Firefly AGM start battery and Battleborn house bank

[Adelie]

Originally Posted by rgleason

So you are just accepting the gradual reduction in capacity.

Originally Posted by sailorboy1

No and I will post it later. But if you think the batteries need this .4C all the time you dont understand. But a start battery hardy needs charging at all.

SailorBoy's got it right. Starting energy for a large engine is on the order or 1Ahr or less even cranking for 5-10sec.

If there is some kind of trickle or float charger, the battery will be maintained at 100% almost continuously unless you have some sort of starting problem or shutdown and restart your engine 50 times per day. As such there will be almost no cycling. LA battery might do well with an equalization yearly but even that may not be needed.

[Adelie]

Option number 3 or whatever for the OP is to charge the starting battery using a 10-30W panel and a PWM controller. 30W panel on a PWM controller should put out about 7.5Ahr/d. That's 7-15 starts per day depending on engine size.

Cheap. Completely separates the starting battery from the rest of the system.

[rgleason]

Exactly, this is quite practical for a FLA or AGM start battery.

Originally Posted by Adelie

Option number 3 or whatever for the OP is to charge the starting battery using a 10-30W panel and a PWM controller. 30W panel on a PWM controller should put out about 7.5Ahr/d. That's 7-15 starts per day depending on engine size.

Cheap. Completely separates the starting battery from the rest of the system.