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Old 11-28-2020, 01:35 AM   #1
Junior Member
Join Date: Aug 2018
Posts: 24
My Lithium upgrade Experience

Lots of stuff out there. Lots of incomplete, dated materials on the web, and stories about installs on other platforms.... Lots of acronyms that aren't explained... I'm no expert, but maybe my experience can help others. 4 photos attached.

I've got a Forest River Forester 2401WS on a 2016 MBS Sprinter Chassis. I knew I needed a Battery Monitor System (BMS) after some trashed Lead Acid batteries left us high and dry last fall in Yosemite. It's a long drive to buy batteries from Yosemite.. It's been so long since I added water to batteries, I let them go dry ;-(. "Doing it right" with Lead Acid seemed a challenge, Lithium seems much simpler. And the cost of getting it wrong is being w/o power at Yosemite when it drops into the 40s at night....

We like to boondock, so went in whole hog, got 2x 100ah BattleBorn batteries. I got the Li upgrade for the converter, since the '16 did not have the PCB switch. Also, got the Victron BMV-712. Asked the nice folks at Battle Born if that was all that was needed, and they said 'yes' in a very reassuring and confident way. Hey, they're salesfolks, and I just gave them over $2K..

Installing the new output stage of the converter was straight forward. Some documentation would have been nice, but there was little room for error.

Next was the battery swap. The old Lead Acid batteries came out fine, and the new Li batteries fit well. But the terminals have a different orientation, and bolts.

Group 27 batteries apparently have a standardized 5/16 lug, so the cables on the Forest River all have 5/16 lugs. Obviously.

But the Victron shunt has ??? Does not appear anywhere I found on their website, and buried in their literature is a reference to a M10 bolt. Pop quiz. What size lug fits on a M10 bolt? 10mm is 0.394", 3/8 is 0.375". Yet a 3/8 lug fits on a M10 bolt. Well that's lucky.... Victron is a European company. Maybe they should do some research on the US market, and at least clearly document that 3/8 terminals will be needed if you have a rig w/ American sourced batteries...

So, Battleborn was not complete. They sold me a shunt that required new battery cables. Seems anyone replacing group 27 batteries would face the same situation.

So, I tried to drill out the lug on the grounded lead. As the bit started to brake thru the lug, the torque tore the lug off the cable. A poor crimp from the factory. So, I pulled the cable thru the battery box, and off the chassis under the coach. A 42" cable. Had one fabed at my local NAPA auto parts store, w/ 3/8 lugs. And they fit (just luck.. ).

Looking at where to install the shunt and the BMV-712, I went w/ KISS. The shunt is mounted on top of the battery, meaning I was able to use a 1ft. 2ga cable I'd purchased from Amazon earlier, and the new 42" 2ga cable from NAPA. In hindsight, both cables could have been a couple of inches shorter. a few cable ties hold them down.

The BMV-712 sits in the battery compartment w/ no ties, just loose. Will use only the app, I like that interface much better in any event.

All fine. Lots of folks w/ youtube videos on how to configure the BMV-712. Used the outdated video on the BattleBorn site. Failed to get the details on calibrating zero current... Not sure any of my readings were accurate, they all looked screwey. Took a few days to visit Samuel P. Taylor State Park in Marin. Beautiful redwoods. No utilities. Batteries were somewhat depleated when we arrived. Alternator not charging batteries. So ran the generator a few times, never really tested the 200ah capacity.

A few days of web searching, questions on this forum, and a call to battle born to a clueless help desk person (hint to Battleborn.. Send you techies into the shop to do an installl Then they can talk like they've done the work before)... I need a new Battery Isolation Manager! The higher voltages of Lithium mean the older BIM never closes the relay, and never charges the house batteries. Went w/ the Precision Circuits LiBIM-225. Was not clear where I'd install a DC-DC converter, just stayed w/ the LiBIM-225. Why didn't BattleBorn tell me that when I purchased the rest of the package?

Found one picture of an install that was similar. Thanks to Riverbend, he gave me the picture I needed to pull the trigger. Post #150 on https://www.forestriverforums.com/fo...ml#post2277635

So, first, had to find out how to remove the ground on the chassis battery in a sprinter coach. That was non-intuitive...

pulled the old BIM and relay. Then tried to figure out how to wire it up.. Hooking up the white, brown and red 18ga wires was easy. Just needed to put on two ring terminals.

But hooking up the high current leads was a larger problem. They are mounted on pass-thru studs that do spin a little. I did not remove the lugs used w/ the relay, instead, I rotated them about 90 degrees. Went to the local hardware store for inspiration. Waited for an older guy to come ask if I needed help. After looking for copper bus bar and failing, he pulled down some 6ga copper grounding wire, like you'd see between a lighting rod and a stake in the ground. And some 6ga lugs.

Attached the Li-BIM to the box w/ one sheet metal screw, and soldered the lugs w/ a blowtorch, used solder paste and the solder you'd use in plumbing. Lots of iteration, work w/ a hacksaw and vice, but really happy how it turned out.

Hooked the negative leads back up, undid the coach negative terminal, did the zero current calibration. readings were no longer screwy.

Wanted to write my notes before too much time passed, not sure when our next road trip is. But fired up the coach, saw about 80a into the battery from the alternator, so looking good! I'll report back if there are any other issues.

In an ideal world, the parts list to do the install would exist, and you could source all parts, and do this install in an afternoon. Glad I didn't need the RV right away, this project has lasted weeks..

I'll try to cross thread on "Electrical, Charging & Solar"
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2016 Forester MBS 2401WSD
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Old 11-28-2020, 08:30 AM   #2
TomAR's Avatar
Join Date: Sep 2017
Posts: 83
Nice write up. I had many of the same experiences with the same install, but on my 2018 Sunseeker 2400R MBS. Li-BIM is definitely needed - my install was MUCH easier; it was essentially a drop-in with some new wires. I also added battery warmers, for winter travels. That took quite a bit of new wiring.
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2018 Sunseeker 2400R MBS (w/dinette)
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Old 12-04-2020, 04:04 PM   #3
Join Date: Dec 2015
Location: Illinois
Posts: 49
WOW, thanks for talking me out of that "little" upgrade. Seriously appreciate that write up though if I ever reconsider, good work man!
2016 MBS 2401w
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Old 12-13-2020, 05:02 PM   #4
Junior Member
Join Date: Aug 2018
Posts: 24
Update, more "shoulda known"

Got out to Harvest Hosts for a couple of nights (Twisted Oak Winery, nice place). First night, woke up at 5am by the State of Charge Alarm at 20%, 1.37v. Pop quiz.. Of the cuff, what is the discharge curve? Don't remember the details at 5am? Me neither. Turned off the heater & went back to sleep.

Called Battleborn, couple of things. One is Charged Voltage. Should be 14.2, not 14.4. oh. If the converter fails to reach 14.4V, it won't register 'full'. And, the converter they sell is known to maybe stop just shy of 14.4V.

The other is more tricky, glad I called, I'd never have figured it out. When you set up the BMV-712 thru the bluetooth app, you'd think it actually worked. You'd be wrong. On power up, the head unit enters setup. If you don't complete setup on the head unit, the bluetooth won't stick. Huh? Be sure to see the voltage on the display, you know setup is finished. So, was talked thru finishing the setup on the head unit (values didn't matter, just need to exit setup), then entered the values into the app that he recommended over the phone.

Next morning, got up, had 90% SOC. I think now I'm done. Well almost, the stairs just failed ;-(
2016 Forester MBS 2401WSD
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