Help with Disconnecting my old battery from the DC Distribution Panel (in RV)

[aluchipawa]

Hi All, I have recently set up a solar system in my RV and the last thing I need to do is connect my new battery to the DC Distribution Panel. It is a chassis return system and the wires at the battery are a bit of a rats nest. I am guessing that the extra positive wires at the battery were for the old battery monitor and to connect the old battery to the old converter for charging. I am thinking that I just need to disconnect the old battery and connect all the green wires to the chassis. Then I will connect the new battery to the DC Distribution Panel (Positive to Hot and Neutral to ground. I have included pictures of the old battery and the DC Panel

 

[mopat]

looks like an engine starting battery

is this the only battery in the RV?

What RV is it, make and model?

 

[Geokilroy]

looks like an engine starting battery

is this the only battery in the RV?

What RV is it, make and model?

That battery looks like you are under the hood in the engine compartment. The solinoid in the background is for the starter boost button. This battery charges from the alt of the vehicle. It also supplies power to the coach 12v system and to the engine starter when you press the assist button. On my class C rig it was the only battery for the coach 12v systems. Is it ok for a LiFePo battery to be charged by the alt of the vehicle? I seperated my coach from this battery with a switch to not have it charge My LiFePo batteries from the alt. My coach batteries charge from solar, generator, or shore but I can change switch to use the boost button if my chassis battery goes dead over long boondock.

 

[aluchipawa]

The engine starting battery is on the other side (There are 2 batteries). This is a Mobile Traveler made by Z Mobile Traveler Inc (a subsidiary of Zimmer Corp). It is built on a 1985 Ford Econoline E350. Also if there is a way I can leave this battery connected while also connecting my LiFePo battery, I would do it.

 

[John Frum]

Since it appears the wire from the starter battery is fused at the dc distribution panel it really should be disconnected at source.
Do you know which red wire goes from under the hood back to the dc distribution panel?
I would just cut the wire off at the ring terminal and leave the terminal stack on the battery alone.
Its my opinion that the rest of that stuff can just stay put.

 

[aluchipawa]

That battery looks like you are under the hood in the engine compartment. The solinoid in the background is for the starter boost button. This battery charges from the alt of the vehicle. It also supplies power to the coach 12v system and to the engine starter when you press the assist button. On my class C rig it was the only battery for the coach 12v systems. Is it ok for a LiFePo battery to be charged by the alt of the vehicle? I seperated my coach from this battery with a switch to not have it charge My LiFePo batteries from the alt. My coach batteries charge from solar, generator, or shore but I can change switch to use the boost button if my chassis battery goes dead over long boondock.

My system sounds very similar to your system in that the 2nd 12v battery in the engine compartment currently powers my DC system. The DC system does not have a neg busbar so I think all the circuits return to the chassis. I want to switch over to using my LiFePo battery but I don't want to charge it from the alternator and I am confused about how to disconnect the 2nd engine battery since I don't want to mess up the engine function. I would be open to leaving that engine battery in as long as it doesn't mess up my LiFePo battery.

The reason I need to switch the DC over to my LiFePo battery is that the converter on my RV is broken so the only way to charge the existing Lead Acid battery in the engine compartment is through the alternator.

 

[John Frum]

My system sounds very similar to your system in that the 2nd 12v battery in the engine compartment currently powers my DC system.

Ok, didn't know it was a "house" battery.
Do you plan on removing the old "house" battery?

 

[aluchipawa]

Since it appears the wire from the starter battery is fused at the dc distribution panel it really should be disconnected at source.
Do you know which red wire goes from under the hood back to the dc distribution panel?
I would just cut the wire off at the ring terminal and leave the terminal stack on the battery alone.
Its my opinion that the rest of that stuff can just stay put.

The wire actually isn't fused so I can just disconnect it from the DC panel. Are you saying I can just disconnect the Lead from the House battery and replace it with a lead from my new LiFePo battery and be good to go? Would I need to connect the negative on the lifepo battery to the chassis then?

Ok, didn't know it was a "house" battery.
Do you plan on removing the old "house" battery?

I am open to keeping it or removing. I am just trying to get the DC panel powered by the LiFePo by whatever way is easiest and also safe.

 

[12VoltInstalls]

Then I will connect the new battery to the DC Distribution Panel (Positive to Hot and Neutral to ground.

I guess I’m the only one that got stuck here… imagining that was a headspace-typo?

I’m not entirely sure what you’re up against. If the converter was charging this battery before (via your solar/lifepo? or shorepower?) then I’d guess that merely plugging in a battery charger would be at least as efficient as the converter- probably more so. Before you keep heading for reinventing a wheel I’d just buy a battery charger.

 

[John Frum]

The wire actually isn't fused so I can just disconnect it from the DC panel.

Personally I would not like to leave a long chunk of wire potentially live but un-terminated and un-fused.
If it shorts on anything, its a fire hazzard.

Are you saying I can just disconnect the Lead from the House battery and replace it with a lead from my new LiFePo battery and be good to go? Would I need to connect the negative on the lifepo battery to the chassis then?

No, connect the new lifepo4 battery to the place on the busbar where the blue positive wire from the converter is attached.
If memory served I worked out the required awg for ampacity and voltage drop in your previous thread.
I recall it was a long run between battery and dc distribution panel.
If I didn't work it out just let me know.
If there is a good spot to connect your new negative busbar to the chassis I suggest doing that instead of running a negative cable.
You can always run it later if the new chassis bond is not effective.

I am open to keeping it or removing. I am just trying to get the DC panel powered by the LiFePo by whatever way is easiest and also safe.

Its easiest to leave it be.
Probably best to remove it.

 

[John Frum]

Manual for the power center.

http://d163axztg8am2h.cloudfront.net/static/doc/d1/c4/3e9324fcdfc13a52dcbea329205a.pdf

 

[aluchipawa]

Personally I would not like to leave a long chunk of wire potentially live but un-terminated and un-fused.
If it shorts on anything, its a fire hazzard.

No, connect the new lifepo4 battery to the place on the busbar where the blue positive wire from the converter is attached.
If memory served I worked out the required awg for ampacity and voltage drop in your previous thread.
I recall it was a long run between battery and dc distribution panel.
If I didn't work it out just let me know.
If there is a good spot to connect your new negative busbar to the chassis I suggest doing that instead of running a negative cable.
You can always run it later if the new chassis bond is not effective.

Its easiest to leave it be.
Probably best to remove it.

Gotcha. I can try to figure out which line off the engine battery is the one going to the DC panel to disconnect it from the battery. Can I connect the lifepo4 to the negative busbar in the ac panel? or does it need a seperate busbar?

Also I ended up finding a better space for the battery in the RV so the battery is only about 4 ft from the DC panel

 

[John Frum]

Gotcha. I can try to figure out which line off the engine battery is the one going to the DC panel to disconnect it from the battery. Can I connect the lifepo4 to the negative busbar in the ac panel? or does it need a seperate busbar?

Also I ended up finding a better space for the battery in the RV so the battery is only about 4 ft from the DC panel

From your other thread you have these components

206Ah Sok LiFePO battery
Giandel 2200W Inverter
Rich Solar 40A charge controller.

I believe they are supposed to all be 15 feet from the ac/dc distro center.
Together they comprise the core of the system and should all be paralleled using a new set of busbars.
Positive wires fused and negative wires un-fused.
The 4th connection to the busbars is a fused connection to the dc distribution center on the positive side and a connection to the nearest good bond to the chassis.

 

[aluchipawa]

I guess I’m the only one that got stuck here… imagining that was a headspace-typo?

I’m not entirely sure what you’re up against. If the converter was charging this battery before (via your solar/lifepo? or shorepower?) then I’d guess that merely plugging in a battery charger would be at least as efficient as the converter- probably more so. Before you keep heading for reinventing a wheel I’d just buy a battery charger.

In my first post I attached a picture of the Label on the DC Panel. On it is handwritten Red(Hot) and Green(Ground) which is what I was referring to when I said "attach positive to Hot and neutral to Ground." I meant to say negative to ground though which is probably why you found it confusing. I'm still very new at this thanks for your patience

The old converter only charged through shore power and wasn't working properly which is why I disconnected it.

I could use a battery charger but I would rather not buy components to keep a 4 year old lead acid battery running when I (hopefully) can just connect my new LiFePo to the DC system

 

[aluchipawa]

From your other thread you have these components

206Ah Sok LiFePO battery
Giandel 2200W Inverter
Rich Solar 40A charge controller.

I believe they are supposed to all be 15 feet from the ac/dc distro center.
Together they comprise the core of the system and should all be paralleled using a new set of busbars.
Positive wires fused and negative wires un-fused.
The 4th connection to the busbars is a fused connection to the dc distribution center on the positive side and a connection to the nearest good bond to the chassis.

The original plan was to have them 15ft away but I was able to find a suitable place to set up the system that was much closer. Everything in the new system is now just 4ft away from the AC/DC panel

Tomorrow I will take a photo of the system I installed so you can see what I am trying to connect to the DC panel.

So what I think you are saying is that I can leave the Green(ground) wire connected as it goes to the chassis and just connect a fused positive wire from the LiFePo to where the old battery was connected

 

[John Frum]

The original plan was to have them 15ft away but I was able to find a suitable place to set up the system that was much closer. Everything in the new system is now just 4ft away from the AC/DC panel

Tomorrow I will take a photo of the system I installed so you can see what I am trying to connect to the DC panel.

So what I think you are saying is that I can leave the Green(ground) wire connected as it goes to the chassis and just connect a fused positive wire from the LiFePo to where the old battery was connected

All that plus you need to connect the lifepo4 battery to the chassis.

 

[aluchipawa]

All that plus you need to connect the lifepo4 battery to the chassis.

Gotcha can I connect the battery to the ground busbar in the AC panel? it is connected to the chassis

 

[John Frum]

Gotcha can I connect the battery to the ground busbar in the AC panel? it is connected to the chassis

That busbar is very likely undersized.
Also I don't like the idea of mixing the two domains.
Instead of saying ground in this context I wish that people would instead say chassis return.
The term "ground" has a lot of baggage.

 

[John Frum]

Actually since the core system is only going to be 4 feet from the dc distribution center.
I suggest you connect the new negative busbar to the dc panel ground lug with 6 awg wire.
For the positive side use 6 awg and a 75 amp fuse.
Your new stuff will have a nice low resistance return path via the new busbar.
The legacy stuff will have a nice low resistance path back to the new busbar.

 

[aluchipawa]

Actually since the core system is only going to be 4 feet from the dc distribution center.
I suggest you connect the new negative busbar to the dc panel ground lug with 6 awg wire.
For the positive side use 6 awg and a 75 amp fuse.
Your new stuff will have a nice low resistance return path via the new busbar.
The legacy stuff will have a nice low resistance path back to the new busbar.

Sounds good. Just wondering about the old battery.... If I disconnect it from the DC Panel but leave it in the engine bay where it is still connected to the chassis and the engine battery, would it interfere with my new battery and system once they are also connected to the chassis?