Batteries again

Kbikes

New member
I am confused again and looking for some help, just replaced the Batteries in my 3 year old Unity MB, I had bought the RV used and originals just did not seem to hold up, had them tested but they came up short, just replaced them with the same flooded Interstates as the originals.
First trip with the new batteries to a campground and back home voltage readings were low, 12.4, they seemed to have charged up alright under shore power at home but did the state park this time and had to use just the house batteries, no shore power or Generator.

I had the inverter on during the trip, just a couple of phone chargers not much else plugged in, using propane for the fridge, would having the inverter active affected the charging from the RV/alternator while driving.

Thanks in advance
Rick
 

mikeme

2015 LTV IB: 2015 3500 V6
a very common failure is the Isolation relay. this device is under the passenger front seat, and is wired through an isolation relay delay device. these serve to connect the engine electric system to the house system when the engine has been running for a few seconds, and the engine battery is charged enough to allow current to be pulled to charge up the house battery.

the isolation relay chosen is a little off on voltage spec, and really is designed for HVAC use. when the relay fails, the Sprinter engine will not charge the house battery, so that the house battery is discharged by whatever is plugged in, rather than being charged while driving.
 

Kbikes

New member
Thanks for the help, I was aware of the relay issues that others have had and thought that might have been problem at first.
Ended up just being a bus fuse (200amp bolt in type AMI FUSE) under the chassis battery box.

Called the mother ship and they put me in the right direction, the customer service dept. was a great help as always.

Also I had read that you need to take the seat off to get to the relay but that is not needed. The hatch can be opened from the side of the pass seat area for access, when I checked the relay it was working but had low voltage on both sides when engaged, 12.7 with the engine running, the chassis batt was reading 14.1 as expected.

Ends up what I was reading was the voltage of the coach batteries at the relay, no voltage was coming from the chassis batt because of the blown fuse, I am still not sure if this problem was self inflicted or not, I had changed out the batteries with new recently and maybe popped the fuse, maybe. Although I have been having problems with getting a full charge on the batts since I bought the LT used this year.

Will see how it works going forward but looks good so far,

Thanks again for the help,
Rick
 
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autostaretx

Erratic Member
One must ask: why did a 200 amp fuse blow?

Normally such an event has a highly visible (sparks and noise) precursor.
(unless it was "simply" too much current trying to flow between the batteries due to one side being quite discharged)

--dick
 

mikeme

2015 LTV IB: 2015 3500 V6
...

Also I had read that you need to take the seat off to get to the relay but that is not needed. The hatch can be opened from the side of the pass seat area for access,....
Rick
We have an awning, and the controls for it and the light mounted there are installed on the side removable hatch on the base of the passenger seat, and are also bolted to the black fabric cover that is on the seat base.

do you not have an awning, or are your controls someplace else? or did you find a way to pull anyway?
 

Kbikes

New member
--dick
Wish I knew, 200 amp fuses are not that easy to pop. I had the battery disconnect switch off when I changed the batteries. As I said it could have been self inflicted but I don't think so, it probably has been this way since I bought the Unity used earlier this year.

Mikeme
LT customer service walked me through how to open the hatch, I have the same switches on the side and cover fabric as yours.
As instructed and looking at the drivers side to compare, there are two release tabs under the fabric, you do not have to put your hand under the fabric just need to push down gently on the tabs through the fabric from the outside and then grip the tabs to pull out just a little to release the hatch.
Once released you can lift the hatch cover and the fabric to gain access, there is enough wire on the switches to be able to do this. It was much easier to do then one would think at first.
 

mikeme

2015 LTV IB: 2015 3500 V6
I think you are right about the fuse being gone when you bought it. the bad batteries were probably that way from being run totally down.

thanks for sharing that bit about access from the side of the seat.
 
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SSTraveler

2014 LTV Unity Murphy Bed
We have an awning, and the controls for it and the light mounted there are installed on the side removable hatch on the base of the passenger seat, and are also bolted to the black fabric cover that is on the seat base.

do you not have an awning, or are your controls someplace else? or did you find a way to pull anyway?
Kbikes is right, I never remove the seat to get under the passenger seat. I attached a photo from someone else that shows the panel and switches removed. The first time I got under the passenger to install my Trik-l-start I just removed the switches to take the access panel off and then I made a new panel for the awning switches, new batteries voltmeter, and Trik-l-start. Recently my Solenoid failed and I replaced the Isolator Solenoid, Isolator Relay and Trik-l-start with the Blue Sea ML-ACR. I put the Blue Sea switch in the old Trik-l-start spot. If I need to get under the passenger seat now I just unscrew my new panel. The Blue Sea gives confidence that all my AGM batteries are staying charged from the various charging sources ( solar, shore power, engine alternator). Here is a thread on the Trik-l-start and Blue Sea installs, https://sprinter-source.com/forum/showthread.php?t=35862&highlight=Intelligent&page=16 and https://sprinter-source.com/forum/showthread.php?t=45224&highlight=Intelligent.
 

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