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24v battery only charging to 12.5v


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hi i got 2 x 24v /5ah batteries with my DeWalt drill kit, this is my first DeWalt and i have several questions if anyone can help?

1) when i plug my charger in a green light comes on, slide the battery on and the light turns solid red after a while it turns back green ? 

2) if i use a multimeter to test the batteries after charge both only read 12.3v and 12.5v ?

3) when i press the test button on the back of the battery there are 3 lights red, blue and green?


the reason i ask is that after all the research i have done nowhere says this should happen and i all so can not locate the model no on the DeWalt website

charger dcb107 battery dcb181


all though the drill seems to work fine with both batteries


many thanks for any help and advice any one can offer

thanks bob.

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Well that's a different kettle of worms then. Since both batteries are charging to 12v you could assume the charger isn't detecting them correctly. Could also be that both packs are knackered and the charger is fine and just can't get them to the 20v.


For that thing to sit at 12.5v from B- to B+ that means every cell would have to be 2.5v, which is beyond dead for a Li-Ion cell.


Test the individual cells in the pack and see what the voltages are.


You should, should get..


B- to C1  = ~3.6v

C1 to C2 = ~3.6v

C2 to C3 = ~3.6v

C3 to C4 = ~3.6v

C4 to B+ = ~3.6v



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hi RDC thanks for your reply 

1) you say charger isnt detecting them properly is there a way to test the charger with a multimeter?

2) you say both batteries may be us but then why does the drill work ok?

3) sorry the bit about b- and b+ is beyond my understanding?

4) i was keeping testing the cells to last as nearly every time i open a tool it never works again

thanks bob.

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1 - Didn't say that. Said you could assume it was bad. I'd be looking at the batteries first. They should be 18v(20v) 1.5Ah, not 24v 5Ah.


2 - I don't have it in hand to tell how it's working, but if the cells are actually measuring 12v and the drill is in fact an 18(20v) tool then it shouldn't work at all. Are you sure all of this isn't a 12v setup that was relabeled or some other shady thing?


3 - The B- and B+ are the battery - and + terminals. Supposedly you have already checked those and measured 12v there.


4 - You don't need to open the battery to test the cells. Looking into the end of the battery connector, not the top the end, the contacts should be..


B+ | TH | C1 | C3 | B-

B+ | ID  | C2 | C4 | B-


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If those are 24v 5Ah packs, I'll eat them.


That all looks sketchy to me. There are only 3 terminals on the Charger, the Li-Ion chargers have 8 terminals. That whole thing looks like some 12v NiCad setup to me.

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yes i did do the same but apparently these versions are sold in Germany,  i have emailed DeWalt direct with the photos and description just waiting on a reply if i get one

unless any one can tell me differently the general opinion is i have bought a scam product but no one knows why it does work, all i can do is hope that it lasts a while before it blows up

but as i said at the beggining many thanks for all the suggestions / remarks offered

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On 3/10/2021 at 2:48 PM, RDC said:

The reason it 'works' is because it's ALL 12v.

Thank you for your help, is there any think on the drill, 2 batteries or the charger that i can check to confirm this and go back to the person i bought it from and tell them they are selling fakes (all though they probably all ready know)? thanks bob.

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You’ve probably checked as far as you can without taking them apart to confirm things definitively. It’s not like people making fakes keep company logs on how they go about making them or quality control checks or whatnot. That’s part of what makes them fake.


The reason all your tools measure 12V is most likely because they are in fact operating on a 12V format of three lithium cells in series that would achieve a 12V Max charge. Also your pics give the impression of small batteries consistent with the 12V batteries a lot of real manufacturers offer which all use 3 lithium cells of size 18650. Whoever the fakers are probably got ahold of actual production files and reverse engineered them before labeling them with that completely fallacious 24-volt marketing claim. You could report it to the seller, but you’re correct that they likely already are well aware. After which the fakers just change their “product” to be more convincing fakes.


What’s really funny to me is for all that effort making fakes that quite possibly work okay (but to be safe you probably should NOT continue to use) they could get a real job with a real company making better products. But oh well.

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While dewalt has built 24v tools they haven't for years.  Other than the names nothing about them is right.  There's no doubt about it they're fakes.  It depends on how much and under what pretenses you purchased them.  As a cheapo Chinese $25-$50 homeowner drill it'll probably drill some holes and run some screws.  If you paid anywhere near $100 thinking you were getting a genuine Dewalt drill I'd be pissed and demand a refund. 

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