70 amp alternator

Hi all,

We will be picking up our 2720sl in a few weeks.. can't wait.. Our tow vehicle's alternator is only 70amp.. will that be big enough to run our refrigerator without draining our batteries? if not, i think i read something about being able to buy a bigger alternator.. any info?

thanks for all of your suggestions and help!
Teresa

You didn't say what your tow vehicle is, but remember these 2 things:
(1) the refrigerator will draw about 10 amps when set on 12VDC. If your house battery is fully charged when you leave, you should be OK, and
(2) if your vehicle is not already equipped to isolate the TV battery from the trailer when you turn off the key, add an solid state isolator to your TV so that when you stop for gas or a meal on the way, your TV battery remains isolated from the house battery.
The house battery will run the refrigerator for several hours, from our experience. Once you back on the road, the alternator will charge the house battery.

Thanks Paul... I was just worried that we would end up with a dead battery like some other people have.. I have a toyota tacoma, 6cyl, 4x4 thanks again, Teresa

[kdrickard]

[quote author=Paul_Heuvelhorst link=board=1;threadid=1057;start=0#msg7280 date=1059107196]

...(2) if your vehicle is not already equipped to isolate the TV battery from the trailer when you turn off the key, add an solid state isolator to your TV so that when you stop for gas or a meal on the way, your TV battery remains isolated from the house battery...

[/quote]

I noticed the TrailManor Owners manual also mentions a battery isolator as something you might want to do. Since I'm not finding much info on if my TV (Tow Vehicle) has this standard or not, I'm wondering how to test for this (I have not called the TV dealer and asked as of yet). I’m assuming you just turn off your TV and check for a 12v or so charge on the TV’s 12v positive and ground connectors on the trailering connector? If there you have voltage, you don't have an isolator, if it's dead you do. Is this the right way to test for this?

Thanks,

Kevin

I’m assuming you just turn off your TV and check for a 12v or so charge on the TV’s 12v positive and ground connectors on the trailering connector?

Basically, YES. Turn off the ignition, disconnect the trailer wiring, and check pins 4 (12+) and 1 (ground) on the standard 7-pin connector. If there is no voltage, the TV already has isolated the connection for you (Fords with factory tow package include this feature).

Check website [http://www.etrailer.com/faq/wiring.asp] for wiring diagrams for connecting trailers.

[kdrickard]

Paul, Thanks for the info! I checked tonight and found I do have around a 12v current on the +/- pins on the TV with the ignition off . Not knowing much about isolators, but knowing basic multimeter-crimping-soldering, is installing one best a dealer thing or something fairly easy to do on your own? As a stop-gap it would seem like a good idea to pull (unplug) the trailer connector if one is planning to leave the rig connected to the TV with the ignition off and the TM 12v Refridge on for some number of hours (and don't have an isolator).

Kevin

Kevin,
Yes, it is a fairly simple job to install an isolator if you are mechanically inclined. There a 3 connections to make from the battery and alternator. The isolator mounts in the engine compartment as close to the battery & alternator as you can get it.

Isolators are available from a variety of auto supply, RV supply places. I recommend you get one rated at least 15% higher than your alternator output (approx. 80-90 amps). It will cost you about $50-$75.

In the meantime, yes, pull the trailer plug if you plan to stop somewhere for more than 30 minutes with the refrigerator running on 12VDC.

Best wishes.

[kdrickard]

Paul,

Muchas Gracias! Found a few products on the internet, and your advice on bumping up the rated amps on the isolator makes sense. In the mean time I'll just pull the trailer plug when stopped for more than a short amount of time and have the refridge running on DC. With two house batteries I should be good for a bit but would hate to not get started up again after lunch :'( ! Thought about just installing a manual cut-off switch between the trailer and TV, but figured the work to install the isolator can't be too much more.

Thanks again,

Kevin

[RockyMtnRay]

One potential "gotcha" is that you sometimes have to match the isolator model to the specific model of alternator on your tow vehicle...and manufacturers tend to use different alternators (with different connectors) depending on year, engine, and what the alternator's output rating is. Also some alternators are mounted up top and are very easy to reach when attaching the connection to the isolator; others are buried under other engine components and would be a real pain to work with.

In my case, the alternator is buried under the A/C compressor and just above a motor mount (plus there's a splash shield under that area) so it would be a royal pain to get to. And I seldomly stop for more than 15 minutes at any time enroute...so I just pull the plug between the tow vehicle and trailer on the rare occasion that I'll be stopped for more than an hour.

Plus I will soon have solar panels that will largely meet the refer's power drain...the refer uses around 11 amps, my panels will provide about 10 amps in full sun so the net drain on the TM's battery will be quite small.