A battery life indicator?
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A battery life indicator?
Anyone have any good ways to show how much juice u got left in your batterys? kindof like the ones they have on the dvd batterys just i wana use one on my rc car batterys. any ideas?
Fire in the hole
For a once off deal, get a small light bulb and connect it to the battery via two wires, and see how bright it is. If you wnat one that constantly tells you how much battery you have left, you could probably find one at a place like digikey.com, or radioshack. I doubt that you could make one though.
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I think you have to make a small voltmeter since batteries lose voltage as they die.
Somthing like this: http://www.redcircuits.com/Page43.htm or this http://www.edn.com/article/CA47312.html
Somthing like this: http://www.redcircuits.com/Page43.htm or this http://www.edn.com/article/CA47312.html
Fry it first, ask questions later.(what usually happens to me)
I made a battery life meter for my second SNESp:
It's an analog meter from a Cold War era aircraft of some type- I painted the color scale on it.
However, these do not work really well with Infolithiums because they have a very small difference from full charge to dead voltage (8.4v to 7.1v). (They discharge very evenly.) As a result, the pointer on the meter doesn't move a whole lot and scale is out of proportion. You may get better results with NiMh batteries, as their difference is something like 9.6 to 6.8.
I just put a 1 megaohm resistor in series with the meter. If there is a better circuit for this, then I will be glad to improve.
It's an analog meter from a Cold War era aircraft of some type- I painted the color scale on it.
However, these do not work really well with Infolithiums because they have a very small difference from full charge to dead voltage (8.4v to 7.1v). (They discharge very evenly.) As a result, the pointer on the meter doesn't move a whole lot and scale is out of proportion. You may get better results with NiMh batteries, as their difference is something like 9.6 to 6.8.
I just put a 1 megaohm resistor in series with the meter. If there is a better circuit for this, then I will be glad to improve.
If all else fails, take it apart!
Hmm, you could probably tear apart a multimeter or voltmeter and either hook it up to the battery measuring current or voltage. I guess either would work but current would be more user friendly.
EDIT: If you're using a 9v Pattery: http://www.guitarelectronics.com/product/PMTLBAT
EDIT: If you're using a 9v Pattery: http://www.guitarelectronics.com/product/PMTLBAT
the "easiest" way would be to use a microcontroller with a ADC on it. i put "easy" in quotes because for some people, it wouldnt be easy at all... but it is for me.
in fact, as i type this there is a microcontroller programmed to read voltage not 8 inches from my hand.
if you know some c programming, and are willing to shell out $40USD for a programmer (or clever enough to make your own. google it), then it really isnt such a major task. heck, ill give you my code if you want it.
the bonus there is that you can get the microcontroler to do other things while its at it. i cant think of anythign cool right now though...
also, its very hard to get a capacity reading off of NiMh batteries, since they discharge pretty evenly. what you could do is get a PIC with some EEPROM, and get it to "remember" how much capacity the batteries have, and keep track of how much has been used.
and... arent infolithium batteries called that because they have some sort of built in capacity measuring circuit?
in fact, as i type this there is a microcontroller programmed to read voltage not 8 inches from my hand.
if you know some c programming, and are willing to shell out $40USD for a programmer (or clever enough to make your own. google it), then it really isnt such a major task. heck, ill give you my code if you want it.
the bonus there is that you can get the microcontroler to do other things while its at it. i cant think of anythign cool right now though...
also, its very hard to get a capacity reading off of NiMh batteries, since they discharge pretty evenly. what you could do is get a PIC with some EEPROM, and get it to "remember" how much capacity the batteries have, and keep track of how much has been used.
and... arent infolithium batteries called that because they have some sort of built in capacity measuring circuit?