cut-off circuit

Do not have an electronic so I try the scheme already done or some good person who is willing to help me and then let me know the circuit, then seeking a cut-off for the batteries that I use for my projects, this cut-off would be great if it were variable with a trimmer that is, I wish I could vary according to which battery pack use


there is some good guy who wants to help me
Thank You

Check out TaskLED drivers, most of them have programmable low voltage warnings and cut offs.

What is your application? Voltage, current? Battery type? Do you want to buy one or make one?

Any proper 'protection circuit' for a LiIon cell or battery pack has low voltage cutoff. Some of the better drivers (like Taskled, but there are others) include this feature.

I'd like to make one circuit that will work both for lead batteries or NiMH batteries, always with voltage from 12v about

Okay I can design a circuit for you. A few more questions first.

When you disconnect the load, the battery voltage will come back up some. More on NiMH than lead-acid, but some on each. We need to make sure the circuit won't turn back on when the battery voltage does this, but allow it to come back on when the battery is recharged. There are several ways to "reset" the circuit.

1. Automatic when voltage rises a lot. This would not be adjustable, but would be the simplest circuit.
2. Automatic when voltage rises to a specific, adjustable voltage. This takes more stuff.
3. Reset manually, with a switch or clip-lead.

The first two methods will draw a little current from the battery even when "off", around one milliamp, maybe a little less. The third method has the advantage that it draws only a few microamps or less when "off".

So here's the questions:
1. Which reset method do you like?
2. Do you have a good digital voltmeter for setting the adjustments?
3. How good a builder are you? Can you read a schematic?
4. What's the maximum load current?
5. Does it have to fit in a specific space?
6. Can it switch the negative side of the load to the negative side of the battery? Or does ground have to be common throughout?

1. The method that I like the most is the number 2
2. Yes I have a good voltmeter
3. I can read a pattern and also know how to do the pcb
4. The maximum current the battery can range from 4Ah to 15Ah
5. I arrange myself to certain space, and normal that I have to do it as small as possible
6. I did not understand the last question, if you mean if I want interromper only negative or both is indifferent

Working on it. Do you prefer surface mount or through-hole?

I'm okay even surface mount
Thank You

Here's the basic circuit. I can help with choosing specific parts as well.




The battery would connect at the two input arrows on the left. The driver/LED circuit would connect at the two output arrow on the right.

There are two adjustment pots, R7 and R8. R7 is the turn-off adjustment. R8 is the turn-on adjustment. If the voltage is higher than the turn-on voltage, the circuit will turn on. If it's lower than the turn-off voltage, it will turn off. Obviously, the turn-on voltage should be higher than the turn-off voltage.

For simplicity of setting, the circuit uses 10:1 scaling on the turn-on and turn-off voltages. That means that the voltage at the tap of R7 or R8 (the point where it is connected to U1) is 1/10th of the turn-off or turn-on voltage. In other words, the circuit will turn off if the battery voltage falls below 10 times the voltage at R7 tap, and it will turn back on if the battery voltage is greater than 10 times the voltage at R8 tap.

Edit: realized the pic looks bad at 800 pixels. Here's the full thing: (new edit: don't read this, it's not the right link) https://www.dropbox.com/s/gvkdcqwdwip2wmi/cutoff2.jpg?dl=0

For some reason, I can't edit in the new link. It looks like the right link, but doesn't show the right picture. I'll try placing it in a new post.

https://www.dropbox.com/s/gvkdcqwdwip2wmi/cutoff2.jpg?dl=0

thanks, I've seen the pattern but I have not figured out if finite, because I do not understand that part is also the Q1 and U1
thank you

For Q1, something like an AOI510, IRFR8314TRPBF, or PSMN2R2-25YLC should be good if you want surface mount, or PSMN2R7-30PL, IRLB8314PBF, or FDP8860 would be good if you want through-hole.

For U1, something like an OPA2244 would be a good choice. It comes in surface mount and through hole.

With these values, the circuit would work from about 5V to 20V. At 12V it would draw about half a milliamp when "on", and about a third of a milliamp when "off".

Thanks but I do not find those components, I do I buy the components on this site
http://www.tme.eu/
can you help me
Thank You

For Q1, the IRL*3034 is one I've used and like. Through-hole is IRLB3034. It also comes in surface mount, IRLS3034. It also comes in a bigger package, the IRLP3034. That's the one I use in my 25A LED driver board.

TME does stock the OPA2244, but only in surface mount: http://www.tme.eu/en/katalog/#search=opa2244&s_field=accuracy&s_order=DESC&id_category=112843&page=1

I couldn't find a good through-hole one there. Ones that can handle 12V don't have low supply current, which is necessary for a cut-off circuit. The TC931A is the best, it draws a little under a milliamp, and could handle 18V (though 16V would be better for the high end). To keep the current well under a milliamp, you'd have to add a few more parts.

cut off ci

I have an e39 and my right headlight highbeam only came on this morning and It hasnt cut off since. I disconnected the battery for an hour and the right headlight is still on. Can anyone of you bimmer bros help me out please?

Re: cut off ci

yaricket said:

I have an e39 and my right headlight highbeam only came on this morning and It hasnt cut off since. I disconnected the battery for an hour and the right headlight is still on. Can anyone of you bimmer bros help me out please?

Click to expand...

Since this is obviously an automotive question, you'd be much better off posting this question as a new thread in the Automotive, Motorcycles Included subforum of the Transportation Lighting forum.