Hello. I have old Amazon Basics 1.2V black batteries that I didn’t use a lot really. Why when I measure with multimeter I get 1.24V but when I measure with digital battery tester I get 1.11V - 1.14V?
Bonus question; why the aforementioned batteries output light with varying intensities despite being fully charged? I use them in Coast AA small flashlight. Also same thing happens with my coffee whisker. When not submerged it spins normally but after submerging it spins slowly that it hardly whisks coffee? These batteries also don’t last long I noticed.
Depends how the battery tester measures it, a voltmeter measure the open circuit voltage but the battery tester might load the cell when measuring.
If you look at the First graph in this test you can see that the higher the current drawn the lower the voltage of the cell is, that’s because cell’s have an internal resistance, so when you plunge your coffee whiscker the resistance of the liquid make it draw more current, lowering the voltage, decreasing its speed. Better cells like Eneloops (white) have relatively low internal resistance, also it degrades with use/age, which can explain why you get different performance with different cells of the same model. In this test you can see the internal resistance rising as the cell is cycled (charged/discharged)
These are white eneloops that have either 1900mAh or 2100mAh and are guaranteed to last for 1000 cycles? On the graph I see that both start going down in capacity after 340 cycles. How is manufacturer guaranteeing 1000 cycles when at 3/4 of them the batteries will probably retain less than half of capacity?
Also, assuming manufacturers are being overly optimistic, maybe I should not buy eneloops Pro with 2550mAh? I was contemplating because in reality they may start going down in capacity at 150 cycles.
Other than capacity concerns are there other kind of benefits to 1900mAh and 2100mAh over 2550mAh in addition to 1000 recharge cycles? Maybe they are better at internal resistance? Discharge slower over time than 2550mAh?
The high capacity Eneloops (or similar cells) START with more capacity and ‘may’ have a higher output to start. BUT, to achieve that goal compromises in manufacturing and chemistry make the internal resistance rise FASTER with use and they degrade more quickly. Really high capacity cells (2800-2900, higher than that are bogus cells) often go bad pretty quickly.
Stock Eneloops are one of the most robust cells currently made. They maintain capacity and have lower internal resistance longer than almost anything, China made Eneloops excepted.
Marketing claims for most cells range from overly optimistic, to downright complete fabrications. The better the cell, the more they lean toward optimistic.
+1 on thefreeman response. Battery testers have resistors in them that place a load on the battery (usually a few ohms) so you get a better idea of the actual stage during use. The multimeter just does the open circuit (no load) voltage.
High capacity NiMH aren’t that bad and LSD batteries like Eneloops (or any Fujitsu NiMH) have long shelf lives. They were a huge leap forward from NiCad batteries and modern NiMH are great for life cycle if not abused with high recharge or discharge rates.
I read about how to revive batteries that display no voltage. The article instructed to test if there’s any voltage with multimeter. If there was then the battery was revived. In my case however I have batteries that show 1.2V in multimeter yet on battery tester show 1.14V. They have higher internal resistance and last very little. It is strange that article used multimeter and not battery tester to determine their condition.
That sounds like it was “revival”, bringing back a battery from the dead=zero volts. A tester would not show anything either. FWIW voltage testing on NiXX has LOTS of problems. It’s very inaccurate and almost useless for capacity or current support.
Lots of smart chargers won’t charge them. A dumb charger, or a straight positive to positive and negative to negative short with a full battery may jump start them and allow them to be charged normally.
Zero volts is not good for them, but most can continue to be used with this technique.
It is pointless to measure nimh cell voltage, (unless you checking if the cell is toast or has some life in it), open circuit or with a resistor makes little difference, nimh stay at constant voltage from almost full until the last minute, that is why there are no battery meters for nimh cells. cuz at 10% or 90% the cells will have same voltage. there is just no way to tell the state of charge for nickel cells.
I have 2 battery testers that show different readings. The old one shows around 1.25v for AA alkaline battery while the newer shows 1.48v and multimeter shows 1.51v
I understand that multimeter applies no load hence the small variance but why it is noticeable between 2 battery testers? Does one apply more load than the other? I tested with other batteries and observed similar behaviour.
looks like the old one has a resistor, and the new one simply measures open circuit voltage. as well as mentioned above fact that those are simple cheap devices. usually those testers only good to tell if the cell is dead or has some life in it. i have one too, it does not even show voltage, just a dial with 3 zones, red, green, and a small yellow strip in between. But those things are no good for nimh cells, they will always show low, they usually are "calibrated" for 1.5v and sometimes also for 9v alkaline cells.
Fresh NiMh can hit and hold 1.4+v for awhile, depending on the cell and age. When ‘working’ they drop to ~1.2v and stay there a good while. Discharge curve shows an ‘S’ shape, with alkaline being more linear.
So, while in the middle of it’s discharge the NiMh will show close to 1.2v for a long time. No good way to determine capacity from that.
My LD NiMh batteries come off the charger anywhere between 1.45v to 1.5V depending on the charger and battery. When packed away and unused they generally settle to > 1.3v and remain so until used. I figure that any of the batteries in the 1.3v range are fully charged, the percent depending on how much self-discharge has occurred.
Once used they dropped into the 1.2v range as flydiver said and the remaining capacity is anyone’s guess.
