Camper Lifepo4 4s4p 100Ah (Topband 25Ah cells) build

liponoob

New Member
Joined
Dec 10, 2021
Messages
5
Hello Everyone,

After watching few of Will's videos on YT, got inspired and started putting together a Lifepo4 battery pack for my DIY trailer camper conversion build.

Not knowing where to start and the supply chain limitations initially I got 4x25ah 3.2 Topband LifePo4 batteries and 120A 4s BMS from Overkill Solar. Batteries were bare metal, didn't come with nuts or busbars. Stumbled around to find the correct size shrink wrap, M6 nuts and DIY busbars using 0.125 copper bar. Cheap crimping tool and good terminals from Grainger.

Measuring and drilling holes in busbars was not easy with limited skills.

I wanted a metal box as this will be next propane tank, assumption being metal box is safer. They were expensive. I found a International Harvester Cub battery box for reasonable price.

Top balanced and assembled the battery with BMS connected to WFCO WF-8955SPEC-B-LIS power center. Worked perfectly. It was sitting there as I build the camper.

Cells were from a local supplier off ebay. They were pricey compared to BatteryHookup which I noticed later.

Now I got 12 more from same supplier(OOS at batteryhookup) and want to arrange in 4s4p "side-by-side" config.

Is this layout correct?
Can I just use longer copper bars and drill holes?
For the right most busbar where 4+ve and 4-ve are combined, can I just use one long copper bar?

Thank You.



IMG_3116.JPG
 

Samsonite801

Photon Sorcerer
Joined
Oct 15, 2020
Messages
1,912
Is it just me, or does your pic show on top set in the middle, 4 + to 4 +, and then on the bottom row in the middle, it shows 4 - to 4 - ?

A 4s series string needs + to - between each of the 4 cell groups around in the circle.

I think all the battery cells along the right side, need to be flipped around, leave the left side the way they are.
 
Last edited:

liponoob

New Member
Joined
Dec 10, 2021
Messages
5
Is it just me, or does your pic show on top set in the middle, 4 + to 4 +, and then on the bottom row in the middle, it shows 4 - to 4 - ?

A 4s series string needs + to - between each of the 4 cell groups around in the circle.

I think all the battery cells along the right side, need to be flipped around, leave the left side the way they are.
Thanks for the observation. After I posted the image I realized my mistake and rearranged the cells.
 

liponoob

New Member
Joined
Dec 10, 2021
Messages
5
Here is the final(debatable) build. It is a 9 1/2 x 9 x 7 3/4 metal box

Lessons learned
-It is not cheap to build your own, but the experience is priceless
-Unnecessarily complicated by choosing 16 cells
-DIY bus bars ie., drilling copper to fit battery terminals is not easy. Measurements go wrong. Thing fly all over the place. If you are lucky enough copper bar is not a complete waste.

Next steps
-Add 12V heating pad using DC adapter bypassing power center for winter
-Powered vent for summer

IMG_3290.JPGIMG_3291.JPG
 
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