Re: [Amel Yacht Owners] Charging AGM batteries

Bill Kinney <greatketch@...>

Because of their internal construction a full on classic thermal runaway is MUCH less likely to occur with good agm batteries. Lifeline claims they have never heard of it happening to their batteries. You can however, melt them down if the voltage is too high for too long causing the electrolyte to boil off. 

Monitoring is simple. Fully charge, disconnect the charge and load, and then check voltage after a bit of time to rest. A shorted cell will quickly pull the voltage for that one battery down to 10.5. Otherwise, capacity testing and such can be the same as a flooded battery. 

You'll also see a bad cell in your charging amps at full charge. They'll never drop down to the 0.3 amps or so that they should at the correct float voltage when the batteries are full. 

Bill Kinney

On Dec 8, 2016, at 11:27, Kent Robertson karkauai@... [amelyachtowners] <amelyachtowners@...> wrote:


Wow! You were lucky you didn't have a fire. I don't know the charge settings for AGM batteries, but whenever you hook your new batteries up you need to monitor the 30 amp charger closely. It's entirely possible that you have a fault in your charger.  This is just another example of why it is so important to monitor your batteries closely. With AGM's I don't know how you can monitor the batteries like you would specific gravity in a flooded lead acid battery. I would like to hear about this.

Since my last battery mishap, I have quit leaving my charger on constantly while I am off the boat. I have instead hired someone to come aboard once a week to flush the Watermaker membranes and top the batteries up with a 2 hour charge.


On Dec 8, 2016, at 9:47 AM, sharongbrown@... [amelyachtowners] <amelyachtowners@...> wrote:


I just came back to my boat after three months and found that my entire bank of 12 AGM batteries melted. I had left the 30A charger running. I am in the processing of replacing them with new AGM batteries (can't get anything else where I am in Grenada). I have an Amel 54 #98 with Dolphin 100A and 30A chargers. Would someone be able to advise which is the correct charge setting I should  use on these chargers for charging AGM batteries?



S/Y Ya Fohi Amel 54 

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