-
Chassis Batteries Won’t Hold A Charge
Okay so I found out the hard way that the H345 has a kill switch that shuts off the coach so you think your batteries are dead when you go to start the coach. Thankfully the Marathon tech support walked me through that one. Then when the coach wouldn’t turn over I learned about the jump start feature, again form the Marathon man. But the fact that the batteries are draining virtually over night can not possibly be normal. Marathon said these coaches have a phantom current draw on the chassis batteries that Prevost has known about for years but hasn’t been able to eliminate. Apparently new coaches now come with trickle chargers built in to deal with the issue.
So I do a little searching around on the PC forum and come across a 2018 post from Travelingman where he installed a charger from Cabelas to deal with keeping the chassis batteries charged. I’m reading this post because I’m tired if having to use the jump start feature to start the coach, and wouldn’t you know I just happen to be staying over night at a Cabelas…go figure. So I go in and purchase a 12/24 two lead smart charger and install it in the battery bay. Ran an A/C line from the block heater into the battery bay, chopped the lines from the charger and installed 110 male and female plugs so I can remove the battery cover and now I’m thinking “problem solved”! I’ll just charge these babies up over night and badda bing…all will be right with the world.
Batteries were reading 24 volts at the jump posts which I was told by Marathon (again) is essentially considered dead. When I checked voltages the next day after charging all night they measured 26 or 27 volts (I think). So I hop in the coach, turn the key and still the coach won’t turn over. Measured the voltage on the 24 volt jump posts while cranking the engine and the voltage drops to 15 volts.Wired the charger per Marathon techs instructions, set the charger to AGM, and after all that work this thing is still not charging enough to crank the engine over. Now I’m getting this god awful smell emanating from the battery compartment that is permitting the entire coach. Still can’t figure out how this stench is getting inside but I’m pretty frustrated at this point. I thought maybe the batteries were’t AGM’s and I’m cooking them hence the smell but I can’t find any info on the batteries that are in there. No fill caps so they’re maintenance free, but I don’t know if that means they’re AGM’s.I’ve also noticed that the 3 battery equalizers all have LED’s that say “LED illuminates only when load is applied” and the LED on one of them isn’t lit.If anyone has any ideas of what I should try next I’m all ears.Here’s a few pics of the install -
8 Replies
-
Larry are you charging 12 volts or 24 volts ,the smell is scary, put a volt meter on battery terminals where you have charger hooked up, what does it read.the way your pic look like you are only charging 12 volt battery.
-
Thosee batteries appear to be sealed lead acid. How old are they?
-
If the chassis batteries need a charger that can be compared to using a band aid on a brain tumor. Chassis batteries should go months without a charge and spin the motor over without hesitation.
If your coach can’t do that you have bad batteries or a phantom load on the chassis batteries.
-
So if they are sealed lead acid and I’m using the charger in AGM mode is that an issue? Charger is supposed to be able to sense if its hooked up to 12 or 24 volts. Voltage when charging is 28-29 on the 24 volt side and 13 -14 volts on the 12 volt legs. Batteries were supposed to be new in July 2020.
-
Those batteries should not be AGM.
AGM’s will not take the heat of the engine compartment.
Match your charger to the the type of battery you are charging.
People have put AGM’s for engine batteries and they will work for a while.
-
Battery’s in a H model are not in with the engine. I can’t tell for sure how you have the charger wired, but on my coach I use a charger with two 12 volt outputs.
The battery’s are wired as two sets of 12 volts series to get the 24 volts. If you are charging at 24 volts you only need one output.
Jack
-
Thanks all…
-
It looks like your charger has 2 – 12volt outputs. if that is the case, make sure each one is connected to one of the 2 12volt post so it charges both 12volt banks. If they are on a 24volt post they won’t charge anything. Preferably you should be using a 24volt charger connected to the 24volt post of the equalizer for the chassis batteries. (looks like the one in the upper left of the picture, btw the LED comes on with a 12v load)
The smell is from a over charged battery. It’s possible you have one or more shorted batteries and that may be why they won’t hold a charge. The gas is deadly, so stop chargingg until you figure it out. At this point I would replace the batteries – all 4 of them – Sealed Lead Acid type, make sure everything works including the Alternator output is correct and the equalizer is doing it’s job before connecting a charger. IMPORTANT – make sure the charger shuts off while driving (often over looked) It’s possible that the charger can back feed the Alternator causing damage or visa-verse. If it’s not a trickle charger then put it on a timer so it only comes on a few hours a day or only plug it in when you need it. It is possible to over charge new batteries even with the best chargers.
Log in to reply.