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Jumping energy monitor

Follow-up to R Smedley's answer in WW March 2016. My batteries dropped to 75% after several days moored up. However despite long cruising days the batteries did not charge beyond 86% as shown on my Mastervolt combi charger. Back at my marina the mains hook-up quickly took the batteries up to 100%. Testing comparative charging rates in the marina shows higher charging rate on the engine than on the mains hook up. What was going wrong with the charging while we were cruising?

Asked by: Colin Davis  | 4.03pm, Thursday 10 March

WW says:

It would be worth measuring the charge voltage on your batteries when the engine is running (without the mains connected). It could be that the alternator is not charging to the same voltage as the Combi-charger; this could be remedied with an alternator controller.
Another possibility is that if the batteries are not in the best condition, this could be masked by the battery monitor when connected to the mains; as it will reset to fully charged status when the charger is working and it knows that the battery is "On Float". The true state of the battery is only revealed when away from the mains supply.

Rupert Smedley  | 10.14PM, Thursday 10 March

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