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Re: Make up a 24V Li 6x 18650 Drill battery?
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Clifford Heath
Oct 11, 2015, 3:07:06 AM10/11/15
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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
>
> 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
>
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