Vent..., no, DRAIN hole in Makita Li-ion charger

[jitter]

I have a Makita power drill that came with a DC10WA charger and today I noticed by accident that this thing was designed with possible leakage of the Li-ion battery pack in mind.

If you look closely at the first attached photo, you'll see that the battery cannot be fully inserted, studs keep it from fully seating. The bottom also has quite a slant from left to right to aid liquids to the lowest point where a tube is moulded into the battery socket. This exits the bottom of the charger (photo 2), through a hole routed out of the pcb. Clearly this was designed so that vented liquids and gases from the battery would be expelled through the bottom of the charger.

I was wondering if other manufacturers do this too or if Makita guilded the lilly here. I don't have anything else with Li-ion packs to compare it to, though, so maybe some of you could have a look at their Li-ion powertool battery chargers? Thanx...

[klunkerbus]

Interesting question. I have an older DeWalt NiCd charger that has a similar "vent". I always assumed it was simply there for any water, coffee, beer, etc spilled onto the charger to drain out.  After all, these would often be used in a construction environment that isn't all that pristine. 

[Monkeh]

I'd imagine it's more for external sources of liquid, condensation, etc.

I've never seen a lithium-ion (or NiCd or NiMH for that matter) expel liquid. Gas, yes, both slowly and rather suddenly, but never liquids.

After the disaster of the first Li-ion tools Makita produced, I would certainly hope they're gilding a bit.

[mikeselectricstuff]

It's to drain any external liquids so they don't accumulate  and cause electrolytic corrosion of the contacts.

[jitter]

Interesting question. I have an older DeWalt NiCd charger that has a similar "vent". I always assumed it was simply there for any water, coffee, beer, etc spilled onto the charger to drain out.  After all, these would often be used in a construction environment that isn't all that pristine.

It's to drain any external liquids so they don't accumulate  and cause electrolytic corrosion of the contacts.

After reading your replies I thought I'd check out the charger (DC9710) of my old Makita drill with NiCd batteries, and sure enough, it too has the hole.
I hadn't bothered to look for it yesterday as I had assumed that it was something related to the more agressive failure mode of Li-ion batteries...

So rather than a vent hole, it seems to be a drain hole...
But there is a notable difference between the NiCd and the Lio-ion charger and that is that the latter has been much more carefully designed to not let the battery touch the bottom of the charger while on the former it can go all the way down to the bottom of the socket.
Why would that be?

[jitter]

I'd imagine it's more for external sources of liquid, condensation, etc.

I've never seen a lithium-ion (or NiCd or NiMH for that matter) expel liquid. Gas, yes, both slowly and rather suddenly, but never liquids.

After the disaster of the first Li-ion tools Makita produced, I would certainly hope they're gilding a bit.

I had a look inside the DC10WA and it looked to be quite a complex circuit with balance charging for two- or three-cell Li-ion packs (7.2 or 10.8 V).
I think I'll post a side-by-side teardown of the DC10WA and the DC9710 on this forum soon, just for the fun of it.

[Monkeh]

I'd imagine it's more for external sources of liquid, condensation, etc.

I've never seen a lithium-ion (or NiCd or NiMH for that matter) expel liquid. Gas, yes, both slowly and rather suddenly, but never liquids.

After the disaster of the first Li-ion tools Makita produced, I would certainly hope they're gilding a bit.

I had a look inside the DC10WA and it looked to be quite a complex circuit with balance charging for two- or three-cell Li-ion packs (7.2 or 10.8 V).
I think I'll post a side-by-side teardown of the DC10WA and the DC9710 on this forum soon, just for the fun of it.

It's not the charger they screwed up, it's the packs.

[jitter]

What was wrong with them?

[Paul Moir]

I'm inclined to agree that it's probably mostly for accidental sources of liquids.  These do get rained on sometimes, and if it's like the DeWalt charger which uses no isolation transformer, you are going to want to be extra careful.

[Monkeh]

What was wrong with them?

Lack of or ineffective (can't recall which) discharge protection. People ran them until they slowed down, packs died left right and centre.

[jitter]

Hmm. That doesn't sound good, and I might still have those. But since I never ran them all the way down, they're still working.
Do you know when it was when Makita sold these and when they solved that issue?

[Monkeh]

Hmm. That doesn't sound good, and I might still have those, but since I never ran them all the way down, they're still working.
When was it when Makita sold these and when did they solve that issue?

Some number of years ago, the early units. Any battery with a star moulded into it should be okay. Those will still kill a cell if you leave them discharged, though.

[Pjotr]

I'm inclined to agree that it's probably mostly for accidental sources of liquids.  These do get rained on sometimes, and if it's like the DeWalt charger which uses no isolation transformer, you are going to want to be extra careful.

+1

Although the Hitachi chargers are double isolated and have the "indoor use" mark, they have that drain hole also.

[cvanc]

Yeah, I suspect it's nothing more exotic than "people use these in the rain"...

[tautech]

Hmm. That doesn't sound good, and I might still have those, but since I never ran them all the way down, they're still working.
When was it when Makita sold these and when did they solve that issue?

Some number of years ago, the early units. Any battery with a star moulded into it should be okay. Those will still kill a cell if you leave them discharged, though.

Yep, my son has a few dead packs, shame he's in Perth.
The Makita chargers would flag a pack as bad if the one cell that powered the pack cell management was exhausted after a period of non-use if left uncharged.

IF you got onto it promptly and used another current source to get some charge into the pack they can be recovered before the Makita charger recognizes the pack as being offered 3 times to the charger, then it's locked out from charging. Period.
There are aftermarket pack management PCB's available on eBay to get around this but you still have to strip the pack to install them and get some charge into the exhausted cell.....that's if it isn't buggered from being left discharged.
My son very recently got these replacement pack management PCB's only to find leaking buggered cells when he opened the battery packs. 

So they'll probably get binned or maybe sent to the "old fella" for me to attempt to mix and match and hobble some into working packs.
@~AUD70 ea I'll give them a try.

[mikeselectricstuff]

I'd heard about that issue with the 3Ah packs ( of which there are always a lot on on ebay ).
I wonder exactly what the lock-out mechanism is and if it could be reversed - my guess would be eeprom or flash in the onboard MCU.
Could be a nice little earner if someone could figure out a way to reset it.
 

[jitter]

I had a look at when I bought my Makita DF330D, and that's over 5 years ago now, but it's still a current model, at least over here.
The battery, the BL1013, doesn't show a moulded star in the plastic anywhere.

The current replacements are specified by Makita to weigh 0.234 kg which is definitely more than the ones that came with my machine. These weigh only ~0.170 kg and are specified the same capacity: 1.3 Ah/14 Wh. So that has me wondering wether or not these would also be prone to over discharge damage.
Edit: hmm... I also had a look at a non-Makita replacement specified at 1.5 Ah/16.2 Wh, and it only weighs 0.166 kg. Looking again I see that Makita added "EPTA" to the weight declaration, but since this is about the battery only, I guess it shouldn't matter.

Now, 0.166/0.170 kg vs 0.234 kg is quite a difference...

[jitter]

Hmm. That doesn't sound good, and I might still have those, but since I never ran them all the way down, they're still working.
When was it when Makita sold these and when did they solve that issue?

Some number of years ago, the early units. Any battery with a star moulded into it should be okay. Those will still kill a cell if you leave them discharged, though.

Yep, my son has a few dead packs, shame he's in Perth.
The Makita chargers would flag a pack as bad if the one cell that powered the pack cell management was exhausted after a period of non-use if left uncharged.

IF you got onto it promptly and used another current source to get some charge into the pack they can be recovered before the Makita charger recognizes the pack as being offered 3 times to the charger, then it's locked out from charging. Period.
There are aftermarket pack management PCB's available on eBay to get around this but you still have to strip the pack to install them and get some charge into the exhausted cell.....that's if it isn't buggered from being left discharged.
My son very recently got these replacement pack management PCB's only to find leaking buggered cells when he opened the battery packs. 

So they'll probably get binned or maybe sent to the "old fella" for me to attempt to mix and match and hobble some into working packs.
@~AUD70 ea I'll give them a try.

Apparently, these replacement management pcbs are sold to be able to rejuvinate a dead pack with new cells. Once the Makita management pcb locks out, there's no way to unlock it (or no one's found out how yet), and replacing the cells alone won't do you any good.

I'd heard about that issue with the 3Ah packs ( of which there are always a lot on on ebay ).
I wonder exactly what the lock-out mechanism is and if it could be reversed - my guess would be eeprom or flash in the onboard MCU.
Could be a nice little earner if someone could figure out a way to reset it.

It looks like it's the BL1830, there's a tonne of videos on this one.
Makita's lock out mechanism is a nice little earner for the manufacturers of the replacement pcbs, so I guess no one's found a way to "reset" Makita's pcbs...

From this thread came this snippet:

The main PCB inside the battery is a bit more involved. Most of the 36V Makita's use a Texas Instruments bq77PL900 as the battery management chip and a NEC 78K0 microprocessor, which monitors the parameters and communicates with the charger. The PCB draws its power from the first cell, since it draws it continously, it is the state of the first cell that dictates the state of the battery. I would suggest to either use a single charger to charge that cell, or and most likely the least invasive solution. If the battery is alreadylocked, it might just be possible use a different (aftermarket) charger. The aftermarket charger will not care about the "chip".

Edit: irrelevant quote crossed out, this is an 18 V system that doesn't seem to use the same parts as the 36 V system.

[tautech]

It looks like it's the BL1830......

I think it is, waiting for confirmation and for the charger model # too.

They have additional pins in the battery pack for coms with the charger......I should've taken pics    when I had it apart to repair the mains cord when I was in Perth in August.

[jitter]

I did some more digging on the BL1830, and it seems that a fusible link is blown on the management pcb. It can be bridged to get the charging to work again, but that's (obviously) not without hazard. Definitely a "do not try this at home" disclaimer worthy.

Charger model no.: DC18xx. Some vids show the DC18RA, others the DC18SD. Currently, Makita doesn't seem to supply the DC18RA with new tools anymore.