maddan
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Post by maddan on Jul 31, 2016 9:28:22 GMT -8
Recently purchased a new tow vehicle which required me to upgrade our trailer wiring from 4 way to 7 way. Installed a 7 way junction box to facilitate the wiring connections for the tail/marker lights. Made all the 7 way connections to the junction box terminals. I'm planning the purchase of a battery to be installed on the tongue. Wondering if there is any reason not to use the charge capability of the 7 way lead (when driving), as it may wear out the battery life over time, as opposed to discharging the battery, then recharging to maintain a longer battery life. Curious as to your opinions as it will provide me with the best "positive" wiring scheme. I have a PD 45 amp converter that will connect to the positive battery feed, either direct from the battery, or via the 7 way charge to the positive feed. A circuit breaker will be installed near the battery as well. Your thoughts?
Thanks in advance!
Dan
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Post by vikx on Jul 31, 2016 21:22:21 GMT -8
Yes, use the vehicle charge wire. It won't hurt the battery at all. There just isn't enough juice running thru the long wire from the front to do much. It just helps the battery charge on the road.
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Post by rogerthedodger on Aug 1, 2016 6:31:57 GMT -8
vikx is right. The charge line from the tow vehicle is like a trickle charger. Also, the tow vehicle will not overcharge the battery.
Roger
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Post by Ross on Aug 1, 2016 7:05:04 GMT -8
I have heard that you should install a battery isolator relay, so if you forget to disconnect the 7-way, it won't drain your tow battery.
Is this still true?
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cowcharge
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Post by cowcharge on Aug 1, 2016 8:55:30 GMT -8
An isolator switches alternator charging to the secondary battery after the vehicle battery is charged.
AFAIK the biggest reason for using one is so that two differently-sized batteries aren't being charged at the same time, leading to the larger being undercharged while the smaller is overcharged. As well as having one battery discharge itself trying to charge the other when the vehicle's not running.
Also, a larger wire from isolator to camper battery than that within the harness would allow the alternator to actually charge with some good current, instead of losing most of it through voltage drop. It shouldn't overcharge, assuming the voltage regulator is working well, because the voltage from the alternator is below what battery manufacturers recommend, just as it doesn't overcharge your car battery. It wouldn't get you to 100% unless it was a very long drive, but it would be great to get you up to 80-90% after a deep discharge.
When I had two big old solar batteries (8L-16s) in my old van, I used an isolator and the alternator as the only charging, and it worked well to run my desktop computer (with 75-watt surround sound) off an inverter in the library parking lot and other places when I was using their wi-fi. I ran #8 cable directly from the isolator to the "house" batteries to get the most amps.
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Post by vikx on Aug 9, 2016 20:33:38 GMT -8
I have heard that you should install a battery isolator relay, so if you forget to disconnect the 7-way, it won't drain your tow battery. Is this still true? Most modern vehicles turn the 7 way charge line off if the ignition is off... So you would need an isolator for an older car or truck. |
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