Power kept cutting out

[Ur3nigma]

So I just built an e-bike. Conhis (I think) 48v 800w hub motor and speed control and a Golden Oasis 48v 1000w battery. I was trying to see what kind of range I could get when, around mile 15, it just shut off. If I unplugged the battery and waited a minute, it would work but it would act like I was blowing a fuse every time I tried to accelerate. I got it home and put a charge on it and it doesn't do it anymore. Does it do this if the charge is getting too low? Theoretically it should be able to go about 30 miles on one charge, so the 15 miles seems a bit weak to me...

[nebriancent]

to me it sounds like you have hit the range limit of your bike
your bms is shutting down the battery to protect it from a under voltage condition
if you are easer on the throttle on take off, cruise at less then top speed, or have less hilly terrain you very well could get the rated range from the pack.... or more
but if you are hard on the acceleration, cruising at max speed , or loading you bike down by climbing hills then your range goes down pretty fast

[dogman]

Unfortunately, you believed the range claims common from the sellers.

You can get that range, if you ride as slow as they do in the tests. Read the ad again, they don't ever say at what speed you get such and such range do they?

Assuming you have a 48v 10 ah battery, you actually did pretty ok. The bms shuts off to prevent you from ruining the battery. Your range might improve a bit, as you learn to ride more efficeint, and waste less of your watthours.

[miuan]

Your range might improve a bit, as you learn to ride more efficeint, and waste less of your watthours.

...or as soon as you buy more battery!
welcome to ES

[Lock]

"Golden Oasis 48v 1000w battery" sounds like this pack:
http://www.goasisenergy.com/products-page/48v-lifepo4-battery-packs/48v-20ah-lifepo4-battery-with-4a-charger-and-battery-management-system/

48V x 20Ah so 960Wh... Using only 90% of nominal capacity, 864Wh... EVen at a fairly high rate of consumption as 40Wh/km, works out to only 21-22km or 13 miles... Many folks on 500W pedal bike conversions see less than 20Wh/km... more like 26+ miles from a pack like this.

Isn't it possible the BMS is cutting power because of one bad cell in the pack? Ur3nigma, what are your average speeds? And are you riding a Lithium pack, but using a lead foot?

Lock

[999zip999]

What amp. is your controller ?

[Ur3nigma]

I was definitely pushing the bike--full throttle and top speed the whole time. It's just good to know that it was doing something it was supposed to and not malfunctioning. I'm a pretty good mechanic but I know very little about electronics, so I was a bit worried about troubleshooting a problem.

The biggest downside to this is that the battery indicator showed a full charge the entire time. Guess I'll just have to keep track of my mileage.

I don't know what wattage my controller is. It came as part of the kit and the instruction manual is less than sparse.

Furthermore, it doesn't completely shutoff. I can turn off power going to the motor but the battery indicator never shuts off. I disconnect the battery everytime i plan on leaving it for more than a few minutes but it sparks pretty vigorously when I reattach it. That doesen't seem very healthy to me. Eventually the connections are going to fail. Plus, it doesn't seem like it should do that at all. It sparks even when the motor is unplugged from the controller so I know it's the controller drawing the current upon connection...

[dnmun]

that low a capacity means the pack is unbalanced. you need a cycle analyst to keep track of the drain from the pack. or get watt meter, but if you wanna fix the pack you have to do a bench test to find the low cells and then decide what to do to fix it.

first put the pack on the charger and measure the voltage across each cell while charging. post up so we can figure out how the BMS is working.

[dogman]

Well, you should be seeing about 30 miles at 25 mph out of a 48v 20 ah pack. What size is yours?

If it was the very first ride, you could see some improvement. Batterys do need a bit of break in. Now you may have done your break in all wrong, but don't fret it. Plug it into the charger, and leave it on the charger when not riding for about a week. Your pack may be simply way out of balance, and one weak, undercharged cell is causing the bms to shut off. If you are lucky, the problem will go away.

On the other hand, cheap peice of crap lifpo4 bike batteries are common. Dud cells inside prevent you from ever discharging more than 15 ah from a 20 ah pack. Good luck getting sellers to fix one. There is a reason we recomend only two or three battery sellers over and over and over.

Hopefully, your pack is just out of balance, and will still discharge 18 of your 20 ah, and be pretty usefull to you for a long time.

[Ur3nigma]

http://www.goasisenergy.com/products-pa ... nt-system/

The seller I got it from on ebay allows returns. He also says it has a 6 month warranty. I sent him an email. If the warranty is good, I think I'll just try to run it through a few cycles before I try the distance again. I'll leave it on the charger as much as possible. Don't think I'll go a full week without riding it though

[dnmun]

why can't you just measure the cell voltages while charging? that will tell you what is wrong.

[Ur3nigma]

I want to get the details of the warranty first. I'll have to cut off the shrink wrapping to get at them. I don't want to do anything that would void the warranty. I'll do it as soon as I know.

[dnmun]

ok, thought it was open already so you could reach the sense wire cable.

[Eprilia]

dnumun,

How did your pack turn out and did Golden Oasis get back to you on your questions. I ask because I'm looking into the same pack as you purchased.

Charlie