Oh yeah, what do you think of this: http://www.hobbyking.com/hobbyking/s...edic_System_6S - at $24.00 it seems like a steal

Wow, I've never seen that. Yeah, that's very nice. Also, I think that battery medic got good reviews, too.

Well, day two of constantly watching these things charge and I seem to have one "problem child." One cell just will not charge past 3.36 volts, no matter what I try. I guess I better troll the posts and see if anyone has seen something similar.

strange. Do you have a single cell charger? If it indeed is a bad one, the warranty should cover that.

Yes, that's what I've been doing. It seems that the output is so low that it takes a long time to charge from 3.36 to 3.38v, after they hit 3.55v they charge fairly fast. It's the waiting methinks.... Took me some time to get it right...

I have 3 cells at 3.74, one at 3.36, then it gets a little wierd - I had hooked the 36v charger up (after an initial charge and waiting, watching the cell voltages drop to around 3.43v or so) and the two end cells peaked at 4.2v as I caught it. I was a little nervous for a while and now they have stabilized at 3.75 and 3.8v....

I had intended to stop at 3.65, but went a bit higher to match the two I almost cooked.

Also thinking I'm going to place those aluminum plates under the velcro straps for extra protection one the sides of each pack.

That's why I recommend people use the 12v black and decker because it tapers off the current once it gets close to fully charged so you don't get the voltage spike. I don't have that charger so I don't know what it's like but a friend of mine who has it says it almost destroyed his batteries too and he caught it just in time. It sounds like that charger doesn't taper off the current.

When you charged all the batteries, do you know what the total overall charge was? I think the highest I've ever had mine up to was about 42.99v on the 12 cells. I think the highest they say you can take it is up to about 43.7v.

Well, it's finally done. All cells 3.65v except the two that had the lowest charge. 43.6v total. I expect that to drop and settle overnight.

I used the trick of connecting the ones with the highest charge to the lowest cell in parallel (and waited) and then used the 36v charger, placing the two weakest cells where the two overcharged ones had been. The weakest still took over 3 hours to top up after the second go, and it's finally holding at 3.65 (I hope)...

I took the aluminum, riveted it and placed it against the cells (strapped) and then wrapped high density foam (the kind in the Pelikan cases) around those packs. The results are below:

http://bikeforums.net/attachment.php...hmentid=143983

One thing about the cells and the charger I used - don't do it unless you are willing to babysit the cells. One they charge, the voltage on the charger increases (and I'm not sure it has a cutoff). I'm trying to find the chip maker that it's based on, but I can't read it (surprise). Either way, I measured the voltage without a battery load to charge and it hit about 6.34v, enough to cause a loud explosion and epic fire as they are all going to go at once. I have decided to name my bike "Pinto" because if I ever get rear-ended, the fireball will be spectacular.

Anyways, there definitely is a curve, and it's long up until the cells hit about 3.5v and then it's every 5 minutes, after 3.6, I monitored them every 30 seconds or so and at 3.70 max, I shut it down. You get used to mentally measuring how long till the next check. The voltage always drops and if I anticipate how much it will drop, balancing the cells becomes an hour of intense measure-move sequences.

It took me about 43 total hours to complete. I wish I had that balancing charger...

If you plan on continuing to use that charger, you'll probably need a BMS. The reason the Black and decker works is because it only charges to about 98 % of the battery capacity which means you have some room for error. Read the other thread "looking for recommendation" if you haven't already. I just don't want to see any of your cells damaged. You could probably make your current configuration work with a cheap BMS like this:

http://www.hightekbikes.com/BMS.html

Or getting rid of that charger and getting a different one.

The overall plan for a BMS was to acquire it just after the balancing charger and just before the 40AH cells. There is an extensive thread in the endless-sphere forums from a couple of people working on an expandable BMS , and I see they are getting close to being able to sell the kits. Link here: http://www.endless-sphere.com/forums...416&start=1710

The main motivator was price and the ability to put it together myself and "tweak" it if I have to. I had hoped to set up a quick-connect to allow me to use it with either the 20AH battery or the 40AH battery by using some sort of connector system. It'll be a wiring mess at the top of the battery with the charger leads and BMS leads. I'd like to mount it on the back rack and have the LEDs function as taillights for the bike as well.

I did look at other BMS, and there are two fairly interesting "bolt on" solutions for the Thundersky cells as well as several others that look quite good, but I'm drawn to anything that requires I learn how to repair/troubleshoot. I believe in being able to fully repair and maintain anything like this so I don't have to rely on anyone else if things go south during a long trip.

Until I get it, I'll be carrying my multimeter and chargers with me everywhere. I'm pretty sure that as long as I don't use regen a lot until the BMS is installed that I will only have to make sure I don't discharge the cells too much between charging/balancing cycles. I'm also hoping that as long as I balance the cells during home-charges that I can use the 36v charger in the field to get me where I need to go.

Since the snow is just off the ground here, I intend to be doing short trips to test AH usage and charging behaviour during the day. The upcoming long weekend holds a lot of promise for a few day rides. The washer (last part I needed) just arrived in the mail, but I was up too late topping the battery off and I need sleep.

I think that charger that you have charges to almost 100 % so be careful. What you could do, is buy two of these

http://hobbyking.com/hobbyking/store...itor_2-8S_Lipo

That'd be only about $35 total and that would solve your BMS problems. You could charge the batteries about 10 ft away from where ever you are in the house and then you could just listen for the alarm and if the alarm goes off then that means one of your cells is about to over charge. It has a low voltage alarm and an over voltage alarm and you can manually set it. So you could set it for like 3.8v and then if it hits that, run into the room and stop the charging and then if you wanted to top-off some of the other cells, use a single cell charger for the others. I don't know how loud the alarm is though.

I have just been reading your thread and just had to make a few comments. Please understand I have 4 of the TS pack that you have and everything I say is just my opinion but it is based on a lot of personal exp. and reading. But mine are setup as 2 24v packs. First off that charger you have that came with your TS packs is crap. I found that out the first day I used it and set it back to Elite for a full refund including my shipping cost. They cried but I canceled the credit card payment until they agreed. Secondly don't believe that BS about 4.2v. The full charge is 3.65 to 3.7v and the normal settle voltage is 3.2v. And they should never discharge below 2.7 to 2.8v. Third, if you are looking at spending $140 on a new charger then why not but 12 2a individual chargers @ $10.95 each =$131.40 . They will do a much better job and you don't need a BMS. Forth, The cell monitor is nice because it can monitor 12 cells with 2 units. But you can also do that with the CellLog 8 also sold at HobbyKing and it's only $14.95 eack for the non-downloadable model.

https://p10.secure.hostingprod.com/@...cdb0cff62a9ebe

http://www.hobbycity.com/hobbycity/s...dProduct=10952

Unfortunately, I went for a 36 volt system so pairing them into two 24v packs would work, but then I'd have to rethink the BMS and how I carry the batteries. The chargers are an okay idea, but when I'm travelling, I'd ride as far as I can, charge, ride more to get to a campsite - the balancing charger I have on order will charge to any specified voltage at 2A and many cell types. The charge is 3 hours at 6A, so 2A basically limits my day (taking 9 hours). It is worth considering, but also the 2 6 cell packs I have barely fit in the panniers now - for city riding.

I do agree that charger bites. It'll do in a pinch tho, and now that the cells are balanced, I'm hoping it doesn't take things too far out of whack the next full charge. I'm liking the 3 * 12V charger idea Morph has, but bulk might be an issue with camping gear and all. I'll have to see how the trailer and 40AH batteries work out.

My choices were all about size, weight, bulk and finally economy. I'm not afraid to spend money, I just don't want to waste money by buying something and then having to replace it.

I also agree with almost all your cell observations, but my cells are holding at 3.60 volts, and other than one time have never exceeded 3.75v.

I think you misunderstood what I was telling you. I said "I have 2 24v packs" I was not recommending that you should have 2 24v packs. I understand that you need 1 36v pack. What I was trying to terll you is you can have a 36v pack (3 12v packs in series) but charge them all at the same time with a 12v charger in parallel. And to do this you just need to make a special plug using Anderson connectors. If you did this it would only take a few seconds to change from "riding mode with series connection" to "charging mode with a parallel connection". And with a second plug you could even charge is series if you wanted. It's the best of all worlds. This setup works with 24v, 36, 48v or any voltage you want. And it would have a fuse in the series connections while your riding too.

Ah, clarity, I apologize.

The choice of the six cell packs made it easier to fit into the panniers as well as wire for the balancing charger and battery medic. I think after all of this, it might have been better to go the same way you suggest (and Morph does).

Took the bike down to the local bike shop as I promised the owner for a test - blew the 20A fuse before I got out of the driveway, but I had anticipated that and replaced it with a 30A. I went about 6 blocks as fast as allowed by law (disappointing - I've been faster pedalling) and got it home. Lugging the bike up and down the stairs with the packs mounted was a lot of fun (not doing it that way again)

When I got back, the cells were back to 3.36v, the Cycle Analyst said I had used .5AH - not sure if this is normal but there was 1 block killer hill and there is a lot of weight, so.... This is something I am going to have to qualify with a longer ride on the weekend.

I realize LiFePO4 cells have a flat voltage they stay at for a long time, and I'm thinking 3.36v is it, no matter what voltage I charge the packs to.

Hooked the 36v charger up and it ran about 20 minutes while I watched the cells. After it was done, all the cells except my "problem child" were perfect 3.65v and the low one was 3.54v... So there definitely is a benefit to starting with a balanced pack.

Yep, 3.36v is about right. You only went .5 AH ? You must have a pretty efficient setup. I go around the block and I use at least 1.5 AH but I have a huge motor and I weigh about 267 lbs.

3.54v Oh that's okay. 3.54v isn't too far off. The cells settle down after charging to something like 3.55v . Yeah, most people run into trouble in the beginning by bulk charging a pack that isn't top balanced. I don't even check the voltages on mine anymore. Maybe once or twice a month, I'll check them. I know the charger is safe and that's all I care about.

Well, I had a whole nother post yesterday that got eaten by trying to send it while the forums were down. My "lost" response was simply pointing out that charging the packs in parallel with a 12v charger would take me about 6 hours, but would be safer. I'm pretty sure you could charge up to 40A, but I have yet to see a LiFePO charger that handles that (12V 20A+), they all are single cell or 24v+ for some stupid reason.

I checked the supplier website and the discharge curve is right there - plainly showing everything. It's not really worth trying to get the cells up to 3.65v except as an indication that they are all at the same state really.

The usage was .437AH for .59mi which is pretty normal - about 1AH for about a mile without pedalling. It just didn't seem that far a distance.

Have to rip the bike apart today. Fenders are too close to the tires, seat is way too low and my heels keep hitting the panniers when I pedal.

That could be. I don't know. I think 3.65v is just an indication that the battery is near full. When the battery reaches near full capacity, the voltage increases considerably faster as you see on the discharge curve. I get mine to near full just to be on the safe side. I think another user is using his batteries for a lawn mower and he just charges his just enough to use it.

Did much better on this try - pulled everything apart and rebuilt it all, decided to go for a ride since it was sunny. Got 32km (20mi) and used 10.8Ah. I wasn't pedalling much - chain has a stiff link that I was trying to work out

Good thing I tied the panniers together - they came off the rack about 4 times, but at least they did't do much but hang a little lower. Guess I need a better system than the plastic clips they use.

Response on the bike was much better and I actually figured out how to use the regen. 4.8% regen - it's great for slowing you down on hills and stoplights. Sure was nice blowing by that other biker on a long uphill stretch - still sitting.

Took it for another spin today, I have to say my choice of the 26X1.95 Tioga City Slickers was well made, they handle the weight well and there's less rolling resistance. Replaced the faulty link in the chain and it worked like a champ. I'd say it's a pretty efficient setup.

I've been scouting bike routes out of the city, and it appears I also struck paydirt there as well (after a lot of riding). I only hit one pothole and had to reseat the panniers only once. Of course, it was a bit of a problem staying to the speed limit on the bike trails, so I've decided to stay off them and stay on the road. I'm still pretty cautious, but the drivers that use the bike-friendly routes seem to be pretty savvy.

Total usage: 13.28Ah, Distance: 39.84km (25 mi), moderate pedalling (except on the 3 major uphills, I still stayed seated) and regen rate 10.4% (1.385 aH).. I was a little worried about the LVC cutoff as I approached home - the voltage on the pack was reading pretty low. I think I'm going to have to tweak that.

This bike has really proven out.

do you remember what the voltage was reading? At 13 AH, you should still have quite a bit more to use as long as you are using a LVC or some kind of monitor.

It was bouncing, the lowest was about 33.8v, it would stabilize at about 35.5v

are you using a LVC or a monitor of some kind like the celllog 8 ? If not, I wouldn't take it below 36v . I don't remember if you said you were using one or not. If you get a monitor, you can use a lot more of the battery.

Did you end up getting a 35 amp controller? That's what I have too. Do you know what the max amp peak is on that? Max amp peak on mine is 43 amps. The cycle analyst should tell you what it was at the end of the run. The Thundersky do fine with anything up to 2C which is about 40 amps.

Currently just using the LVC, Battery Medic should arrive shortly, but overall I'll be counting on a BMS.

Yes, I'm running the Infineon 35A controller, never thought to check the peak draw, but I've limited it to 30A via the Cycle Analyst. 40A would be good for very long nasty hills, especially if I'm carrying a trailer. Hmmm...