NiMh battery to Li-ion conversion and other stuff!

NiMh battery to Li-ion conversion and other stuff!

Maker/DIY

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Attribution

https://www.biltema.se/fritid/tradgard/tradgardsmaskiner/multix-18-v/ and the need to NOT buy new tools

Description

I got two perfectly fine makita power tools using the old NiMh post-style battery. Even if you find new batterys NiMh is way less effective as Li-ion. When Biltema launched their 18V MultiX system it became affordable to convert power tools to li-ion (instead of buying new tools). And while the base model for the battery interface was done it could be used for other useful stuff. It's a system to build on.

WARNING! Running li-ion batterys without monitoring them may cause death and destruction, both to you and your tools. Be smart!

These batterys are also branded and sold by Draper and Sealys. Possibly more brands.

I started by making wooden prototypes, they turned out well so I still use the on my tools! So that's another possibility if you want to.

Materials and methods

You'll need some copper or aluminium sheet metal to make the electrical connections. You'll also need to modify the old "battery shells" (see pics) You'll figure it out, you are a maker after all :)

freecad > slic3r 0.35 20% > prusa i3 mk2 PLA

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Comments

Mini avatarfunkysod commented ago

Erik de Bruijn: You should of course use the charger appropriate for the new batteries. So the problem with overcharging is handled in the charger. Over draining is another issue. I choose a brand where the tools do not handle over draining or over temperature. This is all done in the battery itself. So when the voltage drops below or the temp rises above the battery just shuts off. I found that to be the best solution when using old tools with these new batteries. I've found that most cheaper tools, with cheaper batteries, goes this route. And a cheap lithium battery us still way better than old nicad/nimh batteries. The tools performs excellent!

Mini screen shot 2013 07 15 at 6.49.36 pmErik de Bruijn commented ago

may cause death and destruction

Good point. Anything you're doing to prevent overcharging and draining the batteries too much?

I can imagine it saves weight as well, doesn't it?

Mini avatarfunkysod published this design ago