Sanyo NC-MDU01 AA AAA USB Charger

All right I got it this morning, sorry dont have a camera with me have use the scanner. It's pretty sweet little charger. It charges cells pretty well, warms up the cell slightly, haven't been able to test it throughly. The springs are soft. Some cells can be slightly loose in the slots but still maintain contact. I like it because it doesn't dent the cells. However it may cause connection problems. The AA-AAA contact mechanism is quite clever and it works well. The USB cable is too short for desktop use but it is right at home with a laptop.

It's quite interesting to see a little ferrite bead right next to the diode D1. It looks like they done their EMI testing properly. The circuit board is single layer single sided. The microcontroller is a 8-bit 20MHz Atmel Tiny461 with 4 channel 10-bit ADC. It's nice to see this is a software based charger. 10-bit ADC should have enough resolution to do a proper -mV delta end of charge detection. The AVR Tiny461 has a maximum operating voltage of 6.0V and it is wired directly to the USB port despite a SMD 1A fuse. Any more than that means :sick2:.

There is a massive row of resistors R18-R27(01Y) near the bottom of the board. I suspect they act as a low resistance shunt for current measurement via R38. It's also good to have the thermistor(TH1) between the negative contacts as another fault? detecting sensor. Not sure about the trigger temperature, I think it will be quite high because it is not mounted close to the cells.

Thanks for posting the insides of the charger.
I was surprised at the complexity of the charging circuit in the charger... it looks like Sanyo doesn't skimp when it comes to the quality of its chargers.

I am also amazed by the number of parts under the circuit board. Sanyo definitely did not skimp on the electronics side. It's a 2-channel charger despite having 1 LED, so you can charge 1 or 2 cells. I use it everyday in the office, the size is tiny and minimalist and the ladies think it's some apple product.

For ~$18 bundled with 2xAA Eneloop, it's really something to think about. Should be available in the US now.

Thanks for the very informative post koala.

It appears from this webpage that Sanyo incorporates a fairly extensive set of controls in all of their chargers:

http://www.energy.sanyo.com.sg/chargerproduct.asp#control

Yeap, late Sanyo stuff are quite up to quality and pretty affordable.

I have done some charging test. The Sanyo USB Charger charges cells up to about 94-96% capacity. There is no trickle charging when charge is completed. The cell temperature rose to about 43.1C(109.58F) max at ambient temperature of 21.7C(71.06F). The cells were about ~1550mAh(La Crosse 2000mAh) cells, works out to be about 0.29C charging rate. There is no voltage rise detected during period of 2 hours wait after charging, this confirms there is no trickle charging or top-up function.

Note: The charging rate for 2 Eneloop 2000mAh cells is about 0.225C(450mA) or 1 cell at 0.425C(850mA). I was worried that the charger might not terminate properly at 0.225C. So I tried to charge two Sanyo 2500mAh cells at 0.180C. Amazingly it worked. I was wondering if it is the temperature cut or voltage, the cells discharge capacity test turned out to be within 94-96% actual capacity.

Where can one buy this in the US, online even? I remember reading the press release of this a few months back and was excited to try it. I bought a crappy Digital USB charger but it has 4 slots for AA's or 2 AAA's and has a mini LCD with the 4 segment battery indicators. Not sure how to test if there is trickle charge or not, but a set of 4 batteries takes hours to charge to complete status. I think I paid $15 for the charger with 4 batteries at a dollar store.

Don't expect this Sanyo USB Charger to charge any faster than the one you have. Two empty - 2500mAh AA cells will take approx. 5 hours 30mins.

I don't know where you can get it in the states, have you tried ebay? I bought it here http://www.onlineshop.com.sg/index.php?main_page=product_info&cPath=3_38&products_id=3659

Haven't tried Ebay, I will give it a go.

Thanks for this Tip, sounds really great, so I bought this charger on my last trip to Asia !

Very useful for charging batteries from cordless phones.

so is this temp cutoff or -dV?

Both, temp cutoff for second protection, -dV comes first. Springs are quite weak, might have to wedge them out.

Talk about bringing back an old thread....

Thanks though, made me search for mine, which thankfully I have found . I'm in sudden need of an ultra-portable single cell travel charger for my Eneloops... 5 yrs later, I don't think this can be beat.

Quick question, I just noticed the input ma says "500ma max." Do you think there will be a problem if I use a solar panel that puts out 5V/1a?

koala said:

Both, temp cutoff for second protection, -dV comes first. Springs are quite weak, might have to wedge them out.

Click to expand...

yeah weak springs could be an issue. maybe you could bend them out a bit and fill in with silicone sealant

so it's -dV then. thanks. btw have you confirmed this empirically?

According to http://www.stefanv.com/electronics/sanyo_usb_charger.html its "voltage peak detecting".
Is this the same as -dV??

I have this charger about two weeks,but I am not sure if has two independent channels.Koala are you sure that this charger has independent channels?

can i use this with a 1a usb charger. like the apple charger. meaning would it just pull 500ma for the his 1a charger? or can it be used only with 500ma current like a pc.

It will work with all types of USB chargers. I modded mine to work with my 5V phone charger years ago. I have now changed to a phone with microusb, I might mod it again. :naughty:
I hooked it up to my power supply limited to 5V, no it won't draw more than 500mA. I also checked the current spikes with a scope, it's fine.

wtf can't find this charger anymore!

too bad coz it's such an excellent little charger

Sanyo NC-MDU01 with Solar Panel?

Well this is a very interesting thread for me.

I have two of these chargers which see EDC backup roles when I'm out and about. I use a Maha C9000 at home.

Koala, you seem to have much better knowledge than I do as well as access to some nice test equipment. :wave:
Here is a question or problem you may be able to help me out with.

I sometimes use these chargers when away on camping trips. I have a couple of Cottonpickers solar panels which output to USB (see CPFmarketplace for details) as well as a few of his USB Li-Ion chargers for my other lights. I also want to run these Eneloop chargers from the panel, but I'm having some confusing results with the status LED.

When the weather fine and there are no clouds, the chargers function correctly.
On cloudy days or when there is intermittent passing cloud, the panels of course do not output their full capacity and may drop below the required 500mA.
In this situation, the charger LED displays a series of 3 flashes.
Very short - short - longer (normal pulse)
Very short - short - longer (normal pulse)
This sequence is not mentioned in charger manual, nor anywhere else I can find on the Web. My best guess is that it is an undocumented feature that is supposed to indicate some kind of fault condition.


I suppose I have two simple questions.

• Will a lower input current cause any damage to the charger?
• Is the charger actually continuing to put any charge at all into the cells in this state? (But maybe at a lower rate)

I have a few cheaper "dumb" USB chargers - the silver coloured kind you find for a couple of dollars in the Chinese web stores. These output 130mA to 160mA under ideal conditions. Using my DMM I have found that they will keep charging on cloudy days, albeit at a much slower rate. Sometimes as low as 20mA.

However I don't seem to be able to get an output reading on the NC-MDU01 using the DMM, which I have guessed may be due to some kind of current "pulsing" (possibly for voltage detection?) rather than a steady input.


I would prefer to use the Eneloop chargers to take advantage of the higher charge rates and termination "smarts" but there is little point in leaving them out and connected to the panels if they are not charging at all when the power drops.

My workaround until now has been to put a Li-Ion pack (4*18650 box or ML-102) in between the panel and the Eneloop charger as a buffer but then I have to be quite mindful of keeping the Li cells out of direct sun. I'd rather have less equipment lying about to keep an eye on.

Is there any way you could test the Eneloop charger with a lower input current - even down to say 50mA - and work out what is going on?

I've tried contacting the manufacturer via their web form but have had no reply on this question.

Any help on this would be appreciated.
Thanks.