Seeking Dual Car Battery Installation Advice

I'm about to configure my 97 Plymouth van so that it has two batteries. The second battery will be kept in the rear of the van in a battery box with a vent through the floor. I'm using a Mega-Tron RV-Marine Deep Cycle 12v battery, which will provide power to a medical device at night. I bought a Valmar (Model 31122) battery selector switch. The switch has four settings: Off, 1, All and 2. I suspect that 1 means batter 1, and 2 battery 2.

I have a pretty fair idea how to install it ignition and ground wise. I know the difference between +/-, for example. I'm going to need some wire to go from the rear to front under the chassis. Does #10 seem right? I'll try to keep it tight and away from the fuel tank. It seems best to put the switch inside the engine compartment. I think I'll be able to drill a 1" or so hole through the floor in the rear of the van. Maybe I'll call the Plymouth and ask for advice on that. Any suggestions or comments on all this?

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                          Wayne Watson (Nevada City, CA)

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W. Watson
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                          Wayne Watson (Nevada City, CA)

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W. Watson

batteries. The

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There are a couple of companies which are called Valmar. Your switch comes from Valmar Marine

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Unfortunately, the above link appears to be obsolete or is non functional.

In my opinion a simple battery selector switch is not ideal nor the preferred method of connecting two automotive batteries in a vehicle, especially when they are of different types and capacities as in your situation. You should use a Smart Battery Isolator for your dual battery setup.

You might investigate using one of the battery isolators from Newmar

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There are numerous sources of similar items if you wish to investigate for yourself.

Reply to
Ross Herbert

I couldn't reach the URL you found either. The carton shoes Pompano Beach, FL.There server may be down.

Here's an interesting one .

Because of just too many needs on my time, I didn't get to this until Tuesday when I ordered the battery box Tuesday. I live in a small community, and it took until 1 pm today to get the box. I plan to leave for a 3 week trip tomorrow, and difficulty with cutting a hole in the rear area of the van has put further work off until tomorrow. I think I'm just going to return the battery, box, etc. until I have more time to think this through. This looks a bit chancy at the moment.

I had h> >

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                          Wayne Watson (Nevada City, CA)

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W. Watson

for that you could use a hole saw, you may be able to get by with a jugsaw with steel cutting blade or a burr in a die grinder, if you remove the fuel tank, oxy and plasma become options too.

OTOH I know some guys with a drill press you could drive under.....

Bye. Jasen

Reply to
Jasen

Hi, Wayne. I'm wondering if you might not just be overthinking this a bit. The selection of a marine battery seems to be a good one. I'd guess, though, that the CPAP only requires about 2 amps continuous to run. Using a switch rated for 160 amps/210 amps starting seems to be a little much (the Valmar website is down -- can't give you an immediate response on the switch positions).

How about just switching between the van electric and the marine battery locally (at or near your sleeping space) with a standard switch? You can minimize the extra wiring, and not have to drill holes that way. To be safe, I'd use a 10 amp double throw switch with center-off (available at any hardware store).

Good luck Chris

Reply to
Chris

If you're going to be drawing only 2 amps for 8 hours each night, your van battery should be able to handle that provided you do an hour or so of driving the next day. If the van battery is in good condition, there should be no problem.

I agree that it't not good to mix battery types. But there are other options. One is to use a larger (greater capacity) battery in your van. The larger battery could be a deep cycle type.

If your concern is that you don't want to risk discharging the van's battery to the point that it won't start the engine, then you could construct a simple sensor and relay that would automatically disconnect the CPAP when voltage dropped to some predetermined level. No need to make any mods to the van or its wiring. Just a small box between the cigarette lighter plug and the CPAP unit.

Or you could use something like this:

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Vector 300 Amp Jump Starter Model 010S - Jump Starter

Simple, versatile, cheaper than a second battery.

Chuck

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Reply to
Chuck

Hi, I left for my 3 week vacation on the 9th, my last post. I was unable to really start installing it, so figured I'd do it on my trip. Fortunately, I found a much better solution on my way before I tinkered with anything. It's called a power pack.

When I happened into the Tower campground in Yellowstone, I asked the campground host if he had any electric outlets I could borrow. One thing led to another, and he offered me the use of his Xantera 600W PP. It worked fine in that it powered my CPAP unit for 8 hours. One can recharge it by plugging it into the car's 12v outlet.

Although I don't need it, it has a radio. alarm, and a light. Allows for 3 AC devices. I used it for 3 nights. I think Xantrex makes an ever higher wattage one. Amazon has it for a lower price, much lower depending upon how shipping figures into it. The campground host told me there might be a bigger (wattage) model.

For Amazon, .

I should be order> Chris wrote:

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                          Wayne Watson (Nevada City, CA)

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Reply to
W. Watson

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