There's a few nice implementations of MOSFET-aided anti-spark switches on the German Pedelec forum (worth reading if you're into soldering electronic components):
Bauanleitung Einschaltstrombegrenzung ("Antiblitzschaltung") - Pedelec-Forum
Building a small A123 Battery Pack
- Thread starter jerrysimon
- Start date
There's a few nice implementations of MOSFET-aided anti-spark switches on the German Pedelec forum (worth reading if you're into soldering electronic components):
Bauanleitung Einschaltstrombegrenzung ("Antiblitzschaltung") - Pedelec-Forum
CellLog 8s
This little device turned up and I used it on one of the 6s packs into work this morning. It records Voltage on each cell at intervals you set (this was set to 2 seconds) and then you can download them and use some software to analyse the results.
Here is a snapshot of the voltage table where you can see the voltage overall and of each cell every 2 seconds.
Here is the whole 30 minute ride shown in graph form.
My Turnigy still says at some point I went up to 16amps so I am guessing its for under two seconds as the table did not record any cell voltage below 3.15v which is 18.9v for a 6s pack or 37.8V for both packs. I know again from the Turnigy it goes down to 33V when a 16amp spike occurs. I will try it again decreasing the sample rate to below 1 second.
The cells all decrease in voltage at the same time and at the same rate. Presumably when I find one cell out of sync or with a consistantly lower voltage than the others, I will know there is a problem with it.
Interesting, geeky stuff
Regards
Jerry
This little device turned up and I used it on one of the 6s packs into work this morning. It records Voltage on each cell at intervals you set (this was set to 2 seconds) and then you can download them and use some software to analyse the results.
Here is a snapshot of the voltage table where you can see the voltage overall and of each cell every 2 seconds.
Here is the whole 30 minute ride shown in graph form.
My Turnigy still says at some point I went up to 16amps so I am guessing its for under two seconds as the table did not record any cell voltage below 3.15v which is 18.9v for a 6s pack or 37.8V for both packs. I know again from the Turnigy it goes down to 33V when a 16amp spike occurs. I will try it again decreasing the sample rate to below 1 second.
The cells all decrease in voltage at the same time and at the same rate. Presumably when I find one cell out of sync or with a consistantly lower voltage than the others, I will know there is a problem with it.
Interesting, geeky stuff
Regards
Jerry
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Jerry, these look the business! Much better than the LVC Chargery BMS I'm currently using. Think I'll order some...I really like the alarm o/p port I can use that to cut power via the brake switch when the pack or individual cell drops too low...
This is a very good thread on the RC Forums, simple cct to cut power....
Improved simple auto disconnector for battery charging/testing - RC Groups
This is a very good thread on the RC Forums, simple cct to cut power....
Improved simple auto disconnector for battery charging/testing - RC Groups
Yes NRG I saw that link when I was initially looking. Thats a neat solution. For the A123 cells I don't really need the cutout.
A CellLog 12s would be the business though. There is talk of them making one.
If you do order them you will be really surprised how small they are!
Regards
Jerry
A CellLog 12s would be the business though. There is talk of them making one.
If you do order them you will be really surprised how small they are!
Regards
Jerry
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Herb,
To work and back is about 10.25 miles.
I think I could just about do it. Today was my first trip on the Brompton and I did charge the pack at work. I put about 1.25 Ah back in at work and about 1 Ah in tonight when I got home. As I have not cycled to work for two weeks or so, I did use a lot of assistance
Although I think I could do it, Cambridge is pretty flat as I cycle across the city centre.
The general consensus is this pack is good for abput 6-8 miles depending on terain.
If I cycle tomorrow, I will give it a go without a charge mabe.
Regards
Jerry
To work and back is about 10.25 miles.
I think I could just about do it. Today was my first trip on the Brompton and I did charge the pack at work. I put about 1.25 Ah back in at work and about 1 Ah in tonight when I got home. As I have not cycled to work for two weeks or so, I did use a lot of assistance
Although I think I could do it, Cambridge is pretty flat as I cycle across the city centre.
The general consensus is this pack is good for abput 6-8 miles depending on terain.
If I cycle tomorrow, I will give it a go without a charge mabe.
Regards
Jerry
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Ok despite my puncture again today on the way to work, I will not charge the battery and see if it gets me home.
Either the battery will give out or I will get another punture
Regards
Jerry
Either the battery will give out or I will get another punture
Regards
Jerry
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WTF ??!!
Did you repair the tube with patches, or did you swap the tube for a brand new one ? Did you find the needle/screw/nail/whatever lodged in the tyre wall, when you cleaned the inside of the tyre before re-fitting ?
Cheers, Dan
(never had a puncture, ever...
)
Dan I updated my Damn Puncture thread.
Yes I removed the glass shard from tyre when I had the first puncture on Sunday.
Technically I had a third puncture as well when I put a repaired tube on today, though I think in both cased for the last two punctures I had actually trapped the tube.
I seem to recall someone else that trapped the tube a couple of times when they replaced their tyre
Regards
Jerry
Yes I removed the glass shard from tyre when I had the first puncture on Sunday.
Technically I had a third puncture as well when I put a repaired tube on today, though I think in both cased for the last two punctures I had actually trapped the tube.
I seem to recall someone else that trapped the tube a couple of times when they replaced their tyre
Regards
Jerry
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Who could that be ?I seem to recall someone else that trapped the tube a couple of times when they replaced their tyre
It is very hard indeed not to pierce the tube when dealing with a mega-hard stubborn tyre using brute-force and steel-reinforced levers ...
I just came home after not charging at work. Battery started to cut out at just under 1/4 a mile from home so 10 miles of usable batter power. If I wasn't so lazy and pedelled more I could easily make it last the last 1/4 of a mile
Voltage of each cell was 2.85v so 34.2v for both packs. I will update my battery thread.
I will charge it and report back on how many Ahrs I can queeze back in.
I came home early as I checked my tyre again after lunch and it was flat
Anyway I will post a picture on the other thread as at least now I know what was causing it!
Regards
Jerry
Voltage of each cell was 2.85v so 34.2v for both packs. I will update my battery thread.
I will charge it and report back on how many Ahrs I can queeze back in.
I came home early as I checked my tyre again after lunch and it was flat
Anyway I will post a picture on the other thread as at least now I know what was causing it!
Regards
Jerry
Man this is getting geeky
Anyway my cheap charger ended up putting in 2.128Ah back into the empty pack. The cells are as we know rated at 2.3Ah.
The cell voltages were up to 3.4v but whereas before there was a 300mv discrepency between cells before the charge, this had reduced to around 25mv after the charge indicating I assume that the cells had rebalanced themselves during the re-charge. This lines up with results reported on other froums about these type of cells.
There is also a view that fast charging the cells or warming them up first, allows you to put more charge into them.
Note the above process was not using the Turnigy charger/balancer.
PS even now 30mins after charging the discrepancy between voltages of each cell has gone down further to about 5mv. These cells are quite impressive.
Regards
Jerry
Anyway my cheap charger ended up putting in 2.128Ah back into the empty pack. The cells are as we know rated at 2.3Ah.
The cell voltages were up to 3.4v but whereas before there was a 300mv discrepency between cells before the charge, this had reduced to around 25mv after the charge indicating I assume that the cells had rebalanced themselves during the re-charge. This lines up with results reported on other froums about these type of cells.
There is also a view that fast charging the cells or warming them up first, allows you to put more charge into them.
Note the above process was not using the Turnigy charger/balancer.
PS even now 30mins after charging the discrepancy between voltages of each cell has gone down further to about 5mv. These cells are quite impressive.
Regards
Jerry
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Jerry,
Interesting figures, am I right in thinking the ebay charger charged the batteries to 2.128Ah when measured with your Watt meter and you are concerned that the figure should be nearer 2.23Ah.
Even more than 2.23Ah if you add in losses that are likely to occur – heat etc.
One possible explanation is that the battery was not fully discharged as the 34.2V is quite a high voltage for the low voltage cutoff to operate on the controller.
I am interested because I will have a similar situation in next couple of days when I charge and use my new A123 battery pack.
Herb
Interesting figures, am I right in thinking the ebay charger charged the batteries to 2.128Ah when measured with your Watt meter and you are concerned that the figure should be nearer 2.23Ah.
Even more than 2.23Ah if you add in losses that are likely to occur – heat etc.
One possible explanation is that the battery was not fully discharged as the 34.2V is quite a high voltage for the low voltage cutoff to operate on the controller.
I am interested because I will have a similar situation in next couple of days when I charge and use my new A123 battery pack.
Herb
Herb I am not worried its just an interesting observation
Your right this is what the Turnigy read after I charged it with my ebay charger.
I think I know why anyway. Although rated at 2.3Ah these cells vary between 2.1 and 2.3. The seller even states that in his auction. He tests them and sells the better ones, some as high as 2.35Ah for a little more.
As you said maybe they were not fully discharged though they seemed to be by the time I got home. I did notice that the pack had recovered slightly after I brought it in the house to recharge, its voltage having risen slightly to around 36v.
Next time I will charge each 6s pack seperately with the Turnigy and see how much charge it puts in.
Regards
Jerry
Your right this is what the Turnigy read after I charged it with my ebay charger.
I think I know why anyway. Although rated at 2.3Ah these cells vary between 2.1 and 2.3. The seller even states that in his auction. He tests them and sells the better ones, some as high as 2.35Ah for a little more.
As you said maybe they were not fully discharged though they seemed to be by the time I got home. I did notice that the pack had recovered slightly after I brought it in the house to recharge, its voltage having risen slightly to around 36v.
Next time I will charge each 6s pack seperately with the Turnigy and see how much charge it puts in.
Regards
Jerry
Yes that is what I did and posted in this post
Here we are talking about capacity. What I should have done perhaps was see how much capacity was taken out the battery before it ran out. Unfortunately I never had my Turnigy meter connected during the whole bike ride today.
Would have been interesting to see how close it was to the 2.128Ah I put back in.
Regards
Jerry
Here we are talking about capacity. What I should have done perhaps was see how much capacity was taken out the battery before it ran out. Unfortunately I never had my Turnigy meter connected during the whole bike ride today.
Would have been interesting to see how close it was to the 2.128Ah I put back in.
Regards
Jerry
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