7 pin charging

[Gtx Eng]

Looking for some group wisdom, when plugged in to my truck using the 7 pin connector, the airstream has a dedicated 12v 30a fused pin. Will that pin charge the batteries while my truck is running?

Thanks,

[SSquared]

In general, yes.



The "howevers" are

1) some tow vehicles come from the factory without the fuse installed in the circuit.

2) I believe there are some years/models of Airstream where the batteries only charge when the "use/store" switch is set to "use". But most people always have their switch in "use" when they are traveling anyway.

[Bobbo]

Originally Posted by SSquared

In general, yes.



The "howevers" are

1) some tow vehicles come from the factory without the fuse installed in the circuit.

If I am not mistaken, (I often am), it is the General Motors vehicles that need the fuse inserted.

[Gtx Eng]

Thanks guys - appreciate the help.

[Bill M.]

Even with the fuse in place I think the answer is a big maybe. It depends upon the charging system and the wiring. On our truck we get very little power added to trailer batteries that are low even if we tow all day. If you really want to charge the batteries while towing I think you should look at adding a DC to DC converter to the trailer for that purpose. Try it like it is first and see if it really does charge the batteries.

[lsbrodsky]

Everything above I agree with, but for a little more detail as to why this is iffy:
The wire used by the truck OEM is not big enough to carry a lot of current, but it will provide for modest charging. Your truck's charging system brain can drop alternator output so that the alternator output, minus the voltage drop across the long wire run from the alternator to your trailer battery results in almost no charging.
However, Tow Haul, at least on GM trucks(only ones I have experience with) keeps the voltage up at charging level and I do see charging even on my Lithium cells.
Larry

[Gtx Eng]

I have a towing package on my 2500 Ram and will see how it works. I'll report back to the thread with my findings.

[JDG]

If you have a solar package installed on your coach would the batteries not charge via solar while traveling (day travel)?

[Gtx Eng]

Unsure. I don't have solar.

[BayouBiker]

On the Ram, the alternator regulator does not hold voltage high so once the start batteries are charged, system voltage will be around 13.2 so 12.9-13 at the trailer batteries. Without a DC to DC charger, you won't get much above 80% charge even on a long drive.

[SSquared]

Originally Posted by JDG

If you have a solar package installed on your coach would the batteries not charge via solar while traveling (day travel)?

Yes, rooftop solar will charge your trailer batteries while traveling. If your 7-pin charging line is connected through to your tow vehicle's electrical system, the solar may also charge your tow vehicle battery and/or provide support for the tow vehicle electrical functions.



I have 435 watts of solar on my trailer, and I normally travel with the charging line fuse removed from my tow vehicle fuse box. I don't want the charging algorithm on either end overriding what the other is doing.