Joseph S Wisniewski
Forum Pro
They would say that. But the 204 (like any "series charger" that puts 4 cells on two channels, or 8 cells on 4 channels) suffers from unequal charging and discharging. This has been documented over and over again. On low current chargers like the 204, all series charging does is reduce battery life. On high current "quick chargers", it has a tendency to explode batteries.
These references are more about discharging than charging, but the same principles apply to both:
Here's a nice explanation of the physics from the folks at Everready.
http://data.energizer.com/PDFs/nickelcadmium_appman.pdf
"When cells are connected in series and discharged completely, small cell capacity differences will cause one cell to reach complete discharge sooner than the remainder. The cell which reaches full discharge
first will be driven into reverse by the others. When this happens in an ordinary nickel-cadmium sealed cell, oxygen will be evolved at the cadmium electrode and hydrogen at the nickel electrode. Gas
pressure will increase as long as current is driven through the cell and eventually it will either vent or burst."
http://www.uoguelph.ca/~antoon/hobby/nicadred.htm
http://en.wikipedia.org/wiki/Nickel_metal_hydride_battery
This also agrees with my experience designing battery charging systems at Visteon and years ago at Cummins (long story, ends in a real bang).
And it agrees with my experiences moving from series chargers to independent channel chargers. I used to use a series Maha 204 (not the X with the power supply built in, the F with the external AC adapter). Even operating in a disciplined fashion, with the batteries labeled as sets, I noticed quite a performance decrease on the 2 or 3 year old sets. The first time I ran them through an independent channel charger was a revelation. It was one that didn't have the fancy LCD of the LA Crosse, but it was still an eye opener. The cells ended their charges at radically different times, some taking literally twice as long as others to charge. I did a little research to find out how bad unequal charging could be. The very worst culprit is a load like a flash or a camera that mixes low standby current of 1mA or less, with medium operating current around 100mA to focus a lens, run IS or VR, zoom a flash head, or run an AF illuminator, then a jump of 500mA to 2000mA to run the processor or big LCD for image review, or recharge the flash. This makes cells get unbalanced very quick, and series charging just exaggerates the unbalance. I times the recharge and found that most of my carefully matched sets were now unbalanced by a factor of about 2:1, so my 1800mA-H packs were effectively 900mA-H, and the 2100mA-H packs were like 1050mA-H.
It also provided an explanation of why one pack had recently vented in a flash.
Mostly from Sanyo literature on how to charge the batteries. It's nothing against the Maha 204 in particular, it applies to all 2 channel chargers.
Look at how Thomas Distributing talks about the 4 channel Maha 401 "This allows each battery to be charged to its full potential without risk of overcharging. The charger can charge one, two, three or four batteries."
The implications are that a series charger without independent channels, like the 204, will not let "each battery to be charged to its full potential" and that there is increased "risk".
There is necessary risk in this world, and unnecessary risk.
The reasons it won the awards have not changed. Independent charging is simply better than series charging. Cells last longer and perform better.
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Normally, a signature this small can't open its own jumpgate.
Ciao! Joe
http://www.swissarmyfork.com
