Battery Power Problem

Can anyone help me here? Our problem is when we are on battery power, still even hooked up to tow vehicle, when extending the rear slide the power cuts out. It?s like there is a short because it does extend eventually. It also happens if the pump is on and then the lights may flicker. The battery is brand new, fully charged and all of my connections are in great shape. The trailer is a 2012 KZ Spree. We don?t often boon dock, but with a family of five, the occasional free night helps the travel budget.

One of the things is you do not understand the nature of the connection between your tow vehicle and your trailer.

IT can not haul the current needed to run your slides... As for the water pump... that's iffy.  It is a very low current line.  So lights will flicker when relying on it for power.

ARE your house batteries connected? (yes/no) (Will the lights stay on if you unplug from shore and from the tow vehicle).

What size battery(ies) do you have? Many RVs (epically trailers) come with a single Group 24 MARINE/deep cycle.. and that is not much battery  Not much battery at all.

The battery is brand new, fully charged and all of my connections are in great shape.

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"The battery" may be at the root of the problem. There is not a lot of power available in one single battery, especially one which has not been fully charged since last use. Most good installations use at least 2 batteries in parallel to gain additional capacity. Have you verified the trailer battery is being charged by the tow vehicle while underway? I suspect from your description that the poor thing is far from "fully charged" (Pump left on. lights flickering)

How: Do not plug the trailer in. Connect the trailer wiring and start the engine. Measure using a multimeter, voltmeter section, across the trailer battery terminals. A reading of greater than 13.5 V should be read, otherwise, no charging is taking place...

Using a voltmeter across the terminals of a FULLY charged  battery, with no charge taking place, and not plugged in should read 12.6V. An effectively 'dead' battery reads about 11.9V, so not a lot of room here. A 'marine deep discharge' type of battery should never be discharged past 50% of it's stated capacity, if it is, expect a much shortened battery life. 4 years on this type of battery, is very good at the best of times.

Do not expect to be able to open slides etc by just leaving the truck hooked up. The wiring used to charge the trailer battery (if TV equipped to do so) under normal circumstances, is no where near heavy enough for that job. Result? low voltage and low amps available at the slide motors, and possibly, exactly what you witnessed. NOT a good thing!!

Fully charging a discharged battery take many hours (24+), a couple of hours won't even put a dent in it.

Low battery voltage will result in excess current drawn by the slide motor which will open the overload thermal.  When the thermal cools down, power is again available to the slide motor.  Do the following:

1. Charge your battery before you leave.

2. Add a battery charge line added to your trailer connection so that you will maintain trailer battery charge while driving.

3. Carry some long Battery Cables so that you can parallel your truck and trailer with truck running and trailer pigtail disconnected.

Thank you all for your replies.  I appreciate the expertise!

I will give a bit more background:  First of all, I am fairly mechanically inclined, but I have realized since purchasing our trailer three years ago, that there is a huge learning curve with these things. We purchased an extended warranty, but I will be charged a hefty diagnostics fee to have the shop figure out my battery woes.  I?m hoping to solve it on my own.

The rear slide on my trailer is our bed.  It is a small unit (24 ft without the rear bed slid out).  This is the only slide on the trailer.
We purchased the trailer brand new, and have used it for approximately 60 days each year since purchasing it in 2012.  Generally, we are in campgrounds with full hook-ups, so we rarely use our battery power.  The trailer came equipped with what I now know is not the greatest of batteries - a standard interstate 12V (550 amps).  On our first outing of the season (Easter weekend) we were boondocking our first night and the battery issues began.  I had the battery tested when we returned home and learned it was ?done?.  At that time, I purchased a new battery.  I bought a Kirkland Deep Cycle 12V (750 amps). 

Here?s the issue:

- battery is fully charged
- attempt to open rear slide - it extends about 2/3 and then hesitates - at this point the converter kicks in and the slide will continue to extend - I can hear the converter
- when i try other systems in the TT :- furnace, fridge and a couple of lights - everything starts to flicker on and off

This is a new problem as of this season.  Because we rarely use the battery, I?ve decided to stay with the 12V as it has served our needs fine the past three seasons.  I think it?s the converter.  Does this sound logical to you experts out there?  I do want to be able to boondock the occasional night on longer trips, so I need to solve this problem.  Again, there are no issues when we are plugged in.

Thanks again for your replies!

When you say 550 or 750 amps you are talking CRANKING AMPS

What you need is amp hours.. And it sounds like you have a group 24.. That is 75 amp hours of which you can safely use around 25

Now if you have the room.. Consider two GC-2 in series,,These are (When sitting on the dealer's shelf or being transported) six volt golf car batteries.. you wire them up like this {bat}t{ery}  As you can see that is in series)
and when you hook up the jumper (the "T" in the middle) magic happens... They turn into a single 12 volt battery

220 amp hours (give or take a bit) and you can use half of it..That is roughly 2x the power of that Group 24

Need to cover some basics about power in your RV. The slides, lights, water pump, and a bunch of other stuff runs on 12v DC. Even when plugged to shore power. Your trailer has a converter charger that makes 12vdc on the fyy from shore power, so the battery doesn't get depleted while plugged in, but it's still the same 12v power. Do you know the make and model of the converter?

Your converter is always on, when you are plugged in. What you hear when it "cuts in" is an increase on the converter power output because of a high amp load, e.g. the slide motor working hard.

Kirkland is a "marine" deep cycle, so not much different than a car battery.  A little better for deep cycling, but not great. Still, a new-ish one, well-charged before leaving home (just plug the trailer in for a day), should work ok for a day or two without shore power and indefinitely if the RV is plugged in.

You could have a converter problem, but I'm thinking more along the lines of a poor wire connection at  a battery post.  You may also have a problem with the slide itself, cause it sounds as though it reaches a point where it binds and the power demand by the motor goes up drastically. Apparently the converter can meet the demand, but the motor hesitates a moment. Will the slide go in and out fully without being plugged to shore power? Just on battery alone? It should.

Hi Gary,

Thanks for your reply.  I can certainly get the slide checked out at the dealership ... But what about the lights, heater etc., stuttering?  I can?t brush my teeth with the bathroom light on (using the pump and one bathroom light causes the power to flicker/hesitate/shut down).  This has never been an issue until this season. 

I know the connections at the battery post are good.

The make and model of the converter is: WFCO; model WF - 8955 PEC

Thanks!

It's possible the WFCO is acting flaky - they aren't the best made units in the world, but the typical failure mode is no power at all, not jittery output voltage. Anything is possible, of course, but its rare.  Plus, you say the battery charges ok, right? So the converter/charger must be working most of the time. And even if the converter/charger is out, the battery should still supply nice steady 12v until it is depleted. Batteries don't make jittery power on their own.

What about the battery ground connection to the chassis?

I'm wondering if the 8955 may have a loose wire on its 12v bus?  It's more than just a converter/charger - it is your entire 120vac and 12vdc power center, with buses, fuses, breakers, etc, all in one package.

John From Detroit said:

When you say 550 or 750 amps you are talking CRANKING AMPS

What you need is amp hours.. And it sounds like you have a group 24.. That is 75 amp hours of which you can safely use around 25

Now if you have the room.. Consider two GC-2 in series,,These are (When sitting on the dealer's shelf or being transported) six volt golf car batteries.. you wire them up like this {bat}t{ery}  As you can see that is in series)
and when you hook up the jumper (the "T" in the middle) magic happens... They turn into a single 12 volt battery

220 amp hours (give or take a bit) and you can use half of it..That is roughly 2x the power of that Group 24

Click to expand...

I'll politely disagree with John.

When you are putting the slide out you are using a fairly large amount of amps in a short period of time. Very similar to a starter motor on your engine. (Thin plate, automotive type battery)

When you are using lights and the refer you are using small amounts of amps over a long period of time. (Thick plate deep cycle battery)

A 750 CCA battery should be capable of producing the power you need. The slide out motor is more similar to a car starter than it is to a TV or lights.  I lean towards those who are telling you that you have corrosion somewhere. For that reason you are not getting the amperage/voltage you need to the slideout motor. Check the voltage on the motor when it's operating. That will tell you whether you're getting full power or not to the motor.

Ken

Gary, I have checked all of my grounds - all looked fantastic - cleaned them anyways. 

I?m not sure if you?ve already answered this already or not, but does all 12v go through the converter?  I?m thinking it must.  To simplify things:  When I step into my trailer and turn the heat on, the second I turn on a second light, the power flickers.  The slide is neither here nor there - it really seems to be a converter issue.  Does this sound plausible?

Thanks!

By "turn the heat on" I assume you mean start the furnace, it runs on 12V/propane and the fan draws a LOT of power. Remember that poor single battery???

In some power centres, the 12V from the battery is often distributed through the power centre when you are not plugged in. Operated Relays  connect the 120V AC to 12V converter output (along with a separate charger feed to the battery), to the distribution wiring when plugged and when not, those same relays are released, and connect the battery itself to the distribution network. In other installations, usually the non-power centre style, the distribution network is external.

A converter issue? Yes , it could well be a problem in the converter!! I do not know anything about the distribution system used by the WFCO units that you mentioned earlier though, I would need a wiring diagram. But... WFCO do have a certain reputation for not being too reliable nor long lasting!!

I might be willing to bet that if you unplugged the trailer (provided the battery is charged of course) and went through the same exercise again, there would be little or no flicker. 

Yes Stu I mean turn the furnace on. The trailer is not plugged in. This issue only occurs while being on battery power. I understand that the fan draws significant power, but two single bulb lights. This was not a problem last season with an even smaller battery.

If the 12vdc is flickering without being turned on then the problem is not the converter.  You can verify the Converter by plugging in the Trailer and measuring the voltage at the battery, anything above 13.5vdc says the Converter is working.

All of your symptoms say it is the battery or the connections to it.  I would unplug the trailer and let it set for 3 to 4 hours and then check the battery with a hydrometer to ensure that all cells  are equal or close to it.

Realize you have changed the battery but new batteries go bad.

Hi all,
I really do appreciate the replies. I have checked all the connections to the battery. I have removed the converter and checked all the connections to the panel. I then used the battery from my tow vehicle and connected it with jumper cables in parallel  Same thing!!!!!!!
If I just turn on six lights inside, the flickering starts.

Do I correctly understand that it flickers even when the converter is inactive (not on shore power)? E.g. on house battery only, or when plugged to the tow vehicle?

If so, the flickering is most probably in the wiring for the lights, which are typically all on one circuit.  When the amp load gets high enough (six lights is at least 6 amps and maybe 2x that), a connection is breaking down.

Yes Gary, the trailer is not plugged in. It?s not just the lights, it?s any load. Say the furnace and then turn on more than one light, or the pump and two lights.

Hi again, I just realized that every load that I attempted involved the lights. Just went out to the trailer and turned on the furnace and then the pump or the fan. Same thing happens.

Possibilities include my joke about many RVers having a few screws loose...Only in this connection it is not screws sinc few screws are used on the 12 volt systems.

But it sounds like a flakey connection or 3.. and it possibly a flakey battery.  But that's way down the list.

Don't forget to look for other ground connections, not only the one at the battery terminal