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Old 04-10-2010, 16:04   #1
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New AGMs Not Charging with Prosine 2.0

Hi: I recently replaced my 5 battery house bank with AGM's. Now the Prosine 2.0 inverter/charger will not charge them. Symptoms: The charger display panel shows a higher voltage than the house meter shows, from 1-2 volts higher, ie: the charger shows 13.4 volts, but the batteries are actually at 11.9. It seems that even though the charger says it is supplying (say) 50 amps to the batteries, the batteries do not show any increase in voltage on the house meter. After an hour or so, the Prosine charger display shows higher voltages, and subsequently drops the charging amps. The batteries charge fine on the alternators with the engines running, ie: on a recent 2 hour trip they charged up from 11.2 volts to 12.1. Any help? I have called Xantrex but they do not respond. Marty M.

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Old 04-10-2010, 18:31   #2
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12.1 volts is a battery with less than half its charge. 11.2 is almost dead flat. If they are only at 12.1V after two hours, something is seriously wrong with them or the alternator.

I think your charger is working fine, but your house meter is not reading correctly. Have you taken an actual voltage measurement off of the batteries directly?



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Old 04-10-2010, 18:43   #3
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The charger worked OK on the previous batteries and now after the change the charger will not charge the new batteries and yet the alternator does? It is fair to assume that it would be an amazing coincidence if the charger failed during the install, so the probability is a wiring problem/error between charger and batteries.

The most likely would be a weak/poor connection or a connector that was pulling from its crimp, so it would test OK with a ohmeter but fails when under load. However the only piece of info that conflicts this is that you are reading from the display that susbstantial DC curernt is flowing (is that correct).

Interesting! Refering to the manual online (, have you confirmed that the diagnostic mode is giving no errors? Also does the overall setup still looks like Fig 8 and that the DC grounding of fig 15 is applicable and/or correct.

It is probably something simple and easy to resolve.
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Old 04-10-2010, 18:59   #4
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House meter faulty, connections wrong, a diode in the circuit?

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Old 06-10-2010, 07:49   #5
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Thanks everyone... Looking at your replies I have found the problem, yes it was simply a connection issue. I used the nuts that came with the new batteries instead of the old locking nuts, and due to vibration one of the nuts had come loose making a poor and intermittent connection. Replaced them with new locking nuts, everything seems to work fine now. Sometimes the simplest answers are overlooked. Appreciate the help!
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