24 chinese volts drill battery pack overhauling…

Batteries and Chargers Rechargeable Batteries
20

Barkuti, did you ever get this thing finished? I’d like to see pics of what you did, and know the results.

21

Hi!

Been somewhat “away” from the forum and related stuff lately, got back to labor nearly a month back now.

This project is “oficially jammed”, I guess the drill's owner really liked the way I restored/upgraded his little laptop's battery pack, he really finds use for it at work.

He may not have liked much the drill pack restoration figures I gave him, but for sure that must have had to do with these facts: a) the drill was a über-cheap piss poor tool, hard for any figures to look good in such a case; b) he may not have real need for it.

Maybe if he finds some extra spare €uros to squander on this stuff soon…

Cheers fellas ^:)

22

Scorching news!

Well, just spoke with my friend and, since I was not going to use my LiitoKala 26650-50As, I've ended up proposing this idea to my fellow comrade:

He's a nice friend, a little favor for a friend who has financed this with €20 at my request.

Well, this is all about for now. Waiting to hear any enlightening advice.

Cheers ^:)

23

Additional equipment:

Digital LCD Thermometer Hygrometer Humidity Temperature Meter Indoor @eBay

Thermometer + probe for $1.87, for monitoring battery temp.

DC 0-100V LED 3-Digital Diaplay Voltage Voltmeter Panel Meter with 3 Wires HS $1.18 atm.

Cheers ^:)

24

Cool, looking forward to seeing the build progress!

25

Typical blf mod.
$25 in parts for a $5 drill.
Interesting to see how the rest of it holds up.
Btw a 15a bms will be inadequate.
Stall/near stall may be 50+a!

26

Hello! :-)

snakebite, my BMS choices have been influenced on a tad off-topic handful of posts brief discussion I had a few days earlier about restoring a Hilti TE 10A hammer drill power source.

After reading the information available on this Auxiliary Battery Pack for the Hilti TE 10A Hammer Drill page, plus this picture:

Briefing: 1.2 - 1.4Ah sub-Cs, operating at up to 15A (≈10C cells).

… it more or less becomes clear to me that not even in their wettest dreams would have those AA Ni-CDs provided more than around 8A comfortably. Bottom line: the appliance was a piss-poor electric screwdriver, to start with.

Yesterday I sent inquiries about that inexpensive 15A BMS from Aliexpress to two sellers, asking for the transient/momentaneous operating current values on it. After receiving the same useless copy/pasted answer/information in both cases, already provided in the product ads anyway, I've decided to go with the eBay 15A BMS which, being like the 8A (17A transient current) unit with twice the FETs, I presume its transient current value should also be 2 × 17A = 34A. :THUMBS-UP:

Bidding on this thermometer right now: Hot Digital LCD Thermometer Hygrometer Temperature Humidity Meter Probe Sensor @eBay. Seen it for $1.28 on “Buy it now!” but hell, since I have a few hours to spare, it cannot hurt to save a few cents. :-)

Cheers ^:)

27

Well, done with the shopping cart.

Ended up discarding the thermometer, right now I think it's probably overkill/unnecessary.

Ordered one of these inexpensive units for voltage monitoring: https://www.aliexpress.com/item/Green-Second-line-precision-dc-digital-voltmeter-head-LED-digital-voltmeter-DC2-7V-32V/32590301654.html

Evaluated ImA4Wheelr's #18 post suggestion regarding those 1-8S li-ion voltage monitors (found 'em on eBay from $1.17), but heck, the stuff is gonna have a proper BMS taking care of independent cell monitoring sooo keep it simple stupid.

Oh! Found the https://www.aliexpress.com/item/Free-Shipping-5A-constant-current-LED-driver-module-battery-charging-constant-voltage-DC-DC-power-module/32665140766.html CC/CV buck module slightly cheaper. :-)

Cheers ^:)

28

you might be surprised at the start surge on that motor.
get your shunt and scope out and have a look.
i would use the bms to charge but not run the motor from it.
it will trip every time you pull the trigger unless that motor is a total wimp.
which is entirely possible knowing what that drill is.

29

Are you serious, snakebite?

In the eBay ad the BMS board is said to have been tested on a Bosch GSR 7.2 succesfully.

I was also thinking about this but, maybe I could order one of the cheap Aliexpress 15A BMSes and set it in parallel with the one I ordered. Of course, the predicted slight differences in BMS resistances means that the inter-BMS load distribution would differ, but nothing excessive I think. Even if one of them only channels half the current the other does, we would still be at a 22-23A continuous and probably twice that figure for transient current. Shouldn't be very hard to measure load distribution…

Cheers ^:)

30

“24V”

24 valves it must be a 6 cylinder engine. :smiley:

31

Dammit!

My best bet for now, I believe, is to wait for the ordered BMS and take a look at the markings on its MOSFETs. If it ends up needing some current handling improvement, it'd easy to add up to 4 additional ICs stacked upon the ones onboard.

Just checked out eBay, plenty of SOP-8 MOSFET 5-packs for under $1. I wish I were to have a way to know what model does that board uses.

Over-analyzing as usual…

Cheers ^:)

32

Cool plan Barkuti. Hoping it works out. I wouldn't mind copying it on a smaller scale if it works out.

33

Mmm, been searching for “2S BMS” images on Gmail search but, to my dismay, barely any of them were useful with regards to peeking at their SOP-8 MOSFET IC markings. Most pictures lack detail/resolution and/or their chip markings are “sabotaged”. Could read AO4119 in a couple of unrelated, scant examples.
Mmm, just wanted to save some days by ordering an additional MOSFET pack right now. LoL!

Cheers ^:)

34

Well, you could save some time, but pay for it in cash, by buying enough MOSFETs to replace the existing ones as well. Then you know you’ve got all good ones on the board.

35

Mmmkay, not an expert on these matters DavidEF. According to what I've briefly read about MOSFETs, their resistance (RDS(ON) I presume) increases with temperature so they share the load efficiently (current proportionally diverts to the lesser resistance gates).
The important question here is that the circuit is designed to use either N or P-channel MOSFETs, and I don't have a clue about this (literally).
With regards to nice offers there are plenty, a 5-pack of AO4409s for under $1 or a 10-pack for $1.36 sounds great, with just ≈9.5mΩ typical RDS(ON) at VGS = -4.5V and ID = -10A (P-channel MOSFET), so 4-5A of continuous current handling with ease even if cooling sucks. I have nearly a dozen DIP-8 MOSFET datasheets on my document viewer atm LoL.
Already modding before the first outing, where have I seen this before?
Asked the eBay seller what kind of MOSFETs are found on the 8/15A balance BMS boards, though I'd be surprised if the answer is other than “WTF?” or similar.

Cheers ^:)

Posted on Wed, 11/16/2016 - 20:07. Tiny fix.

36

That…… is just sad. :person_facepalming:
.

:smiley:

37

Got a reply from eBay seller surever9.

Couldn't see jackshit on the thumbnail but, after logging in in eBay, I could see this:

Found this: Vishay Si4324DY

The datasheet figures are @#$% good, its RDS(ON) is so low that at 14A continuous it would be dissipating ⅔W at most.

I wonder what's the thing which makes the protection chip to trip, source-drain dV maybe?

Cheers ^:)

P.S.: got pleasantly surprised by the eBay seller. :-)

P.S.2: Angler, with 24 valves you can also have V8s and V12s. Yes, it was a six cylinder in this case, “soon” to be converted into a Flat/V-twin.

38

good that those have protection diodes.
motors can generate some nasty spikes.

39

Stray capacitance issues? I'll need to use around 3" of wire up and down inside the battery compartment, hope 4×AWG18 current highway width does nice enough. I'll also take a peek inside the screwdriver/drill, just in case.

And with regards to the still yet to know current handling problem, seems the Si4324 isn't so dirt cheap as AO4409s, yet I see it offered for $0.31/piece plus $1.26 of shipping for up to 10 units in Aliexpress. So ≈$2 should “make my day” if this ends up being an issue.

We'll see.

Cheers ^:)