How long to recharge RV battery while driving?

JWRoberts wrote:

korbe wrote:
I have had that same question. I tested mine after I got back from a trip.

My 2 6-volt T-105's (225ah) were down to about 50 percent when we started driving down the road. I used my hand-held volt meter to test that percentage. I tested the rested batteries the next morning after a 10 hour drive. My volt meter tested them at 90 percent. Nothing but the parasitic draws while driving down the road. No fridge or TV. :)

Not scientific by any means but it satisfied my curiosity.

A voltmeter can not determine the state of charge of a battery. Only a load tester can do that. You were probably well below the 50 and 90 percent that you stated.

Well, I have been using my volt meter and measuring the readings in volts for a lot of years. Doesn't the volt reading measure state of charge? I must be missing something.

sgrizzle wrote:
If you are camping without shore power and you basically drain your battery...how much driving (hours) would you need to go to recharge them for the next stay?

Generally speaking, just rough guestimates....thanks!

Assuming you have a Tow Vehicle, then it can supply about 10amps while driving. So if a 200AH battery is totally dead, you'll need to drive about 20 hours. Of course there are lots of variables to consider such as age and condition of the battery and the actual current delivery.

korbe wrote:
I have had that same question. I tested mine after I got back from a trip.

My 2 6-volt T-105's (225ah) were down to about 50 percent when we started driving down the road. I used my hand-held volt meter to test that percentage. I tested the rested batteries the next morning after a 10 hour drive. My volt meter tested them at 90 percent. Nothing but the parasitic draws while driving down the road. No fridge or TV. :)

Not scientific by any means but it satisfied my curiosity.

A voltmeter can not determine the state of charge of a battery. Only a load tester can do that. You were probably well below the 50 and 90 percent that you stated.

8-12 hours generally speaking

'Charge' line for tow vehicle is LONG and UNDER sized.
Best for maintaining a trailer battery vs charging one

Generally speaking......

I have had that same question. I tested mine after I got back from a trip.

My 2 6-volt T-105's (225ah) were down to about 50 percent when we started driving down the road. I used my hand-held volt meter to test that percentage. I tested the rested batteries the next morning after a 10 hour drive. My volt meter tested them at 90 percent. Nothing but the parasitic draws while driving down the road. No fridge or TV. :)

Not scientific by any means but it satisfied my curiosity.

What sort of an RV are you talking about? What size battery bank? Obviously a larger battery bank will require longer to recharge, all other things being equal.

For a trailer relying on the power feed from the 7 pin connector, it may take a very long time indeed, and partly depends on how beefy the wiring is on the tow vehicle to the seven pin connector. Likewise, you have to consider how large or small the continuing loads are that must be simultaneously powered (fridge, LP detector, any lights or fans that are on, the furnace if you leave it on to keep things from freezing, ....)

For a motorhome with good wiring between the isolator and the house battery, it is a good bit faster, possibly on the order of a few hours to mostly recharge the battery. The quality of this wiring and setup can vary.

The best way to find out is to actually measure the charging current and voltage you're seeing at the house battery under the stated conditions, and get actual data for your rig. Otherwise you're pretty well in the "how long is a rope" sorts of questions and answers.

Generally, charging via the umbilical cord will take forever. You're looking at maybe 10amps through that little wire.