Building a small A123 Battery Pack
- Thread starter jerrysimon
- Start date
Ok just got to work (the Marathon Plus held out) and I tried to pedal a little more though still used power on inlcines and when I felt lazy.
This meant that when I got to work only 0.916Ah was taken out the battery. Usually its about 1.2Ah.
I won't charge the battery and we will see if I can now get home on one charge and no more punctures
Regards
Jerry
This meant that when I got to work only 0.916Ah was taken out the battery. Usually its about 1.2Ah.
I won't charge the battery and we will see if I can now get home on one charge and no more punctures
Regards
Jerry
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Well got home tonight and I had taken another 0.895Ah out the battery. So that's a total of 0.916 + 0.895 = 1.811Ah. The battery still had plenty of power in it as I pulled up to my front door and had not started to cut out. From my previous ride where it did start to cut out I am guessing that this happens around around the 2.0 to 2.1Ah point.
I may have assisted more but certainly nothing that really pushed me hard, arriving at work and back home refreshed but not exhausted.
I then put 1.768Ah back in on a subsequent charge, which is all but 0.043Ah the same as was taken out.
I have therefore concluded that this battery more than meets the requirements for my 10.25 mile round commute on my lightweight EBrompton conversion and I don't even need to charge it at work. As I have said though this is in Cambridge where my commute is pretty flat apart from a few inclines, certainly not steep hills.
I guess this thread is now over, apart from the occasional update of how the battery performs over time
Regards
Jerry
I may have assisted more but certainly nothing that really pushed me hard, arriving at work and back home refreshed but not exhausted.
I then put 1.768Ah back in on a subsequent charge, which is all but 0.043Ah the same as was taken out.
I have therefore concluded that this battery more than meets the requirements for my 10.25 mile round commute on my lightweight EBrompton conversion and I don't even need to charge it at work. As I have said though this is in Cambridge where my commute is pretty flat apart from a few inclines, certainly not steep hills.
I guess this thread is now over, apart from the occasional update of how the battery performs over time
Regards
Jerry
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I thought this might be of interest to DIYers, electricwingman are selling ready made A123 packs...
A123 battery packs - Single cells and 2-8 series
They are offering lots of different configurations. 6s packs are priced from £69.90 to £79.90. Uk-based, too.
Chris.
If you read the whole thread you will see that you may not need one for these cells, A123.
Regards
Jerry
I kind of suspected as much, I was thinking that a Turnigy 6 cell charger/balancer might do the trick. I will read through the whole thread now. Thanks.
ELECTRIC AVENUES,
I am not sure you even need the Turnigy. Although I used it initially to balance the cells I have not used it since. The cells seems to naturally balance after use. At the moment none of the cells are more than 5mv out after several weeks use.
Regards
Jerry
I am not sure you even need the Turnigy. Although I used it initially to balance the cells I have not used it since. The cells seems to naturally balance after use. At the moment none of the cells are more than 5mv out after several weeks use.
Regards
Jerry
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Thanks Jerry....where do you get those {and what are they called
} little clusters of wires with the fitting that plugs into the Turnigy???Cheers.
ELECTRIC AVENUES
All the details and links are in the posts if you read back through them
Regards
Jerry
All the details and links are in the posts if you read back through them
Regards
Jerry
ELECTRIC AVENUES
All the details and links are in the posts if you read back through them
Regards
Jerry
Hey, thats one way to make a man read your book!!
Cheers!!
Jerry, I have a question about your ebay-sourced charger... have you checked out what voltage it gives out?
If you remember, I asked you about Tongxin motor supplier in the past. Now the motor has been ordered along other things (like spokes, rim, nipples etc.). I'm hoping to get something done for the project in the following weeks.
Regarding battery I think about 4,5 Ah is big enough capacity for my use. Maybe I'll buy 2 Turnigy lifepo4 packs (2p6s) and connect them in series or even go your way and use individual cells. Anyway I was wondering if I could use my existing 36V SLA charger to charge this series-connected pack easily? I could then separate it in two and balance both packs occasionally with cheap balancing charger.
My current charger gives out these voltages:
41,7 V (measured from charger connector not connected to the battery)
43,7 V (initially when connected to the slightly discharged battery and charging going on). The voltage continues to rise slowly until the green light lights up. Voltage was checked from Turnigy power analyzer screen.
41,4 V (charger has green light and the battery is charged ready). Checked from Turnigy power analyzer screen.
Bottomline, are SLA and lifepo4 chargers basically the same?
EDIT:
I checked ebay and there was this charger:
36V 36 Volt Electric Scooter bike Razor Charger ATV : eBay Motors (item 320489157828 end time Mar-18-10 06:02:51 PDT)
In the picture there is mentioned "equal changing voltage 44,5 V". So this is cut-out voltage, am I correct? Seems to be a little on the high side: 44,5/12=3,71V per cell. A123 charging cutout should be 3,6 - 3,7 V.
When I now checked your earlier posts, the specifications are the same as yours. Has the charger been working fine and do you think it is safe to use daily without worrying about overcharging?
If you remember, I asked you about Tongxin motor supplier in the past. Now the motor has been ordered along other things (like spokes, rim, nipples etc.). I'm hoping to get something done for the project in the following weeks.
Regarding battery I think about 4,5 Ah is big enough capacity for my use. Maybe I'll buy 2 Turnigy lifepo4 packs (2p6s) and connect them in series or even go your way and use individual cells. Anyway I was wondering if I could use my existing 36V SLA charger to charge this series-connected pack easily? I could then separate it in two and balance both packs occasionally with cheap balancing charger.
My current charger gives out these voltages:
41,7 V (measured from charger connector not connected to the battery)
43,7 V (initially when connected to the slightly discharged battery and charging going on). The voltage continues to rise slowly until the green light lights up. Voltage was checked from Turnigy power analyzer screen.
41,4 V (charger has green light and the battery is charged ready). Checked from Turnigy power analyzer screen.
Bottomline, are SLA and lifepo4 chargers basically the same?
EDIT:
I checked ebay and there was this charger:
36V 36 Volt Electric Scooter bike Razor Charger ATV : eBay Motors (item 320489157828 end time Mar-18-10 06:02:51 PDT)
In the picture there is mentioned "equal changing voltage 44,5 V". So this is cut-out voltage, am I correct? Seems to be a little on the high side: 44,5/12=3,71V per cell. A123 charging cutout should be 3,6 - 3,7 V.
When I now checked your earlier posts, the specifications are the same as yours. Has the charger been working fine and do you think it is safe to use daily without worrying about overcharging?
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trepo,
That is the same seller that I purchased mine off. I basically checked out the one that Freedom used and sourced the same model.
Its been charging fine the green light coming on after about 1-1 1/2 hours after charging following my commute.
I used the the charger/balancer initially but to be honest these A123 cells seem to self balance really well and I think just using the cheap charger will suffice.
Your SLA charger sounds identical and this one IS sold as an SLA charger.
Anyway I will continue to report on battery usage.
Did you order your Tongxin from my same supplier ? Hope you get the right one with no roller brake fitting.
Be sure to keep us updated
Regards
Jerry
That is the same seller that I purchased mine off. I basically checked out the one that Freedom used and sourced the same model.
Its been charging fine the green light coming on after about 1-1 1/2 hours after charging following my commute.
I used the the charger/balancer initially but to be honest these A123 cells seem to self balance really well and I think just using the cheap charger will suffice.
Your SLA charger sounds identical and this one IS sold as an SLA charger.
Anyway I will continue to report on battery usage.
Did you order your Tongxin from my same supplier ? Hope you get the right one with no roller brake fitting.
Be sure to keep us updated
Regards
Jerry
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Jerry, I indeed ordered from the same chinese company you did.trepo,.
Did you order your Tongxin from my same supplier ? Hope you get the right one with no roller brake fitting.
Be sure to keep us updated
Regards
Jerry
I paid using westernunion on Friday and now after weekend their tracking page shows that the payment has been picked up. I have never used westernunion service before but it seems to be quite handy, although expensive. I mean the service fee was 26,50 euros and exhange rates are worse than payng by credit card.
Regarding batteries, I have decided not to use ready-made turnigy packs. It seems that they are not very high quality, at least according to this user:
Endless-sphere.com • View topic - New Turnigy liFe packs
Instead I have ordered 8 used Dewalt 36V packs from Germany. Daniel Weck has hinted us of it here:
http://www.pedelecs.co.uk/forum/electric-bicycles/5197-public-service-german-supplier-dewalt-a123-bosh-fatpacks-powertool-batteries.html
Those packs have genuine A123 cells inside and after disassembly there might even be ready to use 6s sections, so I only have to add balancing leads etc. The seller states that 10-20% of cells are bad so probably I'll end with well over 60 cells to tinker with... That's maybe 10 6s packs. And I can re-cell my dead cordless screwdriver battery using those cells too.
The seller was very friendly and helpful and answered my questions promptly even while it was Sunday afternoon. My packs are already on the way and will be here probably next week.
I will start my own thread about Brompton build in more or less diary style later.
EDIT:
An offtopic question: I bought my Brompton from ebay a few months ago for a very fair price. It was a insurance replacement for a stolen one. I have not used my Brompton extensively yet, its winter here and a lot of snow (I did a short testdrive though and everything works fine).
The bike came its right pedal not attached, it was in the package separately. Is it normal that the metal cage is shaped like this, or should I try to straigten it?
brommie
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Looking forward to this !
Mine was too
It's a cheap part, so not a big deal if you can't straighten it up.
Cheers, Dan
trepo,
I look forward to watching your build thread/diary. Lots of pictures needed
The round A123 cells are more robust it seems than the Turnigy lifepo4 packs so I think you have chosen wisely.
Did you order a couple of motors as the cost of postage is the same for two or even three, so it worthwhile getting a spare ?
PS it took about 2-3 weeks for the motors to turn up after they withdrew my payement. Like you I used westernunion which does require an element of trust but they seem genuine. Although it will probably be delivered without an import/VAT charge I received an invoice from DHL in the post about 2 months later. The actual charge was quite small about £10 I think and no admin charge. I ordered two full sets of everything.
Regards
Jerry
I look forward to watching your build thread/diary. Lots of pictures needed
The round A123 cells are more robust it seems than the Turnigy lifepo4 packs so I think you have chosen wisely.
Did you order a couple of motors as the cost of postage is the same for two or even three, so it worthwhile getting a spare ?
PS it took about 2-3 weeks for the motors to turn up after they withdrew my payement. Like you I used westernunion which does require an element of trust but they seem genuine. Although it will probably be delivered without an import/VAT charge I received an invoice from DHL in the post about 2 months later. The actual charge was quite small about £10 I think and no admin charge. I ordered two full sets of everything.
Regards
Jerry
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Daniel, I just fixed the pedal. Some pressing on a bench vice & light hammering and it was as new.
A question about connecting 6s packs together to get a bigger capacity pack:
If two or more 2 x 6s packs are connected parallel like this:
. . . . . . . . . . - 6s A123 - 6s A123 -
. . . . . . . . . /. . . . . . . . . . . . . . \
negative out . . . . . . . . . . . . . positive out - main fuse 15A
. . . . . . . . . \ . . . . . . . . . . . . . . /
. . . . . . . . . - 6s A123 - 6s A123 -
What if one cell in any of the packs short-circuits itself? If I get it right the other half of this big pack starts to charge the other half with a high current ruining the whole pack / maybe melting the connectors etc.
Maybe I should add a fuse just before parallel connecting them like this:
. . . . . . . . . - 6s A123 - 6s A123 - 10A Fuse
. . . . . . . . . /. . . . . . . . . . . . . . . . . . \
negative out . . . . . . . . . . . . . . . . . . positive out - main fuse 15A
. . . . . . . . . \ . . . . . . . . . . . . . . . . . . /
. . . . . . . . . - 6s A123 - 6s A123 - 10A Fuse
10A fuse would blow if something like that happens. It would be easier than using diodes because fuses and holders for them are readily available anywhere.
A question about connecting 6s packs together to get a bigger capacity pack:
If two or more 2 x 6s packs are connected parallel like this:
. . . . . . . . . . - 6s A123 - 6s A123 -
. . . . . . . . . /. . . . . . . . . . . . . . \
negative out . . . . . . . . . . . . . positive out - main fuse 15A
. . . . . . . . . \ . . . . . . . . . . . . . . /
. . . . . . . . . - 6s A123 - 6s A123 -
What if one cell in any of the packs short-circuits itself? If I get it right the other half of this big pack starts to charge the other half with a high current ruining the whole pack / maybe melting the connectors etc.
Maybe I should add a fuse just before parallel connecting them like this:
. . . . . . . . . - 6s A123 - 6s A123 - 10A Fuse
. . . . . . . . . /. . . . . . . . . . . . . . . . . . \
negative out . . . . . . . . . . . . . . . . . . positive out - main fuse 15A
. . . . . . . . . \ . . . . . . . . . . . . . . . . . . /
. . . . . . . . . - 6s A123 - 6s A123 - 10A Fuse
10A fuse would blow if something like that happens. It would be easier than using diodes because fuses and holders for them are readily available anywhere.
Tiberius will supply Ideal Diodes for parallel battery connection, you will find them in the classified section with lots of links to help you.
Herb
I have a 2.3Ah A123 pack in my collection, if I had two I would be tempted not to parallel them but run each of them as a single battery until the LVC operated and then change to a fresh battery.
This way you would always know your remaining capacity.
I run my Brompton on 2 parallel (with diodes) Bosch Fatpacks and use the A123 as a sort of reserve/get you home battery.
Look forward to seeing your build.
Herb
This way you would always know your remaining capacity.
I run my Brompton on 2 parallel (with diodes) Bosch Fatpacks and use the A123 as a sort of reserve/get you home battery.
Look forward to seeing your build.
Herb
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