Magnum MS2012 LifePO4 upgrade

[steved28]

Sorry if this has all been discussed ad nauseum, but I have recently purchased 4 100Ah LifePO4 batteries to replace the 800Ah lead-acid bank I currently run. I have a 2019 Sunstar LX class A gasser, it came with the Magnum MS2012 invertor/charger and a remote head. I did replace the remote head with an ME-RC50-L (note the dash L) This remote was upgraded to include Lithium as a battery choice.
The coach also came with a "Precision Circuits" Battery Isolation Manager.
I'd love to hear of any experiences anyone has with a similar setup. My main questions would be if the Battery isolator is enough to satisfy the coach charging for LifePO4 batteries (when underway). And was also wondering if the generator (I have a 5500 Cummins/Onan) is started by the chassis battery? or the house batteries?
Any other concerns? Thanks!

[creativepart]

There are tons of posts on this topic on www.irv2.com. I know that I have a thread about this exact topic over there.

https://www.irv2.com/forums/f54/dc2d...im-576908.html

The long and short of it… you either have to remove or disconnect the OEM BIM followed by installing other means for charging your battery banks while driving or you need to replace the BIM with a LI-BIM product made by the same company as your current BIM.

The problem is that with your current BIM the alternator will be charging the new batteries and this can be bad for your new batteries and very bad for your alternator. That’s why you need to remove the current BIM or replace it with the new LI-BIM. Most remove the OEM BIM and install a DC2DC charger to charge your new batteries when driving. The LI-BIM let’s the alternator charge the LiPo batteries but, it turns that charging on and off to protect the alternator from overheating and burning up.

As for charging the new batteries on shore power you should be all set with the Magnum setup you have with the new remote.

However, if you remove your BIM then you will need to consider your Chassis battery’s charging - but only on shore power. When driving the alternator will take care of that charging. But without a BIM your Chassis battery will lose charge when on shore power for more that a few days. If you go with the LI-BIM you won’t have this problem.

Replacing your current BIM with the new LI-BIM will massively simplify the process. However, there just isn’t a lot of reviews on how well this works so many choose to go the harder but well document way of removing the BIM.

On my Adventurer the chassis battery starts the generator so this isn’t effected by removing the BIM. I’m not positive on your Sunstar but I think it’s the same as mine.

[steved28]

Thanks so much. BTW, before I go hunting, do you know where the BIM is located? Is it behind the DC breakers?

[creativepart]

Originally Posted by steved28

Thanks so much. BTW, before I go hunting, do you know where the BIM is located? Is it behind the DC breakers?

Usually, it’s behind a removable panel (4-screws) near those 12v push button “breakers.” Mine was just below the breakers.

When you first get behind the panel it will look like a rats nest of wires and impossible to deal with. But actually it wasn’t bad at all. There will be a House disconnect relay on one side (on the right in my rv) and a Chassis disconnect relay on the other side. The BIM is in the middle between those two relays.

The BIM is attached to each relay with one bolt on each side via a tab on each side of the BIM.

If replacing the BIM with a LI-BIM it’s direct wire for wire replacement. If removing the BIM you just remove the bolts holding it to each relay. I actually unbolted it and laid it down behind where it had been installed and I left all the wires attached to it. That probably sounds crazy but it works fine.

You can see all of this in the link to my post on irv2 above. Be sure to read all of the posts because my initial plan did not work so later posts show how I worked all that out.

[steved28]

Originally Posted by creativepart

Usually, it’s behind a removable panel (4-screws) near those 12v push button “breakers.” Mine was just below the breakers.

Thanks. Found and removed today. I feel that somehow my RV got a small lobotomy today.