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Old 01-04-2021, 03:17 PM   #17
catalinajack
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Quote:
Originally Posted by DavidM View Post
Don:

Am I reading you right? Are you saying that a plain vanilla GC2 battery will get roughly the same cycles at a DOD of 80% as a Firefly battery will?

Makes some sense as lead sulfate sloughing is the biggest cause of battery failure and that should happen to Firefly's as well.

How about the other Firefly claims like faster charging?

David
Faster charging requires higher output alternators. Firefly batteries have a charge acceptance rate of about 50% while common lead acid batteries accept about 20%. So, for a 1000ah battery bank a Firefly bank would need 500 amps of alternator charging in order to take advantage of the Firefly's ability to charge faster. Meanwhile those lead acid batteries would accept as much as 200 amps from the alternators. Now, who among us has any more than 200 amps worth of alternators considering the derating that occurs for alternator case temps? So, to me the Firefly battery's ability to accept more amps is pretty much meaningless. Their main advantage is that they can be more deeply discharged but even that is not much of a big deal unless available space for batteries is a limiting factor.

Think about this. A Trojan FLA battery is rated for 800 cycles at 70% discharge. That's 800 nights of really beating up on the batteries. So, ask yourself this. How many overnights do you do each year?

As far as bringing FLA batteries up to 100%, it takes me about five hours of cruising to fully recharge a 932ah bank that has been depleted to 60%. And, as long as FLAs are brought to 100% every few days, they do just fine in terms of battery life.

Firefly battery are rated to last 2 - 3 times that of FLAs at 80% discharge. That would be 2,400 cycles, at most. Eight Group 31s (932ah) would cost $4,344. Eight Trojan T-105s (900ah) would cost about $1,120. Are Firefly batteries more cost effective? Nope.
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