12 volt system troubles

Posted on 11/10/2020 10:31 by AmberPaul

Ongoing Electronic controller box saga:

Dealer replaced the leisure battery and I dealt with a number of loose connections around the Controller box.

I am only getting less than 40AHrs from the "new" battery down to the control cut-off which is around 11.3v.

This tells me two things:

The battery is not in new condition and, having read a lot about Lead Acid batteries, the Bentley controller is allowing excessive discharge which will shorten the battery life even further.

Another issue is the ludicrously over-optimistic prediction of remaining battery capacity given by the Bentley button.  This shows remaining charge good for over 48 hours at 5.2Amps drain which implies the battery is a 232AHr device capable of 100% discharge, i.e complete nonsense.

I have emailed the control unit manufacturer for advice but have not had a reply beyond acknowledgment of receipt.

Any comments?

Posted on 12/10/2020 21:05 by hitchglitch

It would be helpful to know the make, model and age of your motorhome. The Ahr rating of a battery is at very specific discharge rates and in practice you will get quite a bit less, however, discharging to 11.3 volts is very bad practice. A fully charged battery should be around 12.7 volts and shouldn’t be allowed to go much less than 12.3 volts. 
Do you have a solar panel, is the motorhome permanently on charge? The charging regime very much depends on the type of charger fitted and maybe it is not properly charging or maintaining the battery. The simplest way to check is to monitor the battery voltage when charging and discharging.