slide out is slow

There are a number of things it could be.. I'd start by examining the slide system and LUBRICATING where indicated in the owner's manual.

YES it could be bad batteries, EVEN plugged in.. Here is why I say that.. I have a multiple battery system (Remember two six volt in series = ONE 12 volt battery and that is how I call it when I talk about my system) consisting of one six volt pair and a few 12 volt in parallel. Recently my Inverter started going into LOW-BAT alarm like 2 seconds after the 30 amp park breaker tripped (Major pain).. First time that happend the oldest 12 volt jar in the house tested out as "Cell shorted". I replaced it and all was good, for about a month, then it started goign to alarm the instant the breaker tripped (Hazard of a 50 amp rig and a park with anemic 30 amp breakers).

Turns out one of the 8 1/2 year old six volts has a shorted cell, So not I isolated the pair and for now all is good.

Someone said RVers have no use for a clamp on DC ammeter.. Guess what tool in my box identified the bad battery, both times.. YUP that's it. Cause when they are all strapped together the voltages are the same.. BUT current is different. once I isolated it a volt meter confirmed shorted cell status.

IF you have a shorted cell your converter, like mine, may be able to provide enough power for the furnace, fridge controls, water heater controls and lights. BUT NOT the amount sucked by the battery PLUS the slides.

Just went through this on a Cedar Creek Travel trailer and thought I would find a thread to put in some information:
1. Hydraulic is used on many multi-slide applications. Low ATF fluid or air in the system, low/dead battery cell.
2. Other systems use a small electric motor like mine. Dead cells, low battery are common casues. Lube as noted by BFL13 above (This fixed mine). Signs of lube needed is having to lean on the unit the first foot when retracting and slow to extend the first foot. I used Tri-flow silicone lube on the teeth, square bars, and into the 2 rollers. I then lightly greased the contact point of the roll pin and the side of the bracket. All of this is done with the slide retracted and then extended. High salt, long time extension of the slides (long term camping)increase rust.
3. If needed on the electric motor ones, the motor will be at the opposite end on the gear train that has the tube and tube stop on it. In my case that is the rear gear track only and was 18 inches in from the other side. Measure from the slide side based upon how far your slide comes out roughly. There was no need for me to drop my undercarriage panels as I only needed to lube, but at least I now know mine is electric.

Have got it fixed. Battery had a dead cell.

Try lubricating underneath. The two bars with the "teeth" go into square tube bars and rub there. Spray non grease lube into the square tubes and along the teeth bars especially their sides not just the teeth. Best spray by far I find is "Jig A Loo" Made a huge difference in our slide moving better

http://www.canadiantire.ca/AST/browse/4/Auto/3/AutoFluidsChemicals/LubricantsPenetrants/PRD~0381551P/Jig-a-Loo%2BLubricant.jsp

Just bought a Denali and thought the same compared to my previous smaller slide. I feel it is due to the weight and size of the large slide so they have to be geared down to do the job. The smaller slide is quick. The e-jacks are slow too, but have plenty of power.

Pluged in everything else workes ok

Yes, low voltage makes motors run slow and it's hard on them.

Electric, hydraulic? Plugged in or not?