My array of lamps, with ammeter and voltmeter, lets me (with some minor arithmetic) know the IR of my batteries. I haven't tried to measure IR of individual cells, because the information would be of no use to me - I'm not going to dismantle a battery to salvage good cells, I'll just replace the whole battery. But using my lamp array feels a bit crude.
So I got the 7-in-1 meter from Hobbyking, which claims to measure IR. That was a big disappointment, I posted about that before.
Now I've tried another device from HK. https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14857
$19.95, it's a charger/balancer, and glory! It also measures IR. And it's *MUCH* better. I measured ten Hobbyking 4S 20C hardcase batteries, and I got, milliohms, 25, 25, 26, 28, 23, 55, 21, 24, 24, 20.
The 55 is for a battery that has a wonky connection; I have the battery cable taped to the battery so that it can function. So the 55 isn't a surprise.
One peculiarity is that the cell IRs for each of the four cells looks like this: 14, 4, 5, 2. In all cases (except the 55 one), the IR of the first cell is more than half the total IR. I think this is a peculiarity of how they're doing it. And I really don't care; as I said, the only thing that's important to me, is the total IR.
So I'd say, this one works!
Some of the reviews report that it can get very hot while charging, several reviews reported "dead on arrival".
As a charger, it's "OK" (there's no manual included, but all these balancing chargers seem to work the same way, and you can download the manual from the HK web site). Max watts is 50, so I'll only be able to feed a bit over 3A into my 4S batteries. But I'm not bothered, I already have two iMax chargers, 80w each, for the main charging job, all run off old PC power supplies. And now I can check the IRs quickly and easily.
So I got the 7-in-1 meter from Hobbyking, which claims to measure IR. That was a big disappointment, I posted about that before.
Now I've tried another device from HK. https://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14857
$19.95, it's a charger/balancer, and glory! It also measures IR. And it's *MUCH* better. I measured ten Hobbyking 4S 20C hardcase batteries, and I got, milliohms, 25, 25, 26, 28, 23, 55, 21, 24, 24, 20.
The 55 is for a battery that has a wonky connection; I have the battery cable taped to the battery so that it can function. So the 55 isn't a surprise.
One peculiarity is that the cell IRs for each of the four cells looks like this: 14, 4, 5, 2. In all cases (except the 55 one), the IR of the first cell is more than half the total IR. I think this is a peculiarity of how they're doing it. And I really don't care; as I said, the only thing that's important to me, is the total IR.
So I'd say, this one works!
Some of the reviews report that it can get very hot while charging, several reviews reported "dead on arrival".
As a charger, it's "OK" (there's no manual included, but all these balancing chargers seem to work the same way, and you can download the manual from the HK web site). Max watts is 50, so I'll only be able to feed a bit over 3A into my 4S batteries. But I'm not bothered, I already have two iMax chargers, 80w each, for the main charging job, all run off old PC power supplies. And now I can check the IRs quickly and easily.
