Help with battery cutoff switch

I would think an automotive fuse holder and 30 amp fuse would work fine. Get one with 12 guage wire attached.
 
I have used these switches with perfect results for several years of riding 36-66V, 20-45 Amps

Info in an earlier post.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=32463#p470995

Lots of ways to do a brake safety switch

http://endless-sphere.com/forums/viewtopic.php?f=3&t=31503&p=456494&hilit=+brake+lever+switch#p456494
 
Shame on Ping, unless it's a brushed motor. By all means put a properly rated fuse as close to the battery as practical. The proper place for the emergency cutoff for a brushless motor is the same as for a car, ie a low power key switch within easy reach that turns off the brain of the controller without which the motor cannot run. Putting an underrated switch on the battery mains is a risk, no matter how many people tell you they've been doing it that way for years. They haven't been turning that switch under load for years or they would have already learned their lesson after replacing it many times.

Brushed motors require such a switch, and a proper one would be a large expensive relay called a contactor. They need one, because the motor doesn't even need a controller to run, so a controller failure or a short, can result in a runaway condition that can only be stopped by interrupting the main power. The same is not true for a brushless motor. Switch off it's low power line that turns the controller itself on and off, and the motor can't run.

The advantage is that is a low current supply, less than 0.1A , so you can safely run the wire to where it is convenient and easy to reach in an emergency. I prefer key switches, because then you have the added security that a kid can't hurt themselves by just flipping a switch and turning the throttle.

John
 
I won't call a fuse a bad idea. But as an emergency cutoff, I like the controller switch, or just using brake cutoffs better than a huge circuit breaker switch.

But I should talk, not one of my bikes has a fuse or a brake cutoff. All just have a very easily reached anderson plug I can reach down and yank on if I really feel the need. But in a real world situation, I'd likely just do a manuver I've practiced way too many times. A controlled laydown, then deal with it.
 
I've assumed a 40 A controller would run at 40 amps continuous but would be fine above that for short periods. You wouldn't want it too close to the maximum continuous rating if you actually operate there. or you will be tripping frequently I suspect. I have soft switches of the type JohnCR mentions. It is not keyed but I don't have any little rug-rats around anymore.

I have never thought to try it but I bet in many installations, simple application of the brakes will stop the bike and motor. Would burn up the motor of course, but I don't think a runaway ebike is that common. Could be wrong though.
 
you can go to the spot on the signalab BMS where the circuit current goes to the opto series through that white rectangle with the two through holes next to the sense wire plug on some and the comparator on others. i think that spot is where the thermal switch to the pack would connect. but you can open the trace between the two holes and solder a switch into those two holes, through a wire remotely on the dashboard, and then by turning off the switch you would shut off the circuit current and the BMS would shut off.
 
My solution to the problem, easy to wire an emergency cut off as well.
http://www.endless-sphere.com/forums/viewtopic.php?f=31&t=32135&p=465323#p465323
 
I run the brake cutoff switch on my rear brake, a controller on off switch on the controller accessible from the seat of the bike, and battery switch mentioned as well as a 12V 30A blade type automotive fuse with 12G wires. I run at 66V and have a 45A controller. I have only blown the fuse once in several thousand miles. Very few people run their controllers/bike at max amps continually cuz if they do they burn up in short order. 400V and 63A is a bit overkill and likely will not trip at a voltage low enough to stop any damage other than a fire. Circuit breakers are not meant to be used as switches. Most are only meant to be reset occasionally.
 
seems so insane to put a breaker on the BMS. that is what the BMS does. if you want to turn off the BMS then put a switch in the circuit current and it will shut off without the expensive breaker.
 
circuit breakers are not designed to function as high current switches. since the current flow when charging the caps up is so high when the breaker is switched ON, the contacts will burn off fairly quickly. just a waste of money imo.
 
t44florida said:
dnmun said:
circuit breakers are not designed to function as high current switches. since the current flow when charging the caps up is so high when the breaker is switched ON, the contacts will burn off fairly quickly. just a waste of money imo.
Click to expand...

You may be correct. I thought it best to follow the recommendation of Li Ping who makes/sells these batteries in China. I'll let you know if I experience any problems. Cheers!
Click to expand...

I was one of Ping's early customers almost 4 years ago, and his note to you about using an AC circuit breaker on an ebike is the worst piece of advice I've seen him offer. He must have gotten the idea from some cheapie low power electric mopeds that sometime use a circuit breaker on the power wire. While it might last a while a low power, that doesn't make it correct. You will never see something like that suggested in the wiring documentation of any major controller manufacturer. Ping really should know better, and I'm quite disappointed that he doesn't. Maybe he started the Chinese New Year festivities a few weeks early and it's a secretary or some noob answering his emails.

AC is quite different from DC. That's why when houses got away from fuses in favor of circuit breakers as protection, cars still have fuses and relays.
 
I am using a house type CB, it is a dual 50amp 120/240 wired in parallel, it has never tripped even with a 250 amp plus surge starting the perm 130 dc motor it is in series with, the main reason that I am using it is a emergency cut off switch tripped with a pull string, light weight and cheap. I has been in use for over 3 years with no problems, I use a swtich in series with a 250 ohm resistor to charge the caps in the controller first.
 
yes, this is the way you have to do it if you use a breaker. using it with a kill switch cord on the breaker is ingenious.

it is the surge of the charge into the capacitors that will burn the contacts off of the breaker. breakers do not have large contacts, they are made to remain closed at all times, and only occasionally open. using the precharge circuit avoids the current surge when the breaker is turned on. but again you can leave the power wires to the controller permanently soldered together and just put the controller circuit current on a switch.
 
Would this $4 switch work for you?
http://www.ebay.com/itm/330647142361?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_5174wt_1082
 
circuit breakers- used to protect the wiring not the controller/electronics
fuses- used to protect the electronics although not often found in these high-powered motor controllers

it's funny how my 1kW switching supply switches have managed to survive the onslaught of current charging draw of the 4 15000mfd input capacitors all these years without failure

Ping is right but might be assuming you have a controller on/off switch
do install one if you don't already have one.
then turn on battery first then turn on controller- problem solved because there is no problem if you wire the controller's provided circuitry.

some people think this might be a problem- some people ride bicycles above 50mph without (or with inadequate) brakes

however when your motor's not actually running there is minimal current flow and a circuit breaker isn't going to blow under the (very) temporary charge currents drawn by a controller's input capacitors. LOL the contacts will not burn

size the circuit breaker to protect the wiring using the controller's max rated (or programmed) current draw and if the circuit breaker blows and the controller/motor didn't then the controller's max rating was the controllers' design engineer's figment of imagination

don't mind me-just waiting for my batteries to recharge
 
You must log in or register to reply here.

Similar threads

Lectriceye
Kill Switch-Brake cutoff switch
Replies
11
Views
1,243
Lectriceye
Lectriceye
R
Motoring XMR wiring diagram
Replies
2
Views
105
amberwolf
amberwolf
A
Stock Surron Light Bee Controller for diy Project ?
Replies
0
Views
118
Andi-1990
A
Santacruz
    • Like
  • Question
Random cutting out solved
Replies
0
Views
197
Santacruz
Santacruz
J
Unknown bar switch function
Replies
7
Views
188
E-HP
E-HP
Back
Top