I bought a pack of 16 Eneloop AA rechargeables. Made in Japan, not in China, thank God.

My battery charger analyzes the batteries as they charge. Fifteen of these batteries show an internal resistance (expressed in 'mR' which I'm certain is 'milli-something') of 20 to 23, very consistent from battery to battery. One of these batteries shows an internal resistance of 73. This is a new, unused battery.

I've done a bit of reading online and it appears that the variation in internal resistance is to be expected, due to the material used in the batteries and the way the batteries are constructed. I'm wondering if this value being so far out of range of all the other batteries is an indication I shouldn't use this battery.

I have some D cell rechargeables- Tenergy (made in China, unfortunately). While these batteries do have variations in their internal resistance, none of them are as far out of range as this one AA cell.

The internal resistance typically increases with charge/discharge cycles. It should be measured in milliohms.

If it were mine I would probably test the capacity and compare it to the other cells. If it gets hotter than the other cells I might discard it. You will probably see that cell life reduced and it might not put out the same current as the other cells, but it is probably fine for low drain applications.

When I get a chance, I can gather up a few Eneloops and check the resistance on mine.

quote:

Originally posted by BlackTalonJHP:
When I get a chance, I can gather up a few Eneloops and check the resistance on mine.

Sure do 'preciate it.

quote:

I'm wondering if this value being so far out of range of all the other batteries is an indication I shouldn't use this battery.

If it were me, I'd mark it as such and use it for less mission-critical things like that old flashlight.

But that's just me.

I'd also expect the overall life to be less, as well as the time between charges.

What are these batteries going into?

Streamlight Siege LED lanterns and C Crane radios- specifically, a Skywave SSB and a CC Pocket.

Also, I should add that you might check the anode and cathode and make sure they are clean and uniform and are getting good contact in the charger. The resistance can vary based on a small variation in the contacts.

That is a pretty big disparity, but not necessarily indicative of a bad cell. It isn’t going to hurt your device or the other batteries to use it. The big thing it will do is mean that all the batteries will not discharge equally. So, you when the total voltage for the device gets low enough that it needs a recharge, some of the batteries will be below the average cutoff voltage and some will be higher. This always happens, the difference between the lowest and highest cell will just be bigger with a larger spread of IRs.

Does that matter? Only if it makes the lowest resistance cell discharge so much that it damages the cell, or if it makes the highest resistance cell overheat. If you were using these in something with a huge amp draw like an RC car, the overheating could happen, but D-cells? Most things designed for those aren’t going to pull enough sustained amps to matter. As for over-discharging them, it depends on how many batteries are being used in the device. If it is only two batteries, it might possibly be an issue over time, but with three or four batteries and one of them being higher resistance, the voltage on any given cell shouldn’t end up low enough to cause lasting damage.

Well-matched IRs in a pack or device is nice because it increases the chances that all the batteries will drop below desired voltage at the same time, but it isn’t the only factor which determines that. Bottom line: I’d use it.

- Bret

quote:

Originally posted by sadlerbw:
The big thing it will do is mean that all the batteries will not discharge equally.

So, ideally, I should try to use this battery in a device which takes one battery only.

Here's my results from 3 different Japanese made Ni-MH batteries along with a Panasonic 18650 made circa 2003. These AA's don't see hard use, only in things like mice/keyboards/flashlights/etc, but are between 5 and 10 years old.

 
I would toss the one reading 73. It is way too far out of range. The ones reading in the 20s sounds about right for that size battery.

I don't usually bother with smaller batteries, as they are cheap enough to replace, and my charger does not measure it. If one cell takes longer to recharge, I toss it. But I do measure and record the internal resistance on automobile, ATV, and UPS batteries when new, and then keep an eye on it over time. It seems the smaller the battery, the higher the initial internal resistance. A full sized auto battery will read <5mΩ when new. It does increase over time with recharge cycles.

The internal resistance only determines the maximum current flow and nothing to worry about.

At 2 amps output:

.073 internal resistance equals .146 voltage drop
.020 = .040

Thanks for the responses. Here's something I don't understand. I have a Sony radio, takes 4 AA cells. I have Eneloops in it. Since I have my charger out, I pulled the batteries from this radio to refresh them. The display was working, the radio turns on, so the batteries weren't dead. I put these four batteries in the charger (an IQ338XL). Three of the batteries began charging, but one of them is not recognized at all by the charger- it's as if there's no battery in the slot. Obviously, the battery is functioning, otherwise, the radio would have been dead, so, what's the deal? Needless to say, I'm setting aside that particular battery. I'm just curious what's going on.

I would move that battery to another slot in the charger and see what happens.

The battery may not have been making good contact. Roll the battery while it is in the slit.

I assume you tried other batteries in that slot and it is indeed the battery and not the charger.

Some chargers won't charge a battery if the voltage is under about 1.1v. Is the voltage between 1.2 and 1.5v on the battery? Since that charger also charges lithium ion batteries, it may think that it's a 3.7v battery and doesn't want to charge it due to low voltage.

I don't have that exact charger but it really looks like it's made by LiitoKala to me. If so, the 4th slot is going to be the slot used for the power bank function and has additional circuitry that may have failed.

quote:

Originally posted by BlackTalonJHP:
I assume you tried other batteries in that slot and it is indeed the battery and not the charger.

Correct

quote:

Originally posted by BlackTalonJHP:
I don't have that exact charger but it really looks like it's made by LiitoKala to me. If so, the 4th slot is going to be the slot used for the power bank function and has additional circuitry that may have failed.

Well, that's the slot I tried it in- the fourth slot. I haven't tried it in the other slots because I don't want to interrupt the charging of the other batteries. I'll try this battery in one of the other slots when they become available. What do you mean by "power bank function"?

.

There should be a female USB A port on your charger. If you place a Li-Ion battery in slot 4 you can plug in a USB charging cable and charge your phone or device off of the battery placed in slot 4.

If you look at this LiitoKala charger, you can see that it says 'for USB output' on slot 4. Some chargers work the same way but aren't marked as such.

My charger has no such marking on any of the slots, and interestingly, the manual for this device barely refers to the USB charging port and says nothing about its relation to the fourth slot. I don't use this charger to charge power banks, anyway. I have a simple charger for those, or I plug them into my laptop to charge. My charger is quite similar to the one pictured above. The display is nearly identical, except the internal resistance is displayed as "mR".

You did call it correctly, however, about the charger not recognizing batteries with voltage below 1.1v, at least for that fourth slot. The battery in question is recognized when I put it in other slots and is charging now. Initial voltage displayed was .71v.

It just goes to show you that manuals translated from other languages are the bane of users. The charger was designed in Austria but manufactured in- where else- China.

Good deal. Unfortunately all my chargers are made in China since I've never seen one made elsewhere. At least my rechargeable batteries are made in Japan and Korea and primary batteries are USA, Singapore, Thailand, and Brazil.

Seems unlikely to be the culprit, but I'll mention just as a data point for future reference. IR increases as temperature decreases -- recall how car batteries sometimes won't start a car in the very cold.