Re: [Amel Yacht Owners] First Impressions: Firefly Batteries.

James Alton


   Yes, just about everytime I chance something, there end up being some unexpected problems to deal with, so nothing surprising there…  The charge acceptance sounds very encouraging.  I assume that this could help you reduce the generator hours which effectively makes the Fireflies a bit less expensive overall.   Are the Firefly batteries anymore heat tolerant  than the average lead acid battery?   Best of luck and keep me updated.

SV Sueno,  Maramu #220

On Dec 14, 2017, at 2:56 PM, Alex Ramseyer alexramseyer@... [amelyachtowners] <amelyachtowners@...> wrote:

Bill, which charge voltage controle system / unit do you use in your boat?
Regards, Alex

On Thursday, December 14, 2017, 1:06:12 AM GMT-4, greatketch@... [amelyachtowners] <amelyachtowners@...> wrote:


In a previous post I explained my rational for purchasing Firefly batteries in this battery replacement cycle.  They arrived a few days ago (finally!) and here are my initial impressions.

Physical fit:  They are Group 31 batteries, which is nothing but a specification on the physical size of the battery case, so they should be drop in replacements, right?  Wrong!  They are a little bit higher than our old Lifeline batteries, so I needed to trim a bit off the wood brace on the bottom of the compartment lid.  Also, the terminals are high enough that the battery terminal fuses I had been using no longer fit under the lid, so I swapped four 125 amp terminal fuses for a single 500 amp ANL fuse.  Neither was a big deal, but both were annoying.

It is very not fair to evaluate batteries when first installed.  Batteries take at least 10 charge/discha rge cycles to settle in to their long term groove.  That said...  

One of the reasons I went with these was their higher charge acceptance rate.  Wow.  What a difference.  Our Lifeline AGMs (which are very good at rapid charging) would taper down to 18 amps charge rate by the time they got to 85% charge.  The Fireflys were still accepting over 50 amps at 85% charge...  Once they have settled in and I have a bit more experience with them I'll post more hard data, but so far, they look like they will at least match my expectations.

Again, these are not for everybody. They are expensive, hard to get, and need proper charge voltage control (especially on float) that not every charging system can do. The benefits of the extra cost really depend on how you use your boat.

Bill Kinney

SM160, Harmonie

Fort Lauderdale, FL

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