Charge from 7 pin trailer connector

[Yellowreef]

Does anyone know what kind of voltage goes through the 7 pin trailer connector to the trailer? I have heard it's enough to trickle charge the house battery as you drive but just wondering how much of a charge that would actually provide. For example, if I pick up the trailer from storage and the house battery is showing at 3/4 charge from drain would a 6 hour drive bring it to full charge? Would it even make a dent or would it just basically maintain the charge already there?

[336muffin]

If wired correctly, it will bring it up to full charge. Same as your tow vehicle's battery. This doesn't take long at all.

[JimM68]

Due to the nature of voltage and current, it will deleiver what is asked for, until and unless it blows the fuse. Most are fused at 10 or 20 amps.

[Ray,IN]

It depends entirely on the size and length of the charging wiring. Most vehicles and trailers use under-sized wire which reduces the amperage received at the battery,which results in never getting the "house" battery fully-charged unless you drive all day.
This 12 VDC wire sizing calculator will quickly show the effects of under-sized wire. My entered terms were: 14 ga wire with a 25' run and 30A draw. The voltage at the receiving end was 9.2 VDC; which is a 20% drop.

[Luckiest Dre]

After an attempt to unsuccessfully keep my toad charged with a dash mounted solar charger I was led to believe that running the hot wire from the 7 pin connector to the battery would keep the battery charged. I stopped at a RV electric/hitch business in Ft Myers, Fl and requested he run that wire for me. His input was that he did not like that idea and suggested another, which I bought into.
His solution was to remove the small charger (it is powered by that same wire) from the battery pack that you find on trailers with surge brakes and hard wire it to the toad. Here is a link to what I am talking about. Tekonsha Breakaway Kit with Charger, Clamp On Tekonsha Trailer Breakaway Kit 2028
I have driven the coach/toad for approx., 3000 miles since I had this done and so far so good.

[Yellowreef]

Ok, follow-up question... How long does it take to charge a battery using a battery minder type charger? The reason I ask is because a road trip (with some dry camping) has come up before I am able to buy the generator on my wish list. Now, I figure the batteries will charge some during travel, but in case of emergency I do have a 120ac outlet in my truck that I can plug a battery minder into. Would this even be worth it or would that type of device take entirely too long to have the truck running all that time? Or would it be the same as just hooking up the 7 pin connector and running the truck? I figured maybe run the truck with the battery minder plugged in about an hour or two a day as a poor man's generator just for this trip. Any experiences with this?

[JimM68]

I'd just run the charge wire from the 7 pin connector and call it good.

The battery minder type device is not intended to charge a battery, just to maintain it. They will bring a battery to full charge, but it could take a long time, several days.

How many watts is the inerverter in your truck? probably pretty limited, 400 maybe?

[Yellowreef]

Ok, I'm back from my road trip and I don't think the trailer connector was charging the house battery. Luckily I had borrowed a portable genset from a friend, otherwise I would have had a real bad trip. Basically, the runs down the freeway between stops were all 4-5 hours. When I would get to a destination and check the indicator panel, it would read the same as when I left. How do I check to make sure something isn't wrong with the charging system from the TV to the trailer house battery?

[wa8yxm]

Quote:

Originally Posted by Yellowreef Does anyone know what kind of voltage goes through the 7 pin trailer connector to the trailer? I have heard it's enough to trickle charge the house battery as you drive but just wondering how much of a charge that would actually provide.

WRONG QUESTION.. I will list some possible questions

What KIND of voltage: DC
How much Voltage: Up to the battery voltage of the tow vehicle
How much CURRENT: Now that... That is the question.

Due to the length and size of the wire, Not a whole lot of current. perhaps 10-20 amps. This will, given enough miles, charge your house batteries, but ... Well, depending on the batteries it will take anywhere from an all day drive to several days of driving.

A group 24 for example is about 75 amp hours, if it's half full you have 37 amps to replace. Since current falls as battery voltage rises, that's a good half day or more.

A group 29 (Wall-mart MAXX-29) runs about 105 Amp hours (Long story as to why I researched it)

A pair of U-2200's (intersate GC-2 Golf Car) 220 amp hours.

If half full at 10 amps that would take 11 hours but as I said you won't get full current all the time.

[Yellowreef]

Quote:

Originally Posted by wa8yxm WRONG QUESTION.. I will list some possible questions What KIND of voltage: DC How much Voltage: Up to the battery voltage of the tow vehicle How much CURRENT: Now that... That is the question. Due to the length and size of the wire, Not a whole lot of current. perhaps 10-20 amps. This will, given enough miles, charge your house batteries, but ... Well, depending on the batteries it will take anywhere from an all day drive to several days of driving. A group 24 for example is about 75 amp hours, if it's half full you have 37 amps to replace. Since current falls as battery voltage rises, that's a good half day or more. A group 29 (Wall-mart MAXX-29) runs about 105 Amp hours (Long story as to why I researched it) A pair of U-2200's (intersate GC-2 Golf Car) 220 amp hours. If half full at 10 amps that would take 11 hours but as I said you won't get full current all the time.

Aha! No wonder then. Thanks for the answer I was originally looking for.