where to buy stronger bms

[guido]

after blowing 2 bmses in only a few hundred kilometers i think its time for something stronger than the ones i had , I need a 48 volt bms for a lifepo4 battery that can take at least 50 amps nominal and something like 100 amps max.
can anyone advise me on an online store that sells them seperately
thanks for the reply, really want to put some miles on that bike

 

[ohzee]

Well not to be jaded , but I am selling one of Lyen's BMS in the States at what I think is a very good price
that would meet your needs. My url also has the link to the specs if you would like to check them out.

I used both the one's I have for 2 test runs , but then took apart both batteries and made a 20s one so they
are no longer any use to me.

or you could hit up ping for one of his they have nice fancy lights.. I have a 20s one that I really like.

ping you need to email him as he does not advertise his BMS on his site pingping227@hotmail.com

http://www.endless-sphere.com/forums/viewtopic.php?f=9&t=40355 my sale thread

http://www.emissions-free.com/catalog/i12.html specs for the BMS

 

[dnmun]

what did you blow up on your BMSs? the output mosfets?

 

[dnmun]

tom had a BMS from BMS battery that looked powerful because it had a buncha mosfets on top.

you may be able to recover that BMS by replacing the output mosfets or just using the BMS for charging and bypass for power.

what kinda BMS is it and what happened?

 

[guido]

here is the story

ive bought a kit from eclipsebikes, its a cyclone 1200 watts motor, for power i have used 32 lifepo4 16 amp headway cells, 2 parralel and 16 sets serial with the use of one bms (33 amps continuous and 60 max) giving me 48 volts over 32 amps. The main reason for the high amps is that I need range, this bike is a commuter

what happend, I have quite steep hills to climb average 8 (upto 11) percent for distances of over 4 km , the bms just brakes down quick, now I am not into electronics but a few reasons come to mind

My own weight and the bikes weight together is around 130 kg (286 pounds) this might just be to great a load in the hills or/and
keeping the motor at 4500 rpm makes for a speed of 28 kph in first gear, but at these rpms I cannot aid the bike by peddaling myself because the rpms at the crank are just too high
I am still thinking that I need a bigger reduction between the motor and the crank to keep the amps down that I pull at optimal rpms for the motor (4500)
I have another post related to this problem: ``change ratio to avoid overheating``

for what brakes exactly: the first time one of the output mosfets, I tried to replace this one but that didnt help so something else died to. Now I must say that eclipse bikes then send me a bms at no cost, this one had minor damage and was usable after resoldering one connection, nice gesture on their part. however this one broke down as well but the source of the problem was not found, the mosfets appear ok and the repair I did myself held up as well.

my current plan: 1 a heavier BMS, 2 a bigger reduction between the motor and the crank, combined with a smaller reduction between crank and rear wheel to give me better peddaling cadence .........................and mounting cooling fins on the motor but that relates more to the other post.

thanks for the replies

 

[ProDigit]

Split up the battery into 2 separate modules. Connect them with 2 separate BMS'es. Otherwise try BMSbatteries.com.

 

[kentlim26]

for myself, i will set my gear to a max speed 45km/h , gearing 28t . i know cyclone motor can draw 2200watts, or 50amps plus from orginal cyclone controller. what i done i have change the slightly lower power controller to a 2100watts, 42amps. my vpower battery bms has been down too but i didn't order another Bms, i will watch my battery voltage not going below 50v will be just okay. my slight power controller is alot cheaper, i think more really reliable also. in my future i will run lipos with cyclone 55.5volts, 15cells , i will use a LVc alarm to watch battery cells

if you having a very steep hills, gearing must switch to 32t at rear sporket if is possible.

ken

 

[guido]

Split up the battery into 2 separate modules. Connect them with 2 separate BMS'es. Otherwise try BMSbatteries.com.

ProDigit, I was told that this was ''not done'' for risk of damage, or do you mean draining one battery and when voltage drops below minimum switching to the other battery?

 

[dnmun]

nope, you don't wanna do that.

you need to tell us what was 'braking' on the BMS.

did it shut off when the current passed a certain level and then you had to stop and disconnect the battery to get it going again?

did the BMS just not work again after it shut off?

do you have a picture of the BMS and how you have it set up with the battery pack?

can you put the pack on the charger under the BMS and measure the voltages of each of the cells while it is charging so we know something about your pack?

 

[ProDigit]

Split up the battery into 2 separate modules. Connect them with 2 separate BMS'es. Otherwise try BMSbatteries.com.

ProDigit, I was told that this was ''not done'' for risk of damage, or do you mean draining one battery and when voltage drops below minimum switching to the other battery?

There's no damage done, I'm currently doing this right now. The BMS will prevent one battery to charge the other until there's a 3V voltage difference,
Just make 2 batteries, and connect them in parallel, no switch involved.
It's perfectly safe, I'm currently running a setup like this for over 1,5 months now!

 

[guido]

what actually broke down is not clear to me
the first time it was the last mofet (visually overheated and after measuring resistance between all connections it was clear that this one was dead), this one I replaced but the bms didnt work after repairs, so something else broke down as well this is however not within my capabillities to find out.
second time was different, the mofets appear ok (measuring resistance between the connections gives same readings for each one of the mofets) but the bms doesnt work at all.
both times the bms did not work at all after shut off ( an hour later / next day no change)

set up is difficult to show in a foto its very compact, basically 2 16 amp headway cells parallel and 16 of these pairs serial, the bms is not connected incorrectly that is quite simpel i just followed instructions, and it does work for a while. However the pack is 48volts/32amps and i am told that cyclones can pull way more watts than the 1200 as mentioned on the motor, the bms is sold by eclipse for a picture go here: http://www.eclipsebikes.com/48v-bms-16-cell-60a-p-1042.html
this one takes 33 amps continuous over 60 amps max.

I have another problem probably related to my bmses breaking down, the motor overheats often, I cannot get from the village to my home in one go. Its a 1200 foot climb on tarmac at an average of 8 percent this combined with the total weight of the bike plus rider is a bit much, the system shuts down and after a wait I can go again

this is in my view a weakness of the system, when i run the motor at 4500 rpm I go at 27 kph in lowest gear but the cadence at the crank is way to fast to cycle at (over 120rpm) so I will put in a firm extra reduction between the motor and the crank, I will undo most of this by heavier gears between crank and rear wheel giving me better peddaling cadence. bassically i do not understand why the standard reduction between the motor and the crank is not a lot higher, mmmmmmh i just noticed that i am getting off my main issue......................

ffor a look at a picture go to post: change ratio to avoid overheating

thanks for the input so far, ill get me a heavy bms this week and give that a go

 

[dnmun]

did you measure the voltages of the cells while on the charger? did you find the high one that shuts off the charging? can you list them up here?

 

[ohzee]

From what I have read you can use 2 BMS's together you just need to have a diode between them. It's what I did for a while
then I took my cells apart and made a 20s battery.

Gl

 

[guido]

ok back in the saddle soon i hope,
I bought a 16S lyens bms, it came without explanation on the colors
this on has a slightly different setup from my other bmses
there are only 3 cables yellow,blue and black, and the leveling wires are all red exept for one black one
my thinking is: black leveling wire to negative connection on battery and then as usual between every neg/pos connection a wire, last red one on the positive of the pack.
for the cables: yellow to negative charger, blue to negative controller, black to negative battery pack
all positives straight on the positive connection of the battery pack (charger, controller)
AM I RIGHT?
on my other bmses it shows what to put where b-, c-,p- and there is a connection for the 3 positves also the sequence of the leveling wires was shown on a diagram, impossible to go wrong, with this one there is the possibility that i had to start with the black one on the positive side, or that i have to change black and blue.....

anyway if someone can tell me if my set up is right (or wrong) i would be real happy
thanks

 

[dnmun]

it seems like you do not know what you are doing yet so maybe you should take a moment.

from your very brief description of the 'braking down' i suspected that the pack is unbalanced and you are hitting LVC on one of the cells in the pack.

i had asked you originally to put the pack on the charger and measure the cell voltages, but we still do not have that info so there is no way to 'guess' the problem you are having.

since you don't even understand what the wires coming from the BMS do then you need to stop and learn how they work before destroying this one too. if you had balanced the pack then maybe the other one woulda worked.

tried to help but without any real info there is nothing to tell you. not even a picture.

 

[ohzee]

If you ask Lyen he will share a pdf doc showing what goes where on that BMS at least he did that for me.

I have dealt with 3 different BMS so far and 99% of the time they are the same.

Still I agree with the above poster - take a step back and just re validate what's going on in your situation.

 

[ProDigit]

Your motor overheating you can solve somewhat by applying coolingfans to the motor hub (like computer heat sinks).

You can also improve cooling by installing a more powerful motor. It seems like you're pushing the motor to the limit.
If you avail too many amps from the battery to the motor, the motor will grab them, and easier overheat. For instance, changing the battery to a 16Ah battery might solve the cooling issue, but might give you less torque, and thus less speed.

You can also work on the transmission. It is better to have the motor do many rpms, than get the same torque out of lower RPM's, as higher RPM's allow better cooling.

An unbalanced pack should give no problem while using power. If the one pack has a higher capacity than the other, a result could be that the first pack has a higher remaining voltage. When using power, the voltage will drop; and could drop below the voltage of the second pack. When that happens (say the first pack has 55V, the second only 50V (they're unbalanced), and the motor pulls the voltage down to 48V; then the first pack will be working harder, providing the majority of power, while the second will provide less power to the motor).

You just got to be careful not to have a too large voltage difference, as a BMS usually starts charging one battery from a few volts difference (if the voltage of both packs are within a few volts, eventhough both packs are technically 'unbalanced', they still won't harm each other, as the BMS protects the weaker battery).

 

[dnmun]

what a buncha claptrap.

the poor guy doesn't have a clue and you go pour all this stupid mumbo jumbo on his head and he has not the slightest chance of understanding how stupid it is.

you should be ashamed.

if you don't know what you are talking about then don't go confusing the people who need help.

 

[icecube57]

L M A O! AMEN! to Dnmum

 

[ProDigit]

Yeah, you're all lame ass liars!

 

[Kingfish]

Yeah, you're all lame ass liars!

Actually, I find telling the truth to be vastly more entertaining.

Please don't insult my friends: You are without a clue, and have no concept of who you are talking to, or what you are talking about. I suggest cracking open the books for a long deep read before coming back.

Thanks, KF

 

[Ypedal]

Ok, i'm showing up to the party late, been busy with life.

I get the feeling english is not the primary spoken language here from a few ( self included ) and is adding to the confusion.

First, Guido.... D is right here, we need to first insure the battery cells are in good condition before even applying or talking about the BMS at all.

This, requires a volt meter and some time, your headway cells being lifepo4 will have very similar voltages from full to near empty, specially when sitting without power flowing... fyi. expect 3.2v to 3.3v

I ASSUME your pack is made by assembling 2 cells in parallel ( 32ah ) .. and then series 16 of these for 48v. --- vs --- 2 x 16 cells alone, then in parallel ... right ?

---
2nd problem,

Motor overheating, yes, you need to do one or more of a few things,

- slow down, to a point where you can pedal with the motor ( yes, the motor rpm will be lower ) but use partial throttle to work together with your legs and see if the motor still overheats.

- Lower the voltage, use 36v instead of 48v, this will change the power curve of the motor, lower rpm, and heat produced by the motor in a not-efficient range. ( in a way, this is similar to changing gearing )

- Change gearing, so that your lowest gear is something like 10 kph, with options to gear up when on the level..... this is not always easy, or cheap to do, and depending on your frame, and chains, etc.. may not even be possible...

....

If the motor(s) is shutting down due to overheating, your setup is wrong..

sort all this out and THEN we can talk about BMS's. :wink:

0---

edit : oh, and also, get a cycle analyst or similar power meter you can see while you ride... this will help in a HUGE way in troubleshooting your problems .

 

[guido]

allright it has been a while but I am back

I have read all latest comments and understand some of your annoyance with someone like me, yes I can make anything that I can see (steel wood stone) - no I dont know much/anything about electronics, still thanks for all comments most were usefull and right now the bike runs fine, really

1 the overheating problem only occurred at full throttle for more than 4 minutes, I made a cooling ring with fans and that helped, really long periods at full throttle still end up in overheating, however at the speed I maintain right now I am fine. I also placed a 56 teeth sprocket on the crank connected to the motor and so improving the motor rpms in relation to bike speed.
2 the bms was installed as I thougt I should and it works great (at the time I just wondered a bit that my older bmses had 17 balancing wires and the lyens just 15 for a 16 cell battery) the battery pack is and was fine

current situation
I have equiped the bike with a secondary motor (one in the front wheel also 48 volts, a magic pie 3) working on the same battery, the bms does fine (bought stronger bms than I needed before the 2 motor setup), also at full throtlle. speeds are up and easier to maintain without overheating problems because I do not need full power to maintain the desired speed.

I have tried this setup with 2 twist throttles, it works fine but it is a bit of a hassle because I am left with a gripshift for the rear hub in the middle of the handlebar, so i wonder if 2 motors each with their own controller can be placed on 1 throttle, but this is just an extra thought, right now the bike functions as I hoped and has the power it needs.

I will post a pic, but only when the bike is completely finished, also from a visual point of view.
bye for now, guido