Test/Review of Charger ML-102 V7.1 2015

[size=+3]Charger ML-102 V7.1 2015[/size]





This charger is a very small 18650 charger, it need an external USB power source to charge, and can also work as a USB charger / power bank. It only charges one battery at a time. The charger have been on the market a long time with frequent updates. I have looked at it once before.



I got the charger in a envelope without any accessories.



The charger has a micro usb connector for power input.



And a usb connector for usb output power.



When usb output is loaded a blue led is on, it will be glowing weakly when usb output is unloaded.
This led is hidden inside the charger.
Normal charging has the usual red/green led on top of the charger.



The battery slot is fixed length with a tight spring at the minus end.



Only flat top unprotected 18650 will fit. It might be possible to charge smaller sizes with the use of spacers, but with the high termination current the charger is not very good for it.





The charger can only handle 65 mm long batteries, this means unprotected flat top batteries.



[size=+2]Inside the charger[/size]



The charger is easy to open, only four screws must be removed and it can be pulled apart.





The top side of the board, notice the LED below the minus pole. It is the blue led for usb output.





The bottom side of the board.



[size=+2]Measurements[/size]

• When not connected to power it will drain about 0.4mA from battery.
• Below 0.5 volt the charger will flash red/green and not charge.
• Between 0.5V and 2.3 volt the charger will show red light and charge with 0.1A
• Above 2.3V the charger will use full current.
• When charge is finished the charger will charge with 20mA (Very bad).
• Charger will restart if voltage drops below 4.05V
• Charger will restart charging after power loss,
• Charger will not restart after battery insertion.

The charger uses a CC/CV voltage and mostly stops at 4.20 volt. The termination current is a bit high at 200mA.
But there is a major problem, the charger has 20mA trickle current, in the above test I stoppen when the battery was up to about 4.30 volt.



For the next test I used a 4.35V battery and I modified my logging termination to stop at 4.38 volt.
Yes, the battery gets charged to 4.38 volt and would have been charged to more if I had continued.
This charge was running for about 35 hours to reach the 4.38 volt, i.e. it is not something that will happen just because the battery stays in the charger for a hour or two, but a day or two is very problematic.



The charger is a dumb charger, i.e. no microprocessor that needs to initialize or anything, when power is applied it will start charging immediatly. This type of charger works perfectly with a solar panel.



[size=+2]Measurements on USB power[/size]

• Usb output is coded as usb charger (DCP).
• Usb output can be used while charging, this will reduce charge current.
• Inside the charger is a blue led, it will turn on when usb output is loaded (When output is unloaded it will have a weak glow).
• Usb output will be turned off when battery is down to 2.75 volt.
• When nothing is connected to usb output it will drain about 0.4mA from battery.

The usb output can deliver a lot of current with a new battery as can be seen here it does first shut down above 2A.



It works very fine at 0.5A load, except the last few minutes before the battery is empty.



Same with 1A load.



And with 1.2A load (The rated output current).



With 0.5A load the noise is fairly low at 12mV rms and 120mVpp.



Also with 1.2A load it has a fairly low noise at 27mV rms and 213mVpp.



[size=+2]Conclusion[/size]

During all the upgrades to the charger it has gotten more powerful, but has lost the basic capabilities. The battery size is very limited and it will over charge batteries if they are left in the charger.
The over charge is not a problem if you are around and can remove the battery when the charger is finished, but if you let a battery stay in the charger for a day or more it can get serious (A cheap battery may vent, quality batteries will "just" loose lifetime).
The usb output works fine.

I will not recommend this charger anymore due to the over charge.



[size=+3]Notes[/size]

Here is an explanation on how I did the above charge curves: How do I test a charger

Read more about how I test USB power supplies and chargers

I can't believe they put in a trickle charge. I will not recommend this version of the charger either. I wonder if they are still selling the old versions?

Thanks for the update, HKJ - good to know to avoid this new version.

It amazes me that any company would design a lithium ion charger that maintains a significant current after the charge is complete.

What amazes me more is they allow the design to enter the wild and be sold to unsuspecting consumers.

I feel that I should buy another one and leave a bad review. I have bought the V5 so maybe it will let me review it.

Excellent review as always. HKJ! :thumbsup:

Your reviews are informative and very heplful to many people here.

Hi, I don't want to question HJK results but so far my experience with this charger differs. Since he posted the review I am testing my unit and so far I don't see any overcharging behavior. My unit terminates at 4.17V (green light) and I am keeping a fairly new 4.35V cell inserted & connected: it stays at 4.15-4.16 V so far (3 hours now). Yesterday I tested it with a very old cell and the voltage dropped slowly along several hours. So Might this be due to a faulty unit in his test?

iker said:

Hi, I don't want to question HJK results but so far my experience with this charger differs. Since he posted the review I am testing my unit and so far I don't see any overcharging behavior. My unit terminates at 4.17V (green light) and I am keeping a fairly new 4.35V cell inserted & connected: it stays at 4.15-4.16 V so far (3 hours now). Yesterday I tested it with a very old cell and the voltage dropped slowly along several hours. So Might this be due to a faulty unit in his test?

Click to expand...

I can only report on the charger I have. I cannot say if the problem is present in only my copy or 1% or 100% of the sold chargers.

The easiest way to check the charger is to rig it this way (From here: http://www.lygte-info.dk/info/Measurement UK.html):



Write down the voltage one hour after charging terminates and then run a test for 24 hours or when the the battery reach 4.25 volt. If the voltage after 24 hours is the same or lower than the voltage at 1 hour, the charger is fine.

Yeah, my setup is not as nice but should be enough to detect such a gross malfunction.

Ended at 4.17V this morning, that is 6 hours ago . I'll leave as it is till tomorrow

HKJ said:

I can only report on the charger I have. I cannot say if the problem is present in only my copy or 1% or 100% of the sold chargers.

Click to expand...

What are the odds that you happened to receive a copy that is bad and the rest are fine? Very low.

With other good chargers to choose from, who really wants to play Charger Lottery (tm)?


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tandem said:

What are the odds that you happened to receive a copy that is bad and the rest are fine? Very low.

Click to expand...

That is, of course, low to non-existence, especially because some other people has reproduced the problem.

I'm really disappointed Miller over looked this..
My old ML102 has been bulletproof & survived some very rough use.

I just bought the 2cell enclosed version and will have to test it now to see if it trickle/overcharges.

Thanks for the test!

iker said:

Yeah, my setup is not as nice but should be enough to detect such a gross malfunction.

Ended at 4.17V this morning, that is 6 hours ago . I'll leave as it is till tomorrow

Click to expand...

Can you open it up and see what version is on the board?

tandem said:

What are the odds that you happened to receive a copy that is bad and the rest are fine? Very low.

Click to expand...

After new tests my unit also has the same problem. It happens that the voltmeter was directly powered by the Miller so it was eating most -if not all of the trickling charge. After removing the meter battery has reached 4.3V and I have stopped.

Bummed it wont fit protected cells and that it overcharges. I was planning on getting some of these to hand out as gifts. Anyone know the last version that a protected cell would fit and where they can be had?

The ML-202 I just received seems to stop @4.17 on each channel & neither cell was above that after leaving over night.

Seems to be ok so far.

I was gonna order some more 102s but will wait for the next revision.

Miller seem to have really screwed the pooch on this one. Everyone's been hanging out for them to pay attention to us and put in a spring that supports protected cells, but no. And to compound it by getting rid of the bullet-proof charging they used to have?
HKJ, I can't quite make out the printing, but am I correct in saying they've changed the charging chip? If that can be identified, might be one for us to add to the "avoid any with this in it" list?

@Speadfreakz, I think the last version that fitted protected was either the v4 or v3, been a while, but no I'm not aware of anywhere at all that still has them.

First of all thanks HKJ for doing a review on the latest version.

I'm very surprised with the results as the previous versions has all received stellar reviews regarding their use.

Perhaps it is a bad batch or something but my unit is not suffering the issues you reported.

I happen to have left a battery charging in one overnight and then most of the next day as I went to work and forgot about it (dangerous oversight I know) until at night... so it was charging for probably almost a full day. Voltage of battery was at 4.17

In fact, everytime the LED turns green voltage reads out at 4.15 without fail.

I really hope Miller addresses these issues in their next version. Was planning to purchase a few more but for now it'll be on hold I suppose.

xzel87 said:

I happen to have left a battery charging in one overnight and then most of the next day as I went to work and forgot about it (dangerous oversight I know) until at night... so it was charging for probably almost a full day. Voltage of battery was at 4.17

In fact, everytime the LED turns green voltage reads out at 4.15 without fail.

Click to expand...

Looks like it do have the problem, but to a lesser degree.

Normal termination 4.15V, but voltage is up to 4.17V some hours after termination, i.e. the charging was not fully stopped.

Unfortunately I did some extended testing to really confirm the issue of my unit and sadly it is exhibiting the same problems that HKJ tested.

Brand new 18650B, voltage was 4.13 when charge indicated green light for complete charging. So I left it in and checked the voltages every hour for 6 hours. at the end of 6 hours the voltage was 4.19. I left it in there for an additional 4 hours and it got to 4.22, at which point ti removed the battery from the charger.

regarding my results mentioned in my previous posts I was using using laptop pull/salvaged cells, so the age of the batteries may have "helped" prevent it getting charged beyond 4.20

However, since I am now aware of the problem, I will continue using this charger as the other functions (power bank) are still invaluable in that kind of size.

For overnight/forgot to turn off charger I'll be using my mc2 and my soon to be obtained vp2 :twothumbs