AC charging a tow vehicle while driving

[wb9wb]

http://www.genuinedealz.com/ - Very good prices on high quality wire.

thanks, this looks like a good source for many things I will need.

 

[luthj]

It depends on the model, but many CPAPs use about 3-5A, or about 30AH per night. There is a lot of variance though. There are many poor chargers that go to float WAY to soon. This can have a major impact on the life of a battery. So you may want to make sure the charger is doing its job, and holding the absorb voltage for at least a couple hours after a discharge that deep.

 

[shade]

I mainly use it while camping with a CPAP. Which draws about 1ah.

What's the make & model? That sounds extremely low for an entire night.

 

[dwh]

So your are saying that Andrew White (in the video ) is wrong

Dunno. Didn't watch the video. Don't need to since I know exactly how this stuff works. But if you were repeating what he said, then yea, he's wrong.

and there is another reason that my DC charging using a dual setup / battery isolated failed to maintain a proper charge during my 3,000+ mile trip this summer?

Dunno. You said you used an isolation transformer. Since that can't possibly be correct, you must have something else. But since you have not accurately described whatever it is that you actually have, there's no point in trying to troubleshoot it.

 

[wb9wb]

It depends on the model, but many CPAPs use about 3-5A, or about 30AH per night. There is a lot of variance though. There are many poor chargers that go to float WAY to soon. This can have a major impact on the life of a battery. So you may want to make sure the charger is doing its job, and holding the absorb voltage for at least a couple hours after a discharge that deep.

Yes, but I don't use/don't have a humidifier or warm the tube. Just the air pump.

I' have a voltage gauge and check how much voltage the battery is at. This charger desulfates as well.

I had seen Andrew White say in another video that instead of hooking up a dual battery without the proper charging system, you would be better off just buying a cheap $100 starter battery and using it in parallel as a deep cycle battery then throwing it away after a year or two rather than trying to charge a deep cycle and starting battery together off the alternator. I thought I would try my DC to inverter to AC trickle charger idea first and see what happens and so far it works for me.

thanks.

 

[wb9wb]

Dunno. Didn't watch the video. Don't need to since I know exactly how this stuff works. But if you were repeating what he said, then yea, he's wrong.




Dunno. You said you used an isolation transformer. Since that can't possibly be correct, you must have something else. But since you have not accurately described whatever it is that you actually have, there's no point in trying to troubleshoot it.

I said "battery isolator", not "isolation transformer".

You should probably watch the video or not.

thanks for responding.

UPDATE: you are correct. I mispoke. thanks.

 

[luthj]

using the vehicle's alternator and an isolation transformer

Just saying.

 

[wb9wb]

Just saying.

oops. my mistake. thanks for catch that. I meant battery isolator.

 

[dwh]

But let me throw a guess at it.

Perhaps what you actually have is a diode-type isolator. These are sold at any auto parts store. They have a big heatsink for the diode. They are notorious for having about a half a volt drop through the diode.

Perhaps you also have a Toyota vehicle. Notorious for maintaining the electrical system at about 13.9v.

Combine those two problems and perhaps your batteries are only presented with 13.4v as a charge voltage. That might be enough to top off the 0.2 amp hours used from the cranking battery to start the engine, but is nowhere near the 8 hours at 14.5v needed to fully charge a house battery.

 

[wb9wb]

To clarify this is the battery isolator I use.

Batteries & Power

Upgraded batteries and power accessories in marine and power sports vehicles ensure reliable starts, extended power for electronics, and the freedom to crank up the tunes for a more thrilling ride.

stingerelectronics.com

 

[wb9wb]

But let me throw a guess at it.

Perhaps what you actually have is a diode-type isolator. These are sold at any auto parts store. They have a big heatsink for the diode. They are notorious for having about a half a volt drop through the diode.

Perhaps you also have a Toyota vehicle. Notorious for maintaining the electrical system at about 13.9v.

Combine those two problems and perhaps your batteries are only presented with 13.4v as a charge voltage. That might be enough to top off the 0.2 amp hours used from the cranking battery to start the engine, but is nowhere near the 8 hours at 14.5v needed to fully charge a house battery.

You were correct, I mispoke. I said Isolation transformer when I meant battery isolator.

This is what I use.

Batteries & Power

Upgraded batteries and power accessories in marine and power sports vehicles ensure reliable starts, extended power for electronics, and the freedom to crank up the tunes for a more thrilling ride.

stingerelectronics.com

Amazon price is about $49.

I have 2018 Jeep Wrangler Unlimited.

Again, the DC charging during my 3,000+ trip did not work well. My current AC charging setup seems to work great for me.

 

[wb9wb]

Getting back to my original question.

If AC tow charging is safe if its done properly, and from what I have read, it is.

thanks.

 

[dwh]

That's not a diode-type, which is good. That's a solenoid-type, a.k.a. "split-charge relay".

So with that, failure to fully charge the battery is narrowed down to, A) inadequate voltage, or, B) inadequate time for the battery to fully absorb.

 

[dwh]

And yes, using an inverter to feed a battery charger is an old trick. Often used to top off an off-grid solar battery bank by idling a vehicle instead of running a generator.

Still will require many hours to get the job done.

 

[wb9wb]

That's not a diode-type, which is good. That's a solenoid-type, a.k.a. "split-charge relay".

So with that, failure to fully charge the battery is narrowed down to, A) inadequate voltage, or, B) inadequate time for the battery to fully absorb.

I believe it was voltage. Time shouldn't have been a problem Driving from St. Louis, to Big Bend National park in south Texas, to New Mexico, and to the east coast. and back.

thanks.