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VANNER CONTROL UNIT EM70D
Does this unit control charging of chasasis batteries or does it just monitor the charging that is done somewhere else?balance light stayed mostly on today on 400 mile trip and when i shut the engine off the batteries or low and it will not crank. This will be the 3 rd time it was replaced in 7 years if that is the problem, must be built by MONKEES! Help.
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14 Replies
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I seem to recall there being some reliability issues with these monitors. Vanner does recommend they be installed in a dry location, maybe being installed in the engine bay is/was the issue. Anyway, that doesn’t seem to be your problem as you are describing a real problem not one that I would attribute to the monitor. Given the engine won’t start it would seem that some batteries are low or even bad. If bad, my bet you will find two low on voltage and two closer to okay. If true you either have a bad equalizer or you were placing too much 12V load on it. Vanner’s web site has troubleshooting procedures that are specific to the family of the equalizer you have. If you have a charger for the chassis batteries you can bring them back up to full charge if the batteries are okay.
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It’s just a monitor Dan, sounds like you have alternator, regulator or battery problems.
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I had one go bad too. The balance light kept coming on and it was distracting.
Diagnosis was super easy. Just use a voltmeter to read the voltage on each of its input terminals. In my case, the two legs were within a quarter volt of each other. The light isn’t supposed to come on unless the imbalance is greater than 1.5 volts or so, if memory serves me correctly.
I Installed a new unit and haven’t had a problem since.
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Dan,
Fred’s information is correct. It could actually be a problem with the equalizer so it is best to verify if the problem is the monitor or the equalizer, sooner rather than later.
If it turns out to be the monitor you can pull the wire for imbalance from the monitor to make the balance light on the dash go out until you can replace the monitor. A lot of us have had issues with the monitor. Perhaps Vanner will comp you one because they have to be aware of the unreliability.
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Mine (1991 converted in 1992) (imbalance light) kept coming on also and after having a problem with a fried inverter for house batteries. If inverter was on, light came on, turn inverter off it (light ) went off.Have 2 vanners in back on bus batteries. Don’t really know the correlation between the two other than house batteries were down and vanners kept hitting them going down the road. Replaced Inverter a couple years ago and no more problem. I think Monkeys wired mine.
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The Vanner monitor is for the chassis electrical system. That is not to say converters who have 12/24 volt house systems can’t or haven’t provided a monitor, but I have not been aware of any who have.
So the problem as described by Dan is solely related to his chassis electrical system which should be unrelated to the house.
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So Dan, you say it won’t crank. Are you stuck somewhere or did you get a jump or new batteries.
JIM
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That is why I suggested previously it could be related to the eaualizer. If I remember right Dan’s DDEC needs 12 volts off the chassis batteries and if the equalizer has failed and voltage on the 12 volt side has gotten too low DDEC will not function and the coach won’t run.
Even if Dan has a chassis battery charger, if it is set up to charge at 24 volts or he gets a jump unless and until the 12 volt side of the 12/24 volt chassis system is charged he has problems.
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After letting gen run for about 15 minutes yesterday engine cranked with no problem. When trying to crank before batteries would turn engine over very slow acting like it was flooded as it was bucking ( not sure how to describe). Bus plugged in all night and batteries are good and bus cranked and panel reads 12.8 volts for chassis batteries and showing 28 volts on dash charging dial just like always. I do have a guess charger hooked up. JUST ANOTHER PREVOST MYSTERY I ASSUME!!!
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Dan,
You have a problem.
If your chassis is showing 28 volts the 12 volt side should show 14 volts, not 12.8.. Check the equalizer. That’s my guess. Some equalizers have a fuse or circuit breaker on them, make sure that is OK or reset. I hope it is that simple.
The 12 volt reading should always be 1/2 of the 24 volt reading within 1/2 volt. There is actually a formula for the allowable difference but 1/2 volt is close enough for this discussion.
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Like I orginally said, you have an equalizer or battery problem. Based on your symptons I would tend to say it’s the equalizer. If you don’t have the manual, check their web site. The troubleshooting method varies by family. Some have an equalizer status light, some can be reset, some can be troubleshot with a voltmeter, others with a clamp on ampmeter. If you don’t have the equipment or skill to troubleshoot let me suggest you eliminate the batteries as a problem.
It sounds like you have a battery charger for the chassis batteries. If so, charge them overnight. Turn off the charger, remove the ground cable between the bank and the chassis and the ground or negative cable to the equalizer. Next disconnect one terminal of each battery so they are each isolated. Next, let the batteries rest. A couple hours is fine. Now check the voltage of each battery. Each should be in the 12.6 to 12.8V range. If one is really low, say 12.2V, it’s likely bad.
Just to make sure of one data point. The 12.8V you measured or saw was for the equalizer for the chassis battery and not the house bank or equalizer (if it has one); correct? I would rule out the alternator. If you are reading 28V the alternator has an output.
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Will check all batteries tomorrow and will post results. Thanks for all suggestions! Dan
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As youall suggested i removed and tightened all chassis batteries connections and found one fused small wire link completely corroded so I replaced it. Took a ride and presto no balance light. All readings on panel ok. In the meantime I ordered another Vanner monitor so I now have a spare. Knowing the history of prevost buses I am sure I will use it. I love them but they will wear you out.
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danss,
Good to here it was something easily and inexpensively corrected. This doesn’t quite explain why the coach wouldn’t start as the low current monitor lines don’t affect the operation of the equalizer. You might want to load up the 12V chassis demands and make sure. The biggest 12V demand is likely your chassis lights, especially headlights, unless they are 24V.
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