Problem with Uniross 2700mah rechargables

fozzybear

fozzybear

fozzybear

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I bought some of these the other day with a Uniross Sprint recharger.

In the instructions, it said from dead, they take approx 2 hours to recharge the 2700mah's. Actually it took 25 minutes and I actually went through 4 'fully' charged batteries in a few hours on Saturday.

I'm not impressed. My non rechargable Duracells lasted longer.

Does it sound like there is a problem with them or the recharger?
 
I have the uniross 15 minute recharger & batteries, they're all rubbish

the rapid recharging ruins the performance of the batteries and I found they didn't last well at all

I then bought a decent charger and 4 hybrio batteries (they lose very little charge over time) these are excellent, they last for ages and even though the rated capacity is smaller than some batteries they last for ages with even the most demanding equipment, when not in use they still hold their charge
 
I use the Uniross AA's rated at 2300 and have found them to be excellent. My charger is not a rapid one though and takes around 90 minutes for a full charge.

Maybe one of the four batteries is faulty?
 
I remember looking at that charger but ending up going for a slower uniross one. Does that version provide a trickle charge after it is finished or not? If it does leave them in there for awhile.
 
what camera is it? Just wondering seeing as my old Fuji has a setting to use rechargeables and if it's set wrong, the batteries last no time at all!

Plus, the cold really affects nimh batteries, they lose a lot of their capacity if it's cold or hot, and as said above the slower the charger the better the battery will hold the charge!
 
RaV said:
I remember looking at that charger but ending up going for a slower uniross one. Does that version provide a trickle charge after it is finished or not? If it does leave them in there for awhile.
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Yes, it does have the trickle charge. I'll try leaving them in.

I'm just comparing them to a pair of Duracell Ultra's that I previously used. I took around 500 photos (without flash) and used all 4 Uniross 2700mah batteries. Does that sound about right or should I be getting more out of them?
 
fozzybear said:
I bought some of these the other day with a Uniross Sprint recharger.

In the instructions, it said from dead, they take approx 2 hours to recharge the 2700mah's. Actually it took 25 minutes and I actually went through 4 'fully' charged batteries in a few hours on Saturday.

I'm not impressed. My non rechargable Duracells lasted longer.

Does it sound like there is a problem with them or the recharger?
Click to expand...

i find uniross batteries ****. They are only 1.2volts arnt they? My old digital camera could take about 100 shots on uniross 2500mah's 1.2volts, vs 500+ shots on Hahnel 2500mah 1.25volts.

I also found that uniross Batteries died after about 2days of storage, where as Hahnels will hold charge for months. (camera still turns on now, and last time it took a picture/video was November)
 
Try fully de-charging them and then trickle charge them to full capacity.

Your charger should have a function to de-charge the battery.
 
In the instructions, it said from dead, they take approx 2 hours to recharge the 2700mah's. Actually it took 25 minutes and I actually went through 4 'fully' charged batteries in a few hours on Saturday.
Click to expand...

leave them in the charger for 2 hours for the first charge.
 
In the instructions, it said from dead, they take approx 2 hours to recharge the 2700mah's. Actually it took 25 minutes and I actually went through 4 'fully' charged batteries in a few hours on Saturday.

Over the past few years trying to find a reliable substitute for Alkali Manganese and the newer(And superior) Ultimate Lithium cells, I have come across Uniross products that really work well PROVIDED you stay away from high speed chargers and observe the simple rules of only using fully charged cells. A 2700Mah NIMH cell is most reliable when charged in the Uniross (Or equivalent) timed and current limited chargers. The recommended charge for a 2700 Mah cell is C/10. I.E one tenth of its rated capacity. That is 270Ma from a current limited source. The AA cell is designed to withstand this overcharge rate without causing overpressure and puncture of the safety diaphragm. Once fully charged, the evolved gases are converted back into water by a catalytic process. This converts the 270 Ma current into heat by simply combining the evolved gases. The cell can withstand this condition almost indefinately. Exceeding this steady state overcharge rating is bound to lead to trouble and unsatisfactory performance. To charge a 2700Mah AA cell in two hours would need a current of at least 1850 Ma under very closely controled conditions. Subject an AA size Uniross 2700Mah cell to this high over current will almost certainly destroy it in a very short time. Given the right control conditions, most cells can be charged in a very short time - provided the charging current is reliably reduced when full charge is reached. Just as damaging is mixing fully charged and partially charged cells in series under high load service. The partially charged cell discharges first and then is driven into damaging cell reversal by its fully charged companions. The reversed cell quickly goes into over pressure and pops the safety diaphragm. From that point on it rapidly looses its ability to take and hold a charge. To charge a 2700Mah cell in 25 minutes will need a charge current of 6418 Ma thats 6.1 amps. You would need very accurate control to use such a high current and if a few cells are charged in series they had better be of well balanced capacity.
 
JBuk said:
I then bought a decent charger and 4 hybrio batteries (they lose very little charge over time) these are excellent, they last for ages and even though the rated capacity is smaller than some batteries they last for ages with even the most demanding equipment, when not in use they still hold their charge
Click to expand...

Ditto

I have been using hybrio's for quite a while now, would not use anything else. For my Touches my Flashes and even have a set ready to use in my battery grip for emergencys.
 
Sounds like you may have a fault as I have some Uni 2700's and they perform really well and offer fast recycle times and plenty of pops, but like most NIMH batteries, if you don't use them the same day as you take them out the charger they, dissipate ALLOT of their charge.

@ Razor
The eneloops are good, but there are a few tests/review online that show other batteries with higher mah to perform better, especially after you'v let off a few pops.
 
Overlag said:
i find uniross batteries ****. They are only 1.2volts arnt they? My old digital camera could take about 100 shots on uniross 2500mah's 1.2volts, vs 500+ shots on Hahnel 2500mah 1.25volts.

I also found that uniross Batteries died after about 2days of storage, where as Hahnels will hold charge for months. (camera still turns on now, and last time it took a picture/video was November)
Click to expand...

You shouldn't be using NIMH batteries to be used casually in a camera (unless they are hybrids or something, which is still not great), as the batteries lose most of their charge in a few days.

NIMH batteries with high mah even only being 1.2v, provide much better performance in terms of recycling your flash quickly than a Hybrid NIMH, Li-ion or alkaline battery's or similar with higher volts, but they do need to be used the same day they come off the charger if you plan a long shoot with them.

The only batteries that beat NIMH batteries on performance are NIZN batteries, and they self discharge faster than NIMH.

http://strobist.blogspot.com/2010/01/new-nizn-batteries-offer-lightning-fast.html
 
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I bought 2 packs of 4 of the 2700 plus a Uniross charger about a year ago.
They are complete and utter sh1te, I bought them to use in 2 flash guns, but they don't last long at all.
Even in electric toothbrushes, wireless keyboard and mouse, they don't last.
 
^^^

:rolleyes: Noob comment tbh, should be using low discharge batteries for mouse, keyboard etc.

In flashes they should be used the same day you take them out the charger.
 
Most First Time Nicad or Nimh Users are Disappointed

Overlag said:
i find uniross batteries ****. They are only 1.2volts arnt they? My old digital camera could take about 100 shots on uniross 2500mah's 1.2volts, vs 500+ shots on Hahnel 2500mah 1.25volts.

I also found that uniross Batteries died after about 2days of storage, where as Hahnels will hold charge for months. (camera still turns on now, and last time it took a picture/video was November)
Click to expand...

I was involved with providing reliable flashlights for daily use. The normal disposables are very expensive to use and rechargables seemed to be the answer. Fancy Maglites with Nicads at £400 each were soon almost useless. The problem was the charging method. A torch came off shift and had its cells removed and charged. The next shift simply took 5 cells from the "Charged" box. Within a few weeks the torches failed after a few hours use. Its definitely worth taking a bit of time to find out why. We now have Salt and Pepper grinders, electronic flash units and toys that dont need a small fortune in Duracells to keep going.
1. Always use and keep cells in marked "Sets".
2. Always charge the cells in sets or as near as possible in sets.
3. Most store bought chargers hold 2 or 4 cells and charge them in pairs at C/10 (One tenth the mA rating) The chargers are "Automatic" I.E. they have a 10 hour charge timer and no means of temperature or voltage shut-off. Voltage is useless anyway. Current limited to C/10 with a 10 hour timer is the best without spending money on temperature rise sensors. I keep a 4 way DIN socket extension on a (Wood Top) kitchen dresser so the chargers are easy to monitor and battery warmth easy to check.
4. The 4 way charger is the handiest and I use the charger to store unused cells. This makes it easy to pop a set of four back on charge. If they are fully charged, in an hour or so, the cells will all be equally warm. If one isnt, its either faulty or isnt fully charged. Leave them all on charge until all are judged (Or Measured) to be equally warm.
5. Keeping the cells in balance is the secret to reliable performance. One undercharged cell in a string is all it takes to cause cell reversal that if not detected in time goes into overpressure and punctures its "Safety Valve". Once the safety is punctured, the cells life is measured in days at the most. One damaged cell in a set soon passes its problems on to the next and the whole lot are branded as **** by disappointed users.
6. Certainly, a Nicad or NiMh cell is only 1.2 volts compared with the Duracell at 1.5 or so but most primary cells rapidly drop to lower voltage levels and dont have the discharge current capacity of a rechargable.
7. My Son does a lot of flash photography with his Canon accessory flash gun. He has pronounced a set of 4 UniRoss AA 2700mAH cells "Brilliant", and a real money saver.
 
Ejizz said:
^^^

:rolleyes: Noob comment tbh, should be using low discharge batteries for mouse, keyboard etc.

In flashes they should be used the same day you take them out the charger.
Click to expand...
I do use the batteries the same day when using them in the flashguns.
And the only reason I use them in the keyboard/mouse is because I might as well use them for something instead of throwing them away.
 
Same here, 2700mah batteries for a couple of off camera flashes and just didn't last long at all. even when charged in the afternoon for the evening. I've now got some eneloops (or however you spell it?!), which seem to recycle ok but last a lot longer.
 
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