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Old 04-05-2018, 12:31   #1
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Redundant house battery banks - tips?

My old 1967 boat came with a 440 AH flooded lead acid battery, which I will change into 4x Firefly 12v batteries, with a Sterling charger and regulator. I also will have a separate starter battery, with an echo charger. I'd like to separate the batteries into 2 as-redundant-as possible banks, one port-side and one starboard. I can live with 200 AH daily without a problem and dont really need all 400 AH.

Considering how fast the tech develops, I'm curious if you guys have any tips or suggestions esp for new products on the market to set up a redundant house battery bank.
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Old 04-05-2018, 12:54   #2
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Re: Redundant house battery banks - tips?

A split bank is a particularly poor way to setup a house bank. The less depth of discharge you do on a battery the longer its life. So with two 200ah banks if you take out 125ah you are discharging down to 32% charged. If you combine the batteries into a single 400ah bank, then use 125ah you will be at near 70% charge and have much longer battery life.
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Old 04-05-2018, 12:57   #3
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Re: Redundant house battery banks - tips?

If you only need 200AH then why not just fit this amount rather than 400AH which isn't going to be used. Batteries are not cheap, there will be other demands on the budget for an older boat.

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Old 04-05-2018, 14:11   #4
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Re: Redundant house battery banks - tips?

Yes 50/50 split House bank has been proven as wasteful, too much dead lead, see Peukert effect.

But I like the idea of eliminating all batts other than the main House bank, then creating a Reserve composed of the same batts, sized large enough to carry essential loads, safety, navigation etc.

Cranking can be usually done from House, but switched over to Reserve often enough to confirm all is well there.

Belt & suspenders cranking backup is a portable lithium powerpack.

To really take advantage of Peukert, House and Reserve can be combined by an adjustable high-capacity LVD, like a VSR but with a low enough setpoint that Reserve only gets isolated in exceptional circumstances, SoC gets lower than usual, say at 60-70%.

No actual dead lead, maximum bank life so lowest cost $ / AH / year, plus decent redundancy.

Yes unconventional but I would argue no less KISS than most large & robust House setups.
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Old 05-05-2018, 14:44   #5
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Re: Redundant house battery banks - tips?

Quote:
Originally Posted by Cyrus Safdari View Post
My old 1967 boat came with a 440 AH flooded lead acid battery, which I will change into 4x Firefly 12v batteries, with a Sterling charger and regulator. I also will have a separate starter battery, with an echo charger. I'd like to separate the batteries into 2 as-redundant-as possible banks, one port-side and one starboard. I can live with 200 AH daily without a problem and dont really need all 400 AH.

Considering how fast the tech develops, I'm curious if you guys have any tips or suggestions esp for new products on the market to set up a redundant house battery bank.
Why not 3 Firefly in one bank and an ACR to take care of a small (group 24) start battery? Less expense, much more efficient.
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Old 05-05-2018, 17:38   #6
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Re: Redundant house battery banks - tips?

Quote:
Originally Posted by Cyrus Safdari View Post
My old 1967 boat came with a 440 AH flooded lead acid battery, which I will change into 4x Firefly 12v batteries, with a Sterling charger and regulator. I also will have a separate starter battery, with an echo charger. I'd like to separate the batteries into 2 as-redundant-as possible banks, one port-side and one starboard. I can live with 200 AH daily without a problem and dont really need all 400 AH.

Considering how fast the tech develops, I'm curious if you guys have any tips or suggestions esp for new products on the market to set up a redundant house battery bank.
My set up is 2 sets of 2 x 12 Vdc marine deep cycles, to do everything (lights, entertainment, fridge, inverter, windlass, pumps, etc. separated by a A/B/Both/Off switch, with a L-ion booster pack back up for starting should I ever drain the main bank (hasn't happened in 4 years with this set-up), but it's good to have the booster pack as a portable 12Vdc supply for troubleshooting others people's stuff.

The A/B/Both/Off switch is always in the "Both" position so various chargers apply to all, except when isolating half the bank at a time, for service or testing.

Having batteries laying around redundant, doesn't make good use of available resources.
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