I’m a paraglider pilot and I’m using electric heated gloves. The problem is that the gloves barely last 1.5 hours on the highest setting, so I’d like to build a longer lasting pack.
The original pack is 7.4V 2200 mAh LiPo. My idea is to make DIY 2S1P 21700 Li-Ion packs and use them in place. The load is very easy, max 2A, continuous, smooth load.
I’m thinking about using the new high-capacity LG-INR21700-M58T cells, or Samsung INR21700-50E. I think they are ideal for low current usage.
Some things are still not clear though:
Do I need to use a BMS with balancing functionality or I can use a simple one, like those thin rectangular ones?
Do I understand correctly that all BMS have a BM point for measuring the individual cell voltages, but only the more complicated ones balance the charging and discharging between the cells?
Do I need to use a balanced charger like, a B6 Mini, and solder balancing cables? As I see it, balancing cables are not very common on Li-Ion packs, while everyone uses them for LiPo packs, right?
Can I use the original CCCV charger? It has a Y cable so I believe it charges in parallel. It’s very low current, 1.2A for both batteries in parallel, but I’m only planning to charge overnight.
Do I need anything for building the pack, like those insulators and spacers? I bought a spot welder for this, so the welding should be straightforward, I just don’t know about the rest, such as spacers, insulators, etc.
I’d definitely like to have a BMS. First I don’t know if the glove has any kind of cut-off voltage, or it might just infinitely drain the batteries. The other reason is I’d like to have protection for anything which might possibly cause fire, for example short circuit.
What cells would you recommend:
Samsung 50E
LG M58T
LiitoKala 50E
I’m tiny bit concerned about the LG as some people say that it has very thin walls and ends. Also, in those reports it easily gets very hot on somewhat moderate loads.
On the other hand I’ve been using the Samsung 50E in my bike light for years and it’s been flawless in every possible way.
Do you think there are any concerns with the LG? Also, what about the LiitoKala, are these just repackaged Samsung cells?
I have been following this with interest. I have gloves with similar packs. They really don’t last long enough. I have seen some good ideas so far. But my question is this: Have you given any thought about how you will attach a larger pack to the gloves so it stays put and does not get in the way?
The battery pouch on mine is not big enough to accommodate packs that are much bigger than the ones it comes with.
what are the dimensions of the pack it comes with? I’m thinking even you if somehow enlarge the pouch, extra bulk and weight it may be pretty uncomfortable if the size of new pack is much larger, should not be an issue if a pack is slightly larger thou,
you could relocate packs in your pockets, and have wires in your sleeves, the way kids have elastic band sewn to their mittens and pulled thru the sleeves
8 cm X 6 cm X 13 mm.
Interestingly, mine are 5 volt 5000 mAh (16.5 Wh).
So, I think that complicates things (and is different from what the OP posted about. His packs are listed as 7.4 volts).
I did check, and the built in pouch on the gloves is bigger than I remembered. (it has been warmer here and I haven’t used them in a while). I could probably stuff 4 21700 cells in there. 4 18650s would be better. But getting the 5 volts out might be more of an effort than I want to make.
for us USA folks
3.25X~2.4X~0.4 inches. ( I may have rounded up by a mm or so on the length/width and thickness) Not that big really. Definitely lighter than a “D” cell. Certainly lees bulky with the flat packaging.
Now 4 21700s with a way to hold them together plus BMS with some kind of regulation…
Yeah, that is getting big.
Maybe for those used to using the system their entire lives.
I still have to do conversions to visualize the size of something given in metric.
Yeah, yeah, I know it make much more sense. But when one has been doing something their whole life… change is hard. @alpg88 is a US guy. Responding to his comment about the pack being big… I just wanted to make sure he got it.
But just for you @TARTARA , I will make sure I post all dimensions in English units going forward…
oh, my bad, i read it as 13cm not mm, hence i tough it was huge. now it doesn’t look that big.
I’m fine with metric, as well as sea system, i lived in “metric” country for 20 years.
It is a big misconception that americans do not understand metric system, we do, especially those that ever worked on cars, pretty much any car sold in usa has half of nuts/bolts metric, half standard. every mechanic has a set of metric tools, you can’t work on cars without it. 8 and 10mm nut drivers are absolute must. most common soda bottle size 2L. everything in medicine is measured in mg, ml, cervical dilation measured in cm. we really have both systems in use
Actually not all metric countries use/used exclusively metric system, USSR used metric, but all plumbing piping were in inches, thread angle was not 60* like in metric. plumbers had imperial taps and dies. Now former soviet republics do not manufacture their own plumbing, they import from mostly europe, so the plumbing is metric there now too.
OP here, 2x21700 is almost the size of the original pack, maybe 2 mm thicker. There is loads of space in the gloves, I can fit two fingers in there next to the original pack.
For this use, is there any difference in going with an LG M50T, M58T or the Samsung packs? Right now the Samsung? I especially like the fact idea of using the LG M58T as it’s the best W/kg liion available today, but there isn’t too much reports with using it yet.
From the specification I think the M58T would be just fine. The current draw is well within its specs. It would give you plenty of capacity. So, while I didn’t see any reviews, the data sheets show it to be a good cell. Someone mentioned that they were expensive, but I didn’t find any actually for sale.
And they are pretty new so there is not much real world test data on them.
Difference, well maybe a few more minute of heat for you hands…
