Newbie Li Build attempt (for RV)

WharfRat48

New Member
Joined
Mar 21, 2022
Messages
6
Hi all, I have been lurking for a while and am going to attempt an "easy, low cost", build to replace my 215ah Lead acid battery bank with EVE230 cells. Going to follow a build that Will had posted, but as I look closer at the details, some questions have come up. First, main components will be 4x eve 230s, overkill 120A BMS, Victron Rover 30A mppt controller, and 3 x 100 W panels. First question I had was about my application- will a simple build like this assembled into a battery box stand up to being on the tongue of a travel trailer bouncing down the road? Also, do I need to worry about compression, and if so, is it as easy as taping the cells together and adding some foam to secure them in the box. Finally (for now), I assume I should top balance these? I do not have a power supply where I can set the voltage (yet), is there a way I can top balance using the BMS and a lithium battery charger? I'm sure I'll have other questions, but that is a good start. Thanks in advance for the help.
 

time2roll

Photon Sorcerer
Joined
Mar 20, 2021
Messages
3,889
I have a small 5th wheel with a DIY battery in the front compartment. I also built a wood box. I built it with a movable end and used a couple zip-ties for compression and to hold everything in place. I have no concerns about running down the road. Tape or foam is fine too. I don't think compression should be a critical engineering project at this level. Just some basic restraint. A Jeep trailer on a pintle hook for severe off-road might be different.

I skipped the top balance and slapped a Heltec 5a balancer on top. Works fine if your daily charging will be closer to 13.7 to 14.2 volts. Mine charge at 13.8 just fine with very little cell voltage deviation. Even the balancer may not be needed if the cells are well matched and arrive at similar charge levels. The BMS and RV converter should be fine unless there is a specific issue.
 

joanna_lannie

Maybe sleepwalking now
Joined
Sep 14, 2021
Messages
189
Battery compression is important to keep the battery running at high performance for long periods of time. Cell balancing is still important, and BMS has a part of the balancing function that can help the battery pack to achieve charge balance. But it seems it would be better to use a balancer and not need to rebalance for a long time. Otherwise, you may be balancing every once in a while.
 

WharfRat48

New Member
Joined
Mar 21, 2022
Messages
6
Thanks for the replies.... Another question... my system currently has a Victron battery monitor, is there any reason to keep this as my BMS will have Bluetooth capability? Any harm in leaving it?
 

time2roll

Photon Sorcerer
Joined
Mar 20, 2021
Messages
3,889
Thanks for the replies.... Another question... my system currently has a Victron battery monitor, is there any reason to keep this as my BMS will have Bluetooth capability? Any harm in leaving it?
Fine to keep the monitor or let it go. Probably best to keep it for now. Don't be alarmed when the two monitors don't exactly match. If one works better than the other feel free to adjust the system in the future.
 

HRTKD

Boondocker
Joined
Apr 24, 2020
Messages
8,020
Location
Somewhere South of Denver
I have a bumper pull trailer. I chose to move locate the LiFePO4 battery bank inside the trailer. A standard tongue mount battery box isn't waterproof and likely isn't big enough to hold the cells, BMS and a compression fixture. Yes, the cells need to be compressed. The stress and vibration on the cell terminals could be detrimental to the health of the cells and could cause bad connections.

Top balancing is critical to an optimal battery. Charging in series is good to get the cells up to a point, but then you need to put them in parallel and charge to 3.65 volts. A good quality power supply that can be set for 3.65 volts is needed for this.
 
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