UltraFire WF-139 overcharges batteries? other option?

[musicalfruit]

So if I'm going to use just protected Li-Ions, will this charger be OK?

I was thinking that the protection on the batteries themselves will prevent overcharging. Is this correct?

Thanks.

 

[DM51]

So if I'm going to use just protected Li-Ions, will this charger be OK?

I was thinking that the protection on the batteries themselves will prevent overcharging. Is this correct?

Thanks.

I'm not dure whether you are talking about the Pila IBC or the WF-139, but with the Pila you will definitely be OK, and with the WF-139 you will be OK as long as the protection circuit is functioning properly.

You should however not RELY on the protection circuit - it is there as a safety device, like an RPM limiter on a car engine. Even though the limiter is there, it doesn't mean it is good for the engine to be pushed to that limit the whole time.

 

[musicalfruit]

I'm not dure whether you are talking about the Pila IBC or the WF-139, but with the Pila you will definitely be OK, and with the WF-139 you will be OK as long as the protection circuit is functioning properly.

You should however not RELY on the protection circuit - it is there as a safety device, like an RPM limiter on a car engine. Even though the limiter is there, it doesn't mean it is good for the engine to be pushed to that limit the whole time.

Ah, thanks for the clarification. I was thinking about the WF139 since it's so cheap and I will be only using protected batteries. So I guess I will just have to be watchful and take the batteries off the charger as soon as they're done, just to be safe.

 

[gravityz]

i am currently doing some tests with the wf-139

a 1-1.5ohm resistor lowers the current to 250ma which makes it suitable for 10440

the voltage during charging however is 4.28 volt on the end(for 5 minutes)

on trustfire 14500 protected the charger protection kicks in before the battery protection
with aw14500's it is the other way around.

the resistor is not lowering the charging voltage

i think this is because the charge at the end is very low so the voltage drop over the resistor is also
when i get my 10440's i will test them also.
if the voltage is to high i am gonna experiment with a diode in series(GA 0,3 volt drop, si 0,6 volt drop)

this drop however only works when there is enough current running so it might be the case that the voltagedrop is way lower.

 

[MatajumotorS]

I did some testing of WF-139 today too. (my charges with 340mA constant)
1. - it is overcharging to about 4,3V
2. - when the charging is complete, there is 11mA current flowing to battery. It is caused by diode and 700ohm resistor in series from charger Vin to charging output ( i think it is used to get back from protection state protected cells) I lowered it to 1mA, works the same.
3.- you can not change the cut-off voltage of this charger, because it is controlled via uC CF9444 (only reprogramming could help).

I will use this charger only with "good protected" (with cut-off 4,2V not the 4,35V) cells.

I also have this 1A 1x18650 charger from DX. It is better. It has constant voltahe output (my is 4,23V). When cell is empty, current is almoust 1000mA, then gradually drops until cell is full. (at 4,07V it was ~400mA).
But it is not recomended to keep cell in it long after charge is complete, because it still will be tricle charging it (some mA).

I think this one 2x18650 will charge the same as 1 cell model.

 

[MatajumotorS]

iam gonna experiment with a diode in series(GA 0,3 volt drop, si 0,6 volt drop)

this drop however only works when there is enough current running so it might be the case that the voltagedrop is way lower.

It will not help, because it is charging with constat current from 12V. You will need moore diodes . Or maby there is need to place a voltage regulator of 4,20V before current soures. BUT then the charge will NEWER come green, and you will newer know when it is done.

Just thought - you could add a diodes on outputs AND make voltage regulator of 4,26V or two serial diodes on ech output and regulator to 4,32V. Then i think it could do the "right" job.

What do you think?

 

[j3bnl]

This is the kind of set up you need :-

Obviously the M6 is optional!!
This when it arrives will be my second Tenergy set up and I couldn't bear to be without it now as it does all the Li-ion batteries I use, C's 18650's and RCR123's with spacers.
Simply brilliant and worth every penny.

 

[gravityz]

i tested with a si diode in series
cuts of way to early at about 4 volts
the same goes for the GE diode

putting a 2 ohm restistor in series will help but this will lower the current to about 200ma so charging will be slow.

alsi i did some tests today with cells ad now they terminate at about 4.25 volt.
the cells are not aging that quick so i might suspect that the voltage read is not that accurate

anyway 4.25 wokrs for me
i do not care if the cell only last 500 times. that means that i can use it for 1 year if i charge it every day(which i am not doing)

It will not help, because it is charging with constat current from 12V. You will need moore diodes . Or maby there is need to place a voltage regulator of 4,20V before current soures. BUT then the charge will NEWER come green, and you will newer know when it is done.

Just thought - you could add a diodes on outputs AND make voltage regulator of 4,26V or two serial diodes on ech output and regulator to 4,32V. Then i think it could do the "right" job.

What do you think?

 

[adamlau]

Just picked up two Pila IBC units from BOG

 

[cernobila]

Came in here a little late but what about the Wolf-Eyes charger, is it similar to the Pila? I can easily get the WE here, the Pila is a bit harder......is there any difference and can the WE charge the 14500 cells?

 

[MatajumotorS]

i tested with a si diode in series
cuts of way to early at about 4 volts
the same goes for the GE diode

Have you tried AMC7135? With it could be 0,1-0,2V drop. Just need to connect the "enable pin" to somewhere 3-5V on board. (i think same place where uC of charger is connected).

Another interesting thought.
- As the uC every second removes the charge and in this time measures the voltage of the cell, we could add a small capacitor on the input of the uC, making the voltage not to drop so fast (from V @ charging to V @ idle) by that it would cut off earlier.
- but maby doing that it will make some "loop" - charges to "V-norm" - cuts off - (added C discharges, voltage drops) charger starts to charge again..... it would be about 2 sec, what do you think.
-Then you had to monitor the leds, when it is "longer green" it is full.

Comments?

 

[MatajumotorS]

Other i thought, i think usable
to add voltage divider over the diode.
then you will be able to adjust the stop voltage.

perfect i think...

 

[MatajumotorS]

Recently modified one charging channel of wf-139, i placed 2K pott around the diode (see pic in previous post), an now i am able to set stop voltage from ~4V to "factory default" (by default wf-139 charged cells up to 4,28V - on rested cells).

 

[gravityz]

did you check what the impact is on charging current.
i do not know the resistance of a diode when it conducts but this must have a direct impact on the charging current.

Recently modified one charging channel of wf-139, i placed 2K pott around the diode (see pic in previous post), an now i am able to set stop voltage from ~4V to "factory default" (by default wf-139 charged cells up to 4,28V - on rested cells).

 

[MatajumotorS]

did you check what the impact is on charging current.
i do not know the resistance of a diode when it conducts but this must have a direct impact on the charging current.

Charging current stays the same, because no load voltage form AC source is ~8,5V and if using external 12v psu - 12V. Diode drops ~0,6V when charging and for about 0,3V whet ic checks the voltage (because then there is only 1ma flow).
Charging current is ~400mA with 12v psu and ~250mA from AC outlet.

 

[gravityz]

sounds like you have a solution there

can you take a picture of the mode you made?

 

[MatajumotorS]

sounds like you have a solution there

can you take a picture of the mode you made?

I will try to take the picture after work, it looks crappy, but it works.

 

[MatajumotorS]

The pictures:

cutted trace

unsoldered one log of inductor and putted in series there diode ant pot in paralel

It is temporary (will last forewer ) set-up, i made it to test my thoughts. Later i will ad the modifications to secont chanel too.

 

[hank]

What happens with automobile battery DC (up to about 14 volts)?
Is some kind of protection needed rather than just plugging into an automobile DC 'cigarette lighter' socket for power?

 

[gravityz]

i studied the photo's but aparently it is not clear to me
may be you can can post a diagram

it looks like to removed one end of the diode from the pcb
this point goes to the place were the resistor used to be in place
this same point goes to the pot.
the other end of the pot goes to the loosened resistor

if this is the case than the pot is not parallel with the diode

let me know because this sounds interesting