Slight departure from our normal material, but we hoped this Makita battery advice might be of use to you.
Currelec have used and been fans of the Makita 18volt cordless system for years. Our large collection of their power tools have worked faultlessly. We keep reading angry/horror stories about how BL1830 (3Ah) batteries are poorly designed and keep failing. As we’ve never had a problem, we investigated how they work and have come up with two simple golden rules to help keep them alive and well.
1. Never, ever recharge a hot battery!
2. Always store/keep your batteries charged – never flat.
Sounds simple, but it worked for us and our half dozen batteries, most of which are now several years old.
So, what’s the problem?
Makita, like most power tool manufacturers build safety into rechargeable battery packs. If a Lithium Ion battery explodes, it’s like a grenade – which isn’t good! The batteries themselves are made up from a series of small cells, looking a little like a stack of AA batteries, with some connectors and a tiny circuit board with a battery monitoring chip.
This little chip monitors a variety of things, such as battery voltage, individual cell condition, temperature… etc etc. If it’s not happy, it stops the recharge. If it’s very unhappy, it declares the battery “Failed” and stops it from ever being recharged again. There’s your problem!
Always let a hot battery cool down before recharging. If the chip senses it is too hot (or too cold, ironically!) it will prevent charging, but be aware this process isn’t perfect and you may confuse the chip into thinking the battery has overheated during charging and it may be one step nearer to being declared “Failed”…..Batteries should be hand-warm only, before charging.
It seems the second problem is that two of the cells eventually fail due to trying to power the chip when the battery is put away flat. This causes the battery to become unbalanced, which the chip hates. When you try to charge it, you can get the red/green flashing lights. If this happens more than twice, the chip declares a “Failed” battery and you are left with a paperweight!
These batteries are expensive to buy new, but ours have given faultless performance. There are clone copies and replacement parts available on the net, but only delve into the internals of these batteries if you know what you’re doing. You don’t want a grenade going off in your tool shed!