Originally Posted by Utahsailor
This forum has been my best source for installing solar panels and I expect it will be for a question on switching from AGM to FLA in my house bank. This question has undoubtedly been answered before but I couldn’t find it. Improper storage, mis-measurement and an amperage leak have croaked my 840 AHr house bank. I plan to increase to 6 4D batteries for about 1,200 AHr
Charging sources are: 310 A from main engine through 2 Balmar alternators, 90 A from Zantrex invertor/charger and output from 840 WHr solar panels through dual PPM controllers (max about 35 A). Since the alternators very quickly fall below 120 A, the maximum charge rate will be less than .1C.
I would like to replace with FLA but have these questions:
1.Will outgassing be a problem with this low charge rate? (If so, what’s best way to vent the gasses? The engine has a powerful bilge blower that is always on while engine is running.)
2.Why do so many use 6V instead of 12V? Replacing with 4D FLAs gives 200 AHr at $235 each and allows reuse of existing cables.
Thanks for the advice
We run 6 x 6V Trojan T105s. They are now 8 yrs old and still in good condition. They consume more water
as they get older but this is normal. They are purpose built for deep cycle use and can be hand carried. Outgassing is not an issue. We use a syringe and tube to fill using the Trojan remote
fill caps with the level indicator.
We have 130A Balmar alternators and xantrex 3 stage regulators for both engine and generator
We have 280W solar and wind
. We use a heart interface as our primary battery management system.
Starting and winching batteries are a completely seperate charging and regulation circuit.
System sizing to these rules maximises battery longevity:
1) ensure your draw aligns with no more than 30% of your Ahr capacity for FLA.
2) size your max solar to get you to full charge each day.
3) FLA like to be fully charged all the time. 50 - 80% is easy. The last 20% is more challenging but where you maximise your battery life.
4) keep the water
5) size your alternators to give you a net charge increase for typical necessary engine use. Not necessarily the largest Amps.
6) use 3 stage chargers with closed loop temp control. Batteries are sensitive to temp which correlates with life.
7) size cables appropriately. Never scrimp. Ever.
8) keep everything clean. Spotless.
and log your draw, water consumption
and the contributions of all systems that draw and charge. This will highlight what works well and give early warning of issues.
10) before you think coffee in the morning check your batteries. We start the day with 'how is system X', then we ask 'coffee...'.
Good battery management is both art and science.
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