Yeah, that's what I thought - except I bought a little while ago a digital voice recorder/player (like a dictaphone but with Flash memory/USB interface/MP3 etc). This accepts two AAA cells; alkaline work but NiMH don't ;-( ;-(. This is really annoying as the batteries run down even when the recorder is not in use. I had presumed that NiMHs would work without checking (I haven't tried NiCads).
I looked up the processor data sheet online and it described itself as a '3V' device, but didn't have the full voltage range specification.
Not necessarily. Many dont feel that the much higher cost of a multimeter is justified and a cheap tester like that one is certainly better than nothing.
Hard to justify the cost for most.
100 times the cost.
Completely silly using something like that to test batterys.
1000 times the cost.
Easy to see why some dont see its worth it.
It makes a lot more sense to get a better charger that does the best it can with the batterys instead.
Yes, basically yes, it's testing if it can deliver the 'correct current', obviously when it is low on charge it won't be able to maintain this for long as in (3) above and will eventually drop into (2).
I am not sure what it says about the rechargability of he batteries though.
Yes as the battery brcoms more 'drained' the measured voltage will drop from say 1.5 V to about 1.0 V. As for 'measuring the current', how are you planning of doing this? If you connect it trough the current terminals of a meter you are short circuiting the battery, not recommended, basically you are 'testing' the battery by draining it. Use the voltage measurement. A multimeter usually has battery testing settings which are simply voltage testing setting adjusted to scales of 1.5V, 9V etc...
Wrong. Internal resistance is a property of ALL batteries, including brand new, fully charged, perfectly working ones. ALL OF THEM. The load current must be weighed against the particular cell's resistance to determine what the acceptible voltage drop will be. The cost is that cells may be deemed more drained than they actually are and discarded prematurely. In other words, as it applies to this thread, 500mA is a rather high current for smaller alkalines, but more appropriate for mid-sized. Likewise, it's way too low for a battery with even lower resistance like a car battery or typical laptop battery.
Anyone who's tried to use Alkaline batteries in a digital camera may have observed this, the batteries don't seem to last very long because their internal resistance is high relative to the current consumed by the camera.
Dave: Please clarify your remark. Are you referring to alkaline rechargeables (my Renewals), or the non-renwable type? I was talking about new NiMH rechargeables as being 1.2V. My renewals recharge to 1.5V. Gonna miss them.
Duh. What matters is whether the internal resistance has increased substantially so that it can no longer deliver the voltage it should deliver with a decent load, particularly when the batterys are used to power the higher current devices.
Just measuring the unloaded voltage doesnt tell you anything about batterys that have gone higher resistance.
And thats not feasible with as simple a battery tester as the one being discussed. It certainly makes more sense to load the battery than not load it at all tho.
Yes, but thats better than claiming the battery is fine when its internal resistance has increased substantially and it will no longer supply the voltage its supposed to supply when loaded.
Not for the devices that have motors in them etc.
It clearly isnt intended to be used for either of those.
Separate matter entirely to whether its better for a very cheap battery tester to measure loaded or unloaded batterys.
Pretty much splitting hairs there, fact is that on a perfectly working cell it's impedance is an issue when driving relatively high current loads, it is not a matter of defect alone, it is a factor in every use of brand new perfect cells too.
never suggested it did. The load has to be appropriate for the battery chemistry, design and size and the margin for error rapidly goes up as one deviates from that ideal.
never claimed otherwise, but only randomly thinking "load" vs "no load" is pretty irrelevant, the ACTUAL load has beconsidered (by either the tester or designer of the test equipment).
not better or worse overall, depends on the criteria. Some want most lifespan, or lowest cost, or longest runtime per outting, several different things can matter most.
The one thing that should always be avoided is unreliable indication of the battery state so one can't even make a reasonable attempt to choose their own strategy for replacement or recharge intervals.
Yes for devices that have motors. While the motor might load it more, that does not matter! To indicate the battery state it is necessary to load it appropriate to it's size, design and chemistry.
Smaller alkalines shouldn't be used in any high current motorized device to begin with, but if they're used, there will be a voltage depression from the higher current load (same as when tested), a voltage that will RISE AGAIN after the device is turned off, relative to what it was when last running. This completely invalidates a high (relative) current test on those cells, unless your only goal was not testing the battery at all, rather qualifying for particular device usage. Toward that end it is a fair test, a determination of alkaline (for example) is fit at all, or better to use something like NiCad.
Rechargeable alkalines have a lower internal resistance, respond better to loads. Not a lot though, if one is heavily loading packs they're not the best choice, rather such frequent drains suggests NiMH is the better alternative.
Nope, the device obviously has to be designed to allow for the internal resistance of a good cell.
Only for the designer, not for the individual deciding if a particular battery is good or not.
Who's mindlessly hair splitting now ?
Never suggested you did.
And that cheap battery tester clearly isnt even attempting to consider any of that.
Never claimed you did.
Nope, not with a cheap battery tester like that.
Not even possible with a cheap battery tester like that.
ALL the designer of a cheap battery tester like that gets to do is either measure it loaded or unloaded and to use what he considers to be a useful load that will indicate whether the battery can deliver that sort of load fine.
Gets sillier by the minute. The criteria with a cheap battery tester like that, there is just ONE criteria, is the battery still usable or isnt it.
Not WITH A CHEAP BATTERY TESTER LIKE THAT.
And measuring the battery loaded is the best way to do that.
Corse it does when testing to see if the battery can deliver the voltage it should do with that load.
Not even possible with very cheap battery testers like that.
Tell that to the designers who do just that.
Irrelevant to what is feasible with as cheap a battery tester as that.
No it doesnt, it shows that the battery can deliver that current fine. And so will handle a lighter load fine too.
Its clearly a battery tester.
That aint what that particular battery tester is about.
Obviously you haven't a clue. The devices are designed for a target battery type. "Some" can be used with another type but it's not the target. Take a laptop, did you think you could chuck out the Li or NiMH and put some Alkaline in there and use it? Good luck, you'll need it. Too high a load for alkaline.
The individual putting a load on a cell has to use a load causing a current draw that is reaonably compatible with what the battery can provide. To do othewise will result in a misleading reading.
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