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Nitecore i4 and i2 charger teardown (update p2)

djQUAN

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I just received my i4 today from Fasttech and a quick check and it seems to work except that when charging a battery on slot 2, the LEDs for it light up along with the LEDs for slot 4 even when there's only one battery.

I didn't want to wait for shipping back and wait for another and was also curious to see what's inside the i4 so I took the screwdriver out. warranty? what warranty? :shhh:

I'm not going to do a detailed review of the i4 as there already exists a very detailed i4 review with graphs and measurements but was missing some internal pictures so I took mine apart.

Here are some pictures that I took...

Package as received:


What?


four screws are hidden under the foam rubber feet. Pry out with a tweezer to gain access to the screws.


bottom of the PCB. Soldering could have been cleaner but it cost only $20. IPA and a toothbrush should clean it up nicely. It does have the essential isolating slots separating the live circuitry directly connected to the mains to have enough safety clearance to prevent electrocution. The PCB is also a nice FR4 substrate rather than the cheap paper phenolic material.


springs for battery contacts are soldered on both ends which allows more reliable electrical connection - I haven't seen it done in cheap chargers before:


top of the main PCB. On the top left are the AC to DC converter. Top right appears to be the two buck converters that steps down the voltage to charge the batteries. Bottom part controls switching of the two charger channels to four battery slots.


angled view of the board. The switching controller for the AC-DC converter is a VIPer22A device with voltage feedback using a TL431 and optocoupler which is loads better than a self oscillating transistor switcher in cheap chargers.


controllers that route power from two charger channels to four battery slots are controlled by what appears to be dual mosfet devices on both the positive and negative battery lines.


Now there's your problem: I found two shorts on the main controller IC which might be causing my problem but I won't touch it now. I don't have access to my soldering station so it'll have to wait. I'll post again when I've cleaned up the solder joints.


edit: couldn't wait to see if the solder bridges were causing the trouble or not so I used a knife to cut the solder bridges out. Charger works perfectly now. :) I'll still tear it apart again to clean up the solder blobs and flux residue though.

edit 2 (2013/06/24)
I convinced my uncle to buy an i2 and it just arrived. What better way to christen it than do another teardown. :na:

Package contains the charger itself, a power cord and manual.


Same way of opening as the i4. screws are hidden under the foam rubber feet. Once the bottom cover is out, this is what we get. You can clearly see the nice clearance gap separating the live circuitry directly connected to the mains and the DC output which you will come on contact to when inserting batteries.


Soldering looks much cleaner than my i4. There's just an odd solder ball on the bottom right of the pic and a piece of tape which were both easily removed with a fingernail.


Top of the board. Top half is the main AC-DC power supply which used the same VIPer22A device but with a smaller transformer (yellow/black square part). The buck converters are on the bottom left and right corners using drum core inductors (the i4 used toroidals) and the main controller IC is the one in the middle.


Another view in an angle.


You don't usually get these in cheap chargers. Mains input is fused and an NTC thermistor to limit inrush current.


All in all, I think these chargers are a nice decent design especially considering the price. If you don't have a decent charger, I highly recommend you get one. :beer:
 

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djQUAN

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Re: Nitecore i4 charger teardown

Lots of views but no replies? :thinking: Anyways, I resoldered the shoddy looking joints and cleaned the PCB with a toothbrush and a bottle of IPA.




I also found an interesting bodge. An SMD resistor ontop of another with a solder blob connecting several part lands together (I removed the blob and added a wire link for a cleaner look). It appears to have something to do with the voltage feedback of the AC power supply.


I also greased the sliding contacts for smoother movement when inserting/removing the batteries.


Interestingly, I found you can take power out of the DC input jack when plugged on AC power. I haven't tested the max draw but I measure about 8V output from it.
 

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ryansoh3

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Re: Nitecore i4 charger teardown

Great teardown! +1

I don't know why I haven't noticed it a week ago! :)
 

djQUAN

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Re: Nitecore i4 charger teardown

Thanks! I haven't used the charger much since all my batteries are still full but for the few times that I did use it, I'm quite happy with it. Highly recommended :)

BTW, the battery contacts are steel so you can use magnetic connectors to make connections to separate batteries. Here's a pic with the i4 charging my LPM :beer:

 

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grainde

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Re: Nitecore i4 charger teardown

^^^Yup great work identifying the problem you've saved Fasttech some money J/K ;)

Would also be great to hear how well it actually works charging too. Ie how does it handle multiple batteries and how does this eg affect charging current and time. Does it get overly hot and does it cut off when it should without trickle charging the Liions? Also how does it handle low IR cells such as IMR do they cut off at the correct voltage or does it over shoot?

Anyway great review +1 :beer:
 

djQUAN

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Re: Nitecore i4 charger teardown

Thanks! Here's a detailed review of the i4 that I found before I got my unit (forgot to add that in the OP). It's very detailed with a lot of graphs and measurements that's why I didn't bother with those but is missing some internal pics so I decided to take mine apart.

edit: 100th post haha
 
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Lazerbeak

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Re: Nitecore i4 charger teardown

Great job as always djQ :beer: I have one of these too, so it's great to see such a detailed breakdown. Love the repair job you did :)

~ LB
 

djQUAN

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Re: Nitecore i4 charger teardown

Thanks. The soldering could have been better. Must have been the flux wash after assembly. The top side soldering was fine. Only the bottom side needed reworking.

I also made a similar page of this teardown on my site just for completeness sake. :p
 

Lazerbeak

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Re: Nitecore i4 charger teardown

Nice djQ! I like the LPM too :) I also notice some more lasers since the last time I saw the your site :beer:

~ LB
 

djQUAN

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Re: Nitecore i4 charger teardown

I didn't have any latest additions. I just added pics of the incomplete ones. I would love to make a 520 though. Seems I've had only bad luck with 532's. They're too fragile for me :p
 

Lazerbeak

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Re: Nitecore i4 charger teardown

I am looking forward to a diode green too. I don't like the inconsistency and warm up period of those IR pumped Greens.

Last I saw your site was when you first joined :)

~ LB
 

djQUAN

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Re: Nitecore i4 charger teardown

Wanting to build a triplet pen host using DTR's RGB promo. I hope it's still available when I have extra cash. And probably a 9mm too ;)
 

Lazerbeak

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Re: Nitecore i4 charger teardown

Ooooh, an RGB triplet would be awesome :D Look forward to that. I'd like to see what you do with a 9mm too. I recently got a 9mm build from SBA (Scumbagatheist) It's a monster.

I still love your light up button mod. might try it with a mitsubishi red build I'm planning if I can figure out mounting the LED like you did and replacing the rubber button on my host.

~ LB
 

Antharak

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Re: Nitecore i4 charger teardown

Good work \Thanks for the posting, now I'm no longer tempted to open mine.
+1 :beer:
 

djQUAN

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Re: Nitecore i4 and i2 charger teardown

:bumpit:

Nitecore i2 charger added to OP. :wave:
 




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