Battery for Bosch cordless drill

Rather depends on how much you like the drill. If nothing special, I'd go for a Lidl offering (you have to keep an eye out for them) They are all Li-Ion these days which seem to be a better and longer lasting type of battery. The problem being that replacement batteries if not genuine vary a lot in quality. And how much current they can deliver makes a big difference to drill performance.

There are firms around who will re-cell batteries for you. I had one done for a much loved Wickes drill that included a right angle drive. Replacement cells - despite a highish cost - weren't as good as the originals, though.

Google seems to suggest the above is a 12V NiCd battery.

If you're attached to the drill, it would be possible to recell it with lithium ion (a simple 18650 3S pack would fit inside with ease) but you'd need to put a BMS in the pack (basic ones are a few dollars from China) and a new charger. It would likely make the drill work better - you'd keep the 'freshly charged' feeling for a lot longer, and possibly get more torque if you select batteries with a high current capability.

If you buy a replacement battery, pay close attention to the cells inside. Many Chinese cells aren't good.

If the drill isn't terribly special, you might find a new one isn't a whole lot more. I bought a pair of Aldi drills for 25 pounds each the other month

- it was cheaper to buy two drills than a spare battery pack, and turns out having two drills is quite handy (drill bit in one, driver bit in the other, left hand, right hand...). They work a whole lot better than my old NiCd drill.

Theo

You might well find that modern AldiLidls are nearly as nice as the Bosch (and they come with their own standard batteries which can be bought separately, and which fit their other tools).

Or you can re-cell your own. I re-celled the Ryobi that preceded the Mak. Space is a bit tight, the originals tend to be spot welded. You can DIY spot weld, or solder; easisest way is to get ready tagged ones and solder, but it may be very hard to fit these back in the original case.

NiMH are an alternative to NiCad; not as good as LiIon but less likely to catch fire if you screw up.

I very recently bought a Battery type BOSCH 2607335244, High capacity, 12.0V, 3000mAh, NiMH. My old Bosch drill has always been so solid and smooth. I've now got a cheap but effective impact driver, a decent SDS, but preferred the Bosch for everyday drill use. The downside being that it is heavier than so many modern drills. Plus, it is a much appreciated present that I couldn't throw away even if it were a doorstop.

Bought from AboutBatteries FR. Fast delivery. Couldn't find one cheaper at the time from what appeared an acceptable supplier.

My modern(ish) Lidl one locks the chuck when stopped. Something my older ones didn't. It's also soft start.

Very good points. Are you sure it is a positive lock though? On my Mak in low gear the chuck appears locked solid, in high gear you can just rotate it (not normally a problem).

I suspect I'll go down that route unless I come across another good deal on a Bosch or similar in the near future. On principle, I prefer to invest in good tools that will last [1] but the changes in battery designs every few years are a big obstacle to that.

That's good: I like to have a spare. (I'd be up a creek now if the Bosch hadn't come with two batteries.)