What batteries are you using in your ***ex flashes?

Nick_C wrote in post #2750202
Im using 2800mAh NiMh batteries in my Sigma flash, they last quite a while.

Remember NiMh lose 5-10% of their charge each day whether you use them or not though, so keep them topped up in the charger from time to time.

Nick

Are you sure I thought it was 1%.

BradT0517 wrote in post #2751107
Are you sure I thought it was 1%.

1% is correct...on average...

Regardless of the percentage of loss that is great advice. Many people charge the batteries, put them in a device and then assume they will be fully charged when they pick up that device in 2 weeks.
It's always a good idea to give them a charge before you need them if they've been sitting.

To be a little more precise its around 40% in a month, so thats about 1.5% +/- a day isnt it?

Nick

Nick_C wrote in post #2750227
Nimh batteries dont require discharging & have no memory effects, so ive heard where as NiCad rechargables do.

Nick

yep, that's correct

TMR Design wrote in post #2748292
Around here (Long Island, New York) I can get the Energizer or Duracell's at Best Buy or K-Mart.

thanks, brad and TMR Design i'll go check out best buy!

I see that several people use "15 minute" chargers. A depleted 2500 mah battery should require a 10 amp charge rate to recharge in 15 minutes. In reality, the charging energy can be up to 150% of a battery's rated discharge energy, so it could take up to 15 amps to charge these batteries in 15 minutes.
http://www.powerstream​.com/NiMH.htm

I use a (two year old) Maha C801D conditioner/charger, and it is only rated at 2 amps, taking 75 minutes to fully recharge 2500 mah batteries. The charger's literature recommends that lower capacity batteries should be recharged at a reduced (1 amp) rate to prevent overheating. I once tried to recharge some older 1500 mah batteries at 2 amps and they got really hot, so their literature seems to have some validity.
http://www.imaging-resource.com/ACCS/C801​D/C801DA.HTM

So I guess my question is whether there are newer chargers that can recharge 2500 mah batteries in 15 minutes without destroying them. If so, how do they prevent overheating the batteries?

Some of the new fast chargers have fans to cool the batteries, this whole thing seems to be a little over the top if you ask me, 15mins is nice but not if its got to have cooling fans to stop them overheating, whats next? water cooling?

I use a 2 hour charger & they come out warm, ive also got a 40min charger & they come out very hot.

Slow charging is always better for the batteries, ideally the older 14 hour chargers will not stress the batteries at all, however you also have to remember that 2800mAh NiMh batteries are relatively cheap to buy nowdays so a fast charger even though its limiting the overall life might still be worth it.

Nick