ADVICE -Replacing/Repairing DeWalt Battery Packs.

bilabonics

1 mW
Joined
Sep 2, 2022
Messages
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Hi All

I am based in the UK.

I had set DeWalt tools/batteries 4/5 years ago and now the batteries are starting to die, voltage is dropping way below 17/16v on the pack, i good one is over 22v (from memory may be more/less but all my good 4Ah were of the same higher voltage.

I have tried 'jump starting' on by putting a good one in parallel for 30 seconds to give it some charge so the charger recognises it, charges for a few mins, once i put in drill it last 5 seconds and battery voltage has dropped again.

I have not opened the battery up yet but think they use LG cells (perhaps Samsung).

So i am thinking of purchasing a over £50 of 18650's and repairing them as each one starts to die....

I've seen batteries here but prices in Euro -
https://eu.nkon.nl/rechargeable/li-ion/18650-size/sort-by/price/sort-direction/asc.html

And here BUT it seems to be cheaper to purchase a genuine Dewalt 18v/4Ah ready made!
https://www.nubattery.co.uk/18650-flat-top-batteries?sort=price_asc&count=9

Also i did consider used 'A Rated' cells but don't think the C rating/output is enough and not worth the hassle tbh.

Also looking at this spot welder, i want something decent as in the future ui want to build a an elec bike battery.

https://www.ebay.co.uk/itm/185595270197?_trkparms=amclksrc%3DITM%26aid%3D777008%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D243420%26meid%3D5e713670d53d4d2a891a0d32058e7c90%26pid%3D101286%26rk%3D1%26rkt%3D1%26mehot%3Dag%26itm%3D185595270197%26pmt%3D1%26noa%3D1%26pg%3D2380057%26algv%3DWatchlistVariantWithMLRV5%26brand%3DUnbranded&_trksid=p2380057.c101286.m47999&_trkparms=pageci%3Acf2ff2ac-63e5-11ed-a97c-ce9c64ba9e41%7Cparentrq%3A74d4e15e1840a60c1270bd79fffbe0bc%7Ciid%3A1

Plus i will need a charger/discharger to measure battery capacity i presume?

Anyone help me on my journey please!

Thanks
 
UPDATE on battery, starting measuring and one bank only measures 1.067, so i presume i the other seems ok (see pics), it's had water damage from when i was working in the rain a few weeks ago.

What is my nest step, how do i remove the tabs/nickel joining strips, each has a 4 spot weld.

Plus i still need a link to a basic spot welder to get me going for now, will this do (a friend uses it for small repairs on batteries, shavers, small tools with rechargeable batteries etc).

A link to one and how to proceed would be great.

L-N is 17.44v across all cells.

Its 20.04 on a good battery i also have.

Is this saying i have perhaps 1 bad cell? 20.13-17.44 =2.69v ?

Thanks.IMG_8174.jpgIMG_8179.jpgIMG_8180.jpgIMG_8181.jpg
 
I'm just starting to get into the battery learnings, so take anything I say with a whole helping of caution!

I have been looking into DeWalt batteries as I've been looking for a solution to the unavailability of husqvarna batteries here in Aus. I've got plenty of DeWalts, and they're easily available, so I'm hoping to come up with a harness that'll let me run the husqys on DeWalt.

DeWalts appear to be 'dumb' packs - the BMS is in the tool and charger (I think). So not difficult to rebuild.

But, In Aus at least, it appears cheaper to buy a new Dewalt battery than it would be to buy the cells and rebuild, especially when they're on some sort of special (which is nearly always in DeWalt land). It might only be more economical if most of the cells were fine - just one or two had failed.

Judging by the state of your battery, I personally wouldn't bother trying to rebuild. It's a bloody mess!

You need to test each cell individually.
 
It’s probably one or more if 4 cells.
I’ll be repairing more over the years plus looking to build bike batteries.
I’ve got most of the stuff I need know from welder. Tester. And a proper IR battery tester.

Cheers
 
spinningmagnets said:
Thanks for posting this!

No problem.
I’ve learned the smaller cheap lip battery welders will only weld 0.15 nickel plate.
Power tools have thicker plates from 0.3-0.4mm.
Plus it’s very important to use PURE NICKEL.
Plus you can double or triple by stacking/doubling/tripling strips.
kWeld do a great welder with a foot pedal but are expensive.
You can also get the ‘little red welder’ kits that you can easily mod (capacitor or resistor depending on model) and power from a car battery with good results.
Also Google 5000w spot welder (another welder).

Also the OPUS BT-3100 is the battery charger to use/discharge slowly to get individual battery voltage/Ah and resistance.
This also needs a mod as it can overheat and cut out and shutdown during a long test.
(Stear cleat from the cheaper Littokala ones/rubbish)

Another essential tool to test the batteries IR is a dedicated tester that puts a AC voltage and frequency through the battery to give the exact figure with an extra digit that you can match to the stats sheet.
From reading up this is massively overlooked!
The YR1035+ is what u need.

I have more links/pics but what I have found out above will get a LOT of people going.
 
Looking at how rusty the interconnect strips are, those are NOT pure nickel, but, steel.
That is probably why they're thick, because, steel is much less conductive than nickel.
 
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