Servicable 18650/21700 Battery System w/ nickel strips & Busplates

[caza]

One of the common complaints I've seen about typical 18650 builds how they are not easily serviceable and require total disassembly to replace a single cell, as well as not being able to check on individual cells. There are options like vruzend and N.E.S.E modules, but they both have some drawbacks and limitations.

I've thought of a different solution but don't know if I'm missing any drawbacks. Basically you built a more traditional pack with busplates, like you would see on a tesla module or more specifically jonescg's build. But instead of tiny fuse wires or soldering nickel to the busplate, you have a nickel strip spot welded to the battery with a hole drilled into it on the other end, tap a corresponding hole in the bus plate, and bolt the nickel strip directly to the bus plate.

This is obviously more labor intensive and even a small bolt for every cell would add some weight, but the benefit would be a pack that is just as configurable and capable as any, but still be fully serviceable.

What do you guys think? Too much work for too little gain? Any glaring issues?

 

[john61ct]

better with copper strips, just use a little nickel patch for the spot weld

could use ring-terminated crimped tinned copper boat wire as your buss

or going to Wago terminal blocks with push-in "Cage Clamp" connection technology

easy not just to test / replace cells gone bad but reconfiguring your xPyS layout anytime

 

[john61ct]

Cost

space / density

proof against shock / vibration

are the challenges / issues

 

[john61ct]

Cost

space / density

proof against shock / vibration

are the challenges / issues

 

[john61ct]

can buy cells with welded tabs included

 

[caza]

Welgo terminals seem to be way more space-hungry than what I'm proposing though they are a really interesting solution especially since you could modify your s/p config.

It would certainly be less dense than a nickel-strip battery or even a busplate battery, but not by much. It would be thicker by 2x the size of the bolt head. So if you used this bolt for example the thickness added would be less than 2mm compared to a busbar/busplate setup. Imo this is negligible.

Cost of the above example would be an additonal $0.60/cell which is definitely significant and might be better spent on better cells or more cells. Certainly lower cost fasteners can be easily found but it does make one question of modularity and serviceability are desirable enough to be worth the cost.

Shock and vibration absolutely should be tested, but wouldn't it be likely close to just as shock and vibration proof as the many A123 and other pouch cell packs that have been fastened together? Bolts have been used on electronics and motor vehicles of all types, seems to me as long as they are fastened correctly they can generally withstand vibration and shock.

One downside is that there are definitely more potential failure points compared to a pouch-cell pack with bolted tabs.

 

[john61ct]

Yes attachment to soft pouches are likely well cushioned

The WAGOs have an excellent shock-absorbing spring-held mechanism.

Bolts into rigid buss bars plus rigid cells bouncing around are def an issue, loctite, nylocs etc might be enough. . .

maybe Huck bolts?

extra tooling costs but specifically designed to hold no matter what