AND ANOTHER Camping battery question,....

I have plans for a 4-5 day camping trip this summer.
Tent camping that is. If there is a power outlet at the campsite, it would be at the Host site as I do not recall anything.

What I need is a ResMed DC Power Converter
A good ASM Battery, minimum of 35AH. A 75AH would more than likely provide enough power for the trip, but at twice the cost.

So, to keep costs down
If I get the 35AH battery, what would I need to charge the battery from a vehicle?
is it possible? or would the vehicle be idling all...day....long just to charge the battery?

Using the vehicle to charge the battery while NOT DRIVING is a poor solution. It's slow and hard on the engine. Also two 35 amp would be better than a 75 amp, much easier to carry. Two can be charged faster also. Jim

Thats what I thought.

Just trying to check options.
Solar panels would be best but they are $$$
hard to justify that cost for something done maybe once a year.

may just have to suck it up and buy the 2-35AH batteries.

AND ANOTHER Camping battery question,....

by KenM » Fri Feb 23, 2018 10:05 am
I have plans for a 4-5 day camping trip this summer.
Tent camping that is. If there is a power outlet at the campsite, it would be at the Host site as I do not recall anything.

I would find out if there is power at the host's site. Bring a battery charger, three way adapter and an extension cord. If there are hookups elsewhere, some RV'rs are nice and let you "borrow" the 120 outlet, especially since they use the 240v.
The three way adapter is so you don't hog the outlet, and the extension cord is just long enough to get your charging station out of the way.

KenM wrote: ↑

Fri Feb 23, 2018 11:05 am

I have plans for a 4-5 day camping trip this summer.
Tent camping that is. If there is a power outlet at the campsite, it would be at the Host site as I do not recall anything.

What I need is a ResMed DC Power Converter
A good ASM Battery, minimum of 35AH. A 75AH would more than likely provide enough power for the trip, but at twice the cost.

So, to keep costs down
If I get the 35AH battery, what would I need to charge the battery from a vehicle?
is it possible? or would the vehicle be idling all...day....long just to charge the battery?

A typical ResMed or Respironics cpap, without humidifier or heated hose, and not using an inverter, will use 4 to 10 Amp-hours a day from a 12V battery. Whether you're on the low or high end of that depends on the model pump, the pressure, and the altitude. At the low end, a 35 AH AGM battery has a good chance of running for 4-5 days, and at the high end you might well need two batteries, still not a huge expense. A big problem is that you'll really have to guess at the usage. With experience you might be able to translate the voltage to a charge level, but the first time you'll just be guessing!

Your best bet (other than a spare battery) would be to bring the charger and try to plug in somewhere. You could charge from the car - running for an hour would probably add about 8 AH, or enough for a night or two. The deeper the discharge, the more it will accept, so don't expect to top it off this way. When I run an engine to charge on my boat I expect to go from 50% to 85% in about 75 minutes - this actually works out for many AGM setups because they have similar acceptance rates.

Solar power is certainly viable if you have the right location - I rely on solar for most of my power during the summer - but its a large investment for one trip, trickier than you would think to get going well. The second battery is the best insurance. BTW, there are also 50 AH batteries, etc.