r/DIYUK • u/JustGhostin • 1d ago

Cheers Dad!

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Brought my first house earlier this year and needless to say my dad is exited to show me the ropes. He trained as carpenter and also worked as a window fitter in his 20’s before changing careers.

Blessed to have his knowledge and help.

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13

u/boomerberg 1d ago

Big fan of the EXT 18V range. Really good tools IMO. He’s chosen well!

2

u/cactusplants 1d ago

They are great, I always sing praise, but recently I've had 4 5ah batteries die just outside of warranty. £150 quid of batteries down the drain.

Il probably get to swapping out the cells once I get a spot welder for batteries.

2

u/Dry_Variety4137 1d ago

Just be careful with cell balancing before you stick the pack together. You Don't want to start overcharging one of the 18650's.

You probably already know this, others might have just learn something new that will save their house from going up in flames.

1

u/Djuthal 1d ago

Could you elaborate on this, please? What do you mean with 'cell balancing'?

I have a few of the tools above, but corded. But I have a black and decker drill with battery. Anything I should be careful about?

Cheers!

1

u/AreEUHappyNow 23h ago edited 17h ago

This isn't relevant to your average battery tool owner, this is for people making DIY repairs or refurbishments to batteries by opening them up and replacing the 5/10 18650 cells that make up the battery.

Essentially you have five 3.2v 18650 cells in series that make the 18v the tools run on. Say the batteries you put in have voltages of 3.7, 4.0, 3.1, 3.5 and 4.2, when you connect them together the higher voltage cells will rapidly charge the lower voltage ones, which can cause them to become damaged, or even explode.

1

u/Bats_Everywhere 19h ago

So do you put the lower voltage ones first in the series to prevent this from happening?

2

u/AreEUHappyNow 17h ago

No, it makes no difference where you put them in the pack. You need to ensure that every single cell has been charged or discharged to precisely the same voltage, within a small margin.

2

u/cactusplants 15h ago

Yeah, I've got a smart balance charger for my lipos and old nimh batteries. It's an effort to do, but I'll double check when I get around to it that I do it correctly.

1

u/Dry_Variety4137 11h ago

Good man 👌

1

u/Dry_Variety4137 10h ago edited 38m ago

AreEUhappyNow explained it nicely.

But here's my elaborated example:

For Example.... If you assembled a pack of battery cells fully charged at 4.0v but a single battery cel within the pack was at 3.0v, the charger will read the pack as not fully charged. Therefore, it 'could possibly' overcharge the cells that are already fully charged (in the hopes of charging that single battery cell that reads lower at 3.0v) and causes the rest of the cells to overcharge past their rated 4.0v

A result of improper battery cell balancing can possibly lead to the battery cells exploding due to overheating, etc.

The only way the unbalanced batteries can be safely charged is by incorporating a battery with an in-built battery management system (also known as 'BMS') This works by individually monitoring the charge state of each battery cell - and thus automatically self balancing all of the batteries within the pack.

Hopefully, my explanation isn't too hard to understand 😵‍💫

Edit: spelling mistakes