To be brief....I have two new 6 volt Interstate batts in my fiver. Came home from a camping trip yesterday, about a 2 hour drive. My batts were 6.03 when we left camp. Still 6.03 when we got home. I had thought it would have charged some on the trip. Is this typical?BTW, I bought the 6 volt on advice from the good people on this forum. First experience very positive. Thanks all who contributed.

Hoppypoppy wrote:To be brief....I have two new 6 volt Interstate batts in my fiver. Came home from a camping trip yesterday, about a 2 hour drive. My batts were 6.03 when we left camp. Still 6.03 when we got home. I had thought it would have charged some on the trip. Is this typical?BTW, I bought the 6 volt on advice from the good people on this forum. First experience very positive. Thanks all who contributed.You have them hooked up as 12 volt I am sure.What is the combined voltage of both batteries taken as 12 volt plus?Are you getting charge voltage from your tow vehicle 7 pin connector?

As you plug into the running vehicle, the trailer battery should pop up about 0.5 to 1.0 voltsCheck it.

It charges if the tow vehicle is wired to do so.

beemerphile1 wrote:It charges if the tow vehicle is wired to do so.Use your volt meter and measure your seven pin connector at the back of your TV with the trailer plug disconnected. You should have approximately 13.5VDC when measuring from pin 1 (Ground) to Pin 4 (12v). If you have no voltage between pin 1 and pin 4, let us know the type of TV and we'll help you trouble shoot it.Jim

What is your tow vehicle ? ......my 2009 GMC Duramax owners manual says truck has to be in "tow/haul" or "have headlights turned on" to send charge to trailer plug.....don't ask me why, but that's what it says!

Batteries Charging While Towing Question | Good Sam Community

13 Replies

wa8yxm
Explorer III
Oct 30, 2013
Sorry Guess by the time I got down to the reply box I'd forgotten a zero in the voltage.

Another factor is there is a lot of wire and small wire at that, between the tow vehicle alternator and the Trailer batteries.. This can "Slow" charging big time. and you have over 200 amp hours of batteries.
Z-Peller
Explorer
Oct 29, 2013
From GM....
Camper/Trailer Battery Charging Concerns
Some customers may comment that when towing or hauling a camper/trailer, the auxiliary battery for the camper/trailer will not stay charged. In most cases, this concern is blamed on the new RVC system. While the RVC system does reduce the generator's targeted output voltage to 12.6-13.1 volts when in "Fuel Economy Mode", this feature is bypassed if the tow/haul feature is enabled. With the tow/haul feature enabled, the RVC system will stay in "Charge Mode" and the targeted generator output voltage will be 13.9-15.5 volts, depending on the battery state of charge and the estimated battery temperature. To keep the generator in the "Charge Mode", use either of the following two methods.

• The first method is to use the tow/haul mode when towing or hauling a camper or trailer.

• The second method is to turn on the headlights, which will increase the generator's targeted output voltage to 13.9-14.5 volts.
__________________

2005-2009 GM trucks apparently, but The Diesel Forum has lots of controversy over whether it applies to trucks over 8600GVW and if both gas and diesel?.....
pianotuna
Nomad III
Oct 29, 2013
Hi,

It is typical. There is simply too much voltage drop for much charging to happen.
JJBIRISH
Explorer
Oct 29, 2013
sh410 wrote:
umm, 6.03 + 6.03 = 12.06V or about 50% discharged

:h

Charts show 12.6 as full charge on a starting battery, depending on how accurate you need to be… 12.7 for a deep cycle…
salem
Explorer
Oct 29, 2013
Wothout knowing what your truck is I'll just throw this in anyway. My '05 Chevy had to have a fuse inserted in the fusebox under the hood before the truck would charge the 5er batteries. Maybe they don't put them in at the factory because not everyone tows, who knows? You might check that.
sh410
Explorer
Oct 29, 2013
umm, 6.03 + 6.03 = 12.06V or about 50% discharged
wa8yxm
Explorer III
Oct 29, 2013
First, you do not have six volt batteries in your RV (Yes I know we both do but that's not how they should be wired)

you have a 2-piece 12 volt battery.

6.3 + 6.3 = 12.6 Which is the resting voltage of a FULLY CHARGED 12 volt battery

So the reason they did not charge, is that they were full up.
Hoppypoppy
Explorer
Oct 29, 2013
Appreciate all the replies. Gave me some areas to start. Looks like a bad plug from the trailer. Unfortunately, the existing plug is the molded type, and is not long enough to cut. So, the $10.00 fix jumped to about a $50.00 fix, but I love the word "fixed!" Thanks again, all.

(my tv is a 2003 GMC 2500HD, but I have never seen where it had to be in tow/haul to charge. Interesting.)
Z-Peller
Explorer
Oct 29, 2013
What is your tow vehicle ? ......my 2009 GMC Duramax owners manual says truck has to be in "tow/haul" or "have headlights turned on" to send charge to trailer plug.....don't ask me why, but that's what it says!
TucsonJim
Explorer II
Oct 29, 2013
beemerphile1 wrote:
It charges if the tow vehicle is wired to do so.

Use your volt meter and measure your seven pin connector at the back of your TV with the trailer plug disconnected. You should have approximately 13.5VDC when measuring from pin 1 (Ground) to Pin 4 (12v). If you have no voltage between pin 1 and pin 4, let us know the type of TV and we'll help you trouble shoot it.

Jim