Aldi Traveller MPP-7400

[amspire]

Aldi have just released in Australia the Traveller MPP-7400 7400mAH battery pack for about $20.  It includes mains charger, 10 output adapters. I believe it is a limited time sale probably ending 9th to 11th Nov. There is I think a smaller unit that will be $12.99 from the 9th to the 15th.

Not a bad thing at all for the price.

http://www.traveler-service.de/popups/MPP_7400_au_popup/index.php

The thing is it has 5 charging LEDs on the front panel.  The instruction book says 4 LEDs means it is fully charged, but in practice no-one can get past 3 LEDs. So I had to take it apart, and photos will be coming. I can confirm that with 3 of the 5 LEDs lit, the battery is fully charged.

The main charger IC has had the most thorough milling job I have ever seen to erase the identity, so now I want to work out what it is.

More photos soon, but I am just giving some advanced notice in case anyone else is interested.

Richard

[amspire]

I was annoyed that my $20 Aldi Traveler Battery Pack only showed 3 of 5 battery level LEDs when fully charged, and this is the same for everyone. It turns out that the LED to the right of the "Full Charge" LED was a red Battery Low LED.  Very strange layout.  So that means 4 and not 5 LEDS should be on when it is charged.

So I decided to see what is going on, and to fix it if i can.

Here is the PCB.  The battery charger IC near the mini-USB input is unknown.  They have sanded the top or something.  It does  have "TP4XXX"  (x's are unreadable) and below that "1128" or "1123" . Anything else is wiped out. I was unable to track down any charger IC that matched.

The 5V 2A boost regulator is based around a 5 pin  Seiko S-8357F50MC-MHJT2G (U1).  If you are wondering why the part number is so long, they make a massive number of very slight variations, so that the final circuit is as simple as possible.  In this case only 3 connections are needed - one to 0V, one to the gate of the P-Channel FDS4435 FET (U3), and one to the 5V output.  It runs at a fixed 600KHz frequency.  Output was 5.05V no load, 5.00V with 2A load. The other 8 pin mosfet (U2)  is an IRFT807Z N-channel for switching the output power on and off.

There is another 14 pin IC with the top milled on the left that is some kind of control IC. It may be a micro - I am not sure. It does the ON button, and it may monitor the output current.

In the top photo, the LEDS have been bent over so I could scan the board.





The tool that punched the PCB out was very blunt from the look of things.

The LED level indicator circuit surprised me. All charger chips have a LED indicator output to indicate the charging status, so you are going to use that?  No, the designer had a much better idea.  Use LEDs for measuring the battery voltage.

Here is the circuit:



A weird circuit. The problem was the charger limits the battery to 4.2V, and yet the 4th LED turns on at 4.3V, so it never turns on. There was no way to see if the batteries were charged or not. Having taken it apart, I now realize that if the 3rd LED is fully on, it is close to a full charge, but other purchasers were charging for days, wondering if they had a faulty device.

I imagine the designer had the 4 LEDS working perfectly in prototype in the lab, and then different LEDS were purchased for production to cut costs. So much for LEDS as precision voltage references!

I changed the 150 ohm R15 to 130 ohm, and now the 4th LED is just coming on between 4.1V and 4.2V. I am happy now.

The RED led is controlled by something more accurate - probably from the charger IC - and when it is on, the USB output is switched off.



Overall, a good deal for $20.  Two 3.7 AH batteries, 2 USB outputs with a genuine 2A maximum total output with great regulation. 10 adapters. It now works very well. Some of the newer phones will charge very quickly if the USB can source over 500mA, and I could charge my phone at least 3 times from the battery pack.

Richard

[Bored@Work]

So much for LEDS as precision voltage references!

For whatever reason this seems to become again popular these days. Last time I saw such stuff was at then beginning of the 80th, and then just a month ago Electronic Design published a voltage regulation circuit based on LEDs http://electronicdesign.com/article/power/LEDs-Deliver-Voltage-Indication-And-Adjustable-Regulation.aspx Fortunately they added the proper analysis ... LEDs have widely varying forward votlage[sic] drops ....

[ivan747]

That thing doesn't have a very good construction quality. I can see exposed copper on the PCB, the LED's are just hanging there and one USB connector is not very well aligned with the edge of the board.

[amspire]

That thing doesn't have a very good construction quality. I can see exposed copper on the PCB,

Correct - they punched the board out, and the punch must have been as blunt as anything.  Probably at the profit margin they were working at, replacing the punch was too expensive.

 the LED's are just hanging there

to be fair to Aldi, the LEDs fit into moldings on the front case, so assembled, they are not floating

 and one USB connector is not very well aligned with the edge of the board.

Yes, but the USB holes in the case are big enough to compensate.  But for $20 including two 3700mAH batteries, I will live with some slight blemishes.  Functionally, I am really impressed with the way it works (now I have fixed my LEDs). The performance is brilliant. The batteries actually seem to store the rated energy, the 5V output inverter is very efficient, and draws almost no current if it is on with no load. It charges my phone completely in under an hour, compared to  probably 4 hours plugged into a computer's USB 2.0 port. The case itself is very strong and the plastic is good quality.

Richard.

[amspire]

Back in 2011, I did a teardown of this USB 7400mAh battery pack from Aldi.

For anyone interested, it is available again in Australia from the 18th May.

http://aldi.com.au/au/html/offers/2827_26813.htm

My one is still working great after almost daily use for over 17 months. Aldi have changed the brand to Baun, and unfortunately increased the price by $9. If you buy one, at least you will know what is inside. 

[davo77]

So otherwise, the MPP 7400 is all Okay then? And It's fully charged with only 3 leds on (with 4th one flashing when fully charged?)?   

[amspire]

Mine doesn't flash. The Led circuit is a joke, but works OK after the mod I mentioned. The charger itself works perfectly. The biggest gripe I have is they don't have a Led driven by the charging IC to indicate fully charged. I think the IC has such an output. Another mod perhaps?

[davo77]

Is it fine with this circuit/charger to charge the unit while having 2 devices (e.g. phone and camera) plugged in to charge?   

[sorin]

Is it fine with this circuit/charger to charge the unit while having 2 devices (e.g. phone and camera) plugged in to charge?   

Yes.

[amspire]

Is it fine with this circuit/charger to charge the unit while having 2 devices (e.g. phone and camera) plugged in to charge?   

Yes.

I tested mine previously up to 2A total output. The output was 5.05V no load, 5.0V at 2A output. I didn't test for the current limit.

The 5V output uses little power with no load, so if you leave the output power on with no load, it doesn't discharge much at all.

[ajay123]

 would like to know the value of Q1 to Q4 in the led voltmeter circuit....

[SeanB]

would like to know the value of Q1 to Q4 in the led voltmeter circuit....

You can use any small signal PNP transistor there, so long as it is all the same type it will work. 2n2905 or any other will work.