One that comes to mind is the Onan Equinox which was prone to overcharging battery banks and was discontinued after a very short time. Evidently the cause was never determined or Onan decided not to pursue a resolution. Either way it is no longer being produced.
In my opinion, there is always a possibility of a failure in any charging circuitry that could cause it to happen, or possibly failure of a VLRA valve itself.
The one I saw was caused by an Onan Equinox, and probably happened over a period of time, because when we opened up the 8D battery the cells were only half full and we surmised it would be quite rare for all six valves to fail.
Harold and Linda
2009 CT Coachworks siena 35V
W-22 Workhorse 8.1L
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