elle

firstly-----thanks to all the people who helped me with the previous post.....

new problem

what i have - 800W motor, 15amp lifepo4 battery, 48volt, not sure what the rating is on the controller.
circuit breaker - 30amp, 60 volts - trip is 40.5amp... circuit breaker is between the battery and the controller

everything is going incredibly well - extreamly happy with an ebike - hills are no problem.

what's happening - when the battery is fully charged, no problem....
didn't charge it for a few runs, (15km total tops, since the last recharge - and all lights are still good or on) and then the circuit breaker kept tripping.......**********?

left it overnight - still trips

recharged the battery - no trips (even up steep hills)

**** i am assuming that as the battery gets lower power, for some reason it is drawing more amps **********? and yet i still have full power lights assuming the lights work properly....

oh why did i not get a crystillite motor and the CA

dumbass did some calculations for me - and his calculations say that i shouldn't draw more than 33.3 amps......

*******just wondering if i should get a different circuit breaker, 35amp maybe

if anyone has any ideas, i would greatly appreciate it....

On an upside, many people have asked me about my ebike, and seem greatly interested, the more people we can get away from petrol, the better

yopappamon

Do you have specs on the circuit breaker? Does the breaker feel warm after it trips?

Does sound very odd to me.

elle

can't remember if it was warm,

fl amps 30
max volts 80
hertz dc 50/60
delay 34
trip amps 40.5
circuit 80

I should say here, that when it cuts out - the on/off switch doesn't change to off, i have to manually switch it off and then on....
sometimes i can't just switch it off and then on (it will sometimes not allow power through for 10 - 20 seconds)..... (to avoid confusion, the switch works fine, it just won't allow power through for 10-20...... and other times, it will allow power through straight away)....

doesn't make a lot of sense to me

SeizeTech

are you sure its a high current cut off that you are experiencing? maybe you are experiencing low voltage cut off.

When a battery is low, it will sag under load. so the most likely symptoms that you will see is: it'll work, but under a heavier load, the low voltage cutoff will trip.

best way to check is....when it trips......before you reset the bike, check the voltage at the battery. If it isnt there, then its actually the battery that is tripping

elle

the cut off happens when i put the throttle on (even on the flats) - or starting to go up a hill and put more throttle on, coasting down hill or pedeling will not cause it to cut off......

it will have no power for as long as i leave the circuit breaker in the on position (turning the key off and on will have no effect)...... once the circuit breaker is turned off and then on, full power again

someone said to me that a 15amp battery is slightly too small for a 800W

SeizeTech - i am a little confused, if i read you right (and a little assumption), are you saying the lights that indicate power are basically useless "IF" it is a low cut off switch in the BMS (assumingly to protect the battery)............. I must admit, i did suspect the lights were not an accurate gauge when NOT even one light went off after 3 trips (15Km)

okay, i have a voltage tester, have no idea how to use it -it has a big wheel in the center, which can point to many different numbers...... and i assume i put the positive (red) onto the power lead just before it goes into the circuit breaker and the negative to the black lead from the battery.......... i would like to use my light pen (as it would be easier), but that is for a car and only 12v.........

I also have to wait until the battery runs down again to test it (wait until it starts tripping out again)....

anyone know what the wheel should point at - there are basically 4 sections with numbers (2 with V with different cymbols after it, an A and a horseshoe) (if i point to the wrong one and try it, could it break it??)
digitech cat: QM-1500

I love my ebike, and would love to find out what the problem is.....

elle

actually just re-read your post,,,, yes, it does work, then under load, it cuts out......... still, my post directly above has some questions still..

any help appreciated

miro13car

be careful when you type or..
Do you mean 15Ahours=15Ah NOT 15Amps??
How can battery for 800W motor or any other LiFePo battery be just 15Amps??
It must be 15Ah.
O well you don't know how to use voltmeter...
At least double check your connectors and I would bypass BMS first to see if it causing problem, LVC can be faulty on BMS.

to start with what brand, obviously Chinese brand it is?

It just proof the point I made in my another post, Chinese-brand cheap kits require technical person, because they are crude underdeveloped made from cheapo parts ,make-money-fast products.
Buy E+ for example made in USA and it would last you and it is designed for average person to put together and acually has manual in grammar English.
But it costs money.
Honda also costs more than KIA DESPITE THAT kia DO EVERYTHING WHAT hONDA DOES.
MC

chvid

I don't think you have a problem. Lose the circuit breaker. I have seven kit built ebikes and none of them have a circuit breaker. I do have fuses on the brushed ones. I think your peak amps, instantaneously, are higher than you think. Don't worry about it.

chvid

My peak amps, when accelerating from zero mph often hits close to 50 amps for a second or two. Thats with a "35 amp" controller and a 48V 15Ahr battery...according to my CycleAnalyst. Running it without the circuit breaker will tell you if it is the problem.

edcastrovalley

I think you guessed right. A lifepo4 batteries are usually rated at 2C so with a 15 ahr battery: 15ahr x 2 = 30 amps max continuous draw. And then you already rode your bike a few times before which may sag or lower the battery voltage and that in turn could force your controller to increase the amp draw right when you're accelerating from a stop or climbing a hill (both big amp draws). If the controller doesn't automatically increase the amp draw you will either slow down or unconciously apply more throttle. That could probably trip a 30 amp breaker.

SeizeTech

Elle,

you are absolutely correct. the LED gauge ( or anything that is basically a volt meter) is a poor way to judge the amount of charge left in your battery.

Another way to describe this in a way that most of us will understand is by drawing a comparison to a battery on a vehicle.......even a dead battery on a vehicle can show 12volts on a volt meter, yet when you turn the key to start the vehicle, you will get that 'oh so common' sound of the starter solenoid clicking or chattering. What is really happening is the 12Volts is enough to open the solenoid, but the moment the power gets sent to the starter motor you simply dont have enough charge in the battery to turn the starter motor and hold the starter soleniod open. hence the starter solenoid goes click, click, click, click

Now in case of an electric bike, when the low voltage cutoff is tripped on the BMS board that is part of your lithium battery pack, you will need to disconnect ( flip the breaker) the bike from the battery before the battery resets it self.

The BMS also has high current cutoff protection. Again, once the BMS board is tripped, you will need to disconnect (flip the breaker) the bike from the battery before the battery resets itself.

Someone else mentioned that your motor might be a bit much for you battery, meaning that you are always running close to tripping the high current protect, and eventually when the voltage potential of the battery drops, the high current condition starts to happen. A battery that doesn't last a reasonable amount of time before it starts to trip would be a good indicator that this is the case, however symptoms alone shouldnt be used to draw this conclusion.

Also - and this happened to me - after about 3 months of use, my battery was no longer getting charged correctly, due to a crappy charger and a BMS board that doesnt balance the lithium cells. My symptoms were: I'd get the green light on my charger indicating that the charger was done its cycle, yet I could only go about 2 minutes down the road before the bike would trip.....I opened the battery pack up, and found that not all of my cells were measuring the same voltage. When some of the cells were at 4Volts(enough to tell the charger it was done), I had others sitting at 3volts(low enough to tell the BMS that the battery was dead)......I used a power supply to manually charge each cell to the exact same voltage, then I used the battery pack's charger to bring the pack to full charge.

My bike works fine again.