Bunk NiMh Cells Or Are They Just New?

My Titanium branded 4500mah C NiMhs in my FT-3C (TV1J) fresh off the charger only pulled 1.5a. I get higher current readings with fresh Enegizer Max alkalines (1.5-16a). I hear reports of TV1J FT-3Cs pulling around 2a or very close to it on fresh 4500mah NiMhs. Of course I'm not wanting to run it at those current levels, I was just concerned about the performance of my cells.

The NiMhs are only on it's second charge. Rechargeables were supposed to get better in capacity after cycles it's first few times, correct? Or are my cells just flat out bunk or not meeting the 4500mah spec?

I don't know much about batteries specnically speaking so any help is appreciated.

Thanks

It is commonly advised to do a break-in cycle for your first charge. Usually at 0.1C rate. After that, charge at the recommended rate. For cells of this type, 1C is not uncommon although 0.5C is ok. I have found that high current cells take about three to four cycles to get up to snuff, at least at 8A or 4C draws.

1.5A is crazy low for cells of that size and capacity.

Wilkey

Wilkey, sorry I don't know much about batteries. What does .1C, 1C, and .5C mean. I got a feeling I'm gonna have that "duh" feeling.

As far as cycling them, can I just charge discharge and the charge them a few times waiting for them to cool in between cycles? All I have is a Vanson BC-1HU charger and an old Pro-Tech 701 analog charger from my R/C days with current adjust. If not, how can I go about cycling them without hi-tech equipment?

Appreciate the help!

Unless the protech is rated for nimh cells, do not use it. The cells were nimh, right?

Cycles, yes charge and discharge. Do not discharge till dead. You're looking to hit about .9 volts per cell under load.

The C ratings are a fraction of cell capacity. For a 4500mah rated cell (which is 4.5 ah) a 1C discharge rate would be 4.5 amps (4.5 ah capacity divided by 1 hour (the 1C part) equals 4.5 amps). So a .5C rate would be 4.5ah/2 hours or 2.25 amps.

It is highly likely you just need about 4-5 cycles on your cells. Just for kicks see if you can check their voltage under load. Compare this to what happens as you cycle them.

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darkzero said:
My Titanium branded 4500mah C NiMhs in my FT-3C (TV1J) fresh off the charger only pulled 1.5a. I get higher current readings with fresh Enegizer Max alkalines (1.5-16a). I hear reports of TV1J FT-3Cs pulling around 2a or very close to it on fresh 4500mah NiMhs. Of course I'm not wanting to run it at those current levels, I was just concerned about the performance of my cells.

The NiMhs are only on it's second charge. Rechargeables were supposed to get better in capacity after cycles it's first few times, correct? Or are my cells just flat out bunk or not meeting the 4500mah spec?

I don't know much about batteries specnically speaking so any help is appreciated.

Thanks

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You may simply have a luxeon with a slightly higher Vf than others. The ones that are pulling 2A may have a luxeon with a very low Vf. It's not surprising that alkalines are (initially) supplying more current. I wouldn't be very worried about your cells.

Jeez, I didn't even think of that. The cells supply all the current the load demands. Maybe it's just not demanding that much from these cells. I would only be concerned if you aren't getting near the theoretical runtime based on capacity. That would indicate a cell issue.

Wilkey

My 1st run FT3C (bin unknown, have not taken the star off to check) drew 1.62 amps from Titanium 4.5amp Cs the 1st time fresh off my Vanson charger. I think that's typical from what other FT owners have posted. After running the light for several hours, I recharged them again for their 2nd run. They've been sitting in the flashlight for 15 hours without turning it on. I just now checked their draw. 1.39 amps, tapering to around 1.3 amps after 15 seconds.
I'm very happy with this lights performance using these batteries. It was still quite bright before I recharged the cells which were still delivering .5 amps.
Brian

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evan9162 said:
You may simply have a luxeon with a slightly higher Vf than others. The ones that are pulling 2A may have a luxeon with a very low Vf. It's not surprising that alkalines are (initially) supplying more current. I wouldn't be very worried about your cells.

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Come to think of it, you're probably correct. I also have TV1J but of course no two luxeons are created the same. I'm probably a victim of the luxeon lottery. Those who have TV1Js report close to 2a loads on fresh NiMhs and 1.6a with fresh alkies. I get the same numbers with alkies but not with the NiMhs, which is why I thought something might be wrong with my NiMhs cells.

With a TV0K I get 1.3a on the same NiMhs and almost 1.3 on alkies. I only got barely over 1.2a on the NiMhs first charge.

I'm still a little puzzeled why I get low numbers but I won't worry as you guys suggested. I'll cycle them and see what happens, although it doesn't seem that will get me higher load numbers?? Thanks