Make up a 24V Li 6x 18650 Drill battery?

[Charlie+]

This is for a 24v (Ni-Cd originally) fairly powerful hammer drill.
The original 2 batteries it came with are shot and Iv been through the
replacing cells stage but have reached the end of the line with them! So
many cells in series has not been a reliable format!
Could I make up a reliable battery using 6x 18650 cells and two of these
cheap in/out protection circuits (see below) powered out in series? I
could arrange a switch to parallel them when charging if that may be
necessary. There seems to be little information on how these circuits
work.. or might react in a 24/26v connection. Worth a try? I doubt
the current would peak at more than 3A even in a grind to a halt
situation (even if you could hold onto the drill - but I havnt'
measured).
Otherwise the whole drill is for the bin! Its branded McKeller.
Thanks C+

3S-8A-Li-ion-Lithium-Battery-18650-Charger-Protection-Board-10-8V-11-1-12V-12-6V
eBay item number:
141739077302
http://www.ebay.co.uk/itm/3S-8A-Li-ion-Lithium-Battery-18650-Charger-Protection-Board-10-8V-11-1-12V-12-6V-/141739077302?hash=item21004eaeb6
or a slightly lower current board:
http://www.ebay.co.uk/itm/3S-6A-Li-ion-Lithium-Battery-18650-Charger-Protection-Board-10-8V-11-1V-12-6v-/171887035146?hash=item280544030a

 

[Clifford Heath]

On 10/10/15 19:16, Charlie+ wrote:

This is for a 24v (Ni-Cd originally) fairly powerful hammer drill.
The original 2 batteries it came with are shot and Iv been through the
replacing cells stage but have reached the end of the line with them! So
many cells in series has not been a reliable format!
Could I make up a reliable battery using 6x 18650 cells and two of these
cheap in/out protection circuits (see below) powered out in series? I
could arrange a switch to parallel them when charging if that may be
necessary. There seems to be little information on how these circuits
work.. or might react in a 24/26v connection. Worth a try? I doubt
the current would peak at more than 3A even in a grind to a halt
situation (even if you could hold onto the drill - but I havnt'
measured).
Otherwise the whole drill is for the bin! Its branded McKeller.

Like what I did here:
<http://polyplex.org/electronics/ryobi_lifepo4/index.html>

Lithium Iron Phosphate (LiFePO4) are the go for drills, not Li-ion or
LiPo. They're what the big brands use and despite lower voltage
(nominally 3.4, 3.7 at max charge, not 3.7, 4.2 at max charge) and lower
power density, they have better intrinsic safety than the others. Buy
name-brand cells from a reputable supplier, or you'll almost certainly
get crap or worse, repackaged dead cells pulled from old gear.

You need to bring out seven wires to a re-balancing connector. At first
the cells may charge evenly, but they will age at different rates. After
a year or three you'll need to rebalance them after every charge.

For up to six cells, go to Hobby King and get a Turnigy Accucel 6
charger and use it with an old laptop power supply. About $AU25.

I didn't bother with any protection but what is already in the A123 cells.

Clifford Heath.

3S-8A-Li-ion-Lithium-Battery-18650-Charger-Protection-Board-10-8V-11-1-12V-12-6V
eBay item number:
141739077302
http://www.ebay.co.uk/itm/3S-8A-Li-ion-Lithium-Battery-18650-Charger-Protection-Board-10-8V-11-1-12V-12-6V-/141739077302?hash=item21004eaeb6
or a slightly lower current board:
http://www.ebay.co.uk/itm/3S-6A-Li-ion-Lithium-Battery-18650-Charger-Protection-Board-10-8V-11-1V-12-6v-/171887035146?hash=item280544030a

 

[Charlie+]

On Sun, 11 Oct 2015 18:07:00 +1100, Clifford Heath <no.spam@please.net>
wrote as underneath :

On 10/10/15 19:16, Charlie+ wrote:
This is for a 24v (Ni-Cd originally) fairly powerful hammer drill.
The original 2 batteries it came with are shot and Iv been through the
replacing cells stage but have reached the end of the line with them! So
many cells in series has not been a reliable format!
Could I make up a reliable battery using 6x 18650 cells and two of these
cheap in/out protection circuits (see below) powered out in series? I
could arrange a switch to parallel them when charging if that may be
necessary. There seems to be little information on how these circuits
work.. or might react in a 24/26v connection. Worth a try? I doubt
the current would peak at more than 3A even in a grind to a halt
situation (even if you could hold onto the drill - but I havnt'
measured).
Otherwise the whole drill is for the bin! Its branded McKeller.

Like what I did here:
http://polyplex.org/electronics/ryobi_lifepo4/index.html

Lithium Iron Phosphate (LiFePO4) are the go for drills, not Li-ion or
LiPo. They're what the big brands use and despite lower voltage
(nominally 3.4, 3.7 at max charge, not 3.7, 4.2 at max charge) and lower
power density, they have better intrinsic safety than the others. Buy
name-brand cells from a reputable supplier, or you'll almost certainly
get crap or worse, repackaged dead cells pulled from old gear.

You need to bring out seven wires to a re-balancing connector. At first
the cells may charge evenly, but they will age at different rates. After
a year or three you'll need to rebalance them after every charge.

For up to six cells, go to Hobby King and get a Turnigy Accucel 6
charger and use it with an old laptop power supply. About $AU25.

I didn't bother with any protection but what is already in the A123 cells.

Clifford Heath.

Thanks for the info! I happen to have lots of 18650 cells in good
condition - so I may go a different route!! C+