- Feb 15, 2009
- Melbourne - Australia
For review I have the Xtar BC8 AA / AAA NIMH & for their proprietary AA / AAA Li-ion battery technology . ( Sent to me by Xtar )
This charger is not a Li-ion charger and you should not attempt to use it as such !
It is designed to recharge NIMH batteries and Xtars own Li-ion AA batteries .
If you keep reading you will see why it could be dangerous to try and use this charger incorrectly !
This charger does not currently show on the Xtar website .
Using the BC8
Honestly , it's as simple as plugging in the BC8 into a suitable USB power supply capable of at least 5v 2A . To charge NIMH batteries simply pop them into the charger and pull them out when the charger gives a green light ( fully charged ) . The red light signifies the battery is being charged . And this charger is a constant 0.5A charger , so charging is neither fast nor slow . In fact the charger is nice and easy on the batteries and I did not detect any over heating on the AA or AAA I charged . AA stayed in the 30 deg C range and I did see 42C on a few AA , ( Room temp was 20 deg C ) .
A unique feature of the BC8 is the hole in the back of the charger . I believe this is to aid in the extraction of batteries that have completed their charge cycle . It can be a real pain peeling the odd battery out of a charger once it has finished charging and the hole in the back allows you to simply push out the completed battery with little effort .
Charging AA / AAA LI-ion ( From Xtar )
Just as easy as charging NIMH batteries . Just pop them in the charger and he charger automatically detects them and charges them . Speaking off !
The charger starts at 4.2 volts 0.5A and voltage slowly increases to 4.8 volts and then the current slowly decreases and the charge cycle completes at around 5 volts . This is why it would be a very bad idea to try and charge other batteries ( Li-ion / Lipo ) with this charger .
Video shows the charge cycle for the Li-ion AA ... ( Less than a minute = Compressed )
I had absolutely no issues what so ever with the BC8 charger . All the NIMH batteries terminated as they should , there was no overheating of the batteries or charger that I could detect . In fact it just did what it's supposed to do with the NIMH and Li-ion batteries ( Xtar ) .
Xtar Li-ion AA / AAA
I ran a discharge at 0.2A on one of the AA Li-ion batteries .
Initially the voltage dropped slowly into the 1.2 volt range ( being discharged )
The voltage bottomed out at 1.14 volts around 1000mAh having being discharged and then began to rise !
1359mAh / 1.17 volts
1477mAh / 1.23 volts
1485mAh / 1.3 volts
1514mAh / 1.32 volts
1604mAh / 1.32 volts
1745mAh / 1.32 volts
1814mAh / 1.32 volts
1915mAh / 1.32 volts Terminated Discharge .
So the way the AA Li-ion work is .. There is a li-ion battery inside with a driver that regulates voltage ( 1.5v ) .
I did run a discharge against a NIMH @ one Amp discharge .. To see which battery could deliver better voltage under load ( being 1 Amp )
Nimh battery @ 1 Amp discharge = 0.76 volts
Xtar Li-ion battery @ 1A discharge was 0.88 volts
It's a small difference , but the difference favors Xtars Li-ion AA .