Mixing batteries

[Rick kl]

Most of the camping I do involves boondocking, my main problem is my Cpap mask. I don't know if I should connect the batteries in parallel, or put in a battery switch to run them one at a time, and then when I connect my generator turn the switch to charge both.

I have a 100 ah Canadian Tire marine battery. I want to add a second Canadian Tire RV 105 AH battery. If one battery is weaker than the other does this make a difference when charging and discharging?

Another question: I am installing A PD9245C converter, the plan is to remove the 12volt innards from my powertron and install the new unit in its place, is the fan noisy?

Just thought of another question, where can I find a wiring diagram for this operation?

[Alistair Camelford]

Rick, my CPAP runs for an overnight on a group 27 Deep Cycle from K Mart ( My first CTC battery started losing a charge after two years). After one overnight I need to run a charge from my two 15 watt solar panels (CTC) or another day travelling with the TV supplying a charge.
When we boondock we only use LEDs , and the frig on propane. So far no need for a second battery.
On a rafting trip down the Colorado two years ago, I used the same 12v battery for two nights of CPAP use (the rafting crew were quite used to this type of request.)
My solar panels sit on a rack with a 25 foot cable so I can get into the sun for a charge...usually topped up by mid-afternoon!
Some posters carry a small gel battery for emergency CPAPback-up.
Sweet Dreams...Alistair

[Bill K]

I ran my cpap on a 7.2 AH battery and it ran for 9 hours.

I did this just to see what would happen.

I was using 12 volts and not an inverter.

Bill K

[Pete Dumbleton]

Just for the record, there are THREE kinds of batteries labeled Marine (sturdy construction and butterfly-nut terminals)

1. Starting for boat engines
2. Deep cycle for long slow discharge
3. Combination or hybrid of above, a compromise...

It's generally not a good idea to place dissimilar batteries in either series or parallel.

Also, if your CPAP will be hooked to 12VDC system, be sure it can handle the voltage fluctuations typically encountered in such a system without damage.

[Per Walthinsen]

Rick:

I have the same 9245 unit and I've never even heard the fan run. It is designed to come on only when the thing is driven very hard, I believe. If it comes on you're unlikely to hear it if it is installed in a conventional manner. Excellent unit.

[Rick kl]

"It's generally not a good idea to place dissimilar batteries in either series or parallel."

Thats what I thought, I want to keep my CPAP battery seperate and wired to the inverter only, last fall I spent 5 nights out, by the 3rd night my battery was having a hard time keeping up ( I was using it for lights and a small DVD as well). I was charging with a crappy tire 900 watt generator and a conventional battery charger, this did not work well.
I need a second battery to watch football games out a the lake ( Go Roughriders!), my satellite box and TV (19"LCD) draw 7 amps, My new plan is to install a battery switch, when charging from the converter with a 2000 watt generater I will put the switch in the both mode this should charge both batteries at the same time.
I was happy to hear the 9245 is a quiet unit I think it will fit nicely in the old inverter box, I didn't want to install a noisy fan in the middle of the trailer. I am going to rewire the trailer with heavier wire and it would be good to know how the old wire was installed, I have searched all over this forum and the net for a 1978 Boler 1700 12 volt internal wiring diagram and so far have come up empty.

[Don N]

Rick, where did you purchase your converter from and what are they worth? I am just started doing some research on these...
Tks

[Rick kl]

Rick, where did you purchase your converter from and what are they worth? I am just started doing some research on these...
Tks

I bought it on Ebay they seem to have the best price $120 + 25 US shipping = $190 CDN after taxes the seller was Keith's rv surplus, great guy to deal with. I looked at others,everybody that owned this converter seemed to like it, I didn't go with the pendant thing the other owners said they never used it and it has a flashing lights, I don't want any flashing lights!