than the others.
They are AGM batteries. Hopefully I have someone exponentially more electrically literate than I am coming on the weekend to help me do a few checks - like see if there are fuses, check load drop between charger and batteries and we'll check each battery as you suggested....

Thanks all...
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Old 03-11-2016, 15:40   #21
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Re: Baffled - battery charge rate all of a sudden cut in half??

If you have 28-29 volts at each of the batteries they are accepting all the charge current that they can.
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