Isolating RV from the batteries for a solar controller install

[GOUSC]

I’m getting ready to upgrade the stock solar controller to a Victron MPPT and need to isolate the RV from the batteries, etc. From reading other posts it looks like I need to;

Unplug shore power.
Put the RV in “Store” mode
Unplug the current solar panels from the connection on the roof, and
Disconnect the batteries

My question is regarding disconnecting the batteries. I have read that you need to disconnect either the positive or negative terminals to isolate the batteries. I understand there are 2 trains of thought on this but either should isolate the RV from the batteries. My preference is to disconnect the negative. On a previous project I did this by disconnecting both negative connections and the jumper between the 2 negative terminals.

However, I still had power to the CO2 detector when I did this. It didn’t really matter for my previous project but for this one I want to make sure there is no power anywhere in the RV.

Subsequent to that project I replaced one of my AGM batteries. For that project I had to disconnect the positive and negative terminals for the replacement battery and there was no power indicated on the CO2 detector.

For this project, I’d like to just disconnect the negative terminals. Is there some step I missed in this process? Should I not disconnect the negative jumper cable between the 2 batteries?

I’ve attached a picture of the battery connections on my RV. I’ve seen where people add a battery disconnect to either the positive or negative terminals so I would think just disconnecting the negative terminals would work.

[waninae39]

we use the
Victron Cyric-Tc and the
Victron Orion Dc-DC

this is my DC schematic

[GOUSC]

Nice system. Mine won't be as complicated. 3 solar panels / Victron MPPT 100/30 controller / Cutoff switch on the solar side / 40 Amp breaker on the battery side / temperature sensor in the battery box.

My basic question is - why is there still power to the CO2 detector when I disconnect the negative terminals and the negative jumper cable. I can remove all positive and negative terminals if necessary to isolate the RV from the batteries. It just doesn't seem like it should be necessary and I can't seem to get that answer from your diagram.

[JMynes]

Is your CO2 detector getting powered by solar? If your negative terminals are disconnected then the batteries are out of the mix. Solar and shore power are the only sources left.
Unplug shore power, only solar remains.

[smsasf]

Originally Posted by JMynes

Is your CO2 detector getting powered by solar? If your negative terminals are disconnected then the batteries are out of the mix. Solar and shore power are the only sources left.
Unplug shore power, only solar remains.

Well, at least on my new 2020 Bambi the ceiling CO2 alarm is 9v battery charged. Only alarm on main battery is the propane detector.

[JeffofCT]

Originally Posted by GOUSC

I’m getting ready to upgrade the stock solar controller to a Victron MPPT and need to isolate the RV from the batteries, etc. From reading other posts it looks like I need to;

Unplug shore power.
Put the RV in “Store” mode
Unplug the current solar panels from the connection on the roof, and
Disconnect the batteries

My question is regarding disconnecting the batteries. I have read that you need to disconnect either the positive or negative terminals to isolate the batteries. I understand there are 2 trains of thought on this but either should isolate the RV from the batteries. My preference is to disconnect the negative. On a previous project I did this by disconnecting both negative connections and the jumper between the 2 negative terminals.

However, I still had power to the CO2 detector when I did this. It didn’t really matter for my previous project but for this one I want to make sure there is no power anywhere in the RV.

Subsequent to that project I replaced one of my AGM batteries. For that project I had to disconnect the positive and negative terminals for the replacement battery and there was no power indicated on the CO2 detector.

For this project, I’d like to just disconnect the negative terminals. Is there some step I missed in this process? Should I not disconnect the negative jumper cable between the 2 batteries?

I’ve attached a picture of the battery connections on my RV. I’ve seen where people add a battery disconnect to either the positive or negative terminals so I would think just disconnecting the negative terminals would work.

The disconnect should be on the Positive (+) side since the positive will technically discharge if finds a ground.

[GOUSC]

Originally Posted by JMynes

Is your CO2 detector getting powered by solar? If your negative terminals are disconnected then the batteries are out of the mix. Solar and shore power are the only sources left.
Unplug shore power, only solar remains.

Shore powers was unplugged.
Solar connections on the roof were unplugged
“Store” button was engaged
Negative terminals and negative jumper was disconnected.

CO light was on after this

[GOUSC]

Originally Posted by smsasf

Well, at least on my new 2020 Bambi the ceiling CO2 alarm is 9v battery charged. Only alarm on main battery is the propane detector.

My smoke detectors are battery operated. I don’t see a battery for the CO 2 detector. if I take the extra step to unplug the battery ( not inverter) side positive terminal the CO2 light goes out.

[GOUSC]

Originally Posted by JeffofCT

The disconnect should be on the Positive (+) side since the positive will technically discharge if finds a ground.

Before posting, I read a LOT of postS regarding installing a battery disconnect switch. The results were split on whether to do it on the positive or negative side. The consensus was that either should isolate the RV from the batteries. Thus, my question.

Just trying to understand why the negative disconnect is not working. If no definitive answer I’ll just disconnect both to ensure there is no powers to the RV.

[smsasf]

Originally Posted by GOUSC

My smoke detectors are battery operated. I don’t see a battery for the CO 2 detector. if I take the extra step to unplug the battery ( not inverter) side positive terminal the CO2 light goes out.

Oops, in my post for which you answered I mean CO detector, not CO2. Sorry to mislead. Do you have wiring diagram that shows how it is wired?

[Al and Missy]

Originally Posted by JeffofCT

The disconnect should be on the Positive (+) side since the positive will technically discharge if finds a ground.

Not correct. The only way the battery will discharge is if current flows from the positive terminal to the negative terminal.

[Al and Missy]

Originally Posted by GOUSC

My smoke detectors are battery operated. I don’t see a battery for the CO 2 detector. if I take the extra step to unplug the battery ( not inverter) side positive terminal the CO2 light goes out.

My CO detector is battery powered. The only way the positive terminal is involved is if the converter output is also connected there and the converter negative is still connected to the negative buss bar.

[GOUSC]

Originally Posted by Al and Missy

My CO detector is battery powered. The only way the positive terminal is involved is if the converter output is also connected there and the converter negative is still connected to the negative buss bar.

I have a Boondocker 60 converter. It is connected to the Electric panel under the refrigerator by just plugging into the back with a 3-prong electric cord. I’m not well versed electrically so I hope this addresses your comment.

If I am reading it right, the converter Positive is not connected to the CO detector since it is connected to the AC panel through the 3-prong plug.

[GOUSC]

I figured out my issue and just wanted to let everyone know... I'm an idiot.

I went out yesterday to begin disconnecting my batteries to install my solar controller. Looking at them fresh and, 2 weeks removed from the last time I attempted this with another project, I found that you can actually isolate the RV from the batteries if you actually disconnect BOTH negative terminals.

On my last project last time, I started with the battery that just has the nut that screws into the top of the battery. After I removed that connection and the jumper I went to the other battery. I removed the jumper and the negative connection to the Zamp solar input. Stupid me never removed large clamp on negative connection that comes from the inverter side.

Last time I had some wood blocks placed on top of the battery compartment to keep the lid open. Between those obstructing the view and the black negative cable against the black battery box I never even noticed that connection there. This time I was working from a different angle and it stuck out like a sore thumb.

Stupid rookie mistake and I figured I need to bare my stupidity to all so someone else doesn't make the same mistake.

[DewTheDew]

Originally Posted by GOUSC

I figured out my issue and just wanted to let everyone know... I'm an idiot.

I went out yesterday to begin disconnecting my batteries to install my solar controller. Looking at them fresh and, 2 weeks removed from the last time I attempted this with another project, I found that you can actually isolate the RV from the batteries if you actually disconnect BOTH negative terminals.

On my last project last time, I started with the battery that just has the nut that screws into the top of the battery. After I removed that connection and the jumper I went to the other battery. I removed the jumper and the negative connection to the Zamp solar input. Stupid me never removed large clamp on negative connection that comes from the inverter side.

Last time I had some wood blocks placed on top of the battery compartment to keep the lid open. Between those obstructing the view and the black negative cable against the black battery box I never even noticed that connection there. This time I was working from a different angle and it stuck out like a sore thumb.

Stupid rookie mistake and I figured I need to bare my stupidity to all so someone else doesn't make the same mistake.

I found this while searching for the way to disconnect my solar panels for a battery replacement (it still seems like it should be easier than climbing on the roof but I'm still looking!) and was going to mention the double connector if you hadn't figured it out! I noticed this while studying my battery connections and planning out how I was going to unhook and then re-hook for my replacement batteries. :-) We all learn a bit at a time!

[ROBERT CROSS]

Originally Posted by JeffofCT

The disconnect should be on the Positive (+) side since the positive will technically discharge if finds a ground.

Yep...👍

Bob
🇺🇸