Auxiliary Battery Installation

[Mike Cleary]

I am going to install an aux battery in my Reflection 337. For those of you who have done this, I have a question. Underneath the main battery there is a hole in the bottom of the trailer. What is that for? Also, if you could tell me how you installed it, hooked it up electrically, etc, I would appreciate that info. Thanks!

[kregli]

The simplest thing to do is add a second 12v battery with characteristics similar to your current battery. You'll need a second battery box (or a single double sized one). You'll need cables to connect positive to positive and negative to negative (auto parts store). You'll need to ventilate the second battery box to avoid possible buildup of gases that can be dangerous (the hole below and the tube at the top in your current box). There are other configurations that might be better - take a look through the archives.

[Mike Cleary]

The simplest thing to do is add a second 12v battery with characteristics similar to your current battery. You'll need a second battery box (or a single double sized one). You'll need cables to connect positive to positive and negative to negative (auto parts store). You'll need to ventilate the second battery box to avoid possible buildup of gases that can be dangerous (the hole below and the tube at the top in your current box). There are other configurations that might be better - take a look through the archives.

When you installed your did you cut a hole in the floor? I have noticed a couple of dealer installs that only use the vent tube. Does the battery box have a hole in the bottom of it?

Thanks very much for taking the time to respond!

[kregli]

I did quite a different installation. At one point I had 4xL16 batteries and now I have 6xLithium batteries. Each required something different. I think the vent tube should provide enough ventilation. Air will come in through the bottom hole (and other gaps), and gasses should rise out of the battery box through the vent tube. As long as you keep your batteries watered properly and don't over charge them, the gases are pretty minimal.

[Mike Cleary]

So you didn't cut a hole in the floor? Just trying to make sure I do I properly.

[kregli]

No extra hole. With the L16s I had a vent hood rather than a box and so the existing hole was used. With the Lithium's no vent is needed.

[2825Matheny]

Also, when connecting two lead acid 12-volt batteries in parallel, there a best way to do it.
You will have jumpers NEG to NEG and POS to POS.
Then your RV POS and NEG wires are connected to opposite batteries.
This photo is the best way.
This ensures that both batteries are used and charged exactly the same.
Not doing it this way, due to small differences in cable resistance and internal battery differences, will cause one battery to fail early.
Make sure you start out with two "like" batteries.
Same manufacturer, same model, and same age.

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[TucsonJim]

@2825Matheny - Jamey, extrapolating your connections to a three battery bank, I believe this would be the correct method?



Jim

[2825Matheny]

@2825Matheny - Jamey, extrapolating your connections to a three battery bank, I believe this would be the correct method?



Jim

Well no.
They only way you can connect multiple 12-volt lead acid batteries in parallel and ensure equal draw-down and equal charging is if there is an even number of batteries.

The only way to use three batteries in parallel is if they are LiFeP04 (Battle Born, about $950 each). These batteries have on-board smarts (BMS - Battery Management System) to protect themselves.

Link Posted by Dan Gorman:

https://www.impactbattery.com/blog/t...-bwS5qpMeuaDUE




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[TucsonJim]

Well no.

The only way to use three batteries in parallel is if they are LiFeP04 (Battle Born, about $950 each). These batteries have on-board smarts (BMS - Battery Management System) to protect themselves.

Well, I guess I'm okay then. I already have to LiFePo batts, and I'm installing a third.

Jim