Comments jjackstone has made

OOPs

Sorry about the last post. I had more info written but it didn't go through for some reason. Wanted to thank you guys for the compliments.
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.
JJOn A home-built electric bike is working like a champ posted 2 years, 12 months ago 35 Responses

More Info

Hi,

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<...

JJOn A home-built electric bike is working like a champ posted 2 years, 12 months ago 35 Responses

Some Test Results

Hi Guys,

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                   
On A home-built electric bike is working like a champ posted 3 years ago 35 Responses

DeWalt ebikes

Hi,
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. JJOn A home-built electric bike is working like a champ posted 3 years ago 35 Responses