House Battery Balancing and Farewell for 2018

Dean Gillies

Jan and I have just put Stella to bed for winter, and one of the things I did before leaving the boat was to measure the battery voltages in my house bank. Like other A54’s I have 6 pairs of series connected 12V lead acid batteries.

Before measuring the voltage I forced the shore charger into bulk mode by turning it off and then on again. I did this to check that the batteries are fully charged. With bulk charging voltage of 28.3V I measured a charging current of 1.8A, so I’m fairly confident that the batteries were very close to a full charge.

10 of the 12 batteries showed a voltage between 14.1 and 14.2, with each pair showing a series voltage of 28.3V. All good, these pairs are well-balanced.

However one of the pairs showed individual voltages of 13.6V and 14.7V. Poorly balanced, probably due to the battery at 13.6V being slightly low on capacity, causing the imbalance to gradually increase over time. So it looks like one battery of the pair will always be overcharged and the other undercharged.

Sadly I’ll be away from the boat until April 2019 and the batteries will be maintained until then by the solar charger which is set to provide mostly float charging.

This is the first ‘24V’ boat I’ve owned so I am not so familiar with the little tricks of managing series connected 12V batteries as pairs. When I get back to the boat I will probably disconnect both batteries and fully charge them individually to try and re-balance them.

Are there other things I should be doing for these batteries, or for the bank on an ongoing basis specifically to try and keep the battery pairs well-balanced? Is individual charging the best way to try and recover some balance? Really interested to hear what others do.

Just a final comment as we head homewards ... I’d like to sincerely thank all of the forum members who assisted Jan and I through some tricky problems this year. Our cruising plan was to leave Greece in May and winter in LaRochelle. Technical problems with the boat prevented this from happening (we are still in Greece!), however thanks to the support and advice provided by many of you, the boat is fully operational again, and our destination next year is ... LaRochelle!

I’d like give special thanks to Porter McRoberts who, whilst suffering some significant technical problems of his own, managed to find us a new gearbox ‘off-the-shelf’ when all other avenues were quoting lead times of many months. Thanks Porter!

Fair winds to all.

Dean and Jan Gillies
AMEL 54 #154

Join to automatically receive all group messages.