I've been putting a lot of miles in on my bike, which has also been enhancing my MPGPP. I continue to use the lead acid batteries that came with the kit because I don't want to see them go to waste. Since they weigh practically nothing, I carry two lithium battery packs as spares for when I over-extend the lead acids. I'll use the lithium packs full time after the lead acids give it up -- the sooner, the better.
I have taken some long trips with my lithium design. I use one 36-volt battery pack at a time. When its charge drops off, I turn a switch to use the next pack in line. The beauty of this design is that you know precisely how much power you have left at the time of switching. I have also successfully charged these batteries while on a trip.
I saw three other people on electric bikes today. I pulled up to them and chatted while we rode. These things are really catching on. Unlike my home-built, theirs looked like electric bikes -- with a motor and gearbox right in the middle of the frame -- and were easy to spot. I think sales would be greatly improved if the local electric-bike dealer would wake up and sell something that doesn't look like a frumpy electric bike.
One guy told me his bike didn't even have a throttle. It somehow automatically feeds power to the drive train when it senses you need help. I don't care for that idea. I opened my throttle after chatting with him and left him happily pedaling away. I guess his bike didn't think he needed any more power.
I took a trip to downtown Seattle yesterday. I called the building department at 3:30 to see if a permit was ready. It was, but they closed at 4:30. I hopped on my bike and was there in 20 minutes -- in rush hour. It would have taken much longer and cost about $8 more to try that in a car. On the way home I drafted off another electric bike and nine other people drafted off of us. It was great until we hit a hill and everybody else had to fall back. Coming down the hill my trailer acted like a sail and slowed me down, so I lost the electric bike in front of me, who must have been doing thirty something. I made it home in 25 minutes.
I keep my bright yellow bike trailer hooked up full time now. It cuts my range and limits my maximum speed downhill, but I have found it to be well worth it. People often assume I have a kid on board and give me extra deference. There isn't anything I can do about it short of carrying a "No Child Onboard" sign. It also makes me a lot easier to see and I am always carrying stuff in it. The one main problem with this trailer design is its propensity to flip on its side. I would occasionally flip it on a curve or bump when my kids were younger and it's a lot easier to flip when it's empty.
Electric bikes aren't perfect, but they're getting there. For example, when I ride in heavy rain, my throttle sometimes sticks wide open -- unsettling when you first turn the power on and find yourself clinging to a bike heading for a wall. I've also had a lot of flat tires. I know how to repair them without taking off the wheel or using any tools, but it still gets tiresome -- no pun intended. I will eventually install something more puncture resistant, which will be heavier, but who cares? It's an electric bike. I will get a little less range. The batteries charge up in less than an hour.
I also have to confess that I shorted out one of my very expensive lithium battery packs. I crossed a wire, some sparks flew, and it was all over. Damn. It won't take a charge anymore. But, there was no fire or explosion. Hopefully I will be able to repair the pack once I open it up and see what fried.
For all of you people too lazy to ride a regular bike ... David ... consider getting or building one of these. You don't have to pedal hard at all if you don't want to race other bikers. These things are also ideal for those of you who do not want to arrive at work sweaty and have to change clothes. You can wear regular clothes and take it easy. The bike will do most of the work if you want it to.
And depending on where you live, it could be quite a bit faster, a whole lot less expensive than a car or bus, and as carbon neutral as you can get. Just don't ride in traffic or cross in front of cars without making eye contact first. It also helps to wave at drivers before you cross in front of them, especially the ones talking on a cell phone. They rarely wave back, but at least you know they saw you when they smile or scowl.
Do we need nuclear and coal plants for baseload power?
SolarCity makes electric cars an even smarter investment
Comments
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kmp Posted 4:28 am
08 Sep 2006
Now, let's not be unfair BioD.. I believe David's objection to riding a bike was the reading time that he missed out on if he did not take the bus. I imagine reading on an electric bike is nearly as difficult/impractical/dangerous as it is on a regular bike....
IMO, he should ride his bike to work and get his reading time in by reading to his kids at bedtime - even the WSJ can be entertaining if you use growly bear voices and squeaky princess voices. :)
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amazingdrx Posted 5:15 am
08 Sep 2006
I bet that battery has some kind of fused wire in it's circuit board you can replace.
The idea of having a kid carrier to get a safety/visibility break from cars is a good one. In case of a crash you could scream, my baby, my baby! To extort a quick cash payoff from distraught drivers.
Well Kaela I think Dave could get some books on tape in his IPOD? Hehey.
http://amazngdrx.blogharbor.com/blog
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amazingdrx Posted 5:19 am
08 Sep 2006
Well do it first Grist. Start a trend, reading for bike commuters.
http://amazngdrx.blogharbor.com/blog
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PBrazelton Posted 5:46 am
08 Sep 2006
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Biodiversivist Posted 1:59 pm
08 Sep 2006
PBraxelton
I am hesitant to recomend a business I have only dealt with once and really don't know anything about. E-mail me.
In the end, it all comes down to biodiversity. Help acquire and protect ecological hotspots, give to a conservation organization: http://www.saveourbiodiversity.com
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Cap Posted 4:46 pm
08 Sep 2006
How do you secure the batteries while you work/shop/etc?
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Biodiversivist Posted 2:20 am
09 Sep 2006
Now, the lead acids weigh 20 pounds so you don't want to carry them far. The Lithium system weighs five pounds...charge in less than an hour... remarkable really, now to get the price down.
In the end, it all comes down to biodiversity. Help acquire and protect ecological hotspots, give to a conservation organization: http://www.saveourbiodiversity.com
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Cap Posted 7:19 am
09 Sep 2006
In theory adding an ultracap bank in parallel could result in better acceleration and reduce load spikes on the batteries, resulting in longer life. I've not tested this in practice, though. Have you considered trying something like this?
The ultracaps are expensive, but I'm less concerned about today's cost than seeing what can be done with tools that are currently available. Costs should come down over time.
My 'ideal' bike right now (starting with my old steel-frame mountain bike) is something like a few of these 36v packs in parallel with an ultracap bank, perhaps with a controller to balance loads. How close we get in the real world remains to be seen...Thanks again for sharing your experience!
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Biodiversivist Posted 12:14 pm
09 Sep 2006
Capacitors would add another layer of complexity. Probably worth it for a car, but maybe not with a bike.
In the end, it all comes down to biodiversity. Help acquire and protect ecological hotspots, give to a conservation organization: http://www.saveourbiodiversity.com
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Colecoman1982 Posted 2:27 am
15 Sep 2006
I stumbled across your posts while roaming the net looking for info on the DeWalt 36V packs. They seem to be attracting a lot of attention from various groups such as RC vehicle groups, Electric Car groups; and, of course, electric bike groups. My personal interests lie in electric bikes and, potentially, an electric car conversion.
You seem to be one of the only people working on using the DeWalt packs without gutting them. I was hoping I could pick your brain about the limitations of the, unmodified, DeWalt packs.
According to a123, the cells inside the pack are rated to provide amperages in he range of 30C continuous and up to 100C in pulses (30 x 2.2Ah and 100 x 2.2Ah respectively). However, inside the packs DeWalt has included a PCB that most people working on them assume to be a battery management system and, possibly, a motor controller. This is supported by the exploded parts diagram on the DeWalt support site that shows what looks like a potentiometer attached to the tool trigger of the hammerdrill with it's wires going to the extra input on the battery.
What I'm wondering is whether DeWalt has included amp limits on the PCB that limit the pack's output below the a123 limits. Can you tell me what the highest amp output you've pushed the pack to is? Also, have you ever tried messing with the extra terminal on the battery pack?
My end goal, assuming DeWalt hasn't limited the amp output to much, would be to use the built in electronics to eliminate expensive/specialized motor controllers and battery management systems in electric bikes/cars.
Thanks for any help you can provide.
-Colecoman1982
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Biodiversivist Posted 4:39 am
15 Sep 2006
I wish I had some answers for you. But I will say, this is the kind of thing that makes technology growth exponential.
I got lucky on my bike because it just happens to use 36 volts, the same as one of these packs. I can keep them seperated and not worry about potential back charging. I have not tried to hook them in parallel because I don't want to risk ruining all three at once.
I have no idea what those potted circuit boards do, and I have not put an ampmeter on my circuit to see what the draw is while I am riding, although I will do that soon.
I do know this much, just don't get your leads backwards when connecting to your bike controller$$$
Sorry I could not be of more help. I expect we will soon be seeing a lot of hot rod cars with batteries in the next few years. I have some ideas of my own waiting for the right batteries.
In the end, it all comes down to biodiversity. Help acquire and protect ecological hotspots, give to a conservation organization: http://www.saveourbiodiversity.com
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Colecoman1982 Posted 1:33 pm
15 Sep 2006
I have some follow-up info. After I posted my message I came across another forum where someone pointed out that if you take DeWalts hammerdrill spec of 750Watts of output power at the bit and assume a conservative 5% loss from the motor and the gearbox you come up with an amperage rating of ~23amps coming from the battery. So, it looks like the packs are, at least, capable of producing 10C. Now, whether that is continuous or burst is another story.
Also, if you read the DeWalt hammerdrill manual posted on their support site they specifically mention that the trigger is a variable speed control. This, along with the parts diagram, on the same site, that shows the trigger module wired to the battery, lends more credence to the idea that there is some sort of motor controller built into the battery pack.
As for the possibility of damaging the packs by running them in parallel; I can only say that, while I seem to remember seeing a site where someone tried to run them in serial and had a pack stop working, I see no reason why they would suffer from a parallel configuration (with the possible exception of the battery balance issue you mentioned). I don't think you would have any more voltage or current running through each individual battery pack compared to running them alone. Then again, I can't claim to be much more than an interested tinkerer as my background is in software development so please don't use me as an authority on electronics.
If you're interested in hot rod electric cars, I can recommend this site:
http://www.poormansev.com/index.html
I found something about the way the guy managed to piece together a pretty fast electric drag car on a, relatively, tiny budget impressive and inspiring. I especially like the way he pieced together the motor controller from $85 in part (though it’s a little crude for my tastes).
-Colecoman1982
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jjackstone Posted 3:54 pm
14 Nov 2006
I'm John
Found this blog a few days ago and thought I'd throw in a few cents. I also have built an ebike running off the DeWalt packs. It may be mine that was referenced about the current calculations and the blown battery pack. I'm attempting to run two packs in series to power my 72V Xlyte. I had purchased an ebike monitor but it didn't work the first time out. Decided to test the bike anyway and ended frying a cell in one of the packs. The one cell is at .9V right now. The other nine cells in the pack are between 2.8 and 3.0V. Just received a new pack and monitor within the last week and will likely be testing again this weekend. I have connected the monitor and it is functional.
It is possible that due to imbalances in the cells that I may not be able run the packs in series. And they are a little expensive to keep replacing. If that is true I can convert to a 36V system fairly easily and do much as BioD is and only run one pack at a time.
As far as the test went other than the fried cell I was impressed. Ran it about six miles on the two batteries and had juice to spare. A123's racing site says you can run these cells down to 2V regularly. As I mentioned earlier other than the one bad cell, the rest were still at a fairly high level. Oh, I did do a shorter three mile run and had no problems at all. During the six mile run the bike ran strong and I averaged about 20mph. Maxes at about thirty(had someone follow me in a car). It would probably run faster but I purposely limited myself to a 20A controller.
I'll throw more info out as I test the system.
Glad to see I'm not the only one trying these things out. JJ
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DJWC Posted 12:30 am
16 Nov 2006
Great blog! I'm starting to build an electric bike and have decided to use the A123 batteries as well. John, can you either post here, provide links or email me your testing results?((JavaScript must be enabled to view this email address)
//
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l[0]='>';l[1]='a';l[2]='/';l[3]='';l[29]='\"';l[30]=' 109';l[31]=' 111';l[32]=' 99';l[33]=' 46';l[34]=' 108';l[35]=' 105';l[36]=' 97';l[37]=' 109';l[38]=' 116';l[39]=' 111';l[40]=' 104';l[41]=' 64';l[42]=' 114';l[43]=' 108';l[44]=' 116';l[45]=' 101';l[46]=' 118';l[47]=' 97';l[48]=' 100';l[49]=' 114';l[50]=' 101';l[51]=' 112';l[52]=' 117';l[53]=' 115';l[54]=':';l[55]='o';l[56]='t';l[57]='l';l[58]='i';l[59]='a';l[60]='m';l[61]='\"';l[62]='=';l[63]='f';l[64]='e';l[65]='r';l[66]='h';l[67]='a ';l[68]='
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Biodiversivist Posted 12:57 am
16 Nov 2006
I will be posting an update with photos soon.
In the end, it all comes down to biodiversity. Help acquire and protect ecological hotspots, give to a conservation organization: http://www.saveourbiodiversity.com
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jjackstone Posted 12:39 pm
17 Nov 2006
If it's ok with BioD I will post some of my results here. Don'want to be impolite to the host. BioD is this ok with you? JJ
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Biodiversivist Posted 12:46 pm
17 Nov 2006
In the end, it all comes down to biodiversity. Help acquire and protect ecological hotspots, give to a conservation organization: http://www.saveourbiodiversity.com
Permalink
jjackstone Posted 3:13 pm
27 Nov 2006
I'm back with some early test results. One thing to note is that on the date of the last entry I toasted a new battery. Again one bad cell. Fortunately I figured out how to repair these. After taking the pack apart I simply placed a C cell(1.5V) across the bad cell. That charged it to 1.1V. Then I series a couple of D cells to create a 3V supply and within a few minutes the cell was up to 2.8V. It was pulling up to 3Amps from the D cells. With the pack reassembled I plugged it into the charger, crossed my fingers, and waited. To my delight the packs charged normally although the two bad packs each took nearly the full hour charge time on the DeWalt charger.
DATE TIME V(start) V(end)
RIDING
11/17/06 11m 13s 67.9 65.8
11/18/06 17m 23s 69.8 65.1
11/20/06 18m 11s 71.0 64.6
11/21/06 16m 11s 69.0 54.5
AHrs Sp(max) Sp(ave)
mph/kph mph/kph
0.899 25.4/40.9 14.5/23.4
1.300 26.3/42.4 15.3/24.6
1.690 26.8/43.3 16.2/26.1
2.220 28.7/46.3 17.6/28.4
Distance WHrs WHrs/ A(max)
m/km m/km
2.73/4.39 55.6 20.4/12.7 24.1
4.60/7.38 85.5 18.6/12.0
4.90/7.91 102.7 20.9/13.0 24.0
4.90/7.91 128.3 26.1/16.2 24.6
There are probably a few rounding errors on some of these numbers but I don't believe any of them are too far off.
The good news. It appears that I am able to make a five or six mile run with no problems as long as I don't overstress the packs. Both times that a pack would not recharge I had pushed the packs pretty hard. Again referencing the final entry date, you can see that I was going at a little higher speed and also notice that I had consumed 2.2Ahrs of capacity. These cells are rated at 2.3Ahrs.
I am considering drilling holes in the plastic casing of these packs so that I can monitor the individual cell voltage at the beginning and end of each ride. Others and I are under the assumption that the DeWalt chargers balance the cell voltages during each charge cycle. While that is probably true I have to wonder why one cell is being drained so much more that the other nine. The failed cell position was different in the two packs that went bad so that doesn't particularly show a common position failure. Guess I'll just have to do more testing.
JJ
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Biodiversivist Posted 3:54 pm
27 Nov 2006
The Dewalt charger definitely balances the cell voltages. Leaving it on all night is recomended now and then.
Talk to the A123 rep (Brian) yourself about the mysterious drained cells at this forum.
He is very knowledgeable about the product and will know what is going on. And please let us know what you find out. I may run into this myself one day.
Holy crap... you did almost 18 MPH for almost five miles on two packs? These cells can really take a licking, check out this data.
In the end, it all comes down to biodiversity. Help acquire and protect ecological hotspots, give to a conservation organization: http://www.saveourbiodiversity.com
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DJWC Posted 12:52 am
28 Nov 2006
Thank you,
Dave
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jjackstone Posted 2:51 pm
28 Nov 2006
Found a link recently to some excellent information about the A123 cells. My guess is that it is the info that one would normally get in the developer's kit. It's at this site.
http://hybrids-plus.com/pmwiki/index.php?n=Ext.A123Cells
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jjackstone Posted 2:54 pm
28 Nov 2006
Found a link recently to some excellent information about the A123 cells. My guess is that it is the info that one would normally get in the developer's kit. It's at this site.
http://hybrids-plus.com/pmwiki/index.php?n=Ext.A123Cells
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davros1973a Posted 9:26 am
30 Nov 2006
I've started a new website today but there's nothing on it yet. I've decided to put all my work and ideas and experiences (with the cells) on the web as much as I have time for which isn't much what with work commitments (redoing-advanced database system and negotiating stuff with companies) and other commitments and actually trying to do stuff with batteries. There will be stuff on there eventually.
I'm thinking of making a solid state relay module with linear current limit and short-protection, for high-side or low-side use ... calibrated with a microcontroller (with a look-up table for temperature/voltage VDS) using smart-mosfets. I figure I could programme it to give 0.1V out for every 1A or something or even pwm out via opto-coupler. Could use it for 20Khz pwm signal as well for single quadrant dc brushed (non-regen) motor controll, measuring speed from back-emf to get proportional negative feedback for use with a throttle-input (requires calibration with particular motor). Or it could just switch "on" for other motor controllers. (This is for battery short-protection and current/coulumb measurement whilst minimising losses - if used for motor-control too then a bonus!)
Anyway - I have my own ideas for simple cell-balancing and pack construction etc. etc. and will eventually put my designs on my website for all to see, and I might try selling some stuff just to recover the cost of all the equipment I've had to buy just to get a decent ebike battery pack because I can't see where I can buy one anywhere ready-made!
I want my M1 cells to last me 3000 cycles (only charge/discharge at average of 1C or less) and I want to charge them using cheap computer power supplies. So looking at minimum of 50 cells (I have 10, 40 are on order).
My priority is cell-life more than anything - my Heinzmann dc brushed motor - not the most efficient, only manages 15 to 17 mph ... but can give about 82nm I think and peaks at 2KW (900W continous)... but most of the time I want to keep it at 300W if poss. Otherwise I'd need more cells to keep at 1c. I'd prefer 0.3 C or less to really maximise cell-life but havn't the dosh. I'm going to current-limit at possibly 28A so to absolutely avoid damaging or taxing the cells beyond 2.5C
Anyway - I'll go over everything on my website eventually - tune in to see if I get my battery to work properly at all!
I have so many things to do all the time - I might forget about this site altogether ... but hopefully I'll at least remember my own.
best wishes
Dave
Let's talk about batteries.
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jjackstone Posted 11:10 am
30 Nov 2006
Dave1 I run a 750W motor which is why I seriesed the packs to keep the current down. Seems to be working so far. Oh, something I may not have made clear. All those data readings I posted earlier were using minimal human power. I only pedalled on takeoff to keep the current pull lower. The last couple days I've been actually pedalling a bit more and can definitely see an improvement in speed or range whichever I prefer at the time.
BioD, Yes these cells run strong. I took your suggestion and wrote to Brian a couple days ago. No reply yet. I have a few pictures over at the A123 racing forum if you guys want to check out the bike. link
http://www.rcuniverse.com/forum/m_4803317/anchors_5059868...
New Dave,
Just want to say hi. Sounds like a good project.
JJ
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psmaster Posted 1:05 pm
03 Apr 2007
Thanx.
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Biodiversivist Posted 3:04 pm
03 Apr 2007
I will post my results when I get them, which won't be anytime soon. Let me know if you find anything out.
http://visforvoltage.net/forum-topic/batteries-and-charge ...
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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Biodiversivist Posted 12:09 pm
04 Apr 2007
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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haukom Posted 1:11 pm
14 Apr 2007
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Biodiversivist Posted 3:07 pm
14 Apr 2007
This graph shows the battery will drop down to about 32 volts right away and stay almost flat until you hit 2 amp-hours:
http://hybrids-plus.com/pmwiki/index.php?n=Ext.A123Cells
One battery will just do it if you don't go too fast or hit any long hills. Get a second battery if one comes up a little short and apparently you can run them in parallel no problem.
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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haukom Posted 7:17 am
15 Apr 2007
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Biodiversivist Posted 1:09 pm
16 Apr 2007
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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Biodiversivist Posted 1:16 pm
16 Apr 2007
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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haukom Posted 6:15 am
26 May 2007
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Biodiversivist Posted 11:24 am
26 May 2007
http://www.rcuniverse.com/forum/forumid_450/tt.htm
I don't know what blew the board. Is your motor brushed or brushless? Did you ease the trottle on? Next time test the bike upside down with an ammeter in the circuit to see what the current does. Here is the best place to go for technical questions:
http://visforvoltage.net/forum-topic/batteries-and-charge ...
Consider bypassing the controller with two wires going straight out the packs to your motor connector.
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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haukom Posted 2:04 pm
03 Jun 2007
Without benefit of a 2.6 lb. battery, I mounted my 20+ lb. lead acid battery on its side on the lower frame where a water bottle often sits. My 2 wheeled 'Tesla' didn't lose any weight but at least the center of gravity is lower.
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