New guy here- I’ve been lurking for awhile and then the addiction kicked into high gear and I bought a few flashlights, a cheap charger and some rechargeable batteries to get me started.
The charger is a cheapie from ebay- Ultralast Green is the model.
I put a couple of their AA batteries in to charge and let it charge for about 12 hours ( they say it takes 9 hours), but when I took the batteries out of the charger, my DMM read 1.3ish volts.
Are the batteries defective? or do I need to cycle them a few time to get them to take the full charge?
I have some Duraloops ordered but they’re not here yet.
Welcome to BLF! I would recommend getting a better charger as that is probably the reason they are not getting a full charge. I would recommend the intellicharge I4 which can charge both Nimhs and Lions. Out of curiosity what batteries are these?
+1 on the better charger. Also over charging is rarely a good thing.
NiMh cells should be 1.2v. What voltage were you expecting?
1.2 volts is nominal voltage. Nimh cells should charge up to around 1.45 and then settle to around 1.4 volts. This is like Lions which have a nominal voltage of 3.7 and a full charge voltage of 4.2.
scaru is correct. A fully charged NiMH has an open circuit voltage of around 1.45V fresh off the charger.
Some chargers like my Maha BC-9000 will try to take a cell to 1.47v but anything in the mid 1.4s will do. Note that the cell voltage will drop a small bit after you take it off the charger. If you measure your cells at 1.3 volts immediately after you remove them from the charger something is wrong. Either your cells, charger or DMM is faulty. Substitute one of those three things (one at a time) to determine where the problem is. If the cells are cheap no-name ones that is what I would change first.
Although the intellicharger is supposed to be a fair Lithium ion charger I don’t recommend it for NiMh. According to HKJ it does not use -dv to determine the termination point. Negative Delta V is the most commonly used method to terminate a charge for NiMh, and it works well with all but very old cells where the internal resistance is so high that the negative change in cell voltage is so small that many chargers don’t detect it consistently.
If you feel the charger is at fault, try to find a charger that has individual charging channels i.e. four cells, four channels. This allows each channel to shut off independently of the others so that no cell gets overcharged. Look for one that uses -dv for termination, most dedicated NiMh/NiCd chargers will.
Avoid the so called “15 Minute” chargers as tests have shown that charging NiMh cells at much more than 1C reduces their life considerably. Ideally you want to charge a NiMh at .5 to 1C, so if you have a 2000mAh cell you want to charge it at between 1 and 2 amps. Most chargers will state the charging current on the packaging. If one doesn’t, avoid that charger.
Hi and welcome to BLF, Extra Bright. In my experience, some rechargeables take a few cycles to reach full charge capacity, so hopefully this will improve with yours. Definitely don't charge them longer than recommended though - it won't help and may end up damaging them or limiting their useful life.
Duraloops /White tops are a simple smart way to do low self discharge in the states. mine after sitting for a while end up at about 13.5 V I assume your batteries will get a little better with use ..But would avoid cheap nimh unless you get a greta deal and neeed them for dumb stuff..I have cheap kodak nimhbatteries in my phones ...always on the charger
Welcome to blf Extra Bright. Do you have a link for those batteries?
We're very glad to have you here, Extra Bright!
Here is the charger. I bought it mostly because I wanted AA’s for my camera. The flashlight addiction crept in afterwards.
But now I have 4 or 5 lights that use AAA’s, so I guess I’ll probabaly have to buy a charger for the 18650’s… AND the batteries for each. :8)
I was trying to avoid spending $100 on supplies for a bunch of $5 flashlights…LOL.
The images don’t seem to be linking for me…
And thanks for the warm welcome.
I was expecting something closer to 1.5 I guess.
Oddly enough, even with that “low” voltage, the batteries performed very well in the camera. I shot 65 pictures (most with flash) before the low battery warning, and then clicked off 20 more flash pictures just trying to discharge the batteries a little more- and they were still going. :~
1.3 v seemed to be about where the camera rejects regular alkaline batteries as “low”.
To be honest, I have never heard a good thing about those batteries. Take Boaz's advice and try out some Duraloops or eneloops - you will see a marked improvement.
Oddly enough, they have ‘white tops’ that look like Eneloops… but they didn’t come precharged.
On the second charging cycle, I got 1.4 and 1.39, so it may be improving with use. This charging cycle was on a different channel in the charger though.
Meh… whadya want for $7.00?
I think someone mentioned it earlier, but most cells do seem to improve (have more capacity) during the first 5 or 6 charge/discharge cycles.
I have taken fresh cells and put them through up to 10 charge/discharge cycles while measuring the discharge with a C9000. There was a small improvement in capacity as the cells got “broken in”. Some cells did better than others, but all of the ones I tried exhibited some improvment.
The cells I did this with were pre-LSD varieties. I haven’t done this with eneloops or other brands of LSD cells, but I suspect with them the improvement would be less, if at all.
I generally set up to charge nimhs at .1C and charge them overnight. A trickle charge like this is okay for longer periods where a faster charge might overheat the cells if left on. I should get better chargers though.