Conhismotor 48v 10ah LiFePo4 (LiMn2O4) in aluminium case

[shorza]

Thanks for the pics, the bike looks amazing. Quality parts and great finish.
I appreciate the info on the freewheel too, I thought it would be as simple as pulling them all off, taking the large gear off and putting a smaller toothed gear on the other side. Maybe not. The current smallest gear is a 14 tooth i think, which sucks at top speed, but good if I hit a hill and need the extra power.

My frame is good, not great, just good. It feels very strong, light but you can tell it's direct from China. The paint chips easily and i can feel the frame flex when i pull the rear brake. It's not a major issue as it still has stopping power, especially with the front disc and controller regen.

I was going to buy this one: http://au.alibaba.com/product/339724753-Mountain-Electric-Bike-with-7-speed.html. Although the cost was slightly cheaper, I liked the service of the guy I got mine from.
If anyone is interested in buying from this guy, here is the price he quoted my:
Frame-USD70
Front wheel-USD25
Brake(disc and v brake)-USD12
Front fork(ZOOM)-USD20
Saddle(Velo)-USD9
Chain-USD2
Derailleur(Shimano tourney 6 speed gears)-USD13.
So the total cost is USD151,and air freight cost is USD159.
= US$310 obviously without the motor, controller, battery and electrics.

I would like to make a battery box to fit 12s-16s lipo packs purely for the extra current, but that can wait untill my current battery dies.

 

[Magneto]

I like the sound of the speed you are getting from your setup, that is way faster than my 30 klics..

I figure I might try and run a 48V after this battery gives up the ghost, and probably upgrade to a 12 fet controller as well to handle a few more herbs.

Yeah these freewheels if you look at them, have the freewheeling unit itself external to the hub, so the smallest cog you can get for this variety is 13T, which I currently have. So you need to go to a whole new freewheel for the 12T or 11T. But that is not such a bad thing, as they do wear out, depending on how clean you keep your chain, over some several thousand k's, although would be getting a lot less wear with the motor onboard..

Even then I think many freewheels cannot be easily taken apart, but some will allow you to change the smallest 1 or two gears easily.

Going to 13T woudl be easy for you but if you want a real shift in gearing, you should go for the 11T and up the front chainring to 50 plus teeth I reckon. Does your front crakset have interchangeable chainrings?

 

[shorza]

I also have a 36V kit that was my first make, much more happier with 48V
The explanation of the freewheel makes sense, I think i'll just leave it as is. I don't think I need any more speed, it'll just help the battery. Considering work is only 4km each way, it's not a major issue.
My front crankset only has one (fixed) chainring, so I think it'll be more trouble than it's worth.

On another note, it seems Conhismotor has gone suddenly quiet. I was chasing them for a new charger after the 5amp aluminium case they sold me broke within 5 charges. They said that since the battery they sold as LiFePo4 is actually LiMn2O4, the charger they sold is also the wrong type. They said they would send me another, but have since gone quiet.

How are you charging your battery? I have a 2amp charger that seems to work, but I don't want to overcharge it.

 

[jbond]

See also this German site
http://www.ebike-solutions.de/epages/62204758.sf/de_DE/?ObjectPath=/Shops/62204758/Categories/Schraubkr%C3%A4nze
7 speed 11-30, 7 speed 11-32

 

[dnmun]

if you are charging that pack with the BMS still faced up against the pouches inside the aluminum case, that will be a problem so you need to figure out how to get the BMS out of there where it can run cool and not overheat the pouches next to it.

did you measure the output voltage of the 5A charger before it blew up and was it the same as the 2A charger?

did you open up the dead charger yet and take pictures?

 

[shorza]

Yes, the voltages are the same.
Thanks for the advice, I'll see if I can turn the bms around. I'll also open the charger and post pics here. I was more worried about the charger being a lifepo4 charger and the battery not.

 

[dnmun]

when balancing, the shunt resistors can produce a lot of heat. so it needs to be somewhere else. that was just a bad design but i bet there are millions like it. the chinese designer did not think of that, just how to make it cheap and pretty on the outside. that's what sells.

if you were able to get the 41.5V needed, and they won't take the charger back we can try to fix it here.

 

[Magneto]

Is it possible that the bms in these is not a bleeding type balancer and instead tops up the low cells?
Also, If those surface mount resistors are the balancing resistors, then I don't think they could dissipate enough heat to worry the cells, especially if there is a small insulated barrier between it and the cells.

That said, my last bms In the battery I had before this one (different make) desoldered the charging fet by itself somehow, not sure why it got so hot..

 

[shorza]

Hmm, the fast charger seems to be working now. The battery has has about 2.5ah taken out of it, I think it still had over 50v left in it. Maybe the charger's output of 54.6v is higher than the battery's HVC, hence the charger stopping and starting every 5 seconds when the battery's HVC gets triggered. I'll monitor it and stop charging once the charger starts cutting in and out.

Regarding the shunt resistor/FETs, i will have to open the case up and see if i can move the BMS or at least put some extra barriers between it and the cells. I'm not looking forward to it as it can take a while, but better to be safe than sorry i guess.

Magneto, how are you charging your battery?

 

[shorza]

Conhismotor is either on holiday (Chinese New Year), or realised that my Paypal dispute has been cancelled, due to it being opened over 45 days from purchase, and is ignoring me.

I'm starting to think the latter.

 

[dnmun]

the HVC is cell level and the total voltage has nothing to do with it. been trying for awhile to get you to measure the cell voltages while charging to see if we can tell, watching the output voltage does nothing for you. long thread already. still no clue.

 

[Magneto]

Glad to hear the charger is working now, maybe it was just fully charged before? I'm using the 2a 42v charger it came with, plastic case, built in speed controlled fan, for my charge at work. For home using the one that came with the Greenewheels bike, which ISA nice quality 3a aluminum case unit with fan. Seems the one at work ramps down current towards the end, or at least fanspeed slows down, and charge indicator light starts to show more purple than red as charging ends and light goes to 100% purple. The 3a one just shuts off completely when finished, but have not attached current meters to have a closer look at either.

Both measure 41.9v which for this battery being 10s, is 4.19v per bank, the correctchargjng voltage for lithium ion. I still think these are liMnNiCo by the way, too light and small for for limn204 IMO.

Another charger I have, 2a 42v no fan given to me by another Greenewheels rider, does not cut out at the end of charge but just cycles on and off as you describe yours to do, maybe thats how it operates..? Might have a relay that shuts voltage off to battery input that causes bms to accept charge again after one bank hits hvc, and repeats the cycle.

 

[shorza]

Sorry dnmun, I didn't realise you were asking me to measure each cell while charging. How exactly do I do that, considering each cell is connected to two others in a bank? I'll do it this week along with moving the bms.

Magneto, interesting. I'll have to look into the limnnico batteries, pros, cons and dangers.

I do appreciate the info guys, cheers.

 

[Magneto]

You'd have to desolder each cell from it's bank of three to measure individual voltages. To measure each while charging you would need to attach charging wires for each bank to each disconnected cell. Not worth busting up your pack to do this.

There are many of these batteries out there, very popular on small folding ebikes, I think if they had a tendancy to spontaneously combust, the manufacturer probably would have done something about it. The only heat I would be worried about is from the fets on-board, for drive lvc cutout and charge hvc. If these are on the other side of the board to battery, less of a concern.

That is not to say a malfunction mat cause a lot of heat, none of these units include a fdrive side or charging fuse from my experience.

My last BMS as mentioned before desoldered the charging FET with it's own heat, not sure why that happened. If these were Lithium Ion Cobalt Lipos, then I woudl be worried, as they are the most volatile. Then again these are in almost all mobile phones and we dont hear of too many meltdowns for those.

I am happy to leave the BMS in place, personal choice I guess.

 

[shorza]

I think i'll just leave the BMS as is. It's more hassle than it's worth (I hope) and from what i remember, there was a thick board of plastic between it and the cells. I definitely wont be de-soldering anything, as you said, not worth busting it up.

Finally got another email:

Dear Chris,

Sorry for the late reply, because from 25th China begin to enter New Year Holiday. So our reply is late due to this. We already ordered the 5A Fast Charger and after our holiday we will send you.
Please don't worry we have your address, we already wrote your charger on our noteboard, and when we come back we will see it immediately and never forget it.
The difference of the charger is the cut-off voltage. The correct charger we will send you is about 54.6V.
Yes, it is correct, it is with 13 series and 2 parallel. Because we use 5AH single cell. So it is 13*2=26 cells.
The rated discharge Current is 20A. Thanks.
We will send you immediately after we come back in about one week.

best regards
Jason


It seems he still doesn't know exactly what he's selling. The cells are definitely 13*3=39. I would love to know the cells he is using.

 

[Magneto]

Sounds like a better explanation of what is happening, would be like trying to do business over christmas here.

Didn't your last charger measure 54.6V?

In any case this new one should work for you hopefully. My batt is still going well touch wood, at least 10 commutes so far.

Just received my 11T to 34T DNP Epoch freewheel cluster, and it looks neat. Will hopefully be installing this baby soon. I will be able to look like I'm pedaling at a much easier pace now...!

 

[shorza]

Yes both my current chargers measure 54.6v, so i'm not sure what the difference is, but hopefully it works.

Let me know about the cluster.

 

[Magneto]

Didn't manage to find the time to install the freewheel cluster, may be a weekend job, as have to take out the controller out of it's very cramped housing under the battery and that takes forever to get back in. Have to take off the motor plug to thread the new freewheel over it. Being a 7 speed, it's wider by one gear, 6 or 7 speed have same gear spacing effectively. Will mean I move an axle spacer to the outside from the inside to fit the extra width, plus will need about 3mm of washers or spacer tube to increase current spacer tube length to prevent the extra gear fouling the frame. Should be no big deal I think.

Most 6 speed deralieurs can be tuned to 7 speed (they are usually made for 6 or 7) and I have a new 7 speed Shimano 'Tourney' shifter to match.

With my current 53T chainring and smallest cog 13T and 26 inch wheel with 1.75 inch wide tyre, I am pedalling flat out at 55km/hr and it's too fast to be sustainable, with 53T and 11T should allow me to comfortabley spin at 55kays to 60kays and peak up to 70 I estimate (downhill of course..)

 

[shorza]

At least you can fit the controller under the battery. Mine is in the narrow space between the battery and rear wheel. I tried to keep it all neat.




Last night I put Lyen's DC to DC converter in the space below the battery and ran 4 volts up to a Dealextreme torch http://www.dealextreme.com/p/c30-fl...0-lumen-led-flashlight-with-strap-3-aaa-18697. I am very happy with the way it's turned out. I haven't checked it at night yet, and i'm sure it wont be better than the Magicshine's that people are putting on, but this cost me under $30 and is very neat and bright.




Also since Conhismotor has said the the rated discharge current is 20A, I have changed the setting on my Cycle Analyst to 18A. Much quicker off the mark, but it also heats up now.

 

[Magneto]

The bike looks awesome, frame very neat and welds look pretty good. Looks stronger than mine actually but would depend on wall thickness of tubing I guess.

Would love a cycle analyst like that, my controller doesn't have an output and cant be bothered running drive wires all the way to the handlebars, will get one eventually though.

Yeah the only way of fitting a controller under the batt is having a 6 fet one which is no good for your setup at all, in fact I will probably go down this path of a 12 fet and mounting it behind the batt llike you have, looks pretty neat actually.

The light looks decent and good value at that price

I bought a kickrse 10W LED 900 lumen light that can run on anything from 9v to 60v, wired straight into the loom on the bike using existing switch for headlight. Very expensive though at around $150 but military/mining grade housing, waterproof to 3Metres. Lights up the road like two 55w halogens, and transformed my winter night riding. Visionx Solstice I think is the name. Still only draws 10W no matter what voltage you run it on so must have a good DC/DC converter inside. Other riders have told me off for having it pointing too far up in full sunlight. I run it all the time for safety, because LED's last for so long and so much power available in our batteries I recommend this, makes a big difference getting yourself noticed on the road during the day.

 

[shorza]

Why do you say that the 6 FET wouldn't be good for my setup?

My light is no way close to that VisionX Solstice. I just youtube'd it, and they look awesome. I would complain too, those things look BRIGHT! Do they heat up?
I guess I'm happy with my setup for the price, if i find that it's not strong enough, I'll definitely look into these.

 

[Magneto]

The 6 fet designs are usually only good for about 250 to 350W, whereas your 12 fet will efficiently pump through much more power. I can get away with the 6 fet running 36V and a less powerful motor, that said mine would probably be more torquey with more Fets. But then I might start stripping gears in my geared motor, so 12 fets better for gearless direct drives like your one there.

Solstice does heat up, solid heavy alluminium case acts as a heatsink. It is bright, you cant look at it even 10 metres away.. I usually run with it pointing down a bit at the road but pull it up in dangerous situations like freaky intersections etc. Draws a genuine 10W at any voltage, ie. about 780mA at 12v or 250mA at 40v. Reading the latest specs on it now, it seems they have dropped may operating voltage to 50v, used to be 9 to 60v. An in line resistor of the right wattage and value woudl easily drop your 54v hot off the charger to something just under 50 if you ever wanted to install one of these.

The main benefit for me was being able to continue riding at full speed on the commute home in the dark in the winter, where before I had to slow down with my 1W LED because I couldn't see the path/road ahead properly.

 

[shorza]

Great info, thanks.

 

[Magneto]

Regarding the battery chemistry discussion, just had another look at this page:

http://www.elationebikes.com.au/Batteries.htm

The chart 1/3 the way down has some interesting info, although as I mentioned before, they are heavily pro LiFePo4 so they are biasing towards those with frightening claims of fire and explosion for the other Li chemistries. Pays to remember that pretty much all cell phone and laptop batteries are not LiFePo4, and are one of these other Li chemistries and we don't hear about too many accidents with these.

If you look at

Energy density (Wh/kg)
LiCoO2 180
LiMn2O4 100
Li(NiCoMn)O2 170
LiFePO4 130

This would point towards our batteries as discussed being NOT LiMn2O4 as they are quite heavy for a given capacity, and these batteries we have very light.

My last one was much heavier 1.5km heavier in fact, almost 50% I think and it was a LiMn2O4 I believe. It also only lasted 200 charges.

That leaves LiCoO2 and Li(NiCoMn)O2.

If you look at the voltage table, the Li(NiCoMn)O2 has a working voltage of 3.6 volts, that also matches our cells. LiMn2O4 is 3.8V which does not fit with my 10s 36v battery.

Thsi is not to say that conhis is wrong about them being LiMn2O4 but it does look that way to me.

 

[shorza]

Who knows what Conhis is selling, even Conhis doesn't know.

That site is very biased, but it is hard to find reliable information on Li(NiCoMn)O2. This site does a bit of comparing: http://www.xcgdbattery.com/cp_look1.php?typeid=1&id1=65. Googling Li(NiCoMn)O2 just seems to bring up Alibaba sites.