Let's get creative electrically.

[Old Henry]

This is a continuation of my "How many watts will this inverter run" thread here: https://www.fordbarn.com/forum/showthread.php?t=192364

Here's what I'm trying to do. I'm trying to figure out a way to charge a 12 volt battery from my 6 volt generator while I drive to Alaska. I've got to have the 12 volt battery to run my CPAP machine when I'm camping in my tent at night.

The idea I've had so far is to use an inverter to change my 6 volt positive ground to 12 volt negative ground to run a 110 volt inverter to run a trickle charger to charge the 12 volt battery during the day while I drive. I will not be using the inverter for anything else. Just that.

Here's my dilemma so far: The only inverter that I've found that will switch 6 volt positive ground to 12 volt negative ground is the Custom Autosound inverter. The problem with that is that it only puts out 2.1 to 2.5 amps 12 volt. My 110 volt trickle charger only uses 1.3 amps but the inverter to boost the voltage from 12 volts to 110 volts may use enough more to be too much.

So, here's an alternative that I've thought of that I'm wondering whether it will work:

Custom Autosound also makes a voltage booster that will boost 6 volt negative ground to up to 5.0 amps of 12 volts negative ground. That's twice as many amps to run the 12 volt to 110 volt inverter and power a 12 volt battery charger. So, I'm wondering if I could connect such booster directly to the battery using the negative post for it's ground then wire a 12 volt power socket to the booster to run my inverter from? Then I could get 5.0 amps instead of just 2.5. One question I have is whether my generator would put the right kind of current through the wiring to the booster or would it be backwards even though I have the booster hooked up to the battery negative ground? I actually ran my car with the battery hooked up backwards for some time and the generator worked just fine. What do you think. Any thoughts or other better ideas?

[Brian]

I know of your desire to keep the appearance of everything dead stock, but the reality is the 'better idea' is to convert to 12 volt neg ground system. You can do it so the only thing that would not appear 100% stock would be the battery!! No-one sees it anyway unless you've got the hood up. And even then....so what? 99.9999999% of people wouldn't even know!
And now you're talking about 6 volt neg ground? That ain't original either!
You've got other little gizmos 'hidden' away within the interior of the car that you've so proudly posted pictures of in the past that are far more visible to the general populace than a 12 volt battery.

What is CPAP? Honestly? I've got no idea! Please explain.

[Curt in AZ]

Interesting problem. Here is a larger inverter (http://www.powerstream.com/dc6-12.htm) that has adjustable output so you can control the charge rate. A gentle charge voltage of about 13.5 should work as long as the 12v battery is not too discharged. Lots of things to consider but the powerstream.com people are in Orem so why not give them a visit to discuss what you need?

Our carry a second 6v battery wired through an isolator for 12 volts for night use. You'd need long wires to your tent or wherever the CPAP is. And be careful to not discharge to much so the old Ford will still start in the morning. Maybe too creative an idea. And I'm with Brian: what is CPAP?

There is so much wasted energy in a car I'm surprised there aren't waste heat recovery solutions.

[Curt in AZ]

Meant to say converter, not inverter.

[Old Henry]

CPAP: Constant Positive Airway Pressure. For treatment of Obstructive Sleep Apnea. https://www.nhlbi.nih.gov/health/hea...cs/topics/cpap Can't sleep without one.

[35fordtn]

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Why not just get a solar charger and mount the solar panel on the rear package tray shelf.

[35fordtn]

One such as this ... http://www.amazon.com/NOCO-Battery-B...attery+charger

[Old Henry]

Originally Posted by Curt in AZ

. . . carry a second 6v battery wired through an isolator for 12 volts for night use. You'd need long wires to your tent or wherever the CPAP is. And be careful to not discharge to much so the old Ford will still start in the morning. Maybe too creative an idea.

No idea is too creative. I want them all. You've given me a take off idea: Have a second 6 volt battery hooked up parallel to the car 6 volt battery that is charged with the car battery during the day. Then, at night, disconnect the car battery and hook it in series to the spare battery. Voila! A 12 volt battery all charged up and ready to go that will last way longer than a single 12 volt battery would. No double inverters running a 110 volt battery charger. The only big expense is the second 6 volt battery. May be worth it. (The inverters are $60.00-$100.00.) I'd eventually use the battery in the car anyway some day.

Thanks for the tip.

P.S. If it drained the car battery too much I've got two 12 volt jump starters to start it up with.

[Old Henry]

Originally Posted by 35fordtn

Why not just get a solar charger and mount the solar panel on the rear package tray shelf.

Originally Posted by 35fordtn

One such as this ... http://www.amazon.com/NOCO-Battery-B...attery+charger

I had thought about that but was thinking I'd have to cover the roof with panels. I'll will look into that further. It would be cheaper than a second 6 volt battery. (I already have two RV 12 volt batteries if I can figure out how to charge them so I wouldn't have to buy a second 6 volt one.)

[Mtn Wudy]

Just an idea.....
Run a charging wire from the cars battery to the trunk ...Charge two 6 volt Motorcycle batteries in parallel during the day...At the end of the day ,remove them from the cars system,hook in series for 12 volts to run C-Pap....You could just make it a two 6volt system in car but if you went back to use it to start car and it was dead ...You'd be Pushin' the car ....

[donald1950]

make sure your generator can charge all that.. but the two 6v motorcycle batterys sounds like a good idea........

[flatheadmurre]

Not sure how much current the device needs, but a couple of them sealed lead batterys for alarm and UPS and a current limiter to let them slowly charge up during the day.
Hooking uncharged batteries in parallel to a fresh one without a limiter will give fastcharging and lots of fumes that may corrode the trunk.
Solarpanels are real good today so check that out.

[Mart]

Why not carry a 2nd 6 volt battery and use a camper style split charge system to keep it charged. Then you would always have a spare battery in case your main battery goes bad, and you could connect the two batteries in series to give you 12V.

I trust your machine would not flatten the batteries overnight so you would be able to restart the car in the morning.

Personally I'd convert the car to 12V neg ground. Nothing you would do could not be reverted to 6V pos ground at any time in the future.

Mart.

[pooch]

Check the watts needed for your machine.

2.5 watts solar panel would give you about 10 watts of power all day IF you were facing the sun all day.

Would not even gain enough charge to run a flashlight.

If you do not want to carry a FEW batteries or a huge one, I suggest a small quiet generator.

Most people have no idea how much power devices use over a long period of about 12 hours like this cpap machine.

DO NOT involve your starting battery in your equations or you will be breathing very hard in the morning push starting.........


Interesting reading ....seems like how you run it, as to what pressure and if you use the humidifier, can be 4.5 amps, which is about equivalent to one headlight on all night .

http://www.healthyresources.com/slee...s/power03.html

[Terry,OH]

It may be time to convert the car to 12V run one optima battery. An alternator can be installed into your generator body to keep the appearance. What is the CPAP load? Can one optima support the CPAP and maintain enough charge to start the car in the morning. Many camp grounds do have electrical hook ups for RV's.

[jimTN]

Or, put a double pulley on the gen and have a shop fab a bracket to mount a 12vt single wire alt off to the side to charge your 12v bat. There is lots of room under a 46-8 hood. Those double pulleys came on trucks.

[Mike51Merc]

OK, call me crazy Henry, but aren't you going around in circles?

You converted 6VDC to 12VDC so you can run an inverter to make 110 AC so you can plug in a charger to convert 110AC into 12VDC.

Why don't you just charge your 12V battery from the first converter?

[JSeery]

I think the first step would be to determine what it takes to run the CPAP. Do you know how long it will run off of a 12v battery?

[Old Henry]

Originally Posted by JSeery

I think the first step would be to determine what it takes to run the CPAP. Do you know how long it will run off of a 12v battery?

I have run the CPAP all night on a 12 V battery without any problem

[flatford8]

How about a small Honda generator. They dont weigh much and are very quiet. Then you'd have lights and power for other things.... Mark