2800scr with three batteries for a two bank charger conundrum

[George K]

Hello Maxum brethren,
I'm too cheap and lazy to buy a three bank charger - but maybe I should? Here's the issue:
I'm often on the hook for over-nighters on the bay (in the summer that is - water's really hard here right now in Canada). I solved the problem of over-taxing the house battery by getting two. These are NAPA 27 series deep cycle - that work fine. I also have the equivalent size starting battery for a total of three batteries - with only a two bank charger.
Questions:
1. Should I use the two charging banks for the two house batteries only and leave the starting battery for alternator charging?
Or
2. Can I use one charging bank for both house and the other bank for the starter?
Or
3. Should I not be so cheap and get a three bank charger?
Thanks for any advice on this please.
Thanks,
GeorgeK

[mmwjr]

If the house batteries are connected in parallel then they will be charged by one bank of the charger while the starting battery will be charged by the other bank.

[shrew]

With a bank with multiple batteries, the bank is treated like a single battery.

1) Connect the house batteries in parallel

a) Connect the Positive terminals on the batteries

b) Connect the ground (negative) terminals on the batteries.

2) Connect the positive from the battery switch to the Positive at on end of the bank (i.e. if the house bank has three batteries [1 - 2 - 3] connect the positive cable from the switch to the positive terminal on either battery 1 or 3).

3) Connect the Ground from the boat to the ground (negative) terminal at the other end of the battery bank (i.e. if the positive from the switch is on the positive terminal on battery 1, then the boat's ground needs to go on the ground (negative) on battery 3.

4) Connect the positive lead from the charger to the positive terminal where the battery switch is connected too.

This will treat the entire bank like a single battery. The single leg from the charger will charge the entire 3 battery bank in this configuration.

[George K]

Thanks Shrew. Hope things don't get too sparky.