electrical control units

[streetlegalkarts]

is there a circut i can by or make (preffer to make) that i can use to start a engine when the voltage on a battery get to a certin point? ( well before zero ) all i can find is the ones they put on auto start generators. I'm trying to build a hybrid kart. and i have not found any where the engine starts automaticly while in operation.
again i would like to make my own if someone could help me out with the tech.

 

[kendelrk]

are you saying like once you get to a certian speed on electric and its about to die, the gas kicks in and charges the battery of the electric motor?

 

[devino246]

The only way I cant think of would be to use a micro controller.

 

[streetlegalkarts]

well nothing to do with speed.
your average fully charged battery is like 13.? and i want the... lets call it a generator to start automaticly at 11 volts, power the kart, and, charge the batteries. then when the batteries are fully charged shut down.

 

[baer]

You can use a comparator which has the (-) input connected to your battery and the (+) input set to a threshold voltage with a potentiometer and the output will be high when the battery voltage goes below threshold.
It is advised to use schmitt trigger comparator which will allow a more stable output.
comparator
Schmitt trigger

 

[streetlegalkarts]

baer, i dont understand how those will start the engine then kill it. i understand how they will control the electricity after its running.

 

[baer]

What I wrote above is only how to create an electric signal of 5V (or so) that is active whenever the battery voltage is below threshold thus whenever the generator need to work.

The other part of the electric circuit as you said is something that actually starts the generator and kills it. This is more complicated to build:

The starting mechanism will be a relay of high current which will enable the starter and perhaps "push" the throttle a bit to allow an auto-start. You will have to figure what is the optimal period of time the stater needs to be "on" and what level if any does the throttle has to be to allow a smooth start.
The kill mechanism will be just connecting the acc signal to another relay.
Hope it's clear.

 

[streetlegalkarts]

AAAHHHH!!! I almost feel stupid lol. thanks for the diagram! thats crystal clear. would the thery work for controling the throtle? ie working off the altornator out put?

 

[kendelrk]

you could, and its in no way safe, just might need to modify my idea, get yourself a generator with electric start and rig a kill to your sterring wheel, off the prongs that plug into the wall, take some jumped cables, i cant remember exactley but i beleive you put positiving to positive and negative to ground, and get a volt meter on your electric motor, when it drops down, hit the e start, let it charge, when its done kill it, i know the shapes and all in this drawing make no sense and its all messed up, but its a quick drawing of what i mean

 

[streetlegalkarts]

ken that would work but my goal is for it to control it self.

 

[kendelrk]

what about one of those auto generators then? the ones where when the power goes out, it automatically kicks in, you know the kind im talking about, then you could always wire it up like that, and still keep it like that becuse if you kill the motor the generator will start till its a full charge, but itd have to get down to possibly 3 bolts before that happens automatically

 

[streetlegalkarts]

those generator dont start until zero voltage. and then there is a delay. they are also AC not DC. that was my first thought and use a inverter to change it back too DC. thats some big money right there. and i never want the voltage to drop below a working level. ie. the kart always proforms the same, no lag. but great idea

 

[kendelrk]

i dont think they way your going for is going to in any way be cheap to you, why is this kart electric anyway? predators are on sale for 99 bucks, throw in a 2 year warranty and youll be good

 

[baer]

would the thery work for controling the throtle? ie working off the altornator out put?

Controlling the throttle is more complicated, electrically it should use another relay as the upper one in my scheme but mechanically is more challenging to build since it has to push the throttle to a certain level and not interfere with manual control.
And above all that you may not need it at all.
Do you have the generator available? does it have an electric start? if yes try to figure the start time and whether throttle push is needed.

 

[streetlegalkarts]

the project is a street legal HEV kart, slash car depending on your view. and i know for a fact i can get the electoric for less. and i have an engine and an altornator and motor already. price for all the was freebie.

 

[streetlegalkarts]

what about operating the throttle with a selnoid? open in the start/idle postion and closed in the run postion. control it off a secound soleniod with a delay.

 

[r97]

Not exactly sure how you would go about doing this, but....

Get a voltmeter, somehow you need to attach two solenoids to the volt meter. One solenoid will be triggered by a low voltage reading, but only for a short amount of time (so you don't wreck the starter motor). Solenoid two will be triggered by a high voltage reading, and will ground out the magneto on the engine (kill switch).

There are a few tricky parts with this idea:
1. Getting the voltmeter to activate the solenoids.
2. Making sure the starter motor only runs for a short time. You will need to have a device that turns a long or short signal into a timed pulse. Then you must make it so it cannot send another pulse until it is reset by a high voltage reading (just after the engine is turned off).

Here's how the setup would function:
1. Low voltage reading sends a timed pulse to the starter motor (A special circuit will ensure another pulse cannot be sent to starter motor until the engine is killed)
2. Engine starts, runs, and charges batteries until the voltmeter reaches a certain voltage.
3. Volt meter reads high voltage and sends a signal to kill the engine (engine is killed through a solenoid grounding out the magneto). A signal is also sent to reset the circuit mentioned in part #1.

Hopefully that makes sense!

 

[streetlegalkarts]

that souds like your implying alot of mechanical linkage. and i'd rather not have that.

 

[r97]

You could do most of it electronically could you not? I'm sorry my knowledge on electronics only goes so far. Someday I'm going to buy a book or take a few classes to try and get a better understanding. I know just a basic understanding could help me make all kinds of things!

 

[fowler]

i dont think u can have a road vehical that will start its self automatically in a car park
cars have never had this system before
what if u leave it in gear and it takes off

again my understanding of electronics is not great

but surly with the above sugestions

u will have to isolate the volt metre when the engine starts
a full battery is 12.6 and the alernator is putting out 13/15v so as soon as the engine starts the voltmetre will read high voltage

surly u whould need a switch like a relay that can only hold a magnetic feild untill a certain point then it closes the switch
the closing of the switch will have to start the engine and isolate the origonal switch switch at the same time

have the startor switch to turn the engine over till the alernator starts producing power (engine rmps increased due to runnin its self )

then have the engine on a timer i guess u can just guess and test with the timer

i could show u a circuit but i dont know if a switch like i described exists