24 chinese volts drill battery pack overhauling…

Batteries and Chargers Rechargeable Batteries
14

funny thing is it would be 24v if those were li-ion.
i would run it at 24v as a test so you dont waste your time building a pack if it sends up smoke signals.

15

Your math is correct, 7'2 volts nominal; and nothing else, really.

As the drill owner told me it had “adequate” performance when new and he mostly uses it as some sort of screwdriver to play with his bike, I think I'm gonna go the 3SxP li-ion route.

6S li-ion is 21'6-22'2V so, not yet there strictly speaking. And remember W = V²R here so, those voltage levels mean we'd have all the tickets for the Magical Smoke Lotto.

Cheers ^:)

16

Hello!

Well, before summarizing my friend the potential upgrade cost with 3×VTC5s, a proper CC/CV charging module and a small voltmeter, I've made a simple small load test on the drill's charger stand PSU (rated 24V 500mA on its label): after loading it with a 37'5Ω combined load resistor, I've measured 11'21V load voltage… :FACEPALM: so it struggles to deliver a measly 300mA, at a much lower output voltage (no load volts ≈19'7ish).

Do you believe I could find a speedy hamster on a wheel inside of it?

Cheers ^:)

17

open it up and drop in some high protein feed?

18

I have one of three voltage monitors. It flashes total voltage and voltage of each series cell. It also emits an load audible alarm when voltage gets too low. I don't know what it's parasitic drain is and I probably don't have anything sensitive to measure the drain. It fits standard JST-XH connectors like used for hobby chargers.

19

For the purpose of the thing, I aim at minimizing costs, without sacrificing performance. My idea is to install the pack bare inside the housing, attaching it to the terminals with a truckload of copper wire. My smart & cheap plan is to install the multimeter inside, and attach it to the battery terminals in series with a momentary pushbutton and a small capacitor in parallel with the meter; that way voltage can be easily checked with a small push on it, and the pack is not drained by the voltmeter.

Practical and low-cost.

Cheers ^:)

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 ^:)