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

shorza

shorza

10 kW
Joined
Oct 13, 2010
Messages
502
Location
Melbourne, Australia
Hi all,

I recently bought myself a Conhismotor 48v 500w rear hub motor. http://www.conhismotor.com/ProductShow.asp?id=95
and a 48v 10ah LiFePo4 battery in an aluminium case for discreetness and lock-ability. http://www.conhismotor.com/ProductShow.asp?id=43

Motor spins at jut over 60kph without load which i thought would be great. But I recently took the kit for a spin the other day, just to see how it would go, and I am a little disappointed. The bike was fairly slow off the mark, and didn't seem to have a lot of guts (torque). After about a ten minute ride, the motor seemed a little too warm for just a ten minute ride.

I am running this setup with a Lyen 12 Fet controller, so maybe I need to reprogram that to better accommodate my motor/battery? Maybe the battery is just too weak? Instantaneous Maximum Discharge Current is 30A and Maximum Continuous Discharge Current is 12A, could this be a problem?

Could anyone shed some light or offer some tips?
 
Do you know what your controller is programmed to? Sounds like the battery should be at 12 amps discharge, and trying to pull 30a for more than 15 seconds will just dog down the pack.
 
yeah, my guess is also that you're asking more out of the batteries than they can provide, and the result is serious voltage sag. Or you got your phase current ratio messed up ( ask someone else what this means, but i've read threads where it was a problem ).

Aren't those 12fet controllers usually set to like 35 amps draw minimum?? those cells are probably in the discharge range of say.. ping cells. Meaning you need to turn that down to 20amps, maybe less.

These are all guesses. You need a watt meter / cycle analyst / etc to get you some data..
 
Thanks for the info.
I'll lower the controller draw to 20a and see how that goes.
I am fairly new to programming controllers, and have no idea about changing the phase current ratio. I'll do a search on this forum.
I do have a CA also. Any info would be great.
 
If your CA is a direct plug in model, and you have the plug on your controller, you can control the amperage from the CA.

Normally people use a 1:2 or 1:3 ratio for the battery current to phase current ratio.
 
12amps, lol...
that's gonna be slow, let us know how it goes though :lol:
 
Well 12amps was a joke, I have since changed the battery current to 22amps and phase to 55amps and although it can reach 60kph free-wheeling, once i go for a ride it is gutless.
Is it possible that i have wired the hall/phase wires in the wrong sequence?
Can anyone offer a phase/current setting that would be optimum for my programmable controller?
 
First, double check every electrical connection (a "loose" connection could, of course, be the problem here).

While you're at it, can you give us an approximate over-all weight (bike + rider) of your setup?

Otherwise, I would suspect a weak battery cell (or 2) if the above issues check out to be O.K.
 
I have figured out that it was my "haltVoltage" setting being set too low. I was under the impression that this was a LVC setting, but it seems to be something else. Once i set it lower, the bike had plenty of power and wanted to take off. Thanks for your help.
 
G'day Shorza,

Glad you sorted your problem, and sorry to hijack your thread but I also have a battery from conhismotor that I have just started using, a 36v 12ah in aluminium case. Conhismotor advertises these as LiFePo4 but these cannot be that I believe, as cell voltages are 3.7 volts rather than the 3.3 or so you would expect from LiFePo4.

Also they are a lot smaller and lighter than LiFePo4. So these must be either LiMn or Lipo, I would like to find out which of these two just for safety reasons, ie if Lipo I might supervise the charge a bit more. No BMS evident inside the battery case, so must be wrapped up in the very compact battery pack. If Lipo must have some sort of voltage dividing or balancing circuitry in the BMS? Only +ve and -ve wires going into the battery from charging port so who knows..

If anyone can enlighten me on what chemistry these batteries might be, that would be much appreciated. The make is Tehao batteries from china, their website doesn't help with this information either, but seems they either make LiFePo4 or Lipo
 
Don't have any pictures with me, but the battery pack inside the aluminium case is pretty small for a 12ah 36v, there is quite a bit of leftover space, and no BMS visible, BMS must be wrapped up in the heatshrink over the pack inside the case. Cant count number of cells either, so cant be sure about cell voltage but hot off charger voltage is 42v, charger voltage is 42v, labelled 36v, sounds like 10 or 20 3.6V cells that charge to 4.2v, which would not suggest LiFePo4 at 3.4v, also so much smaller and lighter than what I believe LiFePo4 cells must be for this capacity. The whole pack including aluminium case is about 3.8kg.

This is the pack I bought http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=230479521603&ssPageName=STRK:MEWNX:IT

Says 10Ah, mine arrived with a 12Ah sticker on the case.
 
Hi magneto,
I too am skeptical about the "tehao power" battery being lifepo4. I wrote to Jason from conhismotor asking for more details of the manufacturer. I was told that they didn't speak english and to ask him the questions and he would answer them himself. I asked if the battery was lifepo4 and if I could add more cells.
This is the reply:

They are LiFePO4 but not in cylinder, they are in flat shape. And there is already no any space to put more cell inside Aluminium case. Because the Aluminium case is according to the cell, already maximal capacity. If you really need, you can buy more cell from us. Thanks

I have managed to take a peek at the cells and they were square and soft plastic. Tehao Power doesn't have a website but they have an Alibaba account so I guess I could ask them.

On a side note, my aluminum fast charger keeps turning itself on and off every 5 seconds, and it's only a few weeks old. I have written to conhismotor asking them to fix it, but I get a reply to buy a new one at a discounted price. But then says that the Aluminium case has a 1 year warranty. I'll keep you posted on how that ends up.
 
your charger may be turning on and off because one cell has reached HVC and the BMS is trying to stop you from overcharging it.

why would someone advertise a lifepo4 pack and sell you a lipo? and for that money.
 
That eBay auction says LiFePo at the top, but everything about the numbers says LiPo. 10s2p, cells 3.7V 5AH, Charge 42V, LVC 28v. Compare this with Ping's LiFePo 36v10AHr battery. 12s2p, charge 45v. And note the auction says nothing about cycle/life. If it really was LiFePo they'd be bragging about 1000-2000 cycle life.

That's not to say it isn't a bad pack. Just perhaps not the bargain it appears and not exactly as described.

Might be worth looking at these guys as an alternative. http://cgi.ebay.com/36v-10ah-lifepo4-lithium-battery-electric-bicycle-bike-/130380738008?pt=LH_DefaultDomain_0&hash=item1e5b4c2dd8#ht_3974wt_1139
 
dnmun said:
your charger may be turning on and off because one cell has reached HVC and the BMS is trying to stop you from overcharging it.
Click to expand...

I didn't think of that, although the charger even does this after a ride. I have a slow charger (2 amp) which doesn't do it.

I will try to take a photo today.
 
check the voltages on all the cells too, to see if some are high and some low. that will be a useful clue. the lipo goes into thermal runaway if you keep cranking on it with the charger over 4.2V. make sure there is some kinda BMS, maybe the O2 micro BMS? i know the O2 micro BMS has channels that go to 13S which would give them 48V with lipo. just a matter of programming it for lipo instead of lifepo4.
 
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