artfuldodger
St. Catharines on. Canada
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Joined: 10/25/2004
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I've been trailering 6 years now and have a rather fundamental question to ask. Does the trailer battery charge while I'm driving and if so, what is the charging circuit? I want to install an inverter(1200 watts) and the instructions call for a car battery isolator so that the inverter, while in use, doesn't discharge it too. Where does the isolator go? The instructions are not specific. Also how long can I expect to use the inverter before my one trailer deep cycle battery requires recharging? (how many watt-hours approx.)
artful dodger
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Mad_Dog1999
Pullman, Washington
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Joined: 03/12/2005
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It all depends on how you are wired in your TV, 7 pins can charge the battery through the connnector. You can talk to whoever wired your rig or just try and follow a wire from back from the connector to the battery or fuse box. suppose you could also discharge the battery down most of the way and then run your motor and see if you gain a charge but that could take a while and end you up with a dead battery. if you never charge the battery and it doesn't charge on the ac (wall plug) then you must charge off the connector to your rig. good luck with the inverter.
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PA12DRVR
Anchorage, AK
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Joined: 09/17/2003
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artful,
Can't answer all of your questions (maybe can't "answer" any  )
A 7-pin connector should charge your TT while it is hooked up to your TV. On recent GM vehicles you have to put a fuse in to energize the charging circuit.
On my TT with a 900 watt (IIRC) inverter, I lasted about 3 days without charging the battery, but that was in the spring, when I spent little if any time in the TT.
CRL
Displaced Alaskan NO MORE!
My RV is a 1946 PA-12
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Chuck&Gail
In the Colorado Mountains
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If you unplug the cord between the trailer and the TV when using the inverter, you can forget about the battery isolator. That's what we do.
On a Bargman 7 pin connector, used on most trailers I've seen, pin 4 is the battery charge line. You can easily verify this on your rig with a cheap voltmeter.
Chuck
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tcsmith
Centennial, Colorado, and Charlottesville, VA USA
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Here's a simple test to see if your battery is getting "juice" from the tow vehicle:
Disconnect the TT from 110v electric completely.
Disconnect the TT from your TV completely.
Disconnect the TT Battery (negative first, then positive).
Take the neg/pos cables and join them together, in effect "bypassing" the battery.
Plug in the trailer connector into the TV. Check for electricity in the TT by turning on a light or two.
If you get Light, you have 12v coming from the TV. Validate this by disconnecting the TV/trailer connector and watch the light go out.
Don't forget to hook up your battery again - as this is required for the emergency brakes to function on your TT!
Isolators for the TV battery will allow the trailer circuits to be CHARGED from the TV battery, but will prohibit the reverse - DISCHARGING the TV battery.
A lot (not saying all here) of TT's do charge off the 7-pin connector, as it is a convenience to have your battery charge as you're going down the road. Installing an isolator gets into some re-wiring, so I won't go there "here" but you can do it. It may be easier, although less 'convenient' to just disconnect the charging circuit at the TV's socket (if you have one).
Good Luck!
-Tracy
Tracy & Jennifer Smith + 5 Boys (no room for a dog!)
1999 Dodge Ram Maxi-Wagon 3500 and 1999 8300 Trail-Lite TT
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chipster
Lasalle, Ontario, Canada
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Quote:
Take the neg/pos cables and join them together, in effect "bypassing" the battery.
-Tracy
just in case someone does not understand this the way I interpreted it the first time. Connect the POS to the POS and the Neg to the NEG. Do not join the baterry leads together like this could be interpretated.
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YC 1
Yuba City Calif.
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Hook trailer up to tv. Leave engine off. Do not connect shorline power. Go inside and turn several lights on. Start tow vehicle. If lights get brighter, then your battery is getting charged.
Same test applies to using shorline power.
Your alternator on the tow vehicles is what charges the battery. The output will be around 13.5 volts when running. With engine off your battery will be around 12.5 volts. So you should easily see the lights get brighter. This may not apply to fluoresent lights.
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prairiesurfer85
Independence, MO
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Quote:On recent GM vehicles you have to put a fuse in to energize the charging circuit
We noticed this when my 5er dealer installed my hitch and put a plug in the bed. There was no power on the +12V wire. I had not missed it on my TT since I had solar and generator anyway.
Not to hijack this thread, but I have a question. Is there an isolator on the circuit that feeds that fuse on the TV and is there a current limiter? I can see a TT having a low battery, then blowing the TV fuse.
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david&joan
Newport Beach, California
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Joined: 08/19/2003
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Wow, not to be a real smarta** but there is more misinformation and half truths in this thread than I have seen in a long time.
The standard 7 pin connector has a pin for trailer battery charging. It may not always be wired up if it was not a factory installation- it all depends on what the installer did.
But if it was a factory installation, as part of a "tow packeage" it usually is wired something like this (example taken from my 2003 F150):
Power is supplied to this circuit from an isolating relay that only supplies power when the engine is running. So you don't have to worry about running down your TV battery when you are connected to your trailer- the relay isolates the Tv from your trailer when the engine is not running.
There is a 30 amp fuse in the main fuse box that protects this circuit. I have read in this forum that Chevy/GMC trucks leave the factory with this fuse not in place but a dummy fuse installed. Why is a great mistery that only GM can explain. But the fuse can be replaced easily to energise this circuit.
With everything connected properly, this circuit will charge your trailer's batteries at a maximum of about 15 amps. This is due to the fairly large voltage drop in the 10 gauge wiring from your fuse panel through 30-40 feet of wire to your trailer's battery. This amperage will drop off as the batteries become more fully charged.
If my 220 amphour batteries where one half discharged, I could usually add about 40-50 amphours back into them after driving for 4 hours. This was about a day's worth of energy consumption. So, this wasn't a very efficient way to recharge your batteries, but if you do a lot of driving between campsites then it might work out ok.
Another way to determine if your TV is charging is to watch the LED battery monitor. If it is showing 1/2 or so discharged, then hook up your TV and run the engine in idle for a few minutes with all lights and other loads switched off. The LED lights should move up to 3/4 or full charged. It really isn't fully charged but is reading the higer voltage that the TV is sending to the battery thereby fooling the crude battery monitor into telling you that you are fully charged.
A better way is to hook up a voltmeter to the battery terminals. Start the TV's engine and watch the votage go up a 1/2 volt or more.
David&Joan
2003 F150, 5.4L, LWB
Okanagan UL23-5 5er
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