Re: [Amel Yacht Owners] Re: AGM battery equalisation

Jay Perry

Batteries from time to time should be equalized and most battery chargers can do this.
Another way to stop the need for this so often is to have every battery in a bank connected with the same thickness and length of cable to the charger cable, regardless if the cable need to be that long and connect all to a centralized buzz bar. This is to have the same resistance across all the batteries in the same bank.
However as mentioned lead acid, gel, AGM all use acid and have a maximum number of charge cycles. Yet after just 20 to 30 % of the maximum cycles (usually around 1 year) they will be less than 50% efficient at holding charge.
For batteries to last 5 to 10 years you would need to look at alternatives like lithium.

Jay Perry

WHUATI - crew

On 10 Feb 2019, at 19:38, Bill Rouse brouse@... [amelyachtowners] <amelyachtowners@...> wrote:



I believe that the 12.3 battery has failed. The 12.5 batteries are nearing the same point, with probably less than 1 year. 

I would disconnect the pair that has the 12.3 and move things so that one of the 12.5 batteries is also disconnected. In other words, 1 pair of the worst batteries are disconnected from the bank. Then I would start looking for the best place to buy and replace all of the batteries. I am going to guess that you should do this within about 6-8 months.

I am sure that you will find some owner that gets longer than 4 years life, but I will assure you he is not discharging his batteries at anchor as you are. I met a guy in Turkey who according to him got 12 years life from his batteries. Within 5 minutes of leaving the marina, they failed.😀


Bill Rouse
Amel School  
720 Winnie St
Galveston Island, TX 77550

+1(832) 380-4970

On Sun, Feb 10, 2019 at 10:32 AM sharongbrown@... [amelyachtowners] <amelyachtowners@...> wrote:

First, many thanks for all your advice, it is much appreciated. I have 6 pairs for my 24v system. The pairs and voltages, after being fully charged (i.e. drawing 1A) and left disconnected for 12 hours, are as follows:

12.7 12.6 12.5 12.5 12.6 12.6 12.5 12.6 12.5 12.6 12.7 12.3

(I did that in two separate lots of 6 each so as to maintain power to the boat)

I'm afraid I don't quite understand what you mean balancing out the voltages. What do you think I should do with the one at 12.3v? Get rid of it, or pair it up with something else?

Understood about 3-4 year expected life although I was hoping it may be a bit longer!


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