Off the Shelf Lithium-Ion batteries for Low-Volume products - Page 1
Forum section: electronics / projects

author: ConnorGames
author_rank: Regular Contributor
timestamp: January 10, 2021, 08:04:24 pm
content: I have recently been working on a product for a startup that needs an ~30Wh 12V battery. Lithium-ion or LiFePO4 seems to fit the bill well, it we go through worst case 1 cycle per day for 3 years with a max draw of 0.6A or so (With Li-ion I may need to increase capacity to get sufficient cycle life). The device will be on (probably under) a wheelchair, so size is not a huge constraint. Unfortunately, I cant seem to find an off the shelf product that is basically 3 18650 cells with a protection circuit at a reasonable price. I can find the UBBL21-FL at mouser, but it is $60 even in quantity 100 and cycle life looks poor. I know that good cells are usually around $4, so this seems like an enormous markup. Custom packs are an option, but with this being a startup I would need really good justification to spend over $1000 on NRE. Anything based on using raw 18650s in a holder is out of the question for safety / certification reasons. Any idea what gives and any cheaper options out on the market? I would love to be under $30 in Qty. 100 but this is starting to seem impossible with lithium.

author: tooki
author_rank: Super Contributor
timestamp: January 10, 2021, 08:43:57 pm
content: LiIon battery manufacturers (Panasonic, Samsung, etc) make custom packs.Also, look into local battery stores that may be able to fabricate them for you.

author: Weston
author_rank: Regular Contributor
timestamp: January 10, 2021, 09:36:26 pm
content: Can you not use a power tool battery pack? It might be a bit mechanically annoying to connect to the pack, but otherwise it sounds like exactly what you are describing.For example, the M12 battery packs are just three 18650 batteries with protection circuityhttps://www.milwaukeetool.com/Innovations/M12I am unsure about wholesale prices on the prices of the original packs, but aftermarket replacement packs should come in below the target price point.

author: Distinctly Average
author_rank: Contributor
timestamp: January 10, 2021, 11:21:44 pm
content: Don’t know if you have Aldi or Lidl where you are as they both have a range of cheap 12v power tools. As suggested above, they might fit the bill. Both stores do spare battery packs for those tools in a couple of sizes and cheap chargers as well. IIRC, they were about £11 a pack here in the UK, and the 20v ones were £15.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 11, 2021, 12:08:36 am
content: search for a USBC 12V power pack. They usually have 4 or more voltage settings.

author: SVFeingold
author_rank: Frequent Contributor
timestamp: January 11, 2021, 12:34:36 am
content: Quote from: ConnorGames on January 10, 2021, 08:04:24 pmWell...you aren't just paying for the cells. You're paying for the cells, the battery management system (assuming you want one), the labor to weld, shrink-wrap, attach connectors, etc. If you were purchasing in quantities of 100k+ or 1M+ then you get much closer to raw material costs. Low quantities is basically all labor. You can't reasonably expect anyone to take the time to source and set up all this stuff and charge you barely over the raw cost of the cell.The power tool battery packs could be a good way to go. Just make sure you do some research on whichever brand you attempt to use. If I recall some of them (Makita?) had issues where the pack would brick itself if it briefly discharged too low (i.e. you used it and didn't IMMEDIATELY put it on a charger). You definitely want to understand the behavior of the packs in your use case.Otherwise I recommend checking out batteryspace.com. It's where I get lithium cells for my projects. They also sell all kinds of packs and do custom work as well.Here's a 3S, 27W-hr pack for $45.Includes a BMS and a thermal fuse. They'll probably give you a discount for higher quantities. A few more options:https://www.batteryspace.com/custom-li-ion-18650-battery-10-8v-3-35ah-36wh-1-2a-rate-3s-s-ncr18650b.aspxhttps://www.batteryspace.com/Li-Ion-18650-Battery-11.1-V-2600mah-28.86Wh-TRIANGLE-Battery-Pack.aspxhttps://www.batteryspace.com/li-ion-18650-battery-11-1v-2-6ah-28-86wh-4-2a-rate-3s-s-battery-module---un38-3-passed-ndgr.aspxAnd a LifePO pack under your budget:https://www.batteryspace.com/lifepo418650battery128v2700mahsidebyside3456wh7arate.aspx