Dual Battery System Management Recommendations?

[dzzz]

Yeah, the "battery in reserve" is not understanding batteries. Especially with voltage sensing relays.

The $150 Blue Sea ratings:

Cranking Rating: 10 sec. 2,500 Amps*
Cranking Rating: 1 min. 1,100 Amps*
Intermittent Rating: 5 min. 700 Amps*
Continuous Rating 500 Amps*

*2 x 4/0 cable

 

[theksmith]

Yeah, the "battery in reserve" is not understanding batteries. Especially with voltage sensing relays.

explain please

 

[Xterabl]

the ksmith you're right, let me rephrase/qualify:
I also considered bluesea VSR with remote in-cabin switch. But my "feeling" was that the sealed solid state powergate would be more robust and reliable than "marine grade" electromechanical technology over a 5-10 yr time horizon. Generally, I like the sound of "transistor" vs. "magnetic latching". And of course my gamble was that the high price of the powergate meant high quality components, manufacturing, and QC.
No way of knowing for sure if I wasted money...everyone should study the problem in detail and come to their own conclusions based on available literature and personal criteria / experiences.

 

[dzzz]

explain please

Battery life is largely a function of depth of discharge. A setup with one work and one backup battery will have reduced life on the work battery. So the user gets a dead battery by trying to avoid a dead battery.
People who have a large number of house batteries on boats will sometimes want to divide the cells into groups. But that usually ends up running one bank way down and shortening the life of that group. While at the same time underutilizing the investment in the other bank. Not that groups can or should be extremely large. But recreational vehicles should almost never have more than one group of house batteries.
Having a backup battery or multiple banks is not always sub optimal. Just that the tendency is to over separate batteries. Ultimately reliability is a function of total system design.
Take a simple example of two starting batteries. With a $70 ACR discussed here they can normally function as one bank. But if the lights are left on, as voltage drops the device will separate the batteries. One is sacrificed to the lights while the other will still have capacity left to start the vehicle. Which is one of the reasons to use an automatic system.

 

[theksmith]

the ksmith you're right, let me rephrase/qualify:
I also considered bluesea VSR with remote in-cabin switch. But my "feeling" was that the sealed solid state powergate would be more robust and reliable than "marine grade" electromechanical technology over a 5-10 yr time horizon. Generally, I like the sound of "transistor" vs. "magnetic latching". And of course my gamble was that the high price of the powergate meant high quality components, manufacturing, and QC.
No way of knowing for sure if I wasted money...everyone should study the problem in detail and come to their own conclusions based on available literature and personal criteria / experiences.

i agree solid state is the way to go, just couldn't quite justify the up-front cost myself. also, i was unclear on if the powergate had a manual switch to force combining for self jump like the auto-relays we've been discussing?

powergate is also made in the US i think and looks to be a quality piece of engineering.

 

[dzzz]

Blue sea is certainly a blue water company. I don't know bep marine, but many people use it.
Both make products to marine and non-marine standards such as ABYC and IP67.

 

[smslavin]

I have been running the Painless Wiring setup for the past few years with the switch inside the cab to share the batteries or isolate them.

Corey, I'm planning on using the Painless solenoid in my FJ as well. What battery tray is that? How do you have it mounted?