24 chinese volts drill battery pack overhauling…

If those NiCad were in 6S arrangement, a 2S lithium will be the same voltage, so make sure what voltage the drill motor actually needs before upgrading. Maybe put in some high capacity instead of high drain cells, and make it 2S3P to match the voltage and give a lot longer run-time.

Get a beefy LiPo for your Drill.

I tuned my Makita with a 4S 5Ah LiPo from hobbyking - this thing is so powerful, I can’t believe it. (It has 60Nm with the original NiCD battery)

I understand that but my friend just told me the drill was barely capable of drilling holes; a pretty much understandable fact having now revealed the level of beefiness of the power source.

Since electric motors can withstand a lot of over-spec abuse, just thought at least 4x the nominal output would do fine.

In fact, before dismantling the pack I was evaluating the possibility of using a 7/8S li-ion assembly; however in this case I'll refrain since that would probably allow the thing to drill at ludicrous speed…

Yeah L4M4!

Cheers ^:)

Perhaps check the drill motor anyway. I know DC motors can take a little over-voltage. I don’t know about 4x voltage! However, maybe the motor IS rated for 24 volts, in which case, the battery pack here would have been seriously under-volt as well as obviously low current. That would explain the poor performance. Build to what the motor can use reliably. There’s no point in ruining the drill motor. With the right voltage and plenty of current, it should have no trouble drilling holes!

The trick is to make sure your friend does not drain the cells too far. Especially, if you increase the voltage. Most protections that can turn off a pack also limit current. Maybe install a cheap voltage meter that clearly displays voltage while in use. Is he the type that will watch the meter and stop using when the cells get too low?

If he isn’t and you still feel compelled to give him lithium power, maybe consider those LiFePo4’s you showed me. They can go down to 2 volts. If he goes lower, the performance decreases, but they don’t become explosion hazards like other lithiums (Please double check me on that). Obviously, you would want some type of balancing protection. Unfortunately, the one you showed me only prevents overcharging of each S cell bank. It doesn’t prevent the others from charging if one or more banks stop taking charges. I don’t know how dangerous LiFePo4 are with reverse charging, but I would assume they can explode like other lithiums.

You get the picture.

Got it.

Since he says the drill could “do something” with that puny battery pack, I am going to presume it could deliver 30ishC discharge rate, for up to 7'2V×18A=129'6W of power being fed on the motor. Now, by the law of Ohm, if we increase voltage by 50%, current increases by another 50%, for 225% of the expected power output with the default pack. Now, if we assemble, for example, a 3S2P battery pack with, for example, LG HE4s, we can be sure for it to be able to consistently deliver at least up to 10'8V×27A=291'6W of power. Sounds really good for such a small battery powered drill, and a 6-cell battery pack fits inside that plastic box with ease. A $1'29 voltmeter can also fit inside.

With regards to charging the pack, I was even thinking in using independent TP4056 charging boards in series attached to the cells inside the pack, which could be fed with standard smartphone chargers in an independent fashion, maybe even build a special charger with three isolated AC/DC boards in order to allow each TP4056 to charge its serial 2P unit uninterdependently: the cell pack would auto-balance on each full charge.

Cheers ^:)

Well I’m curious as to how you can actually check it given the obvious evidence that these pricks will print any kind of label on anything!

Perhaps if you had access to a bench power supply you could test it to the point where it starts smoking and melts, then build your new battery pack from that info.

While the motor may take the raised levels, the wiring and switch circuitry might not.

With cheap tools there’s no great loss when the “magic smoke” escapes. I have a few cheap tools which I keep around to abuse so that my nice tools stay nice. One refuses to die no matter how hard I push it so you never know until you try!

Phil

Well, small electric motors are already very cheap. I wouldn’t expect the Chinese to make a new motor just so that they could label it improperly and stick it inside a tool where it is highly unlikely that anyone would see the label. Additionally, I’d expect a cheap, off-the-shelf motor to be rated at least 12V DC. Those motors can run on less than 12V. They are just slower with lower voltages. And, as Barkuti says, they can take actually a little over their rating as well. But, the best thing is to know what it is rated for, so that you have a starting point.

Once upon a time I had an electric motor which I removed from a hair drier, ducted fan style. It was fed with 12VDC (100Hz pulsed) by a diode bridge off the hair drier. I however, plugged it into a linear 24VAC output transformer rectified with a bigass electrolytic capacitor pack (10000+μF = 10+mF). I can estimate the motor started being fed with well above 30V and 3+A, with a total combined output power surpassing 100W.

An intense “continuous spark donut” was clearly seen on the motor's conmutator. It pulled so hard that you had to firmly hold it on (or else it would blast off). LOL!

Cheers ^:)

We eagerly await the video on this one Barkuti. See if you can find a suitably big-assed drill bit and let us know how it pans out. :smiley:

check my math i am stupid!

first the photo shows 6s1p of an aa sized 600mah ni-cd cell. the holder clearly says 24v

hum

6x1.2v=7.2v way short of the 24. maybe there are 3 sets of these 6s1p packs?

as I’m an idiot i might be tempted to put 5 to 6s1p of 14500 cells in. they want 24 lets giv em 24

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.

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 ^:)

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 ^:)

open it up and drop in some high protein feed?

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.

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 ^:)

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

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 ^:)