low voltage cut off

Tom_Cook

1 mW
Joined
Sep 27, 2010
Messages
16
I have a ecrazyman controller with the low voltage protection set atb the adequate level. I still have a bit of a problem though, because this lvc protection only seems to function when high currents are drawn. If I forget to disconnect the battery or do not completely turn off the controller, the Cycle analyst and controller will continue to draw a tiny current and slowly drain the battery. Does anyone know a good way to make the controller turn off completely at low voltage?
 
Yeah, unplug it when you park man. Or use an on off switch on the second red wire.

I got sick once, forgot, left the controller powered up by a close to empty battery when I rode home with a high fever. When I got better a week later, that battery had ruined itself. BTW, the bms did not help. I never found out if that was a failure of the bms or not though. Might have been, 4 year old battery.
 
Same here. Not feeling too well, quickly putting the bike in the garage, hit the sack and about a week later.... :x

I don't use a BMS as I use a balancing charger, so I can't blame a malfuntioning BMS. I really want to find a proper solution. Now I keep checking whether I really did flip the power switch to the off position.
 
you could use a lv alarm and invert the output to turn off a small latching relay in the ignition wire of the controller..

Edit: push button to turn bike on and lv alarm to unlatch the relay
 
Interesting it happened to you the exact same way. I was not thinking at all that afternoon, I had a brain fever that day, West Nile Virus. I thought you were just looking to avoid the hassle of turning your bike off.

It would be nice to have a self off feature on controllers. No throttle or pas signal for 15 min, turns itself off.

I have a light switch on my house for the porch light. It's a crude timer you can set for 1 to 12 hours. One of those could be put on the ignition switch wire to your controller. Set for 2 hours, then auto off in two hours.
 
I use those winding timers for several things: Grainger or McMasters Carr has them. I use one for my shop wood stove intake air "turbo fan", one for the crane exhaust hose when running it in the shop, and of course the way most of use them, after stinking up the bathroom.

But they are made for a few amps of 120 AC, and are pretty bulky, or are you just disconnecting/switching the controller, while leaving the battery plugged in? I'm still learning so bear with me. Switching the main battery leads would take a pretty good switch to handle the amps, do most just pull the connectors?

One good source I've used for decades is www.surpluscenter.com Great prices and service. they carry many different DC rated switches plus different DC motors, they are one of my favorite suppliers, I check their site before anywhere else.
 
most controllers have a ignition wire that uses a very low current to turn the controller on and off so nearly anything can be used to switch it on or off, when the controller is off the lv side of the controller circuit is not powered so there should be no main current flowing as all the fets in the controller will be off and should be open circuit, just like when a bms turns off (disconnects ) the battery.
 
I meant put the timer switch on the ignition wire. Not a good switch for the main current.

Here's another idea, maybe you could do something with the kick stand. Put the stand down, it hits a contact that switches off the ignition.

But except for that unusual situation where you ride in the door of your garage with a fever of 103, just getting in the habit of switching off, or unplugging will generally be all you ever need.

And me, I definitely think even if I return home that sick again, I'll still remember to unplug this time. :!: I definitely learn the hard way, but I do learn.

You could have a key switch, and keep your house key on the same ring. It works for remembering to turn off your car..
 
Dogman Dan, I am not so sure about me remembering to turn off the controller when ill :?
And eventhough it would be better if the controller had some time out function or even the kick stand system, for the moment I am looking at a somewhat simpler solution.

I had a look at various low voltage protection circuits on the internet and it seems not too difficult to make something simple yourself.
Below is a circuit I kind of modified so that it disconnects the on-off switch as gwhy describes.


The original circuit with a short description can be found here: http://kopka.heimat.eu/elektr_e.htm#Tiefentlade

In my case I want low voltage cut off to be 22V and there is about 20V on the controller power switch lead when the battery is at 34V.
 

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dogman dan said:
It would be nice to have a self off feature on controllers. No throttle or pas signal for 15 min, turns itself off.

I had an old Currie controller from 2009 that did exactly this... it would save a lot of batteries out there if this became more popular.
 
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