Going from 2 AGM to 1 12V 300Ah LiFePO4 Battery

[Scubawise]

Again not sure i wire old battery a to batt chassis on bim 225

 

[ducksface]

Because your bim is is internally trying to send 12.8 volts to your non-existent batteries. It thinks they're dead it thinks it's charging them.

Your old Bim and your new Bim are built exactly the same externally. Mount the cables where they came off of the old one onto those positions on the new one.

 

[PS89]

There should be a 100 amp DC breaker under the hood as well. Trip it and see which side goes to 0. That's the chassis side.

That breaker is for the feed to the Thor/Bussman fusebox under the hood. There is no circuit breaker between the BIM and either battery/bank.

When I put the multimeter on both Batt A & batt B shows 12.8 votts. Even red black multimeter reversed and reading 12.8.

That indicates the internal solenoid is closed (engaged).

Your old Bim and your new Bim are built exactly the same externally. Mount the cables where they came off of the old one onto those positions on the new one.

That would work if the old one was wired correctly. Probably not...

 

[Chateau_Nomad]

Again not sure i wire old battery a to batt chassis on bim 225

You're overthinking this... The Li-BIM 225 terminals are clearly marked... TRUST that! Ignore how your previous BIM was wired, considering all the banter about being wired backwards, etc.

Since you have your house batteries disconnected, but your chassis battery is STILL connected... WITH THE CABLES DISCONNECTED FROM THE Li-BIM 225, check voltage on the cable coming from the chassis battery... 12+ volts, correct?

Now check voltage on the cable coming from your house battery area... 0 volts, correct?

If you DEFINITELY have house batteries disconnected, the cable with 12 volts (not 0 volts) HAS to be the chassis battery cable... and connects to the "Batt Chassis" terminal.

Connect the cables to the appropriate labeled terminals...

 

[Scubawise]

You're overthinking this... The Li-BIM 225 terminals are clearly marked... TRUST that! Ignore how your previous BIM was wired, considering all the banter about being wired backwards, etc.

Since you have your house batteries disconnected, but your chassis battery is STILL connected... WITH THE CABLES DISCONNECTED FROM THE Li-BIM 225, check voltage on the cable coming from the chassis battery... 12+ volts, correct?

Now check voltage on the cable coming from your house battery area... 0 volts, correct?

If you DEFINITELY have house batteries disconnected, the cable with 12 volts (not 0 volts) HAS to be the chassis battery cable... and connects to the "Batt Chassis" terminal.

Connect the cables to the appropriate labeled terminals...
View attachment 1320443

I am overthinking. BUT. I turned my multimeter to 20amp. The coach batteries are physically removed. BUT. I must not understand something. When I put the multimeter black probe on batt A & red on bat b ...it reads 12.8 & same in reverse.

 

[ducksface]

There's no need to understand.
Just hook up the new one exactly as the old one was.
If it is one of the few that were wired backwards...Who cares?
It worked for you for years the way it was.

Quit thinking and wire it up.
We can all think about theory and minutia when the job is done.

 

[Chateau_Nomad]

I am overthinking. BUT. I turned my multimeter to 20amp. The coach batteries are physically removed. BUT. I must not understand something. When I put the multimeter black probe on batt A & red on bat b ...it reads 12.8 & same in reverse.

Why are you measuring that? I think Duck stated that when you connect the chassis battery to the Li-BIM 225 (with no house battery connected) the relay in the BIM will close... trying to charge a non-existent house battery. That's where you're getting the voltage read across those terminals.

That voltage is meaningless at this point. But when you get your house batteries installed and connected to the Li-BIM 225, it will monitor both battery banks and connect them as necessary.

 

[dkoldman]

Trust the man that has a RV coach just like yours with 6 X 6 off road capabilities. You can't go wrong because it is Duck Approved.

If it makes you feel more comfortable, think of it like your software code. You just write the damn code and if it does not work, you fix it. Just do it!!!

In the meantime, your dogs have called me wanting to know if they can come to Texas for a little while until you finish this project.

 

[16ACE27]

If the BIM is used to 'jump start' the chassis battery from the coach battery, would there still be a breaker on that line? I would think the starter draws more than a 100 amps, no?

You're right. That breaker supplies the Thor chassis loads.

 

[16ACE27]

I am overthinking. BUT. I turned my multimeter to 20amp. The coach batteries are physically removed. BUT. I must not understand something. When I put the multimeter black probe on batt A & red on bat b ...it reads 12.8 & same in reverse.

Remove one of them.
The chassis battery lead will still have voltage on it.
The house battery lead will not.

 

[Scubawise]

Why are you measuring that? I think Duck stated that when you connect the chassis battery to the Li-BIM 225 (with no house battery connected) the relay in the BIM will close... trying to charge a non-existent house battery. That's where you're getting the voltage read across those terminals.

That voltage is meaningless at this point. But when you get your house batteries installed and connected to the Li-BIM 225, it will monitor both battery banks and connect them as necessary.

Yes. Thx I see that logic now

 

[Scubawise]

Remove one of them.
The chassis battery lead will still have voltage on it.
The house battery lead will not.

Great. That bim 160 screw configuration is a pain in the ASX.
Labeled wires covered ends removed all wires.
Removed bim 160.
Installed new li 225 without wires.
I guess I could now test independently the Removed bat A & BAT B to see which is hot?
The multimeter has black red probes.
Can I put the black & red probe on each one to see voltage?

 

[ducksface]

It doesn't matter black or red.
It will read
12.8
Or
-12.8
It doesn't matter for what you're doing.

And
You dont set the meter on amps.
You set it on DC volts.
If a selection the dial is 20v, use that.

 

[lwmcguire]

I am overthinking. BUT. I turned my multimeter to 20amp. The coach batteries are physically removed. BUT. I must not understand something. When I put the multimeter black probe on batt A & red on bat b ...it reads 12.8 & same in reverse.

0-20 volts DC, right, not amps? My meters do measure amps so just checking

 

[ducksface]

It doesn't matter black or red.
It will read
12.8
Or
-12.8
It doesn't matter for what you're doing

 

[lwmcguire]

Great. That bim 160 screw configuration is a pain in the ASX.
Labeled wires covered ends removed all wires.
Removed bim 160.
Installed new li 225 without wires.
I guess I could now test independently the Removed bat A & BAT B to see which is hot?
The multimeter has black red probes.
Can I put the black & red probe on each time see voltage?

Be sure you have a good ground for the black lead or it will mess with you when reading voltage, and as noted if your reversed then the negative voltage

 

[16ACE27]

Great. That bim 160 screw configuration is a pain in the ASX.
Labeled wires covered ends removed all wires.
Removed bim 160.
Installed new li 225 without wires.
I guess I could now test independently the Removed bat A & BAT B to see which is hot?
The multimeter has black red probes.
Can I put the black & red probe on each one to see voltage?

This sounds like multimeter 101.
One lead goes to the metal chassis - usually the black lead.
The red lead goes to where you are trying to measure the voltage.
If you reverse the leads the voltage will be reversed.
You DO NOT measure from one cable to the other.

 

[Scubawise]

It doesn't matter black or red.
It will read
12.8
Or
-12.8
It doesn't matter for what you're doing.

And
You dont set the meter on amps.
You set it on DC volts.
If a selection the dial is 20v, use that.

Yes sorry did 20V on multimeter.
Mine showed - 12.8.
I have 2 leads. Trying to use the probe to see exactly which is 12.8 to confirm chassis

 

[Scubawise]

Y

This sounds like multimeter 101.
One lead goes to the metal chassis - usually the black lead.
The red lead goes to where you are trying to measure the voltage.
If you reverse the leads the voltage will be reversed.
You DO NOT measure from one cable to the other.

Yes thx that was my problem
Will re check

 

[Scubawise]

Ok. Here is the latest based on everyone's help. My BIM 160 on Bat A must be coach.
My Bat B must really be coach.
So I need to reverse for LI bim 225.
My results.
Both cases used metal rig frame for red or black probe & lead for test.
Case #1 Connect multimeter to Bat A lead and zero on multimeter.
Case #2 Connect multimeter to Bat B lead and 12.8 or - 12.8

ALSO there is this yellow wire that was connected to BAT A lead?
Do I leave with Bat A and move to new Coach location on Bim 225?