Community Forums

NM.West · 06-28-2017, 08:34 PM

I have two questions related to power supplied to my Mobile Suites 36RSSB3 while it is in storage.

The storage facility provides 30 amp service for charging, but due to distance (about 100 feet) from the service to the RV, I have always stepped that down to 20 amp, as I don't have a 30amp cable that long. At the other end, it is stepped back up to the 50 amp cord that comes with the MS. The unit has a Magnum 1000w inverter to power the fridge and other things, and a smart charger to charge the two six volt batteries.

To date, I've had absolutely no problems with this set up. The batteries stay nicely charged.

First question: Given the power limitations, do you see any issues if I turn on the residential fridge a day or two before a planned trip? It would be nice to have the fridge up and running before the trip.

I also have a 24 foot car hauler parked next to the MS. The car hauler has a 12 volt battery in it that I would like to keep charged. Like the MS, the car hauler has a smart charger built in. I think it is one provided by LCI.

Second question: Do you see any problem if I used an exterior outlet on the MS to provide power to the car hauler? I know, that may be pushing it a bit, but thought it was worth asking.

Regards,

vsheetz · 06-28-2017, 08:44 PM

I don't see any problem with any you describe. Just set the magnum charger to limit max consumption, if not already done.

Skip426 · 06-28-2017, 08:48 PM

A little will depend on the gauge of wire in your 20 amp extension cord and its length, and if the inverter has an auto by-pass you need to know the fridge start up amp draw.
The battery in the car hauler will hold a charge for a long time if disconnected , JMHO; I'd consider disconnecting the battery. Re-connect and charge for a few hours before use.

Ray,IN · 06-28-2017, 08:55 PM

This totally depends upon the size of your extension cord. See this wire size calculator for information. In the calculator " half the total circuit length" means one-way distance from your MS to the receptacle.
You must know the total amperage draw from your MS battery charger and refrigerator amp draw, + amp draw from the car hauler battery charger.
If the extension cord is too small it can cause low voltage at the 5er.

MtnTrek · 06-28-2017, 09:31 PM

Welcome to the forum
Like the others suggest you'd want to spring for the best 100' drop cord, 12+AWG
Well the Whirlpool if like ours is rated 7.1A @115VAC
the Magnum MS2012 is charger rated 15A @120VAC if providing 100A DC (it's doubtful you'll match that even bulk charging rate for just two two 50% DoC batteries)
You need to know the rating of your other trailers breakaway charger.??
Also would be helpful to know the actual voltage on the end of all those cables when hooked up. Depending on the actual voltage drop, you'll know your amperage probability (OHM's law)
The good thing will be that the batteries will be mostly fully charged especially if left in float condition. This leaves plenty of wattage for the refrigerator's 800W.
FWI: the MS external outlet is probably a GFI circuit so if you've been OK with the breakaway charger in the past, great. The other trailer "could" present a neutral / ground bonding issue (nuisance trips) if you've not used it in that scenario.
So there may not be enough there if the batteries are all run down, all charging at once plus the fridge. But the fridge should run fine with the batteries all on float or maint. charge. Go for it.
Happy trails.

NM.West · 06-29-2017, 10:30 AM

Thanks everyone for your quick replies. Generally, I have the car hauler battery disconnected, but the battery is a bit of a pain to get to, and I was looking for a lazy way out. I think I'll just disconnect that rather than pushing the envelope. As an alternative, I've ordered a 15 amp to 30 amp dog bone extension, and I can then plug the car hauler directly to the supply if I'm worried about charging the battery (after hooking it back up, of course).

I also appreciate the suggestion about the power supply cord, and after looking at it yesterday, will be moving to a 12 AWG cord for safety and to ensure proper power goes to the MS.

paz · 06-29-2017, 12:57 PM

The problem I see is the power source has 30-amp breaker, and you're using a 100' extension cord. If you're not very careful, you could overload the cord and neither the breaker in the 5th wheel nor the one on the post will ever trip. If someone accidentally turns something on that shouldn't be on, you could be in trouble. Note: Even a 12-gauge cord is marginal for 20 amps at 100'.

Can you get away with it? Probably. Is it 100% safe? Probably not.

nothermark · 06-30-2017, 06:36 PM

I'm trying to figure out what would be unsafe. I am also trying to figure out where there is a problem. The 10:1 current vs voltage is in play so 10 Amps @ 12 VDC takes 1 Amp at 120 VAC. Battery charging loads are pretty low on the AC line. If you leave the chargers on the batteries will be in float mode and draw very little current. If I had a concern I would just unplug the trailer when I turned on the fridge. I would also be using a maintainer or a multi stage charger on the trailer if it does not have one built in.

Given the setup in question I'd be running an A/C while I was getting ready.

Texastbird · 06-30-2017, 08:46 PM

A heavy duty contractor grade extension cord would probably be just fine. Some of the discount store cords claim to have a certain gauge wire, but I have seen some pretty flimsy ones claiming to have "12" gauge wire, yeah, right.

Cypressloser · 06-30-2017, 09:26 PM

Texastbird, that's a good point.
I would go and buy bulk 12awg rubber cord and ends at a BORG, much cheaper than prefab. and you know exactly what you got.

nothermark · 06-30-2017, 09:35 PM

There are two common types of wire used for extension cords. The 300 V version is significantly thinner than the 600 V version. Either one is fine but the 600 V looks more impressive as well as being stiffer and bulkier.

Given issues like water intrusion I would much rather have cords with molded ends. I would also cut off a bad end and put on a good one as long as the wire was good.

jks · 07-01-2017, 06:17 AM

Quote:

Originally Posted by Texastbird

A heavy duty contractor grade extension cord would probably be just fine. Some of the discount store cords claim to have a certain gauge wire, but I have seen some pretty flimsy ones claiming to have "12" gauge wire, yeah, right.

BTW, for about the same money you can get a 30AMP RV extension cord from Amazon.

MtnTrek · 07-01-2017, 03:27 PM

Quote:

Originally Posted by paz

The problem I see is the power source has 30-amp breaker, and you're using a 100' extension cord. If you're not very careful, you could overload the cord and neither the breaker in the 5th wheel nor the one on the post will ever trip. If someone accidentally turns something on that shouldn't be on, you could be in trouble. Note: Even a 12-gauge cord is marginal for 20 amps at 100'.

Can you get away with it? Probably. Is it 100% safe? Probably not.

Very good point indeed.

Quote:

Originally Posted by jks

BTW, for about the same money you can get a 30AMP RV extension cord from Amazon.

Most 30A extensions are only 30' long and are marginal when attached to the 30A coaches cable. For 100' you'd need a significantly heavier gauge wire.