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 > Tow vehicle charging RV batteries

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theoldwizard1

SE MI

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Posted: 12/05/20 11:52am Link  |  Quote  |  Print  |  Notify Moderator

jdc1 wrote:

Dual alternator. Best you could ever do. Some super duties come equipped that way.


time2roll wrote:

Single alternator has plenty of amps. The trick is getting the proper voltage on the battery that needs charging. A DC-DC charger will work excellent for this purpose. Still takes 3 to 5 hours to get a flooded battery from low on charge to 95%+.

I agree with t2r ! The time it takes to recharge depends on the size of the battery bank and how far it is depleted.

One 12V "dual purpose" battery will recharge much faster than four 6V golf cart batteries if both are at 50% state of charge.

BarabooBob

Baraboo, WI

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Posted: 12/05/20 11:52am Link  |  Quote  |  Print  |  Notify Moderator

I added a 6 gauge wire from the alternator to the TT battery. I did install a circuit breaker on each end to avoid problems. My voltage meter in the TT definitely shows and improvement over the charge line on the 7 pin TT plug.

When I owned my Class C, I had to replace my battery isolator and I ran 6 gauge wire from the isolator to the battery, about 8 feet. I improved my house battery charging immensely.


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BarabooBob

Baraboo, WI

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Posted: 12/05/20 11:53am Link  |  Quote  |  Print  |  Notify Moderator

I added a 6 gauge wire from the alternator to the TT battery. I did install a circuit breaker on each end to avoid problems. My voltage meter in the TT definitely shows and improvement over the charge line on the 7 pin TT plug.

When I owned my Class C, I had to replace my battery isolator and I ran 6 gauge wire from the isolator to the battery, about 8 feet. I improved my house battery charging immensely.

theoldwizard1

SE MI

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Posted: 12/05/20 11:55am Link  |  Quote  |  Print  |  Notify Moderator

JCK wrote:

I’ve seen as high as 18 amps going to trailer batteries on start up of truck. And hour later or so still seeing 6 amps. Even if voltage is 13.2 to 13.4 amps is what gets the job done. Sure it won’t fully charge but on a 4 to 6 hour run I’m usually close to full charge.

You will NEVER get a "full" charge on any type of lead acid battery if the voltage is only 13.2V. "Close" is very vague. 80% ? 90% ?

theoldwizard1

SE MI

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Posted: 12/05/20 12:01pm Link  |  Quote  |  Print  |  Notify Moderator

BarabooBob wrote:

I added a 6 gauge wire from the alternator to the TT battery. I did install a circuit breaker on each end to avoid problems. My voltage meter in the TT definitely shows and improvement over the charge line on the 7 pin TT plug.

Try this test. Run your TT battery down to about 75% SOC (12.4V with no load). Start your tow vehicle and immediately check the battery voltage using a meter. As quickly as possible, check the voltage at TT battery. Drive for about 10-20 minutes and repeat the two measurement with the engine running. Check also at high idle.

You will be surprised how low the voltage at the TT battery is !

Seon

Lake Camanche, CA

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Posted: 12/05/20 12:13pm Link  |  Quote  |  Print  |  Notify Moderator

valhalla360 wrote:

theoldwizard1 wrote:

Seon wrote:

As a backup I carry a 12v charger powered by a 2K generator.

The 12VDC output on most of today's generators does a poor job of recharging a lead acid battery. You are better off plugging in a AC battery charger.


I presume he meant a generator putting out 120v AC power a dedicated charger outputting 12v.



Yes, I plug a 12v a/c charger/maintainer into the 2k generator putting out 120v ac to charge the batteries.

JCK

Ohio

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Posted: 12/05/20 12:13pm Link  |  Quote  |  Print  |  Notify Moderator

Old wizard 13.2 to 13.4 is measured at the trailer batteries truck idling. After a 6 hour run home stop for lunch in camper Refrigerator on gas lights on for lunch a few other parasitic loads. I back in barn use battery disconnect 24 hours later I can check battery voltage and it will be 13.1 volts check it many times . The AGM do carry a higher voltage though.
What I’m getting at is my truck has no trouble keeping my batteries up traveling even after a night of Wally World. Where you run into trouble is when you try to charge a big battery bank. I have 2 AGM capable of supply 80 amps to 50 % state of discharge


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pianotuna

Regina, SK, Canada

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Posted: 12/05/20 02:50pm Link  |  Quote  |  Print  |  Notify Moderator

a 2nd alternator works well--but best bang for the buck is a dc to DC device. If you are doing flooded--set it to 14.8 volts.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, soon to have SiO2 batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

noteven

Turtle Island

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Posted: 12/05/20 02:57pm Link  |  Quote  |  Print  |  Notify Moderator

DC-DC battery charger with correctly sized wire, breakers, and connector to the tow vehicle.

A 40 amp output Renogy charger will draw up to 60 amps.

This equipment works really well in overcast, rain, snow, and at night.

wanderingbob

monticeeo, fla

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Posted: 12/05/20 03:21pm Link  |  Quote  |  Print  |  Notify Moderator

Lwiddis asked whats for lunch , today we are having poached armadillo over swamp cabbage , possum gravy ,greens , black eyed peas and venison ribs ! Just a plain ole Florida Cracker meal . Maybe alligator fingers if I ken find em . YUM YUM .

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