A kill switch...How many amps?

[alsmith]

I'll go over it one more time before giving up. ......

Just so I'm clear....... for a brushless setup you mean a switch isn't needed on the higher current battery main line? Only on the low current switching wire? And a fuse is recommended?
I think I've nearly got it. Maybe just .........

(kudos- you've got some patience typing all of that without using colored letters, a large font, underlines, italics, CAPITAL LETTERS, or cOmBiNatIOn of them used by some contributors at times.
Oh, and mustn't forget the smilies- :wink:

 

[riba2233]

Fuse is not recommended, fuse is must have, whether you have a switch or not. Large switch maybe isn't necessary as a safety feature (you should have switch that is easy to kill in case of panic), but I like to have as to ensure that my battery isn't being drained.

 

[mlt34]

I'll go over it one more time before giving up. ......

Just so I'm clear....... for a brushless setup you mean a switch isn't needed on the higher current battery main line? Only on the low current switching wire? And a fuse is recommended?
I think I've nearly got it. Maybe just .........

He's talking about what's commonly referred to as an ignition wire. It's the little red or orange wire that is often bundled with the main discharge wires like this:

Here is on the board of my KU93, goes down to the bottom left by the VCC. Not sure if your controller has it or not. Not all do.

 

[skeetab5780]

Wont the battery still have a slight drain on it from the controller if you wire it with the ignition wire as the only off. Go on vacation for a week and come back with no battery voltage? I know its happened to a lot of people.

If things are now different all of a sudden I guess I'm unaware

 

[alsmith]

I'll go over it one more time before giving up. ......

Just so I'm clear....... for a brushless setup you mean a switch isn't needed on the higher current battery main line? Only on the low current switching wire? And a fuse is recommended?
I think I've nearly got it. Maybe just .........

He's talking about what's commonly referred to as an ignition wire. It's the little red or orange wire that is often bundled with the main discharge wires like this:
....

 

[John in CR]

Wont the battery still have a slight drain on it from the controller if you wire it with the ignition wire as the only off. Go on vacation for a week and come back with no battery voltage? I know its happened to a lot of people.

If things are now different all of a sudden I guess I'm unaware

Measure the current when it's turned off to find out if you have any parasitic drains. I've only had a small number of controllers that do, and it's caused by a tiny drain down resistor which I just clip off. It should take months not a week or two for a drain down resistor to deplete a pack, so they must have had some other issue. Maybe they parked the bike after deep discharge, and didn't recharge it. I only disconnect my battery mains when I make changes, and 2 of my bikes have had their batteries connected for over 2 years. Some I rarely ride, so I make it a point to check pack voltage every few months, though on my son's ebike I forgot for over a year, but I haven't killed a pack yet. I did have a couple of parallel strings go to zero, but that was caused by cells with an unusual self discharge rate, but no switch of any kind can prevent that.

For those with big switches on the battery mains, they also should have circuitry to precharge the capacitors more slowly before the main connection is made. Otherwise the inrush of current will arc across the contacts scarring them a little each time they turn it on. This leads to a shorter life, increased resistance of the connection when it's ON, or in the worst case cause a failure in the ON position right at the time you need it most.

 

[mlt34]

Wont the battery still have a slight drain on it from the controller if you wire it with the ignition wire as the only off. Go on vacation for a week and come back with no battery voltage? I know its happened to a lot of people.

If things are now different all of a sudden I guess I'm unaware

Like John said, the drain is very small. The longest I left my pack for was three weeks and it was still charged. Generally if it's more than a week I unplug at the battery though.

 

[skeetab5780]

Just threw a Klein amp meter in series with my battery input on 2x lyen 12 fets and they draw around 35ma constant with the ignition wire hooked up to the positive
so my 8ah 20s pack would last 228 hours 1.35weeks

With the ignition wire removed it draws 14ma constant
so my 8ah 20s pack would last 574 hours 3.4weeks

 

[Scott]

To apply with NEDRA rules to race my bike I need to have a lanyard kill switch that automatically kills the bike If I were to fall off.

Will one of these boat/jet ski kill switches take 135 volts?



Do I need to get a relay and use the kill switch to open the relay? If so, I am unable to find a relay that is rated for 135 volts and less than 5 amps. The only one I can find is 200 something volts and 35 amps at around $50 which seems a little ridiculous if it is my only option to turn off less than 100ma. Does 135 volts at 100ma really arc that badly , could I just use a 24 volt relay instead?

 

[skeetab5780]

If its a high voltage race bike it is probably a good idea to have some type of kill switch on the main battery cables, if you need a contactor to do it there are plenty available if that's the route you take.

this place has them up to 600amps dc http://www.ev-power.eu/DC-Contactors/DC-Power-Contactor-200A-Coil-12V.html

that little kill switch can then just get wired in series on the coil side to control it.

But yes if you don't care to be super safe and have brushless controller with ignition wire, you can use that kill switch there, although I'm not sure if its NO or NC

 

[alsmith]

It depends where it is wired. As pointed out earlier if it is on the switching wire then not a problem because that is a low current but if it is on the main battery power wire you need to know the switches current rating and how many Amps your controller can draw to be able to know if it is sufficiently highly rated for the job you want it to do. No-one here can tell you with any certainty without you giving that information.

 

[Scott]

Thanks guys you answered my question!

I hope the switch is NC

I just want to use it in series with the ignition wire going to the controller. It's not a race bike, I wanted to race it on the road course but bikes/motorcycles are not allowed. I will only be drag racing it. I will tie an Anderson to my belt so if I fall it would pull out and break the circuit. A contractor would be nice but I can't afford one right now.

The specs of my bike are:

Volts: 135
Max amps: 150

Top speed so far 66mph

 

[d8veh]

Just threw a Klein amp meter in series with my battery input on 2x lyen 12 fets and they draw around 35ma constant with the ignition wire hooked up to the positive
so my 8ah 20s pack would last 228 hours 1.35weeks

With the ignition wire removed it draws 14ma constant
so my 8ah 20s pack would last 574 hours 3.4weeks

That's a very high drain. For modern controllers, like the S12S, it's in the order of microamps. The switch is on the LCD, so nothing to wire in either.

 

[alsmith]

Thanks guys you answered my question!

I hope the switch is NC

I just want to use it in series with the ignition wire going to the controller. It's not a race bike, I wanted to race it on the road course but bikes/motorcycles are not allowed. I will only be drag racing it. I will tie an Anderson to my belt so if I fall it would pull out and break the circuit. A contractor would be nice but I can't afford one right now.

The specs of my bike are:

Volts: 135
Max amps: 150

Top speed so far 66mph

more switch info but that sounds like it's not what you need.


NC = normally closed. this indicates a temporary switch which will only be off when held off- it's on again as soon as you let go.

You need an on/off switch SP ST (single pole single throw) but you can use more poles and use only one and wire them in parallel, of more throws but have unused positions