Design of a Battery Canister

[Scuba-guy]

One more, question. how long are your dives?

 

[Mobulai]

Looks prudy!
One more q from me: where did you source your canister from?

 

[AdrianHe]

How heavy is the battery on land and underwater? Also how do you charge it? How many amps and what voltage is the charger and how long does it take to charge the battery? How much did it cost to build? How long did it take to build? Would you do it again or just buy one off the shelf?

Weight on land: 2.7kg (6lbs)
Weight underwater: 1.1kg (2.4lbs)
Capacity: 447Wh
Charger Voltage: 25.2V
Max. charging current: 8.85A
Charging time @8.85A: ~2h

I'm charging the battery with a lab. power supply, the cell ballancing is done on the integrated pcb.
Total cost is about ~660€ (delrin parts: 280€, wam cord + cable gland: 100€, cells: 136€, electronics & pcbs: 100€, other stuff ~60€)
No idea how long it actually took to design, but when calculating labor costs this is probably the most expensive battery canister ever built . This project was not about saving money, but mostly about having fun and learning new stuff. And as always: "We do these things not because they are easy, but because we thought they were going to be easy"

I've designed the battery to power my Santi 110W heated undergarment for at least 3h, as this is the time my second smaller canister can supply 35W to my heated gloves and 30W to my light.

 

[AdrianHe]

Looks prudy!
One more q from me: where did you source your canister from?

They were machined by the CNC machining service of PCBWay in china. Had some problems with porosity in the core of the material and tolerances. Would probably choose a different manufacturer next time. Ended up having to select the radial o-rings by the actual measurements and not the initially designed parameters.

I wish I had a lathe