So are we going to piece something together, representative of the forums views? or just write in individually..........

 

I know we are probably split between pedelec and crank owner/users, but surely we all agree on the main issues.

 

maybe it is time to leave Europe

Wrong post replied to I think eddieo, I think you want the next one down

 

Jerry

Thanks Taisto,

 

What is a MMC box ?

 

Regards

 

Jerry

 

MMC box is an additional "controller" box to be connected between the battery, throttle, pedal sensor and normal motor controller. It's main use is to make throttle legal in most European countries if you use elfkw ebike kit (not available for other makes, at least at the moment). It just detects when you pedal and the throttle operates only at those periods of time. Of course some motor controllers have this feature built-in without need for any additional electronics.

 

You see, at least here in Finland ebike motor can only operate legally in the same time you pedal. Otherwise your ebike is considered as electric moped and you have to go through expensive type registration process etc. and it costs several thousand euros on top of the fine police gives you.

 

That is something I don't want although I have to admit it is a very unlikely to happen.

 

Sorry for my tangled english but hope you get what I mean.

 

Regards

 

Taisto

They are larger than I expected. I am use to using Sub C cells for my RC models here is a comparison of the two. The Sub C cell is a 3000 mAh NiMh cell. In fact I had thought of using NiMh cells in 3 packs of 12v connected in series. The problem is they are heavier and I would probably have to charge all three packs seperately. They do however go up to I think 4600mAh now so it certainly worth thinking about.

 

 

 

 

 

Just saw these on ebay from a UK based supplier and wonder if they could do the job?

 

4600mAh SubC SC NiMH rechargeable with tab Vapextech on eBay (end time 18-Jan-10 09:52:10 GMT)

I don't see why they wouldn't work as they seem to be able to cope with 30amps draw.

 

You would need 33 cells to match the 39.6v of the A123 pack in this thread. Two of my packs would give you about the same capacity and you would need 24 cells which would work out cheaper.

 

For charging the NiMh cells in a 33 cell pack you would need a dedicated charger capable of detecting temp change i.e. you would need to incorporate a thermister into your pack.

 

The alternative is to buy 3 of their 12v packs but again that would only give you 36v in series. You could then charge the three packs seperately without a thermistor, like we do in the RC environment, but you would have the hassle associated with splitting them up everytime to charge and the charger would probably be more expensive than the ebay one I am using here to charge the A123 packs in their series form.

 

Horses for courses really. I thought about it, but the A123s offer a better, simpler and more managable solution in my opinion.

 

Regards

 

Jerry

Edited January 11, 201016 yr by jerrysimon

There's a big condensator in the controller, which charges-up when you plug the battery or when you use the switch to let the current flow. This may induce high Amps for a limited time, thus the reading picked-up by the power meter. My Cycle Analyst registers a peak Amps value that is higher than what I see when I climb the most serious hill...so it must be related. I read that some high-power applications require the use of a MOSFET in addition to a regular physical switch, to avoid the high-amp spark when connecting the battery.

 

 

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

 

http://daniel.weck.free.fr/BromptonBafangTongxin/MOSFET_Anti-Spark_Switch.png

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.

 

http://farm5.static.flickr.com/4063/4284852754_bbf1e63f61_o.jpg

 

 

 

Here is the whole 30 minute ride shown in graph form.

 

http://farm3.static.flickr.com/2796/4284107111_94f452b3d5_o.jpg

 

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

Edited January 18, 201016 yr by jerrysimon

That's very geeky indeed

Useful too.

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

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

Edited January 18, 201016 yr by jerrysimon

Jerry, can you get to work and back on one battery charge ?

 

Herb

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 :o

 

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

Edited January 18, 201016 yr by jerrysimon

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

Edited January 19, 201016 yr by jerrysimon

Ok despite my puncture again today

 

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

Edited January 19, 201016 yr by jerrysimon

I seem to recall someone else that trapped the tube a couple of times when they replaced their tyre

 

Who could that be ?

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 ...

Yep, did that on my Peugeot, blamed the cheap Chinese inner tube but LBS showed me where I'd pinched it fitting the Marathons.... :o

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

Man this is getting geeky :o

 

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

Edited January 19, 201016 yr by jerrysimon

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

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

Its the voltage under load you need to observe not the resting voltage.

Its the voltage under load you need to observe not the resting voltage.

 

Good point.

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

NRG, have just looked again at your battery setup, Impressive. What sort of range do you obtain from your 5ah battery pack ?

 

I would also be interested if you have you carried out any tests to compare the actual charge with the battery capacity?

 

Herb