Slide-out current draw?

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DonTom

DonTom

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Joined
Apr 21, 2005
Posts
13,368
Location
Auburn, CA or Reno, NV
My new RV is far from being level so I cannot put out the slides to check. I recently installed a couple of Smartshunts. One for the 200 AHs with of stock lead acid batteries and another Smartshunt for the 300 AH lith house battery I added for my 2nd house system.

But I am curious what the normal 12.5 VDC current draw (in amps) is when putting out and in an average size slide-out. Anybody here ever check for such?

-Don- Reno, NV
 
I don't know if this info will help you or answer your question or not, but I'll give it a go. I have a Grand Design Momentum with the LCI hydraulic 6 point leveling and it is the same hydraulic system for the tow main slides in the living/kitchen area. When that motor is running the hydraulic pump for those systems, my clamp on ammeter is showing just under 70 amps. Obviously, current rates will vary depending on whether a unit is hydraulically operated like mine, vs. a rack and pinion motor driven slide..vs. a Schwintek slide.....and also the size/weight of the slide being moved.
 
Since I am leaving here in the morning, I decided to load up my electric motorcycle as I won't be using it here anymore. So I put in the slides and unlevelled the RV to bring it down a little to make it easier to load up the bike.

As I was doing it, I unplugged my shore power and watched the current draw of my slides with my Smartshunt as they went both in and out, two slides. I tried both directions to see if there is any difference.

I got reading MUCH less than I expected, makes me wonder if the engine battery is doing most of the work, which I cannot measure. Anyway, here is what I got in and out:

Slide one, max was 12 amps and reduced from there to only a few amps as it was going in. That is the kitchen slide. ~144 watts max is all it takes, but mostly only a few amps at 12V? My added 300 AH lith battery and other stuff is in this kitchen slide.

Slide Two (Bedroom Slide) 9 amps max, yet that is the larger slide. 108 watts is all it takes?

I would have expected them to draw a lot more than that!

Am I overlooking something or what?

-Don- Crescent City, CA
 
If you leave the trailer plugged into the running TV while you work the slides you won't need to worry about it
 
Amp draw is of course dependent on load, so as long as the slide moves easily the motor isn't working too hard. My guess is that over time dirt build-up, deteriorating surfaces, etc will increase the draw somewhat. Still, 11A & 9A is less than I would have expected too.

Those must be relatively small slides in that size coach. My last coach had two 16 ft long lounge-area slides, each carrying a substantial load, e.g. the entire galley plus a sofa.
 
Gary RV_Wizard said:
Amp draw is of course dependent on load, so as long as the slide moves easily the motor isn't working too hard. My guess is that over time dirt build-up, deteriorating surfaces, etc will increase the draw somewhat. Still, 11A & 9A is less than I would have expected too.

Those must be relatively small slides in that size coach. My last coach had two 16 ft long lounge-area slides, each carrying a substantial load, e.g. the entire galley plus a sofa.
Click to expand...
Yeah, this is one of the smaller Class A's (an inch less than 30' long). Slide two is only for the king bed in the rear and slide one is to give more room in the kitchen area where I now am. This slide is very short, enough room even without the slide out. Perhaps less than a two-foot difference. I will measure it the next time it's out.

But even that 11 & 9A was just the starting current. Only about 3 amps as it went in (or out) after a second or so. I guess it is geared quite low so the motor can run fairly high RPM.

IAC, not the big load I was expecting.

-Don- Trinidad, CA
 
xrated said:
I don't know if this info will help you or answer your question or not, but I'll give it a go. I have a Grand Design Momentum with the LCI hydraulic 6 point leveling and it is the same hydraulic system for the tow main slides in the living/kitchen area. When that motor is running the hydraulic pump for those systems, my clamp on ammeter is showing just under 70 amps. Obviously, current rates will vary depending on whether a unit is hydraulically operated like mine, vs. a rack and pinion motor driven slide..vs. a Schwintek slide.....and also the size/weight of the slide being moved.
Click to expand...
The current draw should be proportional to the load on the motor, above the baseline needed to make the motor rotate. I can understand that much of a load raising or lowering the trailer, but I'm surprised the slides also take that much power. Make sure you leave the outside door open when you're operating the slides. You're making a huge change in the interior volume, essentially operating a large bellows and if the change in air volume can't get in or out you'll drastically increase the load on the motor.

This was dramatically driven home to me many years ago when I saw a Tahoe trailer at a show with a small, manually operated sofa slide (you grabbed a couple of handles on the exterior wall and pushed or pulled it). With the main door open the slide operated effortlessly. But if the door was closed it was impossible to push the slide in or out against the confined air.
 
Lou Schneider said:
The current draw should be proportional to the load on the motor, above the baseline needed to make the motor rotate. I can understand that much of a load raising or lowering the trailer, but I'm surprised the slides also take that much power. Make sure you leave the outside door open when you're operating the slides. You're making a huge change in the interior volume, essentially operating a large bellows and if the change in air volume can't get in or out you'll drastically increase the load on the motor.

This was dramatically driven home to me many years ago when I saw a Tahoe trailer at a show with a small, manually operated sofa slide (you grabbed a couple of handles on the exterior wall and pushed or pulled it). With the main door open the slide operated effortlessly. But if the door was closed it was impossible to push the slide in or out against the confined air.
Click to expand...
First let me say, having a door open when operating a slide or slides, is not just a suggestion, it is and always should be SOP...Standard Operation Procedure....and I agree with that 100% Lou.

One of the reasons that operation of the slides on this trailer will pull the kind of current that it does is because when the slides are deployed, BOTH living room/kitchen slides deploy at the same time. They are big slides. Curbside is ~10' long and the street side slide is about 12 1/2' long. The streetside has a 18 cu. ft. Norcold fridge, a stove, a Microwave, and the "L" shaped sofa/recliner as well as cabinets (floor based as well as overhead) and lots of windows/glass. I have no idea of the weight of that slide, but obviously, it is a very heavy slide.
 
In my last two coaches, having anything slightly open made a huge difference in slide operation, relieving the suction dramatically. The smaller the opening, the faster the air had to move, but the slide moved much more easily.

Once or twice I've opened slides in nasty weather and relied on the gaps around the slide itself to break the vacuum. So much air has to move thru those narrow gaps that that it whistled. That's when I learned that opening a window even a few inches made a huge difference.
 
Lou Schneider said:
To a lesser degree.
Click to expand...
True, it's not quite as big. But note that, at least with the slides on the 3 coaches I've had, the area around the slide is not air tight except when fully open or fully closed- everywhere in between there is air leakage, though not as much as with a window. And my slides are pretty slow, so that alone allows my slides to operate normally. But anything breaking the seal will do the job unless it moves too fast. It's certainly not like trying to close the doors on a VW bug or Squareback, which WAS air tight.
 
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