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Old 07-10-2016, 08:47 PM
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Flat towing behind MH - power connection to battery

The wiring harness was installed but we will not be towing the Cherokee for another month. I still have to get power to the battery to keep it from going flat.

I'd be interested in learning what other members of this forum who flat tow have do to provide power to the battery from the motorhome.

Thanks
GR

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Old 07-11-2016, 06:47 AM
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Re: Flat towing behind MH - power connection to battery

In the best of cases, the tow connector on your MH already has a pin which is "hot" when the ignition is on, and it is controlled by a circuit breaker (or fuse). THe tow cable you get should have an extra wire for this power, e.g.
L-turn/Brake
R-turn/Brake
Taillight
Ground
*12vPower*
(Some MH's may be wired with separate turn and brake signals, in which case a converter may be in order).

I suggest you start by checking the connector on your motorhome; if it's a 6-pin or 7-pin, there's a good chance that it has wiring for all the above but, if it's got everything but the ignition controlled hot line you may be able to wire that line in.
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Old 07-11-2016, 09:58 AM
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Re: Flat towing behind MH - power connection to battery

We have a 7 pin and it has a positive connection (Itasca Impule 26 Silver). I just wonder if it provides enough power to keep the battery adequately charged. Reports of the battery being drained in 3 hours with the new Wiring Harness is what has given rise to my concern.

I currently only use the turn signal and brake light connections and those four wires go out to a four pin connection for mag lights. I'll have to add a power line to the positive terminal and a ground and that is where I start running into a lack of electrical knowledge. The wiring kits I've seen on the web connect right to the positive and negative terminals of the chassis battery of the MH and they have a charge regulator to ensure they don't overcharge the toad battery. Also have no idea what size positive line to run. I assume I don't need anything to the negative terminal. Is the power supply from the 7 pin already grounded?

I dumped an Escape and bought the Cherokee (for DW) in 2013 since I wanted a transfer case so I could hook up to the MH very easily and not worry about anything. So much for that idea - although we towed 6 times for 1500 miles and had no wobble.

I'm still of the view that FCA should be providing a power connection for owners who tow.

GR



ps. My first toad was a Colorado and the dealer who installed my towing package (for a 04 Journey) installed bulbs in the back. When I switched to a 07 Tahoe LTZ (and an 06 Ambassador) I went with a Blue Ox light bar that fitted into the receiver on the Tahoe. I could not use mag lights as they would have been higher than allowed by law. When I downsized the MH and toad I went with mag lights and I find them highly adequate as we only use the MH a couple times a year max.
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Old 07-11-2016, 11:17 AM
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Re: Flat towing behind MH - power connection to battery

Like rpasetto said there must be a way to get power through the harness. That's the only way that makes sense. Towing a vehicle behind a motor home has been done for decades. I'm sure that problem has been anticipated and resolved long before now.

Your best source of info will probably come from a motor home and camper supply dealer. You may have to rewire or add something and the motor home folks can probably do that for you.

I think ground between the vehicles comes from contact between the ball on tow vehicle and hitch on the towed vehicle. Sometimes it takes a few miles for rust to get rubbed off before ground is made and lights will work on my utility trailer if they haven't been used for awhile.

I've never towed a vehicle behind another vehicle so I'm guessing at a lot of this. Worst case you may have to upgrade to a stronger alternator on the motor home to keep up with having to keep so many batteries charged. Best of luck. Again, contact the experts who do this for a living. Maybe a dog chewed a wire in two.

Also as rpasetto stated chech for tripped breaker or blown fuse.
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Old 07-11-2016, 02:48 PM
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Re: Flat towing behind MH - power connection to battery

Quote:
Originally Posted by grandriver125 View Post
We have a 7 pin and it has a positive connection (Itasca Impule 26 Silver). I just wonder if it provides enough power to keep the battery adequately charged. Reports of the battery being drained in 3 hours with the new Wiring Harness is what has given rise to my concern.

I currently only use the turn signal and brake light connections and those four wires go out to a four pin connection for mag lights. I'll have to add a power line to the positive terminal and a ground and that is where I start running into a lack of electrical knowledge. The wiring kits I've seen on the web connect right to the positive and negative terminals of the chassis battery of the MH and they have a charge regulator to ensure they don't overcharge the toad battery. Also have no idea what size positive line to run. I assume I don't need anything to the negative terminal. Is the power supply from the 7 pin already grounded?

I dumped an Escape and bought the Cherokee (for DW) in 2013 since I wanted a transfer case so I could hook up to the MH very easily and not worry about anything. So much for that idea - although we towed 6 times for 1500 miles and had no wobble.

I'm still of the view that FCA should be providing a power connection for owners who tow.

GR

ps. My first toad was a Colorado and the dealer who installed my towing package (for a 04 Journey) installed bulbs in the back. When I switched to a 07 Tahoe LTZ (and an 06 Ambassador) I went with a Blue Ox light bar that fitted into the receiver on the Tahoe. I could not use mag lights as they would have been higher than allowed by law. When I downsized the MH and toad I went with mag lights and I find them highly adequate as we only use the MH a couple times a year max.

If you opt for a separate cable, which sounds like your easiest solution, you could use trailer connectors at each end, using only two of the wires therein, one for ground and one for "hot". Be sure the cable is adequately sized. Based on what I have heard, a 10amp charge line (and ground) should be adequate; that line should be protected with 10 amp fuse (or circuit breaker). Also, a diode, rated accordingly should be placed in the line to prevent the MH end from drawing down the toad battery. Many have said the latter is unnecessary due to the unlikeliness of such an event but my view is that Murphy's Law is always around. :-)

If you go with 10amp line make sure the cable fuse/breaker and all wiring to/from is at least 16gauge. If you feel only 7 amp is enough you could get away with 18awg wiring.

You may want to consider changing to 6-pin or 7 pin connectors at each end so you only have a single connection to deal with. You already have a ground connection with your 4-pin but that line may not be heavy enough to accommodate a charge line also.

I agree with your last sentence, "FCA should be providing a power connection". For the trouble some of us have gone through they should install a charge line, tell us the max and average current draw of the EPS system, and give us a case of beer. :-)
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Old 07-11-2016, 05:46 PM
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Re: Flat towing behind MH - power connection to battery

I'll let you know what we** do and how it works.

GR

**This is where I turn it over to my sos (with all the comments here) and I supervise. He has an MEng and works in the auto manufacturing biz and has also built his own race cars (DSR and GT2). That way I can blame him if anything goes wrong. I mean, a CPA isn't supposed to know a darn thing about electrical connections.
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Old 07-22-2016, 11:48 PM
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Re: Flat towing behind MH - power connection to battery

Finally found exactly what I want and will hope to get one in the next week or so (have to get it across the border).

It covers off the fuse and diode. It also provides a short instructional video. We will not put a connector in the front of the vehicle but will runt the wire right to the 12V pin on the 7 pin connector on the motorhome.

RVibrake Towed Battery Charger, charge line replacement
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Old 07-23-2016, 08:24 PM
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Re: Flat towing behind MH - power connection to battery

Quote:
Originally Posted by grandriver125 View Post
Finally found exactly what I want and will hope to get one in the next week or so (have to get it across the border).

It covers off the fuse and diode. It also provides a short instructional video. We will not put a connector in the front of the vehicle but will runt the wire right to the 12V pin on the 7 pin connector on the motorhome.

RVibrake Towed Battery Charger, charge line replacement
It's your prerogative to spend $50 for a fuse & holder, a diode, and 8' of 16 gauge wire.

You may want to also provide your son with the following information; much of which he probably already knows:

- The MH alternator with voltage regulation (i.e. the motorhome's charging system) will monitor/regulate the voltage and generate the current necessary to keep the toad battery charged.
- Your Itasca probably has a switched 12 volt feed (my 2010 Itasca does) which means you do not need a diode to save your toad battery draining back into the MH battery. IOW, the 12 volt feed is made by a relay that is only closed when the MH ignition is turned on. When the MH ignition is turned off, the 12 volt connection is severed; no way for the toad battery to drain into the MH battery. BTW, there is a cost in using a diode for battery isolation. My understanding it is .7 volt. That's .7 volt less pressure available to do the job.
- It's likely your MH socket has a fuse or breaker protecting the MH side of the connection.
- Your MH's 7-pin socket has a ground prong at 7 o'clock and a 12V+ prong at 1 o'clock as you are facing the socket.
- FCA's Accessory Kit to Enhance Flat Tow harness uses a 10 amp fuse to power up the Electric Power Steering. Using that estimated draw plus the draw for the tail/brake lights and potential toad battery draw, I doubled it to 20 amps max draw. 16 gauge wire will handle that for the about 10 foot stretch of umbilical cord, but I used 10 gauge because it's cheap. Did that for both the negative and positive wires between the MH and toad.
- I bought a marine-grade 10 gauge waterproof fuse holder and a 5-pack of 30 amp fuses for $10 Amazon. That goes in line close to the toad 12V+ battery connection.

My charge line cost me $10 (I had 10 gauge wire laying around my garage) and I would argue it is better than what you will get with the $50 product.
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Old 07-24-2016, 11:19 AM
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Re: Flat towing behind MH - power connection to battery

What you are saying may be true but it may also break down a bit when one considers the value of the time involved. One takes 15 minutes and the other could be much more.

GR
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Old 07-26-2016, 02:16 PM
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Re: Flat towing behind MH - power connection to battery

Here is another for $80 that is even more elaborate.

I ruled this out a few weeks ago as overkill.

GR

https://www.rvupgradestore.com/TOAD-...-charge-40.htm
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Old 07-27-2016, 10:07 AM
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Re: Flat towing behind MH - power connection to battery

Quote:
Originally Posted by grandriver125 View Post
Here is another for $80 that is even more elaborate.

I ruled this out a few weeks ago as overkill.

GR

https://www.rvupgradestore.com/TOAD-...-charge-40.htm
I was going to use the Hopkins (Brake Buddy) battery maintainer for $20 until I learned I could DIY with heavier gauge wire and less cost.

https://www.amazon.com/Hopkins-39332.../dp/B004RCXB8A
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Old 07-29-2016, 02:01 AM
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Re: Flat towing behind MH - power connection to battery

Quote:
Originally Posted by Array View Post
I was going to use the Hopkins (Brake Buddy) battery maintainer for $20 until I learned I could DIY with heavier gauge wire and less cost.

https://www.amazon.com/Hopkins-39332.../dp/B004RCXB8A
Have you done it yet? If you have could you describe in detail the connections and results? I assume wire run from positive terminal on Jeep battery to the 12V pin in the 7 pin plug going into the 7 pin female unit on the MH? And how did you ground or are you relying on the existing ground?

GR
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