Onoff

Makita to Aldi/Lidl/Einhell Battey Adapter

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Posted (edited)

Figured carry on this thread:

 

I have a number of perfectly serviceable 18V tools of various, dubious, here today gone tomorrow brands. All bought on a whim, dirt cheap or got as a present:

 

Champion circular saw

Rolson 4 1/2" grinder

Performance Power hedge trimmer

Jigsaw, can't remember make.

 

These came with Nicads originally. There is some interchangeability between batteries though I think with the hedge trimmer the + & - are reversed. The grinder batteries fit but the wrong way round and with the aid of some tape. Some batteries fit and work but the holding clips are in the wrong place. Tbh I'd use them more if they had good batteries that lasted and the charge times weren't "3-5 hours" and you didn't need multiple chargers. (OK, the grinder is 1 hour). So here's the plan:

 

I had considered 3D printing but found these Makita battery Stealth Mounts moulded from tough ABS at £15 for 4. Aim is to graft these onto the top of the various tool batteries, the section that slots in. Then a couple of down pointing tags to line up with the Makita batteries + & -:

 

20190402_121838

 

20190402_12180920190402_121920

 

20190402_121935

 

These are injection moulded rather than 3D printed btw.

 

Watch this space but don't wait up! :)

 

Edited by Onoff
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Stripping the grinder and it's battery down tonight:

 

20190402_162712

 

The battery lid:

 

20190402_162843

 

Inserted into the grinder:

 

20190402_163238

 

The stealth mount held against the battery lid:

 

20190402_163339

 

Tbh a rectangle of plastic (or timber?) a few mm thick screwed to the grinder base then the Stealth Mount on that should work. The grinder body plastic is really tough and would pass the "drop test" :)so would take a couple of self tappers:

 

2019-04-02_08-35-25

 

Hedge trimmer, the + & - reversed for a start:

 

20190402_163707

 

Lid moulding is quite complicated...So we'll ditch that:

 

20190402_164154

 

Stealth Mount balanced precariously:

 

20190402_164207

 

20190402_164604

 

Again probably a rectangle of something to bring the base flush, deeper than for the grinder, then the Stealth Mount is the way forward I think:

 

20190402_165140

 

20190402_165154

 

"Infill blocks" next then figure the battery connections. I think I'll open the tools up and hard wire the new battery connections direct to the switch etc to bypass the remnants of "tangs" that attach to the original battery. 

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Do I understand correctly that you intend to use Makita batteries on these other tools? If so, won't this leave the Makita batteries vulnerable to over discharge and hence a very short life?

 

AIUI, with the Makita system the battery determines when it's discharged as much as is good for it and sends a signal to the tool to inhibit operation. Even when it thinks it's flat the battery's terminals still have voltage on them; the little work light on my circular saw comes on even when the motor in inhibited for a flat battery.

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2 minutes ago, Ed Davies said:

Do I understand correctly that you intend to use Makita batteries on these other tools? If so, won't this leave the Makita batteries vulnerable to over discharge and hence a very short life?

 

AIUI, with the Makita system the battery determines when it's discharged as much as is good for it and sends a signal to the tool to inhibit operation. Even when it thinks it's flat the battery's terminals still have voltage on them; the little work light on my circular saw comes on even when the motor in inhibited for a flat battery.

 

That was the rough plan but in the back of my mind is the fact there's some sort of feedback between tool and battery. I'm not using genuine Makita batteries (BL1830 clones) btw. The circuit board on two different clones I have are both very different from each other and the genuine Makita battery.

 

I wonder if there's a way of adding something to the cheapo tools?

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7 minutes ago, Construction Channel said:

How's the bathroom going? 

 

Bored with that! :)

 

Started clearing the adjacent room with a view to digging that floor up. Roughly mid house it'll be where the UFH manifold will site and possibly a UVC/TS, buffer etc.

 

This is just a distraction from a whole lot of other sh!t going on!

 

Off to search "avoiding Makita battery discharge" circuitry.

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When I was racing a boat powered by a Makita lithium powered drill the battery packs got too hot to touch after a run.  The Makita rep was at the event (I won a set of Makita tools) and confirmed there was no discharge protection, something that surprised me at the time.  I can confirm that packs that I severely overheated (as in you needed gloves to get them off the drill) are still working fine now, some 6 years later.

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@Ed Davies, random search for the aftermarket battery  pcbs suggests discharge protection is in the batteries? Whether it needs to "talk" to the tool though???

 

https://m.ebay.co.uk/itm/18V-Battery-PCM-PCB-Li-ion-Protect-Circuit-Board-DIY-for-Makita-Drill-Green-T3J9/123317535564?ul_ref=http://rover.ebay.com/rover/1/710-53481-19255-0/1?

 

"Lithium battery control circuit board Protection chip for electric tools battery Compatible With: For Makita Its main function to battery are: over charge protection, over discharge protection, short circuit protection, over current protection, reverse charge protection, over heat protection Color: Green Material: CCL Voltage: 18V Size: Approx. 4.5x3.3cm/ 1.77x1."

 

 

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There's no big power transistors on that PCB so it does suggest it's sending something to the tool.

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Posted (edited)
23 hours ago, JSHarris said:

The Makita rep was at the event … and confirmed there was no discharge protection

 

Yep. AIUI there is a fuse but it's for a huge current (100A). If you blow that the battery's officially dead so it's just a last ditch protection against a fire:

 

https://youtu.be/AsTJKSH7mCU?t=224

 

Bit about the switching being in the drill:

 

https://youtu.be/AsTJKSH7mCU?t=317

 

The follow on in the video about using it to start the truck is mildly entertaining, too.

Edited by Ed Davies
Set/correct times in video.

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Just reading on another forum someone tried two, good, genuine Makita batteries on their 18V B&D hedge trimmer. Polarity correct but nothing happened. Thereafter both batteries showed up faulty on the charger.

 

Oh!

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Makita packs have a flawed (IMHO) protection scheme, which sets a parameter inside the pack that scraps the pack (makes it unable to be charged) when the cells get out of balance.  The flaw is that the first cell pair inside the pack powers the battery management system inside the pack, so if a pack is discharged to the point where the first cell pair gets too low, the pack will flag a charge error.  The BMS will tolerate two attempts to charge (using the Makita charger) and on the third attempt the pack will be a write off (but can be resurrected with a new circuit board). 

 

The key thing is that if you ever get a charging error with a Makita pack, then never try it in the charger again, but charge it at a low current using a power supply connected to the terminals on the pack.  Once the pack is partially charged in this way it should charge OK on the Makita charger.  If in doubt, then it's best to open the pack and measure the cell group voltages.  If necessary, cell pair one can be charged on their own to bring them up to the same state of charge as the others, when all should be well (as long as there's no cell damage).

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44 minutes ago, Onoff said:

Just reading on another forum someone tried two, good, genuine Makita batteries on their 18V B&D hedge trimmer. Polarity correct but nothing happened. Thereafter both batteries showed up faulty on the charger. 

 

Oh!

 

“Oh”, indeed. Probably with another word after it. Bit courageous to try two batteries, though. But I suspect there was something wrong in the way it was connected up if nothing happened with the hedge trimmer. Wired properly, I think you'd only knacker the Makita batteries by over discharging.

 

It's a pity they work that way (switch off in the tool) really as I'd quite like to rig up something to run my work lights or telescope off my Makita batteries but don't really want to take the risk.

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I've recently acquired a couple of Dewalt XR-XRP adaptors. One is dumb, but one has inbuilt protection- it turns off the battery at low voltage (which happens very easily with the 1.3Ah battery on the grinder...). The dumb one needs watching...

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Posted (edited)

Looking at my two Makita cordless hammer drills they just have two "tangs" that attach to the battery + & -. The Makita impact driver though has a third tang that engages with the "TH" terminal on the battery. The impact driver also is the only one of the three with the  symbol.

 

 

Edited by Onoff

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Posted (edited)

Came across this:

 

http://bl1830-failureprevention.blogspot.com/2013/07/makita-radio-1-cause-of-battery-failure.html?m=1

 

His Advanced Solution #4 is for installing an undervoltage switch to protect from over discharge. Here's the circuit:

 

Screenshot_20190404-061052_Chrome.thumb.jpg.576c35972602765d0a5ea414cdbfed54.jpg

 

https://www.circuitlab.com/circuit/dk4vzq/makita-undervoltage/

 

Can't say I understand the circuit...the cells on the left...are these the battery cells?

 

Figuring this could easily be built into the space where the old battery slotted in?

Edited by Onoff

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One snag with that circuit is that the quiescent current of the 7812 and associated circuitry is high enough (~8 to 10mA) to discharge the pack when it's stored for any length of time, so you really need a way to disconnect the circuit from the battery pack.  The existing monitoring circuit inside the pack only has a very small quiescent current (of the order of a few µA), yet that's enough to cause problems when packs are stored for any length of time without being charged first.

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1 hour ago, JSHarris said:

One snag with that circuit is that the quiescent current of the 7812 and associated circuitry is high enough (~8 to 10mA) to discharge the pack when it's stored for any length of time, so you really need a way to disconnect the circuit from the battery pack.  The existing monitoring circuit inside the pack only has a very small quiescent current (of the order of a few µA), yet that's enough to cause problems when packs are stored for any length of time without being charged first.

 

Thanks for that. So what are the 9 & 6.3V cells on the left? 

 

Is that the Li-Ion pack itself? Why not 18V if so?

 

V1 is the drill motor?

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19 minutes ago, Onoff said:

 

Thanks for that. So what are the 9 & 6.3V cells on the left? 

 

Is that the Li-Ion pack itself? Why not 18V if so?

 

V1 is the drill motor?

 

I assumed that the badly drawn cells on the left were the battery pack.  The pack is 2P, 5S, so has a two pairs of cells in parallel for each cell group, and five cell groups at a nominal 3.7 VDC in series, making 18.5 VDC.  When fully charged the cell groups will be around 4.2 VDC, so the pack voltage will be around 21 VDC.

 

The circuit shown looks odd, in as much as it's using an op amp that's over 50 years old now.  I can remember building a voltage-controlled synthesiser in the early 1970's using 741s, and they were an old chip even then.

 

I've no idea what the AC source V1 is, maybe it's related to whatever specific application this was designed for.

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23 minutes ago, JSHarris said:

 

I assumed that the badly drawn cells on the left were the battery pack.  The pack is 2P, 5S, so has a two pairs of cells in parallel for each cell group, and five cell groups at a nominal 3.7 VDC in series, making 18.5 VDC.  When fully charged the cell groups will be around 4.2 VDC, so the pack voltage will be around 21 VDC.

 

The circuit shown looks odd, in as much as it's using an op amp that's over 50 years old now.  I can remember building a voltage-controlled synthesiser in the early 1970's using 741s, and they were an old chip even then.

 

I've no idea what the AC source V1 is, maybe it's related to whatever specific application this was designed for.

 

Thanks. Yes I thought the 741 opamp was old/odd. Pretty sure I made an audio mixer years back eschewing the noisier 741 for a CA4032. Something from an R A Penfold book I think. Used to love him and F G Rayer. I was always building something as a kid.

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That's a very weird circuit. In addition to what @JSHarris says, the lack of a resistor on the base of Q1 is cause for raised eyebrows, I think.

 

Also, I'm not sure how it's intended to be used but I assume the idea is that the relay switches the radio off. Good luck finding a relay which can consistently switch more powerful devices like circular saws of a size that can reasonably be fitted in hand tools.

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13 hours ago, Ed Davies said:

“Oh”, indeed. Probably with another word after it.

 

Absolutely.

 

Oh ! Ooops !

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Interesting, found on another forum:


"However, I notice that my Wickes el cheapo batteries almost fit. The prongs are the right width apart, the holding grooves interphase, just the metal prongs seem a bit too long and need 10mm trimming off. But they work when loosely wedged in.

And the Makita only have two prongs/contacts, instead of three the Wickes has. 

It it almost like they were designed in the same factory then sent in different directions".

 

CEF92692-7265-44D1-8F03-D785DA7C0EC0.thumb.jpeg.dc032138c8f0972e1831f24598b67aca.jpeg

 

EEFF965E-DC3D-4511-9BC4-355456260616.thumb.jpeg.b1d66ae197ee6bc61f804e60d0a69cf2.jpeg

 

170528-d109ec04fb4e16164fb19082885a73a3.jpg.adfea44f22fe5acabc02c086f3c5028c.jpg

 

He goes on:

 

"Both batteries have three connections, the Makita tool has two connections, Wickes has three, but when I plug the Wickes battery into the Makita drill it works perfectly.

I think I could trim the Wickes battery terminals 1/2” and resurrect my far superior Makita drill and driver. £50 Wickes set, versus £350 for the Makita combo.

Not sure how much a couple of spare Wickes 
batteries would be".

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56 minutes ago, Onoff said:

It it almost like they were designed in the same factory then sent in different directions".

 

Apologies if I’ve said this before but the Wickes and Makita 10v stuff is remarkably similar. They both use the same tri-lobe Samsung battery pack, and the mouldings are the same for the drill case. Only difference seems to be the colour and the rubber inserts on the handles. 

 

Makes me think that Wickes own brand is a contract mould and manufacture by Makita. 

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