Li-ion Pcb Charger Not Working

[johnyradio]

I'm trying to charge 4 x #18650 4.2V 4.5Ah Li-Ion batteries. Like these:

http://r.ebay.com/zu9OjA

i'm using this charger:

http://r.ebay.com/6hk1Op

This charger does not appear to be working. Surely my own error. When i charge some good 18650's (not full, but have at least 3V charge), i do not see any of the batteries getting charged. After a couple hours, most of the batteries DROPPED a few tenths of a volt.

What am i doing wrong? Is it a mismatch between this board and the ultra fires? Or maybe these are just fake li-ions?

THANKS!

 

[itsmoked]

Have you measured the input voltage? You're supplying it with the correct 24V right?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[johnyradio]

how do you know it requires 24V?

the chip is one of:
S-8243A/B
S-8254A
S-8204A
S-8204B
S-8225A
S-8225B
S-8205A/B
(trying to determine which)

datasheets are here:

http://www.sii-ic.com/en/semicon/products/power-management-ic/lithium-ion-battery-protection-ic/

 

[johnyradio]

it's the 8254AA

http://www.sii-ic.com/en/semicon/da...ic/lithium-ion-battery-protection-ic/s-8254a/

http://datasheet.sii-ic.com/en/battery_protection/S8254A_E.pdf

 

[LiteYear]

Compatibility should be fine. How have you hooked it all up? What's your power supply? What are your measurements?

 

[itsmoked]

how do you know it requires 24V?

It showed your exact same setup on the ebay page with a 24V input supply...

Keith Cress
kcress -

http://www.flaminsystems.com

 

[johnyradio]

The product page says:
"Input volt (between B+ / B- VSS-0.3~VSS+26 V"

see op

 

[LiteYear]

The product page says:
"Input volt (between B+ / B- VSS-0.3~VSS+26 V"

That's between B+ and B-, so that's describing the battery voltage, not the supply voltage.

You want: "Operating voltage 2.0 / 24.0"

Of course, this is just a linear charger, so no charging going to occur at 2V. 24V is a good place to be, but anything above 18V for 4 cells will probably suffice.

 

[johnyradio]

i'm using 19v. the datasheet says "Wide operating voltage range 2 V to 24 V"

 

[johnyradio]

Ok, success! I managed to discharge and recharge 4 cells.

To discharge, i drove 3 computer fans in parallel off the pack. The controller properly turned off at about 3.5 V to prevent over-discharge. That's a pretty high cutoff, i've read the cells can be discharged to 2.5 V without problem. But future testing my prove me wrong about the behavior of this pcb.

On charging, the pcb stopped charging at about 4.1 V, a bit shy of the standard 4.2.

But hey, at least it works!

I had success with different brand cells than in my initial fail, which may have been the problem. The brand that worked is also an UltraFire knockoff-- one poster said you can get legit cells from some ebay outlets. More testing will be needed to determine how legit these are.

Thanks everybody for your comments!