RDC
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Posts posted by RDC
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OK, replaced the FETs (only the one damaged pair as the other 2 pair were still good) and replaced the 2 Capacitors that are missing in the last posts image, and she was still a dead duck. So I dug a little deeper and found an open Resistor in there as well, one of the 53B, 3.48k. Replaced that and she took right off. After I pull the PCB back off one last time to clean it up and recoat it then she'll be ready to wack some more weeds.
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It most likely has a bad cell in it. You might get it going again if it were taken apart and the pack was balance charged, but that's a 50/50 shot at best and flat out dangerous if you're not familiar with messing around with lithium batteries.
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If you pull the trigger and only get a tiny 'bump' from the motor, that's a pretty classic symptom of the motor driver board being bad. That can also show up as nothing happening when pulling the trigger.
I'd pretty much guarantee you it has some bad MOSFETs on the thing now, as I just tore one of those down here looking for that exact problem. It'll probably come as no surprise that none of that stuff is even remotely easy to replace. Even if you can get parts, you'd have to replace the entire field/driver assembly of the motor to avoild any soldering or real PITA PCB de-potting, unless you're far enough off your meds and rocker to replace the FETs like I'll be doing to this one.
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Are you using a right heavy gauge wire for the B+ and B- connections?
Can the Relay handle the current?
Triple checked everything is going to the right places?
Try powering the Relay externally for a test.
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The reason it 'works' is because it's ALL 12v.
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Google for DeWalt 24v and see what you find.
Google the DCB107 DeWalt Charger, that's an actual thing, in 120v and 220v versions, and it looks nothing like that one.
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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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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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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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Honestly, if they are new just take them back and get another set. Digging any farther into it will just be voiding any kind of warranty it has.
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The DW616 is a Router, the DC616 is a nailer.
You could hit up McMaster-Carr and look around for something that might work in there
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I haven't dug into a pile of the tools, but it most likely depends on the tool. The DCD780 needs the B+ and B-, but then it also needs C3 and TH to work correctly. If it gets no voltage from TH (the Thermistor in the pack) it throttles the drill back as it 'thinks' the pack is overheating.
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I'd try 3D printing up a suitable replacement. It may not look identical or last as long, but at least you'll be able to replace it again and again as well as improve upon it along the way.
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The connector on the FlexVolt tool is what enables the higher voltage of the pack. There are 2 things that need to happen, correctly, for the battery pack to output the higher voltage.
First the slide switch needs to be engaged.
Second, AFTER the slide switch has been engaged, the 54v tools connect C1 to C3, which enable the 54v mode.
WARNING: If you connect C1 to C3 before the slide switch has been engaged, it WILL damage the battery pack and ruin 2 of the cells in there. If you are going to use the handle from a 54v tool, which would be the best way to go about it, then you'll be fine as it will do all of that switching properly.
Also be aware that while it's running at 54v, it's going to be 1/3 the rated Amp hour, as that rating on there is for the 18v mode. So a 6.0Ah pack is only 6.0Ah at 18v, at 54v it's going to be a 2Ah pack.
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14v to 15v is far from charged.
Make sure your DMM battery is good and check the voltage of the battery again measuring from the B+ to B- terminals.
Thermistor check #1 Measure the voltage from B- to TH, you should get the same voltage as the B+ to B- measurement.
Thermistor check #2 Measure the Resistance (Ohms) from B+ to TH, it should be around 12k
If that is all good, then test the individual cells to see if one has gone bad. Measure..
B- to C1 = ?.??v
C1 to C2 = ?.??v
C2 to C3 = ?.??v
C3 to C4 = ?.??v
C4 to B+ = ?.??v
All of those measurements should be the same, or within a hundredth of a volt of each other.
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That's the DCB118, single pack charger. The DCB104 will for sure be higher.
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The DCB104 is a fast charger, same as the DCB118, but it can do 4 packs at once. The AC rating for it should be on the bottom of it. The DCB118 is rated at 120v 3A, so that thing alone should be around 12A, if it can charge all 4 ports at 8A each like it says it can. I haven't had the DCB104 apart but have torn down the DCB118. Charging current and what it pulls from the wall aren't the same, so that 32A it could charge the 4 packs at would only be 12A on the 120v side, and it would only be that if you had it loaded with 4 of the FlexVolt packs.
Having that many plugged up isn't going to hurt anything, the breaker in the circuit should trip if you pull too much there. If you're plugging them into who knows what then no one is going to be able to say what kind of issues might happen. Really long and thin extension cords with multiple things plugged in at the end drawing 15A isn't any good.
The chargers monitor the pack temperature, so too hot/cold and they'll cry and just not charge them until they get to where they need to be.
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Picked up a broken few of these to mess with. Had one that wasn't really worth repairing, but it still made itself useful.
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Opened a couple of these up to see what kind of 'protection' they have in them. Nice to see they are setup to be balance charged, but sadly no charger does it that I've seen so far. Figured I'd schematic them up while I was in there for anyone interested or just curious.
DCB203 Type 2.pdf DCB204 Type 2.pdf DCB203-DCB204 Type 2 LED Board.pdf
Dewalt 20v DCST922 string trimmer stopped working
in Dewalt
Posted
Ran across another one of these that was supposedly 'dead', but after tossing a battery in there the thing technically worked. The motor sounded horrible and it had more grass in it than it probably ever cut, but the top motor bearing was shot, which was making all the noise. Fun part about this one, the marking on the top bearing was 695Z, but the 695Z bearing is 5 x 13 x 4mm, and the one in this thing is 5 x 16 x 4mm. So I had to toss a 625Z in there instead, which is 5 x 16 x 5mm, just 1mm wider, but there is plenty of room for that in there and now this one is good to go again.