Hi all,

 

here comes my report about A123 cells taken out from used Dewalt DE9360 36V power tool batteries. I read a tip about those here in this forum (thanks danielweck) and went ahead and ordered 8 pcs. from ebike-solutions.de. Have to say that customer service was great, it was Sunday afternoon when I asked about these by email and 10 minutes later I had paid them using Paypal and they were already posted next day. Delivery took about one week and here they are:

 

http://taistor.wippiespace.com/images/view/dewalt/dewalt.jpg

 

Of course you have to open the case to get the cells out. You will need a star-shaped Torx-bit with hollow center to do that, correct size is T10. You'll also have to drill some plastic away from the case to get access two recessed screws:

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0001_2.jpg

 

Just drill slow speed until torx bit gets grip with the screw head:

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0001_3.jpg

 

Lift the case lid and you can see the cells under the charging/discharging control circuit:

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0427.jpg

Next you have to unplug the balancing lead connectors. They can be found from the both sides of the pack under the tape:

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0423.jpg

 

Now you can tilt the bms circuit and take take away the temperature probe:

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0425.jpg

 

Now it is time to cut the actual power wires (the red and two black ones). Just don't short-circuit them! I remember when I was repairing electricals on my car some 20 years ago and somehow the ring in my finger got between + and - wires, that did burn and hurt enough. Take away rings and metallic wristwatch if you are wearing one to be on the safe side.

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0426.jpg

 

Now we still have to get the cells out of the black plastic bottom part. Just use flathead screwdriver and pry the cells up little by little:

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0429.jpg

Wow. Do you mind telling how much you paid for 8 of them? You can PM if you want. I paid £83 for 20 cells contained in 2 36v packs from a guy on Ebay who was selling them "as is"....I think 4 of the cells were broken and the packs were useless for power-tools because of bad wiring.

Once you have got the cells out the black plastic end parts drop off easily. Here are the cells exposed:

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0434.jpg

 

I am going to use two 6s packs on my bike connected in series. If you cut here (I used a Dremel-clone) you will get a pack with that needs only balancing leads and power leads added. You don't have to cut all through, just cut a little and the metal strip breaks with a light twist.

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0432.jpg

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0435.jpg

 

I added some electrical tape to keep the cells in shape. Next I added the balancing leads. I got 10 pcs. 6-cell ones from Electricwingman - Online shop for quality RC power systems and components for electric flights The price was quite cheap 0,80 each and delivery took a week from UK to Finland. It is important to connect individual leads in right order. The red wire goes to the positive end of the pack and each wire before that between the cells in the series. The last wire goes to the negative end of the pack.

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0001.jpg

Kapton tape is good to insulate and keep the wires in place. Should be heat resistant also, got mine from eBay for 7-8 euros / 33 m. Ideally you should not shorten the individual balancing leads, otherwise the charger may read false voltage when balancing the pack:

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0437.jpg

 

Here are all the leads soldered. The power wires are 14 AWG silicon wire. Just ordered some more, its great! So much more flexible than ordinary pvc-coated one.

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0442.jpg

 

At last we can add shrink-wrap to keep all in place. Again bought from eBay.

 

http://taistor.wippiespace.com/images/view/dewalt/DSCN0445.jpg

 

So now I have two 6s packs and of course you all are eager to know how they perform...

 

I charged and balanced the packs using Poli max B6 RC-charger. It was 28 euros delivered, again bought from eBay. By the way there seems to be many essentially same chargers around, I chose this as it was cheap and they sent it from Germany so no tax/duty. I had to change the charger settings and choose LiFePo battery type to get correct charging voltage which is 3.6 V.

 

Charging takes a little bit time but I used only 2 A charging current. With higher charging current the charger shows error message about low input voltage. It seems that the cheap ebay ac/dc adapter can only supply 2-3 A, but I don't complain, it was only 10 usd anyway.

 

All the cells get to 3,60 volts and the pack is full. After the another pack is charged it's time for a test drive. I made a adapter to connect two 6s packs together in series and there was powerpole connector for connection to my bike.

 

Start voltage 43,04 V, temperature -13,6 Celsius, no wind. I got 7,63 km until the bike suddenly started to feel very sluggish. Here is the big difference compared to SLA batteries, their voltage drops little by little, but these new packs gave plenty of power to the end. I just connected the SLA battery and drove back home to check Turnigy screen (it was cold and the lcd screen was messed up).

 

The pack gave 2086 mAh / 74 Whr. Minimal voltage during the trip was 29,72 volts. This means I can get 15 km if I double the pack, probably almost 20 km because I don't have the 15 kg extra weight from SLA batteries.

 

When re-charging the individual cells were around 3 volts, the difference between smallest and highest reading was below 0,1 V but the voltages became essentially same shortly after charging had started.

 

Eventually I am going to use 36V SLA charger for charging the packs. It charges to a little higher end voltage 3,708 V / cell so there might be a slight capacity increase also.

 

A note about the Dewalt packs. I ordered 8 pcs = 80 cells and there was 5 bad cells (voltage was under 2 volts, the good cells had over 3 volts and they were even pretty well balanced).

 

I remembered reading somewhere that bad A123 cells may be fixed by giving 12V zap to the cell. So I tried that and after connecting 12V to the cell with 1,25V voltage for 1-2 seconds I was able to get the cell voltage to 2.2 V. After that I was able to charge that cell, it took 2275 mAh. Haven't tried it though but I expect it to perform just fine.

 

OK, I have been writing for a while this long post. I just hope you bear my bad english and that I have been helping anyone building their DIY battery packs.

Wow. Do you mind telling how much you paid for 8 of them? You can PM if you want. I paid £83 for 20 cells contained in 2 36v packs from a guy on Ebay who was selling them "as is"....I think 4 of the cells were broken and the packs were useless for power-tools because of bad wiring.

 

I paid 197 euros including delivery from Germany to Finland, is that about 180 GBP or so for 80 cells? By the way the batteries are not listed on their shop but just ask by email if you are interested.

 

You could also try to feed 12 V to the bad cell maybe it "wakes up". At least my RC-charger refused to charge the bad cell until I did that.

 

The packs I bought were used ones but I believe they still have many charge / discharge cycles ahead and the capacity is certainly acceptable for the price.

I paid 197 euros including delivery from Germany to Finland, is that about 180 GBP or so for 80 cells? By the way the batteries are not listed on their shop but just ask by email if you are interested.

 

You could also try to feed 12 V to the bad cell maybe it "wakes up". At least my RC-charger refused to charge the bad cell until I did that.

 

The packs I bought were used ones but I believe they still have many charge / discharge cycles ahead and the capacity is certainly acceptable for the price.

 

That sounds like an outstanding deal, even for used. Well done. I think I paid $6 per new cell for a batch of 44 that came from the USA, which I thought was a good deal, as I heard the retail on these cells is well over that, except for the cheap rejects they sell on Ebay.

 

Jerry's were not the rejects. The rejects are white and you can see where the old spot welds were on them. Anything that comes out of a DeWalt pack or out of the USA is usually fine.

 

The rejects probably work fine, it's just you can expect 2 in ten to be shoddy.

 

Thanks.

I paid about twice that (£5) for my new cells with tabs.

 

I would have definately gone down the ex DeWalt pack, which are great value for money at those prices and are pretty much soldered up for you

 

I wanted to use new cells though to prove the concept (not original I know but original on this forum) so that other could follow on if they chose.

 

I am glad you have found it useful.

 

Regards

 

Jerry

That's 16 cells, then. Suppose now that each 8 cell block provides 24v@2.26 Ah. Thats 8 in series. 24v {just taking the round figure} per strip.

 

I think that is wrong

 

At 3.3v nominal and 3.6v max that is 26v nominal and 28.4v max for 8 in series.

 

Regards

 

Jerry

I think that is wrong

 

At 3.3v nominal and 3.6v max that is 26v nominal and 28.4v max for 8 in series.

 

Regards

 

Jerry

 

Yes, I just took the lowest figure of 3v per cell....I do this so the pack I end up with always has a few volts over what I want it to be.

 

For me, a 36v pack is one that has around 44 volts, if you see what I mean:cool:

Yes, I just took the lowest figure of 3v per cell....I do this so the pack I end up with always has a few volts over what I want it to be.

 

For me, a 36v pack is one that has around 44 volts, if you see what I mean:cool:

 

May not be wise to do that as you could end up blowing the controller FETs IE: for 48V using your calculation two 8s packs in series would give 48v and seem to be OK but when fully charged its 57.6v...that could blow some '48v' controllers out there which have a maximum 55v limit...

http://www.powertoolsuk.co.uk/webcat/pics/dewalt/de9280-battery-275.jpg

 

Do these also contain the 3.3v-3.6v A123's??

 

Thanks.

I don't think they do from what I recall reading. If you search the links in the earlier posts of this thread I think you can confirm.

 

 

Regards

 

Jerry

I don't think they do from what I recall reading. If you search the links in the earlier posts of this thread I think you can confirm.

 

 

Regards

 

Jerry

 

So that's why they are so cheap...... Too bad I guess.

 

Cheers.

Start voltage 43,04 V, temperature -13,6 Celsius, no wind. I got 7,63 km until the bike suddenly started to feel very sluggish. Here is the big difference compared to SLA batteries, their voltage drops little by little, but these new packs gave plenty of power to the end. I just connected the SLA battery and drove back home to check Turnigy screen (it was cold and the lcd screen was messed up).

 

Trepo nice pics BTW. The DeWalt packs have the advantage of being ready soldered together mostly with tags incl.

 

I get about 8-10 miles (13-16 kms) on my 2*6s pack depending on how much I pedal. What are you powering ?

 

I guess my Brompton/Tongxin combination are a low demand setup.

 

PS Aah I wonder if that is why my Turnigy screen messes up soemtimes in the cold ?

 

PPS Hopefully your Tongxin will turn up soon

 

Regards

 

Jerry

Edited March 8, 201016 yr by jerrysimon

Just got confirmation from some dudes over at ES that the Dewalt 28v do in fact contain 8 A123 M1 cells. Nice. These are going cheap because they are being phased out over some trademark issue or something. In the meantime, UK tool retailers are still asking huge money for them.

Trepo nice pics BTW. The DeWalt packs have the advantage of being ready soldered together mostly with tags incl.

 

I get about 8-10 miles (13-16 kms) on my 2*6s pack depending on how much I pedal. What are you powering ?

 

I guess my Brompton/Tongxin combination are a low demand setup.

 

PS Aah I wonder if that is why my Turnigy screen messes up soemtimes in the cold ?

 

PPS Hopefully your Tongxin will turn up soon

 

Regards

 

Jerry

 

Thanks Jerry! Yes, your range seems to be about twice compared to mine.

 

It's probably due to the higher weight of my bike, its 35 kg all together (25 years old steel-framed trekking bike and SLA batteries worth of 15 kg). I myself weigh a little over 90 kg... yes, I know, I should eat more healthy and cycle more to get fit.

 

So the bike and rider are about 130 kg together, no wonder it takes 10 WHr / km. And my controller is a 14 amps unit, your Tongxin one probably eats less current.

 

It's now two weeks since they picked up my payment for the Tongxin kit in China. Hopefully the kit gets on the way this or next week! I already have all the other bits ready.

 

Today I had my second ride with A123 batteries (2060 mAh consumed until weak motor performance) and this time I am charging them with the same ebay charger as yours. Charging is going through Turnigy meter so I will update charged capacity to this post later.

 

I just have to monitor the end voltage that it doesn't get too high. Build and adjustment tolerances seem to be quite wide on these cheap chargers. My unit even had a bare negative charging lead inside, it had been chafed to the heat sink. I just insulated that part of the wire and the charger seems to be working fine.

 

The charging has just ended as of writing the post. Unfortunately I did not notice the peak charging voltage but the charger had green light and the pack rest voltage was 42,87 V.

 

Poli max B6 was able to push in only 20 extra mAh to the first pack and 27 mAh to the another one so this 36V charger seems to be doing good job. The cells were also quite well balanced (20-30 millivolt maximum difference).

 

Regards

 

Taisto

Thanks for the update. My Tongxin/Controller are rarely pulling more than 5-6amps so that probably as you say explains the range.

 

Fingers crossed that your Tongxin will turn up soon. As I said he seems reliable and its been new year so probably things a little slower.

 

My charger seems ok and as you say it does not seem to over charge. Not state of the art finish I agree. I put a new three pin plug with a 3 amp fuse on mine for safety and am rarely far away from it when it is charging. I always turn it off after the green light comes on and never leave it on when the charge is complete.

 

Regards

 

Jerry

eBay.ie: Hobby Spot HS300A2 Capacitive Discharge Metal Welder (item 170453925159 end time 10-Mar-10 20:37:36 GMT)

 

Nice hobby welder, the very thing for doing tabs. Obviously quite expensive but I am sat here, thinking about it.....

Well that money would get you quite a few tabbed A123 cells

 

Regards

 

Jerry

Well that money would get you quite a few tabbed A123 cells

 

Regards

 

Jerry

 

Ain't that the truth! And that is one way to look at it for sure. Biggest mistake I ever made was buying a job-lot of non-tabbed when I should have got the better tabbed versions in the DeWalt packs.

 

Lives and learns, I suppose.

 

Anyway: the reason I was looking at it was because I wanted to go into further education as a provider of bespoke e bike solutions for the private market.

 

Cheers.

Capacative Discharge welders are easy and cheap to make if you know a bit about electronics. I built one for myself a few years ago, but never managed to get hold of any nickel strip to use for the tabs. It's still in the garage gathering dust...

 

$100 CD Battery Tab Welder

Yes, I heard about these welders, and I am making inquiries about them.

 

Here is a link for some nickel tabs......eBay.ie: 50 Solder Tabs. Build your own battery packs. (item 350316912267 end time 16-Mar-10 00:28:44 GMT)

Thanks for that link... I should have more accurately said.. "The only place I could find Nickel strip was in the States, and I was too lazy/stubborn to order any for myself"

 

At the time (2004/5) I phoned round a dozen different metal suppliers in the UK, but couldn't find anyone with thin enough nickel in sheets (I wanted sheets so I could cut out L-shapes etc). If you're ordering from the states though... please get some for me too

Thanks for that link... I should have more accurately said.. "The only place I could find Nickel strip was in the States, and I was too lazy/stubborn to order any for myself"

 

At the time (2004/5) I phoned round a dozen different metal suppliers in the UK, but couldn't find anyone with thin enough nickel in sheets (I wanted sheets so I could cut out L-shapes etc). If you're ordering from the states though... please get some for me too

 

The tabs are quite cheap, and shipping is probably very low.....most sellers send stuff by USPS Priority Air Mail and that takes around 2 weeks or 12 days. I will order bulk and then come back and see if anyone here is still interested....