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Old April 15th, 2011, 07:00 PM   #1
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Join Date: Mar 2003
Location: Netherlands
Posts: 126
Dangerous Hawk-Woods Li-Ion charger without cell balance?!

Hi Folks,

Quite some time now have a Hawk Woods VL-L1 Li-Ion charger and a Swit 126 Wh 14.4 volt Li-Ion battery. (Sony V-lock mount)



Meanwhile I learned a thing or two about Li-Ion batteries (and NimH eneloop, Li-Poly, LiFe) And rule number one about Li-Ion and Li-Po batteries is that they should always be balanced charged. This means the charger does not only charge up to a certain total voltage, but also keeps track of every individual cell and makes sure every cell has the same voltage after charging.

Today however, I noticed the Hawk Woods VL-L1 charger only has TWO pins to charge the 14.4 volt Li-Ion battery! So this means it just charges tot a certain total voltage before it cuts off and shows the 'full' led. To balance charge one would need extra pins to measure the individual cell voltage of a pack.

So now comes the scary part. If a charger only checks the total voltage it could potentially make the battery explode! For example, if one cell gets worn out before the others or for whatever reason doesnt get to the normal voltage while charging, the charger would keep charging forever because the pack as a whole would never appear to be full. Same would happen if the cell imbalance grows over time, making one cell for example fall more and more behind. This would eventually damage that cell because of deep discharge and then would cause the other cells to overcharge because with only TWO pins a charger can't see what's going on inside of the pack and will only measure the total voltage and will thus keep on going to get to the charged total voltage!

And over charging Li-Ion cells or Li-Po cells is VERY DANGEROUS and could very much burn down your home or cause serious personal injuries! Ask an electric RC car/plane helicopter owner and they know exactly what this is all about..

Needless to say I don't trust this charger for one bit and I am also very disappointed because it was quite expensive too! By the way, the battery itself DOES have the required terminals to charge the pack balanced...

So please tell me guys I'm just missing something here, because charging a 4 cell Li-Ion battery with only two connectors just can't be right....
Bram Corstjens is offline   Reply With Quote
Old August 30th, 2011, 04:48 PM   #2
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Join Date: Aug 2011
Location: London
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Re: Dangerous Hawk-Woods Li-Ion charger without cell balance?!

I was at Hawk Woods factory today sorting out my camera, lights and Nano power supply. As I own a Hawk Woods single bay charger , I pointed out your post to one of the engineers. Lets just say they were not happy.

For my part , I am satisfied with Hawk Woods, they have been around for years and I think would have heard of exploding batteries and burning houses by now. But hey , I think they they should clear this one up , I am out of my league here but you did worry me for a few minutes.
Jeff Willis is offline   Reply With Quote
Old August 31st, 2011, 12:11 PM   #3
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Join Date: Dec 2001
Location: Tavares Fla
Posts: 541
Re: Dangerous Hawk-Woods Li-Ion charger without cell balance?!

Is it possible the battery contains a small amount of electronics (zener diodes ) onboard that accomplishes this ??
Don Parrish is offline   Reply

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