Battery Separator Question paralleling Inverter Install

[dtcerrato]

We're getting close to pulling the trigger on a Magnum MS 2812 inverter install mainly to run the roof air & microwave OTR w/o the need for the genny. We are set up with two battery banks. One is two 8D deep cycle/start batteries that are primarily used for engine start (& second for back-up house bank) & the other bank is currently four group 31s primarily for house power. We're not sure which bank we want to be powering the inverter while OTR (comments welcome) but which ever bank we decide to use I'm thinking there has to be a battery separator on the 200 amp alternator charge cable that now feeds direct to the 8D diesel start batteries if we use the house bank (four group 31s) for powering the Inverter OTR. We'd been beating the ole' brain to death reading on line & are looking for comments here directly from the best!
We were also toying with the idea of being able to power the inverter from either or both banks simultaneously but am sure that gets more complicated... Any experienced comments on this subject matter would be greatly appreciated.  TIA.

[luvrbus]

Contact the guys at Texas Industrial Electric in San Antonio tell them what you doing and they will fix you up with the right switch or isolators   

[dtcerrato]

Thanks Clifford
I found this interesting smart ACR since posting this. Still learning...
https://powerwerx.com/blue-sea-7622-auxiliary-battery-separator-500amps

[lostagain]

I replaced the start batteries with 4 12V golf cart deep cycle batts. The are directly connected to the 4 deep cycles that used to be the "house bank". So now I have one single bank of 8 golf cart batts. It powers the "house" and the engine starter. Works very well. I always pre heat the engine with the generator for electric block heaters, or the diesel Webasto, so it doesn't take much to start it. The generator has its own dedicated battery.

Works very well.

JC

[sledhead]

with the MCI the inverter was on the house system so everything would work without 120 v power and when I was driving the big engine alternator would power the inverter and with the bogart meter all the power needed was from the engine and not from the battery bank until I turned off the engine . with my system being 24 volt battery bank the amp draw was not that bad when using the a/c . the biggest drain on the inverter when off the 120 v pole was the microwave ?

dave

glad to here the battery bank worked out JC

[hogi6123]

My thoughts are, while driving, use the engine alternator to power the inverter and charge all the batteries.  When not driving, the start batteries need to be disconnected so they won't drain.

So my setup is:
Inverter connected to house batteries.
Alternator connected to start batteries.
An automatic relay that connects the two systems when a charging voltage is present on either system.  Just like the one you found.
Note: this has the benefit of keeping all batteries charged with 1 charger.
A manual override to connect the systems manually in case the start batteries end up dead for whatever reason.

I have used this setup very successfully in a van, now setting it up that way in my bus.

[hogi6123]

If left connected for a long time while not charging, the two banks would discharge each other.

I could see some benefit to an additional manual switch to disconnect the house batteries from inverter (and leave only start batteries connected) but I don't have enough experience or knowledge to know how useful that would be.

(Edited)

[chessie4905]

I have a booster relay to use the house batteries to start the coach if the start batteries are unable to.

[thomasinnv]

As others have already said, i would recommend using a smart battery combiner. Leave the inverter connected to the house bank. I use a Magnum me-sbc with an external 500 amp relay. The sbc acts as a maintenance charger to keep the engine batteries up while parked, and it also controls the external relay through an ignition relay to supply power to the house bank and inverter while running the big engine. I can run 2 roof warts through the inverter while driving.

[buswarrior]

If you only had one battery bank...

If your generator has a dedicated battery, just how much expensive duplication does the observant busnut need?

If you have any of the decent battery monitoring systems, you sized your bank properly, you know how to keep a battery bank healthy...

Waiting for the generator to re-charge if you happen to have a self inflicted wound, is punishment enough?

Are we building multiple battery banks without thinking about it, because the peeps before us did?

Happy coaching!
Buswarrior

[David Anderson]

Contact the guys at Texas Industrial Electric in San Antonio tell them what you doing and they will fix you up with the right switch or isolators   

This guy is good.  I've used him several times.  Dick Wright at Wrico in Eugene OR is great too.   He is a bus nut, also.

I have a relay to merge my Trace SW2512 inverter and house bank with my alternator tied with 0000 cable.  It has worked well for 20 years for me.

David

[hogi6123]

Buswarrior, I feel better having my starting reserve separate.  I don't want to have to monitor the battery monitor.  And I don't see a big difference in cost?  On one side, extra engine start battery(ies); on the other side, extra generator start battery and better battery monitor.

I think the actual connections with either approach are very similar, since large enough battery banks almost certainly have batteries in parallel, the main difference would be how the disconnect switches (or lack of) are configured.

[dtcerrato]

Thanks! Great responses and I am working through all of them.
Here's a side bar question - when the Magnum Inverter charger is maintaining the state of charge on the house battery bank while parked on the pole - does that mean I'll be deleting the present WFCO 55 amp converter? TIA

[luvrbus]

Thanks! Great responses and I am working through all of them.
Here's a side bar question - when the Magnum Inverter charger is maintaining the state of charge on the house battery bank while parked on the pole - does that mean I'll be deleting the present WFCO 55 amp converter? TIA

only the charging part of the converter

[sledhead]

when you get it all connected you should not need the converter and just use the magnum to do all of it . inverting and charging as it should do a better job keeping the batteries up

plus you can do a equalization charge to keep all the batteries equal when needed

dave