The 'F' cell NiCad pack which I use to drive my Hilti TE5A (24V) has finally died and needs to be replaced. I think it's probably time to move to Lithium cells. I'd welcome recommendations of what to get and where from.

The drill takes 15 - 20A when running.

You need Bottlebank....oh, hang on.....lol

No, other people know about cells, not just bottlebank.

You need LiPo cells, the current draw of a big hilti is too much for cheap 18650's unless you move to ?5-6 per cell and you will need 10-20/of them, and a 10s capable balance charger

http://ukcaving.com/board/index.php?topic=17551.0 and http://durmitor.yucpc.org.uk/misc/drill_batteries.php may be of interest?

I think that you wouldn't need to share our worries about overly high current draw if you switched from NiCad to LiPo.

NewStuff said:

No, other people know about cells, not just bottlebank.

You need LiPo cells, the current draw of a big hilti is too much for cheap 18650's unless you move to ?5-6 per cell and you will need 10-20/of them, and a 10s capable balance charger

Click to expand...

I'm fortunate to be in the position where cost is a secondary factor to performance.

When I built the NiCd pack I knew all there was to know about power tool batteries, but I've fallen a long way behind in the intervening 20+ years! I had in mind that it would need 7 cells, presumably "10 - 20" means a series/parallel arrangement is worth considering?

Can you provide any links/recommendations?

MarkS said:

http://ukcaving.com/board/index.php?topic=17551.0 and http://durmitor.yucpc.org.uk/misc/drill_batteries.php may be of interest?

I think that you wouldn't need to share our worries about overly high current draw if you switched from NiCad to LiPo.

Click to expand...

Thanks, I'll read and digest later.

Don't know the operating voltage for this drill, but I'd seriously consider sticking with a maximum of 6s Lithium cells (nominally about 22V) . For 7s and more you might struggle/need more time to find a charger and balancer and everything. If you think about building the battery pack yourself, take a look at LG18650 HG2 cells for a sufficiently high discharge rating. Obviously, put two or three in parallel if you like extra capacity, and maybe stick in a "BMS/PCM/PCB" circuit board for battery protection. Some of these circuits come with a built-in balancers as well.

nickwilliams said:

NewStuff said:

No, other people know about cells, not just bottlebank.

You need LiPo cells, the current draw of a big hilti is too much for cheap 18650's unless you move to ?5-6 per cell and you will need 10-20/of them, and a 10s capable balance charger

Click to expand...

I'm fortunate to be in the position where cost is a secondary factor to performance.

When I built the NiCd pack I knew all there was to know about power tool batteries, but I've fallen a long way behind in the intervening 20+ years! I had in mind that it would need 7 cells, presumably "10 - 20" means a series/parallel arrangement is worth considering?

Can you provide any links/recommendations?

Click to expand...

It depends on the space available in the pack, if you can fit more in, then you would have a very capable pack. The 10/20 was me thinking that you had a T6 (36v), but it's a T5 (24v), so 6s2p is the way to go if you have room, and most hobby chargers can charge a 6s pack, so it opens up your options greatly.

If you want to use 18650's (Cylindrical Li-Ion cells, 18mmx65mm) then I would look at getting some tagged Samsung 30Q's which has the ability to deal with high current draw. These will easily handle the drill, even under stall conditions. I would look at Torchy on ebay (seller name Big_f_d_d) or Ecolux on ebay. Both are top-notch sellers. They might have them or be able to source them.

If you are looking at LiPo (Flat cells, better energy density, but more prone to disliking abuse) then anything over 20c should be good to go, as long as you use a reputable supplier. They come in a vast array of sizes. Anything meant for RC use will do the job.

For either pack, you will need some sort of alarm or cutoff to prevent the cells going below the minimum voltage, as this causes permanent damage to the cell. Thankfully, a simple programmable alarm is very cheap indeed.