Off topic Battery advice? (power tools)

Off-topic Chatter
1

Ok - I've been mulling over my options for too long - its time to make a decision.

I'm looking for opinions, but just sort of thinking out loud, too

I have about a dozen power tools that use Sub-C Nicad power packs.

About half of those are Craftsman C3, the rest each have a different pack shape/charger.

I'm mostly concerend w/ the C3 stuff - the others I don't use enough to wear out.

I've gone through 6 C3 packs in 2 years (if you include buying 2 Harbor Freight 18V batteries, taking the cells out and putting them in the C3, then addinig the best one from the old pack).

This is a major PITA - running all the old cells from a pack through a full discharge/refresh on my BC700 takes a LONG time and has also taught me that the charge they take (the mAH of the last charge in a series of discharge/refresh cycles) doesn't necessarily mean the cell will maintain that charge, or have a decent discharge rate.

So - what to do next. I'm done w/ the NiCads...

Good NiMH Sub-Cs? lots of capacity, very safe, should work ok in stock charger. but...still heavy, still lots of cells, so one or two go and I'm back to trying to rate each one and rebuild a pack

5xProtected CGR18650CH? Make my own spring loaded holder, wire that inside the stock battery pack case. To charge I could take them out of the case/holder and charge them in parallel w/ my hobby charger - or wire a balance connector (never take them out) and use the hobby charger balance board.

LiPO RC pack? wire inside stock case, use hobby charger to balance charge.

all three of those options cost roughly the same...ie lipo is probably the most expensive, but also the easiest...i think...

I would suck it up and buy the craftman C3 lithium packs - but w/ charger and 2 batteries I'm looking at well over $100...and I doubt the charger will maintain batteries as well as my hobby charger...

ideas? opinions?

2

For what I think is best and cheapest option, I would go with 2nd option. You could get unprotected NCR18650s 2900mAh for $6.30 for that 5pcs (focalprice). The panasonic has built in protection called HRL (I think heat resistant layer or something), it will survive even short circuit without overheating / blowing up. Not making this up, I've actually read the spec from Panasonic some time ago about this specific battery.

Then buy battery cases (2pcs, 3pcs, 4pcs, whichever you need) from Buyincoins, and wire in balancing lead as needed.

Now you have your ACTUAL 2750mAh (minimum) pack that will retain charge and deliver amps, for fraction of the NiCad price.

NCR18650 Reference

3

In the last 6 months, bought these SubC batteries twice, one for my 9.6V (Green) BOSCH tool (10 year old) and one for a professional friend, who's using a (blue) BOSCH 14.4V

They seem to work much better than the previous NiCd pack and the BOSCH charger works without a problem

Much cheaper solution than getting a new battery pack (which would probably be NiCd also...)

If you can "open" the battery pack without destroying it and have soldering skills (to "rebuild" the pack), proceed with solution No1 (good NiMH SubCs)

4

I will probably go this route, but with the Panasonic High Drain instead. The peak draw of the drill must be about 40 amps - probably more if you stall it. I actually found the spec sheet on the motor awhile back, to check the input voltage range, but I'm not finding it now w/ a quick search...

5

If you go the "18650" way,

please upload a few photos of the process and the "final" pack - others might also be interested (including myself!)

6

has anyone ever opened a li ion tool bat pack? i'm wondering what size is generally used

i have a sears 12v lith drill/driver that i use for small jobs, as well as 12&18v nimh ones and i gotta say that little sears is always ready to go even after months of sitting around where as the nimh will always need a charge.

7

I haven't, but guessing by the size, their compact C3 packs can't have more than 5x18650. I bet the full size one has 26650. but again, just guessing.

8

40A? Wow. I didn't know that... in this case I don't think the battery case can be used unless the whole wiring is totally replaced with thick leads..