2 things the cells and the BMS

We rotate 12 makita 3 amp/hr lithium batteries since they came out more than 10 years ago, I have lost 3 batteries to date, my mistake using them on a machine that is not star rated (the old makita blower) I have not idea how much they have degraded because I dont have a device to test them, and because we have a pile of them, it doesnt matter if it only lasts 5 hours, we just swop out with one from one of the chargers. I highly recommend makita for site work. Yes I am rough with the batteries and yes I do drop them, even off the ladder.

I am down to 17 bosch 10.8VDC batteries for all the machine we use in that platform, I also highly recommend these little 10.8 V devices and batteries. I have lost about 4 batteries so far, they just died. Consider I purchased them in 2006, I cant complain. These batteries are used more than any of the other brands on site.

I also have about 10 Hilti batteries in the 22 VDC and 36 VDC, the 22 V batteries seem to be lasting a lot longer than the 36 V, but not impressed I have had to replace all my 36 V batteries and boy they are not cheap and you all the know about the crap support Hilti offer as they age. I have around R150 000 worth of Hilti machine and not one is is supported by Hilti anymore. They dont even allow me to book them in for a service anymore because they are older than 5 years. I thought Hilti supported machines for 20 years, clearly I didnt read the small print. I wouldn't recommend any Hilti machines, especially if you are a small contractor like myslef, only have a small employee count (which affects your discount structure) and buy to last. Dont get me wrong Hilti make a good quality product, I just got burnt trying to get machines serviced. I am sitting with a R30 000 machine that they cannot fix after numerous attempts and then offered to replace but 2 years later the machine is collecting dust in the storeroom

Like any cell, you do get different grades of 18650 cells which are used in laptops, battery powered machines and other battery packs like cycling lights etc.

What seems to happen with lithium batteries is the little PCB (BMS) on the battery packs break long before the cells.

For example the Makita packs that I have stripped once the charger prevented them from charging (I should have boost charged them like we do with the little lead acids once they drop below 10.5 V) I stripped the cells out of the pack and purchased a lithium charger. I now use them the torches. Apparently you can buy the little BMS and replace it, its just not worth the hassle.

The same with the bicycle lights, they dont seem to last as long as they should (around 10 years) they should considering they have 18650 lithium cells the same as the machine tool batteries. As I mention 10 years and both my makita and bosch batteries are still in daily use.

What should be the highlights features of any lithium battery sold, the make, type and grade of cell used and the BMS, not all the other crap to make it sound great.

If the cells have an expected life span of 15-20 years and BMS warranty of 2 years, that would pop up a red flag. You pretty screwed if you have cells that will last 20 years, but a BMS that will destroy the battery in less than 5. It doesn't take a genius to figure that out.

Once I figued out the problem with bicycle light, I stripped the cells and bought a plastic case which has charge state LEDs and the batteries can be replaced at any stage. They are still the same cells from the original 4 pack heat shrink pack I purchased 7 years ago

Just imagine if the solar batteries were serviceable, you could just pop out the BMS once it breaks ( looking at battery warranties , this is going to be the case with many battery packs with short warranties) the BMS is going to break long before the cells regards less of the grade.

BMS - short life (Check the warranty) This is going to fail long before the cells.

Cells - 10 years plus regardless of the grade.

If used with other devices, the communication protocols is just as important.