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Battery Charge Rate Drops Off

Yahoo Message Number: 88085
Normally when our house batteries are discharged by (for instance) 150 Amp-Hours and we run the generator or plug into shore power, the charge rate will stay high (50 to 80 amps) until the batteries approach full charge. All measurement references are based on readings from our Xantrex Link 10 "E-Meter". This meter provides battery voltage, Amps in or out of the battery bank, and cumulative battery discharge in Amp-Hours. Recently however, the charge rate will start at the high rate and within a few minutes drop to a charging rate around 20amps and even decline to less than 10 amps. All the while the batteries are still discharged by nearly 150 AH.
Our system has a bank of 8 Trojan T-105 wet-cell batteries that are only 4 months old and in good condition and the total battery capacity is 900 AH so 150AH is only about 16 percent. Our Inverter/Charger is a Xantrex 2500.
Based on the above one might point fingers at the charger. However the same thing has been happening when we are on solar. We have 500 watts of solar and a Xantrex C-40 controller that will begin charging at 20-30 Amps in full sun and then in a little while will drop to only 7 or 8 amps. All the while the battery bank is still down 150 AH, it is mid-day full sun, and there are no clouds or shading of the panels.
So this backing off of charging with the batteries discharged 150AH happens with both the non-solar and solar charging circuits. Any thoughts as to why the charge rate is cutting back long before the batteries are close to being fully charged?

Thanks, Steve

2002 Intrigue #11382

Re: Battery Charge Rate Drops Off

Reply #1 –
Yahoo Message Number: 88111
It sounds like maybe your Link 10 is out of sync with the battery state of charge. I know I had to reset my amp hour register every now couple of months especially when using solar. I would look at the battery voltage after the charge rate drops off and see if it is near full charge. You may also use a hydrometer to determine the state of charge.
This is the most likely fix but you may have other issues such as a battery temp sensor shutting down the charger.

Norm