Engine not charging coach battery

wlf00 · 01-22-2012, 03:51 PM

At times when traveling down the road with the fridge running off of the inverter, the coach batteries get so low that the inverter shuts down and the fridge starts to beep due to low DC voltage. At other times, it seems to work OK. But lately, I have been traveling with the inverter off and the fridge running on LP so that I do not run the coach batteries down so far.

When I was at Forest City this last summer, they found nothing wrong with the system. I was told that the only thing that could be the problem is a Solenoid which connects the two batteries together. I purchased one while I was there just in case that is indeed the problem.

Looking at the electrical diagrams, it looks like the solenoid is the Aux Start Solenoid. Is this the same thing? Is this solenoid energized by both the Battery Boost switch and by a signal when the engine is running and charging the chassis battery?

I located the solenoid behind a panel in the coach. My thoughts were to connect some wires to both battery connections as well as the control signals and run them out into the storage bay where I can check them with a voltmeter. The next time it is not charging while driving, I can go and see what is going on. Do I have a signal to energize the solenoid? Do I have the same voltage on both battery terminals at the solenoid?

Has anyone had a similar problem? Any other suggestions?

Thanks,

JBDISCOVERY · 01-22-2012, 04:02 PM

WLFOO,
I had a problem similar to what you describe. After $550. at a very excellent Cummins shop the problem turned out to be corrosion on a stud between the alternator and the first fuse on the hot side of the alternator output. The stud was so corroded it did not allow a full charge to come through to the DC electrical system to power all the DC systems and charge the batteries. Once cleaned, and reconnected, all worked fine.
Good luck.
JB

az bound · 01-22-2012, 04:08 PM

Good advice:
The place to start troubleshooting is at all electrical connections. Especially ground wires.

cmpncrsaider · 01-22-2012, 05:27 PM

I agree withe last post, check as many connections as you can, almost a hobby, whenever I have some spare time and the energy I start checking connections seems like there are thousands of them, also on small terminations I put liquid electrical tape on them after tightening.

Pusherman · 01-22-2012, 05:46 PM

Quote:

Originally Posted by wlf00

At times when traveling down the road with the fridge running off of the inverter, the coach batteries get so low that the inverter shuts down and the fridge starts to beep due to low DC voltage. At other times, it seems to work OK. But lately, I have been traveling with the inverter off and the fridge running on LP so that I do not run the coach batteries down so far.

First, if you are only running your inverter while driving, the engine should be able to keep up with charging the battery bank. If it's not, then you probably have a problem. The above posts are good advice on what to chase down.

Second, if you run your inverter most of the time, which includes while the engine is off and not plugged into shore power, you may be inadvertently pulling down your batteries.

My recommendation is to run the refrigerator on LP and keep the inverter off. Inverter's are nortorious for drawing a lot of current out of batteries.

You can check your voltage charge rates at your 'One Place' panel; if you are seeing 13-14V on the house batteries, then it is getting a charge (with the engine running). Resting voltage w/ no charge will be about 12.6V or so. If you're below this voltage with the engine running, then you have a problem in your charging system.

Clay L · 01-23-2012, 09:41 AM

Winnebago usually uses the continuous duty AUX solenoid for both emergency starting and for charging the house batteries. The MOM AUx switch activates it for emergency starting and a wire connected to the RUN terminal of the ignition switch activates it for charging the house batteries when the engine is running.

Mine was intermittent for a while and has now failed completely. The solenoid pulls in but the contacts don't make contact. I have a new one with silver contacts instead of copper. The company that makes the solenoids (Trombetta) says it will last longer.

Now I have to get ambitious enough to install it. Maybe after the RV show in Quartzsite...

jdcosgrove · 01-30-2012, 05:03 PM

I'm experiencing a problem similar to what wlf00 describes above; my batteries charge up just fine through the Dimensions inverter/charger when I'm plugged into a shore line, but when I'm driving, or when I just try to charge the batteries using the generator, I can't seem to get the batteries recharged. I spoke to Winnebago service in Forest City earlier today and was told to check the solenoid. At the risk of REALLY exposing my ignorance, where is the solenoid? what does it look like? I peeked into the battery compartment but didn't recognize anything that I thought might be a solenoid. Also, I thought the suggestion above regarding checking connections made sense, but what connections should I be looking at and where are they? I've made sure all the connections to the battery posts are clean, but I'm not sure where else to look.

I'm driving an 08 Itasca Meridian 37H.

Thanks in advance for your help!

wlf00 · 02-04-2012, 03:48 PM

In my coach, it is located inside a panel in the rear most compartment behind the rear wheels on the passenger side. It is directly across from the batteries on the opposite side of the coach. The panel has a 6 Amp Solar Panel resettable fuse and 3 55 Amp resettable fuses going to the coach breaker panel. It also is marked "Battery Mode Solenoid and Disconnect Relay located inside". On mine, it also has the rear awning switch located on the panel.

The solenoid in question has a U-bracket mounting it to the side wall, has 2 large studs on the top where the battery connections from both the chassis and coach batteries connect, and two small connections near the bottom for the control signals.

I hope this helps.

garyspang · 02-04-2012, 04:59 PM

Underrated solenoid. 32% more watts generated inside than designed to dissipate.

Mine gave out also. Since I designed solenoids at on time I disassembled the bad unit enthusiastically. The internal plastic parts were partially melted, extruded into the moving plunger space and prevented the contacts from closing. The unit was send to the manufacturer for potential product improvement. Instead they told me that there was a moisture problem and send me a free new solenoid and one in a plastic housing which was to be more moisture proof. I shook my head in disbelief, but appreciated the new solenoid. Reinstalled it and am ready for another 8 years or so of operation before failure.

The solenoid is designed for 12 volts direct current as per labeling and specifications. It is only energized when the alternator is running and the RV system voltage is at least 13.8 volts. using the wattage formula W=E2*R (note: E 'voltage' squared), it is plain to see that at 13.8 volts the coil in the solenoid is heated by at least 32% more watts then at 12 volts. That is 1/3 more than the design specification. A good way to stay in business and get solenoid re-orders.

For the steering jets on the space capsule (back in the 60s) the jet-solenoid was hit with a high voltage and after valve opening the voltage was reduced for holding without overheating ever. Unfortunately that solution may be to complex to use in a motor home.

Hikerdogs · 02-05-2012, 05:52 AM

The problem you describe is fairly typical of the way this solenoid/relay fails. Ours worked fine when it was manually activated to link the batteries. However it wouldn't allow the alternator to charge both the house and chassis batteries.

When the engine was started you could hear and feel the solenoid plunger move to complete the circuit but no current would pass.

I did some research and found Tekonsha (the people that make electric trailer brake controllers) also make this type of relay. I called the tech line and explained the problem I was having. The tech said it was definately a faulty relay.

Apparently after numerous activations (thousands) and releases carbon deposits build upon the face of the plunger. Enen though the magnetic coil forces the plunger to the contact position the carbon deposits insulate the surfaces enough to keep current from passing from the alternator to the batteries.

As mentioned by others the replacement solenoids have silver contacts. They don't arc nearly as much when tne circuit is denergized and are more resistant to pitting and carbon deposits

I took the technicians word and bought a new relay for about $18.00. It took all of 15 minutes to install and cured the problem. Now the alternator charges all the batteries while driving down the road

The Tekonsha relay definately has a 100% duty cycle. It gets warm when activated but never gets to hot to touch. If you buy a new one make sure it has the 100% duty cycle. They look almost identical to the old Ford starter solenoid. However the Ford solenoid only has about a 5% duty cycle. It will burn out in less than an hour of continuous duty.

hshiner · 02-06-2012, 05:32 PM

Hi
I am having the same problem on my 1995 Vectra. Where did you find the relay?

Thanks

mackpeteno · 02-06-2012, 06:03 PM

Go to any Mack dealer,ask for accesory solenoid.It is on anytime the key is turned on.Itwill last.

Hikerdogs · 02-06-2012, 06:12 PM

In our Adventurer the relay is behind a steel panel at the back of the top step. I have to remove the carpeted back panel, then the steel panel behind it.

On some models it's in the engine compartment on the right side near the heater core. The easiest way to find it is to have someone push and release the MOM switch while you listen for the clunk of the solenoid engaging.

jdcosgrove · 02-10-2012, 06:07 PM

Very helpful! I'm in the process of buying a new solenoid and hope to get it installed next week.

RKL · 02-10-2012, 06:25 PM

after replacing the solonoid described above a simple monitoring solution as to whether the coach battery is being charged while driving is to simply plug a digital 12 volt charge meter into the 12 volt plug on the dash...this outlet is on the coach battery system. A simple glace at the meter while driving tells you voltage being charged on the coach batteries....RKL

Hikerdogs · 02-11-2012, 06:11 AM

Quote:

Originally Posted by RKL

after replacing the solonoid described above a simple monitoring solution as to whether the coach battery is being charged while driving is to simply plug a digital 12 volt charge meter into the 12 volt plug on the dash...this outlet is on the coach battery system. A simple glace at the meter while driving tells you voltage being charged on the coach batteries....RKL

I believe that the 12 volt outlets are connected to the chassis batteries at least on the gas coaches until 2005 or 2006. The system was then changed to the house batteries to avoid starting problems due to charging cell phones, radios, and other 12 volt accessories running down the chassis (engine starting) batteries.

Clay L · 02-11-2012, 08:17 AM

It must have been earlier that 2005 because the one on the dash of my 2004 is connected to the house batteries. I just double checked to make sure. It reads 13.6 volts and the engine battery reads 12.6.

dirko · 02-11-2012, 11:56 AM

Hi Ho: I think you are on the right track. The solenoid in question is very common. Any parts house will have them. The only thing to watch is that it is a continuous duty coil. I just put one in. Took about 15 minutes and cost about $17. This solenoid is rated at 100 amps. The problem is that what it does is to connect all batteries together so that they can all be charged by the alternator.

After use the house batteries may be at a voltage that is considerably less than the truck battery (or vice versa) When you start the engine the solenoid pulls in and one tries very hard to charge the other. The current is limited only by the internal resistance of the batteries and can be hundreds of amps. Of course this only lasts until the alternator gets gong and starts charging the batteries but can cause the contacts to fail over time. I have had two fail in 12 years, but at $17 and 15 minutes time it's not a big deal.

hdmoxness · 02-11-2012, 12:12 PM

Dirko, would you please specify the model number and source (and alternate sources) of your $17 solenoid? Thanks in advance.

Paul T · 02-11-2012, 02:28 PM

I took this picture by NAPA to find out they were out of stock then ran into a RV Store and asked their parts department if they had one and they did. My symptoms were the same as described here Dean.