AGM Battery and Victron Battery Monitor Install

[KatanaPilot]

Due to recurring problems with off-gassing and the CO/LP detector going into alarm, I decided to replace the OEM Group 27 flooded batteries with Group 31 AGM's. I also installed a Victron Energy BMV-702 monitor which provides detailed monitoring of the coach batteries and auxiliary voltage monitoring of the chassis battery.

Once I removed the original batteries, it became obvious to me why there was so much off-gassing. The battery cable terminal connected to one of the high amperage fuses was improperly swaged - which likely led to high current draw and ultimately killed one of the two batteries (picture attached). I would have thought that hydraulic swage tools with the proper dies would be used in a factory - as opposed to $20 hammer type crimpers that DIY'ers buy at Harbor Freight. Oh well, it's fixed now.

Also figured out why the rubber covering the step wasn't staying attached - too much sawdust and shavings stuck to the contact cement. That's fixed now, too.

The Crown AGM batteries are a bit taller and a bit heavier than the OEM batteries, which made for a tight fit in the battery compartment. The shunt for the Victron monitor fit nicely on the back wall of the battery box and may be visible in one of the pictures.

Hopefully, this will be a good mod to our MH. One thing the Victron did was to verify that the converter/charger will charge both the coach and chassis batteries under certain conditions when on shore or generator power.

[Rkloud9]

Nice job! Please keep us posted on the performance of the new set up.


Bob & Cynthia
SunSeeker MBS 2400W Under Construction, to arrive April 1st
Sent from my iPad using Forest River Forums

[BEMR]

What type of cost on all that, curious if while my batteries are still good I would want to replace.

[KatanaPilot]

Reviving old post as I thought this was an appropriate place for this.

During the latest mod of replacing the Jensen DVD/Nav with a Kenwood unit, I verified one issue that had confused me during the previous battery replacement.

On the MBS chassis there is a (MB factory) chassis ground quick disconnect near the accelerator pedal that is used, of course, to disconnect the chassis battery. Or at least that's what it is supposed to do. During the DVD unit mod, I used the disconnect and once again, I found that it did not disconnect the chassis battery at all.

A little more in depth digging showed that due to the way that FR connects the chassis battery to the BCC - there is another path to ground - so disconnecting the MB quick disconnect does nothing. You actually have to take out the carpet and factory rubber mat, remove the chassis battery cover and disconnect the ground terminal at the battery. So if you are storing your MH long term without charging it and expecting the factory ground disconnect to actually disconnect the chassis battery - you might find that it doesn't.

Am I missing something obvious?

[BEMR]

Originally Posted by KatanaPilot

Reviving old post as I thought this was an appropriate place for this.

During the latest mod of replacing the Jensen DVD/Nav with a Kenwood unit, I verified one issue that had confused me during the previous battery replacement.

On the MBS chassis there is a (MB factory) chassis ground quick disconnect near the accelerator pedal that is used, of course, to disconnect the chassis battery. Or at least that's what it is supposed to do. During the DVD unit mod, I used the disconnect and once again, I found that it did not disconnect the chassis battery at all.

A little more in depth digging showed that due to the way that FR connects the chassis battery to the BCC - there is another path to ground - so disconnecting the MB quick disconnect does nothing. You actually have to take out the carpet and factory rubber mat, remove the chassis battery cover and disconnect the ground terminal at the battery. So if you are storing your MH long term without charging it and expecting the factory ground disconnect to actually disconnect the chassis battery - you might find that it doesn't.

Am I missing something obvious?

5000 miles on my unit had out 6 times in 8 months, last time out dead batteries when battery switch was off, is there a known issue, seems you've got it figured out, suggestion please, thank you!

[KatanaPilot]

Although I believe I have figured out why the chassis battery disconnect does not work, I do not have a competent answer for you as to what would.

I'm quite sure that disconnecting the battery cables at both the chassis and coach batteries would work, but that is considerably more difficult than it should be. There are plenty of posts indicating that the coach disconnect switch does not disconnect everything and you already know that to be true.

I am working on a simplified solution and if I'm successful, I will post again here. It will probably be something similar to prior posts - like quick disconnects at the coach batteries. Not as simple as a switch at the doorway, but practical and easily installed.

[ScottBrownstein]

Generally the battery disconnect switch by the doorway disconnects the house batteries, but the chassis battery remains connected. My 1997 Bounder had a separate disconnect for house and chassis, but my Georgetown does not. So far this has never seemed to be a problem for me.

[FFred]

Non use is always a hassle as LA batts will self discharge 1/2% (NEW) TO 3% (OLD) PER DAY.

Weather connected or not , connected parasite losses kill the batt quicker.

Simplest cure might be a method of charging like solar .

ALL batts suffer from internal discharge , so spending huge bucks may not be a solution.

Solar is a rational solution.

For Boondockers that wish to dry camp a SOC meter (state of charge) would be first investment , so you can observe the batts "gas gauge" and see where (how charged or discharged) your system is.

Bogart Engineering Trimetric is a modest cost ($150)
that should keep a house set alive for many discharge cycles , if the no discharge over 50% rule is observed.