I would like to test my 9V, C, D, AA, and AAA under the proper load. I don' t know what that would be for each size though. I want to build a little te st fixture for this with a meter and the appropriate load connected for eac h size. Can someone please tell me what the appropriate loads would be. Tha nks, Lenny
Well, you could try bouncing the cells: I tried it and couldn't make it work, but maybe you'll have better luck.
Lots of commercial alkaline battery testers available. I have one of these:
There are quite a few do it thyself battery tester construction articles. Pick whichever looks good:
Note: I've on a campaign to purge from my life as many alkaline batteries as possible. I'm tired of leaky batteries destroying my equipment. Mostly, I'm switching to LiIon. Where that's not possible, LSD (low self discharge) NiMH cells. If the device will not run on NiMH, it gets recycled.
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
on't know what that would be for each size though. I want to build a little test fixture for this with a meter and the appropriate load connected for each size. Can someone please tell me what the appropriate loads would be. Thanks, Lenny
That second one is good. (I'd say they figured it out.)
For alkaline, I just measure the open circuit voltage... that seems to be good enough for me. 1.6 fully charged,
Looks like the consensus is 10 ohms 5 watts for all the 1.5v batteries: However, Googling around, I'm finding schematics and recommendations varying from 8 ohms to 15 ohms.
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
** The ESR of a cell or battery is a good guide to its condition.
A fresh AA alkaline measures 0.1 ohms or lower while a tired one measures 1 ohm or greater, a fresh 9V measures under 1 ohm. Along with a voltage test you have enough info to match or discard used cells.
don't know what that would be for each size though. I want to build a litt le test fixture for this with a meter and the appropriate load connected fo r each size. Can someone please tell me what the appropriate loads would be . Thanks, Lenny
+1, simple & adequate for noncritical uses. Clocks stop at around 1.1v, it varies.
Althogh it is not an ideal method, if I am in a hurry I quickly measure the short-circuit current. You'll need a meter with at least a 10A range and maybe more if your test leads are short and the meter shunt resistor has a low value. Obviously if you take too long to do this test, it will ruin the battery. With NiCd and NiMH cells you would want the resistance of the ammeter and leads to be at least 0.12 Ohms, so that nothing will melt, as the cells themselves are capable of extremely high currents.
IIRC, you take the open circuit voltage and write it down. You take a volt age reading under a known fixed load and write that down. You plug those tw o voltage readings along with the load resistance value into a formula (tha t I can't recall) and you get the internal resistance of the battery.
Waaaay too much trouble IMO. In recent years, I've found OC voltage suffic ient to determine battery condition of basic alkaline cells. For high drai n applications such as flash lights, anything at 1.5 is fine. For lower dr ain things like pocket radios or remote controls, anything above 1.3 works for many months. Any cell that reads 1.55 or above is virtually new.
Have you ever tried to measure the ESR of a battery with one of these?
I bought an EBAY RLC/ESR tester. Found it useless measuring batteries. NO, putting a cap in series didn't help. Tried testing two batteries in series(reversed so the terminal voltage was zero). Not sure why, but I couldn't find any way to test battery ESR with it. Had to go back to pulse generator and scope.
ltage reading under a known fixed load and write that down. You plug those two voltage readings along with the load resistance value into a formula (t hat I can't recall) and you get the internal resistance of the battery.
icient to determine battery condition of basic alkaline cells. For high dr ain applications such as flash lights, anything at 1.5 is fine. For lower drain things like pocket radios or remote controls, anything above 1.3 work s for many months. Any cell that reads 1.55 or above is virtually new.
Wow, too much trouble? It's just ohm's law. Say V_O is open circuit voltage, V_L is with load R. I = V_L/R Bat_R = (V_O-V_L)/I (The ESR may change with load current... I don't know.)
voltage reading under a known fixed load and write that down. You plug thos e two voltage readings along with the load resistance value into a formula (that I can't recall) and you get the internal resistance of the battery.
fficient to determine battery condition of basic alkaline cells. For high drain applications such as flash lights, anything at 1.5 is fine. For lowe r drain things like pocket radios or remote controls, anything above 1.3 wo rks for many months. Any cell that reads 1.55 or above is virtually new.
Yes, waaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaay too much t rouble. With alkalines, a volt meter tells me *immediately* what I need to know if I don't have my battery checker with me. If it's 1.6, it's new.
1.5 good as new. Anything above 1.3 is good for at least half the life of a new battery. Anything lower I don't bother with.
In the old days, some batteries would read decent OC voltage and still sag under their intended load. I haven't seen a battery in many years that wou ld show good OC voltage and sag under load.
You take a voltage reading under a known fixed load and write that down.
You plug those two voltage readings along with the load resistance
value into a formula (that I can't recall) and you get the internal resistance of the battery. Which voltage do you use? When you apply the load, the voltage starts to drop. So, which voltage along that curve do you use? And when you "let go", the voltage won't return to the original level. Note that the voltage at the instant you apply the load won't be available unless you use a scope, or some otherwise accurate sampling to measure it.
Great in theory, but not nearly so simple in practice.
If you're applying a load suitable enough to cause a constant drift of volt age or the OC voltage doesn't return to pre test state, the load is too hig h for the battery in question or the battery is shot. Old School battery t esters used to use a switch to select which resistor to load down the batte ry in question, AA, AAA, C, etc., while displaying the battery voltage on t he meter. The only time I saw the meter drift downward was if selecting a D battery test for a AAA for instance.
ltage or the OC voltage doesn't return to pre test state, the load is too h igh for the battery in question or the battery is shot. Old School battery testers used to use a switch to select which resistor to load down the bat tery in question, AA, AAA, C, etc., while displaying the battery voltage on the meter. The only time I saw the meter drift downward was if selecting a D battery test for a AAA for instance.
If your battery voltage is drifting down, its ESR is drifting up. If you wa nt to know what state it's in after the test you'd use the last voltage re ading. But there's no point, if it's dropping noticeably either it's had it s day or the test load is too high.
Do the math. How much current do you apply? How much voltage represents 0.1 ohm of ESR? Compare that to the change of voltage over a second when you apply that current to a brand new battery. The battery model is more than a resistor in series with a fixed voltage source. Maybe someone here can supply the actual model of a battery that represents the voltage over time for a given current as a function of recent history of the battery load.
The only way I got usable ESR results for matching cells was to apply a square wave switching from one non-zero load to a different non-zero load and measuring the amplitude of the square wave...always using the same frequency of square wave. The devil is in the details.
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