1 post tagged “aa battery”

B-powered is a compact and small emergency battery charger running from a single AA battery.It is hardly larger than the AA battery itself and suposedly adds about 240 mAh to your phone battery charge or to call upto 3 hours on the phone. It seems the perfect companion allowing you to go the distance without worrying to get in a tight spot because you drained the phone battery all the way. Got me one, thus time to test it!

The first picture shows the package. One buys the b-powered stick and the connector required for your phone separately. Also a led-light can plug-in in the b-powered stick is availabe. The b-powered storage box holds the b-powered stick (containing an AA-battery), a second spare AA-battery, the led light and my N95 connector. The connector is available, but not at the shop were I bought it so I built my own ;-)

The built quality is nice. The stick is made of sturdy feeling metal, with a metallic looking plastic top that has a solid feel to it. (right side of the stick in box). The main question does it work and how well does it work? It is specified to give up to 3 hours of talktime extension and capable to charge you phone battery above 70% of its capacity.  A single AA cell should add about 240 mAh to the battery.

The alkaline test:

b-powered connectors

For testing I wanted to drain my phone battery until the low battery warning popup appeared, the quickest way for this is to record video for an hour. Then I had 1 powerbar indicated on the phone. I put a Duracel alkaline AA battery in the stick powerstick and connected it to the phone. About an hour later it quit charging and had added  2 powerbars from the 8 to the phone battery indicator, indicating a total of 3 bars. If this is indeed 1/4 of the battery capacity, about 240 mAh is added.The powerstick casing got warm during the charging indicating that the AA battery was heating up due to the large powerdrain. Alkaline batteries can deliver upto 3000mAh if you extract the power slowly over a long period. During fast discharges however the internal resistance becomes a factor and most of the power can actually be converted to heat inside the battery. However performance was as specified.

The drained alkaline battery registered in my Garmin e-Trex C as 75% empty. Open contact voltage dropped from 1.6 V before charging to 1.25 Volts after charging the N95 with 2 extra powerbars. Open contact is not the best way to measure the powerdischarge but I did not wanted to dismantle my powerstick. Send me one for free and I'll be happy to do the test proper ;-) I put in a fresh alkaline in the powerstick and started charging again. That only added one more powerbar to the N95's battery status indicator. So I played a bit of video quickly reducing the battery status indicator back to 3 power bars again.

The NiMH test:

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The powerstick should also be able to cope with rechargable batteries. I took two fully charged NiMH rechargables of  2500 mAh. Loaded one into the stick and started charging again (3 powerbars on the display). After charging ended it had added 5 bars to the phone and the battery indicator showed the full 8 bars. However I did not get the battery full beep. The powerstick kept cool during the charging indicating that the NiMH battery actually copes more efficiently with large powerdrains than alkaline ones. One should know however that rechargable NiMH loose power over time even when not used and the larger the capacity the faster the batteries loose power. After a week the 2500 mAh NiMH charged batteries are useless. Also of interest is that charging becomes less efficient with as the phone battery gets slowly charged. The NiMH battery performed excellent compared to the alkaline. The NiMH battery dropped its open contact voltage from 1.37 Volt to 1.22Volt.

Still I had not yet got a battery-full beep, so there was more charging to do. It took another 2500mAh NiMH and partly a 2300 NiMH battery (ran out of charged 2500 mAh NiMH's) until I got my battery-full signal. Going for the full battery signal is very inefficient. Since I did not measure the actual power drain on the AA battery compared to the increase of the N95's battery capacity there is plenty room for discussion about the results. Still, enough is known about batteries and charging to draw some conclusions.

Conclusions:

The b-powered works as advertised. At best it can roughly add a 60% of battery charge to the BL-5F in your N95 using a single  2500 mAh rechargable NiMH's or rougly 25% at best of the BL-5F battery capacity using a single longlife alkaline. If you do use alkalines buy the kind that are designed for large power drain, not the ones for long term but low power, as in your kitchen clock. It is best to charge the phone's battery when it is at low power. Topping off the phone's battery is very inefficient.

Of course the phone can draw power directly from the b-powered stick. Waiting for the charging to finished is not required nor practical. Comparable products deliver currents from 240 mA up to 420mA maximum. The charge time versus battery added charge of my alkaline and NiMH tests fall in that range. Thus the b-powered stick is unusable as a contineous powersource for videorecording. For this a power source or charger should deliver do about 800-900 mA (when connected). Satnav takes about 480mA. A high capacity NiMH cell could probabely run satnav for roughly 1 hour and a quarter with a bit of support of the phone's battery.

If you want small as small gets the b-powered seems an excellent backup charging solution. It is hardly larger than than the AA-battery itself. Works on the most widely available battery. However if you plan to take the complete storage box with you on trips, know that the storage box is only slighty smaller than the solarcell equipped lithium battery based Solio recharger. It is probabely larger than most other lithium-ion battery based backup chargers too. The b-powered however does not need the sun or a power-outlet. Any AA-battery widely available even at remote locations around world will work.

One question pops up though: How well does the b-powered and the N95 work at low temperatures? The tests were at a comfortable temperature of 22 degrees Celsius.

12-1-2008, updated spelling.