Modifying your Trustfire TR-001 for 4.20V

The Trustfire TR-001 is a remarkable charger, with some good properties for very little money. It has a true CC-CV charging algorythm for instance, and it accepts either line voltage or 12V DC from your car! It will charge virtually ANY Li-ion battery, and has spring-loaded bays so there's no need for spacers etc! All sizes from 16340 to 17670 and 18650 are charged without any problems.

It has, however, two major drawbacks:
1. charging voltage always is a little too high (4.22 - 4.24V)
2. it NEVER switches off, even when the LEDs go green, indicating full charge! You have to remove the batteries from the charger as soon as the LEDs turn green!

The first drawback can be overcome by a small mod! The second one is built into the design of the charger, you'll have to monitor it constantly. When the LEDs turn to green, remove the batteries from the charger and unplug it from the wall outlet.

What's needed for the mod?

1. a #1 Phillips screwdriver,
2. a soldering iron,
3. a multimeter, with a good, accurate 20V DC range,
4. a few resistors, ranging from 470k to 680k.

And here's what to do:

1. measure open voltage in one of the charging bays and remember it.

2. open the charger. Take care, one screw is UNDER the sticker! Just pierce it with the screwdriver.

3. locate R12, a tiny SMD-resistor (330k-ohms). Remove it by using the soldering iron, taking care not to damage anything!

4. now, put the charger together again, without the screws, and measure voltage on one of the charging bays. It should be about 4.15 Volts. This indicates you didn't ruin anything :thumbsup:

5. Was the initial voltage around 4.22V? Then try an extra resistor of 470k in the place of the resistor R12 you just removed, this can be any normal resistor. You can bend it in such a way, that you can solder it around the pins of the 1000uF/16V electrolytic capacitor on one side, and one of the pins of the TL431 on the other side. Just follow the PCB-tracks and it will become clear.
Did you measure more something like 4.24V? Then try a 680k resistor.
In all cases: close the charger after modding it, and measure voltage again. Not fully OK? Try a LOWER resistor to INCREASE voltage and vice versa. By using the right resistor (best buy a few in the range from 470k to 680k or 820k, with all values in between from the E24 series) you can adjust the voltage very accurately.

6. Want to upgrade your charger even more? Then, replace that low-quality electrolytic capacitor (1000uF/16V) by a good one. A 1000uF/10V(!) high quality, 8mm capacitor with a pitch of 3.5mm will fit the PCB! The one fitted now is too big...
Take one with the lowest ESR you can find, and is no higher than 15mm (0.6").
Farnell or Digikey or RS components or another electronics vendor will have them. For example Rubycon has some excellent capacitors for SMPS (Switch Mode Power Supply)-purposes.

7. After everything is OK, put the charger together, replace the screws, be sure NOT to overtighten them,

8. Be confident your batteries will from now on be charged to the brim, but NOT be overcharged by applying exactly the right voltage... I use this charger for any battery I have at hand, ranging from Ultrafire 16340s, to AW 18650-2600s and AW IMR 16340s. All charge very well :thumbsup:


Happy modding!

Timmo.

Hmmm interesting but pictures would be super !

I've had this charger for some time now , and on a few occasions have forgotten the charger , and left it overnight , it did not overcharge by much , 4.22v is negligible . If I pull the batts as it goes green , there nearly spot on 4.2v .

The Trustfire TR-001 must be the most under rated charger out there .

Oh , pictures please !

I'm no computernut. Don't know how to post pictures here. And, by the way, I don't have internet @ home at the moment. I'm with my parents now, and they DO have internet

So... unfortunately, no pictures. But, I can guarantee you: open your TR-001, and everything will be clear!

Timmo.

Thx a lot for the post! I've been looking for an all-in-one LiIon charger, sounds like this might be it (especially after the mod).

Do you know if this charger will work with 10440 and 14500 as well?

Also +1 for the pic if it's not too much trouble.

Thx!,
Tim

EDIT: Just saw your reply, ok, np, maybe I'll just pick one up anyways. As for the resistor, can I just grab these at Radio Shack? If not, do you have a site you can recommend?

the trustfire charger has a true cc-cv charging algorithm? how did you find that out?

Yes, 14500s will definitely be no problem. 10440s will work, but the charging current may be a bit high.
Radio Shack is OK! Any 1/4W resistor will do.
You can pick this charger up for less than $8,- at www.dealextreme.com.

Timmo.

Pictures? Here is a picture from one that blew up: http://www.upload.ee/image/99223/TR-001.jpg

and some another quotes are:

"Mine caught on fire while trying to charge 2 18650 batteries. Lets just say that I am lucky that I was in the room when it happened."

"Well, after 15 months of use one status LED stopped working, then a week later I plug the charger in, and it makes a loud "POP" sound and stops working. ...aaaand smells of burnt wire insulation too... Off to the rubbish bin. Make your conclusions people. Buy better chargers."

"I turned it on today and heard a series of loud cracking sounds, with visible blue spark flashes showing through the plastic. I turned it off straight away, but it's completely dead."

to find this out isn't too difficult: regularly measure voltage. When the charger goes on for hours(!) after the rising of the voltage has more or less stopped, it has switched from CC to CV charging. It's that simple :thumbsup:

Another clue is the temperature of the charger. First, it will become warm, it has to work hard. Then, when current drops (voltage has risen to the maximum value) the temperature of the charger will also drop.

Experienced users can determine the way of charging (CC or CV) by just laying their hands on the charger, hahahaha


Timmo.

turboBB said:

Also +1 for the pic if it's not too much trouble.

Thx!,
Tim

Click to expand...

Found some pix here: https://www.candlepowerforums.com/posts/2182336&postcount=26

Cheers

325addict said:

The Trustfire TR-001 is a remarkable charger...
3. locate R12, a tiny SMD-resistor (330k-ohms). Remove it by using the soldering iron, taking care not to damage anything!...

Click to expand...

From the images below, the R12 resistor is marked "102" which corresponds to a 1000 ohm resistor...not sure why it is not the 330 kohm value indicated by 325addict ???

digitor said:

Found some pix here: https://www.candlepowerforums.com/posts/2182336&postcount=26

Cheers

Click to expand...

Here are the pics compressed to about 100KB each:

Actually I was thinking one of these, modified to take banana plugs, might work with a hobby charger easier than trying to make a bay charger. I thought someone was offering that earlier. (basically throw out the circuitry)

I guess I've been lucky with my TR-001... I think my batts always have come off at less than 4.2 v (like 4.15 or 4.18, usually). And this despite having left some in overnight. I put the voltmeter on every one of them when I pull them off.

You say the unit continues to charge when the light turns green. Yet the voltage remains the same. Ok, I'm not that bright I guess. How can it do that? And if it is somehow stuffing more amp-hours into my Li-Ions while keeping the voltage less than 4.2, how is that bad for my battery? If the danger to these batteries is charging them to too high a voltage, seems like I should be able to leave mine on the charger all week, as long as the voltage stays low like that.

Rexlion said:

...You say the unit continues to charge when the light turns green. Yet the voltage remains the same. Ok, I'm not that bright I guess. How can it do that? And if it is somehow stuffing more amp-hours into my Li-Ions while keeping the voltage less than 4.2, how is that bad for my battery? If the danger to these batteries is charging them to too high a voltage, seems like I should be able to leave mine on the charger all week, as long as the voltage stays low like that.

Click to expand...

You're right on that point: You should be able to leave the unit on continuously with no effect on the battery as the no additional charge will flow. Think of it like a balloon that is being inflated with a constant pressure (i.e. CV mode). As the balloon inflates and the internal pressure increases, the flow decreases until the both the external pressure and internal pressure equalize. The result is that the balloon stays at a constant pressure and does not blow up.

There is also a danger with Li-Ion chargers that "maintain" voltage. When a LiCo Li-Ion cell is near full charge and current is still applied, even if it is just enough to maintain the voltage at say 4.20 volts, metallic lithium can be deposited on the anode. This makes for a very unstable cell and there is the possibility of . This is why a proper algorithm cuts the current completely off at end of charge.

If you take a charged cell out of your charger (EDIT to add: After the charge has terminated, and the cell is left on the charger for a few minutes. *EDIT*) and the voltage drops, at all in 15 minutes, your charger is unsafe to leave cells in after charge completion, period.

(EDIT: The cell's voltage should start to drop while the cell is still in the charger, after the charge has terminated, with a charger that terminates properly, ie. charge current is zero. *Edit*)

Dave

As I said slightly more indirect above: TR-001 is a piece of crap and a fire hazard (just check the DX forum).

@ mfm and others, two things:

1. the pictures of the exploded one show an old version, indeed there is no R12 on the place expected. The current model also has a small glass-fuse for when things really start to go wrong (chances are small, as the current model uses a reliable IC by SGS-thomson).
2. Don't you see the plumbed (I can't say: soldered) wires that are on the PCB of the exploded one? Clearly someone tampered with it....

Indeed, there is NO SHUT DOWN when the batteries are full, as I wrote in my first writing. This is some serious drawback of this charger. ONLY when used with care, it is to be recommended, as it DOES charge your batteries the right way (CC-CV and after some modding, end-voltage will be no more than 4.20V).
Batteries should be removed from the charger when the LEDs turn green!!

Besides this, there are a few good point too: it also accepts 12V DC from your car-battery, it's light and cheap and... well built! No sqeaking, ugly plastics here. Remarkably good finish for such a cheap Chinese product.
And... although I have four of them (as I write this, two are charging batteries, 2X IMR 16340 and 2X 17500) no one failed on me yet.

Maybe, Trustfire learned, and made it a better charger... clearly, the pictures show an old version, without the fuse(!)


Timmo.

325addict said:

@ mfm and others, two things:

1. the pictures of the exploded one show an old version,

Click to expand...

I think this is one of the big problem with this TR001 charger. That is: there are too many version of it. :sigh:

It's not necessarily a problem any longer as it seems likely that new ones purchased from now on will all likely be the improved more recent model.

The one I recently got seems to be reliably charging to 4.12 to 4.16 at the point when the LEDs turn green (without any modifications done to it) which is fine with me as I prefer it to undercharge slightly so I can hopefully get some extra cycles out of my batteries.

So as the OP said, just remember to pull the batteries when the LEDs turn green (which is a bit of a hassle to be sure, but on the other hand, it only cost about $8 including shipping). All in all, I'm pretty satisfied with the performance I'm seeing so far.

325addict said:

the pictures of the exploded one show an old version

Click to expand...

I don't know if anyone else noted or not, but the silk screen printing on the that particular circuit board actually says WF-139 V1.2 :thumbsup:



I thought the layout looked familiar

325addict said:

The first drawback can be overcome by a small mod!

Click to expand...

I have the same charger. It's charged my batteries to 4.24V or even more. I don't have suitable resistors, so I just simply removed R 12. The charger is still working.
Now my 14500's at 4.16V when led turn green. They reach 4.18V after +1 hour on green. I think it's much better now.

Thank you for the info. It was very useful.