Replacing NiCd with Li-ion cells in cordless drill battery

XXX-Man · 2018-10-07T11:47:34.000Z

I believe someone here can help me with this.

I have old drill with dead NiCd battery which hasn’t seen much use so is like new. I would like to replace cells with Li-ion (18650).

Original battery is 14.4V but I believe 4S (16.8V) would be ok and not a problem.

I have found this board on aliexpress and I wonder what else do I need?

aliexpress.com

0.85€ 8% OFF|3S 4S 5S Li Ion Lithium Batterie 18650 Ladegerät BMS 25A 30A 40A...

Smarter Shopping, Better Living! Aliexpress.com

Do I need special charger to use with this?

Kame_Sennin · 2018-10-07T12:42:15.000Z

Despite the title saying "charger pcb" this board look like it's a simple BMS that will do the following :

Protect the cells from over current (this board is rated for up to 40A) and shorts
Protect the cells from over charging (usually limit voltage to 4.25-4.30V/cell but not always very acurate)
Protect the cells from deep discharge (a typical low voltage limite for this kind of board is 2.7-2.8V)
Try to keep the cells balanced during charge

But it won't limit the charge current and the over charge limit is somewhat high so you need to use a CC/CV charger with a CC (current) setting matched with your cells recommanded charge current and a 4.20V limit (or lower if you agree to trade some autonomy for longer life)

Note : Beware that powertools require high current batteries

Zelda · 2018-10-07T12:51:52.000Z

You need a balanced RC charger, which support 4S Li-Ion.

I did the same with two cordless drill.
—> Be aware that after the rebuild, the drill will fall over easly, because the batteries are lighter!

XXX-Man · 2018-10-07T13:10:48.000Z

Kame Sennin:

But it won't limit the charge current and the over charge limit is somewhat high so you need to use a CC/CV charger with a CC (current) setting matched with your cells recommanded charge current and a 4.20V limit (or lower if you agree to trade some autonomy for longer life)

Note : Beware that powertools require high current batteries

So something like this can be used?

https://www.aliexpress.com/item/1-Pcs-EU-US-UK-Plug-5-5mm-2-1mm-AC-100V-240V-PC-16-8V/32651843493.html

I know about batteries and I have them already.

Zelda:

You need a balanced RC charger, which support 4S Li-Ion. I did the same with two cordless drill. –> Be aware that after the rebuild, the drill will fall over easly, because the batteries are lighter!

Can't this board from first post take care of balancing?

Zelda · 2018-10-07T14:12:43.000Z

I’m not sure, if the board can balance. Usually the balance current im ma should be indicated.

XXX-Man · 2018-10-07T14:23:37.000Z

I missed that.

So balanced version should be ok from here?
https://www.aliexpress.com/item/4S-40A-Li-ion-Lithium-Battery-Protection-Board-18650-Charger-PCB-BMS-For-Drill-Motor-14/32840714633.html
It says 100mA

Kame_Sennin · 2018-10-07T15:07:14.000Z

The four 43 ohms resistor (with 430 written on it) on the left of the picture are balancing resistors.

But who knows if the picture is accurate ...

The last link shows (edit : ) nearly the same board from an other seller ;-)

XXX-Man · 2018-10-07T15:32:28.000Z

Well if the board is balancing can I use this charger?
https://www.aliexpress.com/item/1-Pcs-EU-US-UK-Plug-5-5mm-2-1mm-AC-100V-240V-PC-16-8V/32651843493.html

BlueSwordM · 2018-10-07T15:50:48.000Z

1. Yes you can. It will work fine, especially if you only use new cells, but the BMS will be only the only thing to trust that the battery pack is fine.

If possible I would add this:
https://www.aliexpress.com/item/F00872-Low-Voltage-Buzzer-Alarm-Volt-Meter-Indicator-Checker-Dual-Speaker-1-8S-Lipo-Li-ion/32601463913.html?spm=2114.search0604.3.16.307a79c7Hn22uu&ws_ab_test=searchweb0_0,searchweb201602_5_10065_10068_204_10130_318_10547_10059_10884_10548_10887_10696_100031_10084_10083_10103_10618_452_10139_10307_532,searchweb201603_60,ppcSwitch_0&algo_expid=793efc28-492c-4a19-b797-c89a9d7ba0d6-2&algo_pvid=793efc28-492c-4a19-b797-c89a9d7ba0d6&priceBeautifyAB=0

Quite nice, and allows you to check the individual cells voltages, and if the BMS cuts off at the right voltage.

2. If I were you, I’d pick a 24V charger/laptop power supply, and wire a buck converter with adjustable CC/CV, and set it 16-16,4V for much higher cycle life, like this:

https://www.aliexpress.com/item/Lithium-Charger-Step-Down-Power-Supply-Module-5V-32V-to-0-8V-30V-5A-for-Mega/32399062651.html?spm=2114.search0604.3.2.1b903378AqrHu4&ws_ab_test=searchweb0_0,searchweb201602_5_10065_10068_204_10130_318_10547_10059_10884_10548_10887_10696_100031_10084_10083_10103_10618_452_10139_10307_532,searchweb201603_60,ppcSwitch_0&algo_expid=966020f0-156b-43c6-b4e0-32dc3a3f9a52-0&algo_pvid=966020f0-156b-43c6-b4e0-32dc3a3f9a52&priceBeautifyAB=0

It’s really nice. You can adjust the current so you can do a slow charge at 1A, a fast charge at 3A, and if you put a heatsink on it, super fast charge at 4A.

XXX-Man · 2018-10-07T16:45:32.000Z

1. My plan was to put small voltmeter on battery pack to check voltage, but this is even better. I just have to think of how to make it fit

2. That is perfect. I was looking for something similar but couldn’t find it, I guess my keywords were wrong.
I have many laptop chargers I can use for this so this would make it even cheaper.

chadvone · 2018-10-07T17:52:43.000Z

Hope this works out for you. If it doesn’t you could always convert it to a 12v car plug or gator clips and throw in you trunk.
Not as portable. But they work in an emergency, I had one in my last RV with some old drill bits and a few screw tips. Came in handy a few times.

XXX-Man · 2018-10-07T19:04:11.000Z

We will know in about a month from now.
Shipping is slow from China to here.

JasonWW · 2018-10-07T20:05:31.000Z

From the title I thought you were going to adapt a lithium battery pack and charger from a newer drill to fit your older drill with an adapter.

XXX-Man · 2018-10-07T20:30:26.000Z

Fixed
Sorry not the best English speaker here…

That would be easier, just print adapter and you are good to go