Milwaukee Electric battery pack for GoHub!

I began to write about this on the old voltage forum. I finally made a lithium battery pack using Milwaukee Electric power tools and have been testing it for about three months now. I got four of the V28 batteries and two chargers from acetoolonline.com ($581.74). I also got 6 connector blocks (22-56-1729) directly from milwaukee electric ($45.25) and wired them to the battery bag from my gohub kit.

So how's the performance? Not bad. I've hit 26 mph on the flat and 28 mph with hard peddling. The pack has 56v (more like 52v) at 6 ah. It's good for 6 miles of hard acceleration or 20 miles with peddling at 12mph. I'm estimating around 12 miles at 20 mph with some peddling as a happy medium. Maybe not so different from SLA but it's soooo light! It's 10 lbs. That's crazy light! Honestly it makes a huge difference in performance. It's like ridding a normal bike. It doesn't thump over curbs like when the SLAs are on the rack. But the best part is that the batteries charge in less than an hour! I only have two chargers so it will take me 2 hours (usually much less) to charge the whole pack but that's not bad. I'm used to 3 or 4 hours to charge the SLA pack.

So anyway today I finally took some pictures and videos.

Enjoy!

Nice vid. I believe those are the connector blocks used in the Monster Garage episode "electric dragster". I grabbed this vid on torrent some time ago:
http://isohunt.com/torrents.php?ihq=monster%20garage

Unlike the dewalt/a123's it appears from your report these work ok when connected with each other through their respective BMS...So you get the 5 year warranty by keeping the batteries intact...
Do you have any idea how many amps you can pull through the BMS?
Any troubles running them down to zero?

It's nice to see one of us give these a go. I really wanted to use them for my entire pack, but it would have taken 28 V28's at the 2.5kw I wanted, and that's just too expensive for me!

I've been arguing that lithium manganese, as these are, should not be overlooked as they seem to be when discussion turns to the a123 lithium iron phosphate batteries. At 15C, power density is roughly half-that of the a123's, but with even only 6ah, 15C is still 90 amps maximum -- plenty by our standards. There's some prismatic lithium manganese cells now available from some online rc parts vendors. Price should be dropping soon.

Compared to the a123's, lithium manganese recharges normally with any lithium-ion or li-poly charger, carries a little higher voltage, 25% more capacity for the same cell size, and *should* have roughly the same 2000 cycle/10 year longevity.

As my lithium cobalt pack takes a slow, 3-5 year dive into demise, I plan to replace each of the 15p 33ah subpacks one-by-one with 24-30 ah's of these emoli's, or their generic equivalent.

Thanks for the report. You've got at least one very curious observer to keep updated!

Emoli's and a123's are also sold here in pre-built and custom packs for those who aren't into ebay/powertool disassembly:
http://bigerc.com/index.php?cPath=21&osCsid=b83a10c93c0fb6a181338fe5a2ca5eaa

I haven't bought from this individual, but he was very nice and helpful on email. He's been around the RC world awhile.

Yes, it's nice not having to bypass the BMS like on the dewalt's. It seems to me that the emoli has traded discharge rate for a higher overall capacity compared to A123. The emoli also runs at a slightly higher voltage.

I understand that the BMS will allow 30 amps continuous. With my 2s2p set up, i should theoretically be able to pull 60 amps. The GoHub controller is only 20 amps so 60 amps is plenty.

I've never brought the packs down to zero but I plan to try that soon for a true range test.

It might sound strange but the next battery technology i'm actually looking forward to trying is the one from firefly energy which is similar to lead acid. They use some kind of graphite foam instead of the traditional lead plates. With this technology, they're getting performance equal to lithium at a lower cost. Plus we wont have to keep buying new chargers all the time.

That's cool!
I like the connector blocks. Those could be mounted to a frame of some sort to make swapping really easy.

What's the Ahr rating?

Hi Fetcher,

I thought about mounting the blocks to a bracket but it would be very difficult. I think the connector blocks were originally a replacement part for one of their handtools-- a circular saw or something. It looks like it was designed to be sonically welded into the tool housing. There's really no flange or anything to bolt the block to. I have often thought it would be nice if my goped scooter had little pockets under the deck lid to slide these packs into. I remember that dankers guy on the old forum used 7 packs worth of batteries and got over 20 miles at over 20mph on his ESR.

The V28 packs are 3 Ah each so the whole pack is 56v @ 6 Ah.

Nice work J !!!.. i like it !

I'm going lithium this summer for sure.. it will either be a 72v 15ah pack from Forsen, or a home-brew powertool getup..

Are you able to measure voltage sag under load on your bike ?

Hey Buzz,

I haven't measured voltage drop. I imagine at only 6 Ah it might be fairly significant. I can get to 26mph on a flat without peddling but that drops to about 24mph after only a half mile ~ 1 mile with the throttle pegged. Can the drain brain record maximum drop? Are you selling any yet

Jon

Yes the Brain will measure Max Amps, Min Volts, Max Speed,and many more.. 8)

I'm waiting patiently on my order of 45 motors !!!!!.. if i can still afford to eat mac and cheese with hot dogs once they arrive i'll get back to you on the DB 's ! lol. I hate waiting for stuff..

Nice job John. Can't wait for our ride after work tomorrow. Nimh vs Lith's...

Ric

Hey folks,

Ric and I took our ride yesterday. Except for being a little cold, it was fun! Here's how things stacked up:

Ric's bike: WE brushed hub motor, 36V @ 20aH NiMH
Jon's bike: 408 Brushless, 56V @ 6aH Lithium

Performance is amazing similar. Fully charged both bikes pull up to 26 mph. Actually the brushed motor can keep pulling past 26 up to 27 or 28 mph on a slight downhill or slight peddling but the torque on the brushless motor is better.

The ride was 8 miles with peddling. It was a slight downhill going and uphill coming back. We were traveling above 20 mph pretty much the whole time. There was a pretty steep hill on the last half mile or so. When we got back, the charge indicator on the Lithium batteries indicated about half charge. It took about 40 minutes to fully charge a battery pack so that's 1 hr and 20 minutes for all 4 packs.

I'm still pretty confident with my 12 mile range prediction at 20 mph. It might be more now. I don't think 16 miles is out of the question.
Not bad for just 6 Ah, eh?

John forgot to mention that on that last quarter mile semisteep to steep hill we both floored it and he just pulled away and kept going. I was surprised to find out at the end of our trip that his was just a 20amp controller.

Click to expand...

Probably, Jon's voltage advantage made the difference.

I was using the Vego SX brushed controller at stock settings. I think stock setup is 40-50amp (I'm not sure, Fechter would know). I think I need to bump up the amps on the pot. I can turn it up to 100amps but will not try. Maybe its because its the Brushed WE BD24/36 motor or maybe the Batterspace.com's Nimh 10ah packs limitations.

Click to expand...

The motor, if it's anything like the brushed crystalyte,
http://www.crystalyte.com/brush%20Motor.htm
won't even pull 30 amps at 36 volts -- see graphs.

They are supposed to handle 30amps each pack and since I have them in parallel it should handle 60amps. Next time we will have to the hill test again with me using 36v12ah SLA's and see if the BD motor has better pull.

Click to expand...

Let us know what you find. From these results below, even if you adjust the controller's amp rating to 100, I bet it'll take a bump to 48v for your setup to be competitive.

When I ran my 5304 and 35 amp controller at 28 volts, it would only pull 10 amps max! At 80 volts it pulls the full 35 amps available.

Nice report guys,
The stock current limit on the Vego controller is around 50 amps. If you tweak the pot all the way, it will be around 60. To get a higher limit, you need to hang a resistor on the circuit board, but I wouldn't recommend it unless you upgrade the main cap and beef up a couple of the traces on the board.

Where is that hubmotor simulator? I'd like to put a link to it in the sticky on How Motors Work.

Here's the simulator:

http://www.ebikes.ca/simulator/

BTW, my 'puter didn't like the video format, so I used YouTube to see it.

It can be found here:
http://www.youtube.com/watch?v=sKeSzdMlwHU

Edit: not anymore, create an account and upload it thyself if thou want to...

Nice batteries Jondoh. So when the batteries come off the charger, how much voltage do they have when you plug them into the bike?

57.2v -- but that's not fresh of the charger... that's still 28.6v per battery pack and 4.08v per cell.

thinking...

wow, that's a lot of volts! It's really not so different from 60v, isn't it?

I wonder how many volts these controllers can actually handle. I thought it was only 55 volts.

i heard from danny that someone was operating the bike at 60 v using sla batteries. I think my few volts over isn't a big deal. ironically, on a freshly charged pack, the low charge yellow light comes on dimly and then goes off as soon as you start using the bike.

Johndo, Hoping you're still around. I'm doing a battery pack configuration similar to the one that you did in this post, except I'm using 6 packs. I was wondering if you could show me, or explain to me how you wired the Connector Block Assemblies. I would be super greatful for the informational how-to. I'm going to be building my first e-bike, and I'm piecing together as much information as I can before I receive all of my parts and get started.

Thank you very much.