Performance Question: Eneloop Stick booster and Mobile Booster.

[victory]

Where the mobile booster is concerned, i'm referring to the one that operates with 2x AA eneloops, not the lithium ion one.

If anyone has one, i'm wondering what your impression has been using it to give a quick charge to your mobile devices.

I recently got a stick booster from Japan to provide a quick, portable battery boost to my HTC Evo if necessary. I depleted the eneloops fully and recharged them with my Duracell mobile charger. I put the freshly charged batteries in the stick and plugged my phone in. I only got about a 30% charge on the Evo's 1500mah cell by the time the eneloops ran dry. I wasn't using the phone during the charging. Though the phone was on, the screen was off, superfluous apps were killed and the processor was underclocked to 245mhz (root ftw), so it shouldn't have been consuming that much power.

Am i right to feel like this is underwhelming performance from the stick charger? Might I need to condition the off-the-shelf eneloops a bit with a couple more charge-discharge cycles?

 

[AnAppleSnail]

Where the mobile booster is concerned, i'm referring to the one that operates with 2x AA eneloops, not the lithium ion one.

If anyone has one, i'm wondering what your impression has been using it to give a quick charge to your mobile devices.

I recently got a stick booster from Japan to provide a quick, portable battery boost to my HTC Evo if necessary. I depleted the eneloops fully and recharged them with my Duracell mobile charger. I put the freshly charged batteries in the stick and plugged my phone in. I only got about a 30% charge on the Evo's 1500mah cell by the time the eneloops ran dry. I wasn't using the phone during the charging. Though the phone was on, the screen was off, superfluous apps were killed and the processor was underclocked to 245mhz (root ftw), so it shouldn't have been consuming that much power.

Am i right to feel like this is underwhelming performance from the stick charger? Might I need to condition the off-the-shelf eneloops a bit with a couple more charge-discharge cycles?

Off the shelf eneloops are pretty good.

Most cell phones these days have an onboard charging system - it's fed 5v (USB) and puts 3.7-4.2v to the lithium battery. So here's the steps for charging with this thing:

2.4 to 5v, then 5v to 3.7v. If the battery charged through a resistor instead of smart electronics it'd only be 75% efficient, but that would only rise to 80-90% with spending more money on that part. Call that 80% efficient.

2.4*2000 mAh * 0.8*0.8 = 3.072 Wh.
3.072 Wh / (3.7v average) = 830 mAh charge

30% of 1500 mAh = 450 mAh

So you're getting about 55% of estimated charge. BUT WAIT. If the HTC Evo lasts about 10 hours on a charge in save-power settings, then each hour of charge accounts for 150 mAh of that difference. Finally, how much power does the charger itself take for whatever it does to indicate status? It seems to be not stellar performance, but I bet you didn't pay much either.

 

[victory]

i'm rooted and underclocked on screen off, so my evo lasts the better part of 2 days in powersave.

The eneloop stick doesn't have any sort of status indicator. It has an on switch. you know there's nothing left when it stops charging.

Unfortunately, it's not like i paid $4 for the thing, the eneloop stick boosters are about $35

hopefully it improves a bit, otherwise i'm gonna have to give it a thumbs down. 55% efficiency is pretty bad.

 

[Mr Happy]

Mobile boosters are what they say they are. They give you a small additional boost of charge to get you out of a tight spot. They are not intended to provide a full charge like a regular charger does.

 

[victory]

Obviously. I was hoping for a little better efficiency and build quality from this device...might as well get a $6 booster and load it with eneloops, because that's really all you're getting for $35.

 

[shadowjk]

My Tekkeon MP1550 on 4 eneloops fills up a 1500mAh Li-Ion.

 

[MarioJP]

I have this exact same mobile booster, although would not call it a booster since it really does charges usb devices very well and some power left over with 4xAA's.

I guess the problem here is even though these so called mobile booster is only suppose to get you out of a tight situation. I guess the expectation is people want more charging power lol.

 

[KiwiMark]

I have found that I can get from under 25% to a full charge on my N85 from 2 pairs of Eneloops.

I am curious about the 30% charge - how accurate it that? I have found that my battery gauge on my N85 is horribly inaccurate and I really can't tell to the nearest 10% how much charge I have. Have you tried draining 2 pairs of Eneloops to see how charged the phone is then?

I have a cheap 1 x AA charger as well as my Eneloop Stick Booster - running 4 batteries through the cheapie is probably pretty close to running 2 pairs through the Stick Booster. With the Stick Booster I only have to swap the batteries once though, with the 1 x AA charger I need to change the battery 3 times to get 4 x AA worth of power into my cell phone. I also have a bit more trust in the reliability of my Eneloop Stick Booster - less chance of it just dying on me when I need to get some power into my cell phone. My cheapie gets MUCH hotter during charging too.

Consider this:
1500mAh cell phone battery at 4.2V fully charged may need close to 6.3wh of power to get a full charge from flat. Assuming that no charging device that has to step up the voltage is going to be 100% efficient then you can't expect any where near a full charge from two 1.2V x 2Ah = 2.4Ah batteries - you have 4.8wh at most and with the best efficiency you can expect from a well made charger you still wouldn't be likely to get 50% charge. If what you thought was 30% charge was actually close to 40% (surely this is possible?) then you have done pretty well.

 

[kreisl]

Where the mobile booster is concerned, i'm referring to the one that operates with 2x AA eneloops,

Panasonic or Sanyo never made an 'Eneloop Mobile Booster' which runs off 4x AA eneloops. All their NiMH attempts were with 2x AA eneloops. Then they switched over to Li-Ion based 'Eneloop Mobile Booster', exploiting the Eneloop brand name omg. And nowadays the company has stopped entirely the production of any 'Eneloop Mobile Booster'. Afaik. The products are still available in stores, unsold stock, but they are not being manufactured any longer.

I would have loved a Panasonic-made 4xAA powerbank for testing purposes. I have 2 good ones, their efficiency (device output/device input) lies between 70-85%. And i am getting a 2$ el cheapo from ebay for comparison.

This topic ain't over for me yet. Powerbanks, based on Eneloop AA or LiIon 18650, are fun enough!

 

[ChibiM]

Hey Kreisl..
I havent found 4AA mobile boosters either.
Panasonic still produces "mobile boosters", but not under Eneloop brand anymore.
The boosters now include Panasonic Evolta cells.

Also, Sanyo already produced a mobile power bank in 2006, (KBC-L1)with a 1800mAh lithium cell inside.
But that time it was specially designed for Japanese phones (which required a special connector).
output was 5.4V and 400mA.

in 2007 they produced the KBC-L3S (and L2S)which had an USB out.
Battery inside was 2500mAh, and output was 5V and 500mA.

So they had the Lithium based ones before the 2AA eneloop booster stick (2010)