Test/Review of Charger SkyRC MC3000

Batteries and Chargers Chargers
86

Ouch!

This is my concern. I guess I’m lucky that mine hasn’t had any of the posts break (ordered December 2015). Having heard of this issue, I’ve been rather careful with the sliders, and perhaps that helps. The dilemma is what to do when it breaks. The top cover has been in my shopping cart for a while now, but i’m concerned that I might run into trouble putting it back together, as this has been reported quite a few times.

The sticking point is that the bloody top cover is expensive. At $20.00, it is nearly a quarter (22.22%) of the cost of a new charger (currently $89.99)! Unfortunately, there really isn’t anything else like it (despite my hopes when I first heard of the Xtar Dragon), so if it breaks I’ll likely get a replacement. If I buy the top cover, screw up putting it back together, then get a replacement charger, I’d be $109.99 poorer (instead of just $89.99).

87

I got a 2 cell MC3000 charger now, and ordered another MC3000 at discount for $90, so it's on the way

I got $20 credit from Gearbest which I used to buy the cover - funny because I had 2 slots working before, and 2 slots now, but for different reasons.

88

EXPERIENCE BY REPAIRING MC3000 AND EXPLANATION OF ITS MEASURING METHOD.

Many things have been written about repairing the hardware of MC3000.
This is a hands on repairing of the electronics and something about its inner basic functioning with block diagram - drawing maybe later :slight_smile:

I hope some members with experience or interrest in electronics and a MC3000 can benefit from this. It will be rather technical so you are warned.

First the repaired errors:
error 1: Slot 1 and 2 not working, 5V regulator burning hot.
Reason:
The metal rail for slot #2 was loose (prob. because the plastic support, middle, was broken), moved a bit and made a short to the AD-circuit with IC16 (MCP3424) that got a defect and drew excessive current.
I cut the +5V pin on IC16 and the uP now would not start up as the I2C-bus did not answer from IC16.
Remedy:
Exchanged IC16 with MCP3424E-SL from AliExpress ($3.5)

error 2:
True charge- and discharge-currents wrong (one too big and one too small, worst at higher voltages (LiIon)).
Reason:
Probably small short-circuits and reverse battery insertion (carelessness).
slot#3: Leakage in zeener diode type ZM4734 (5.6V), in clipper circuit just before input to the AD-converter IC15.pin1. Measured –7.1mV on pin1 (normally –0.3mV), thus a 6.8 mV error (unbalance).
The AD-converter interprets 1 mV differential as 0.040A (measured), so now it measured discharge 6.8 x 40 = 272 mA too high and charge 272 mA too low. The uP reacts by turning the discharge current 272 mA lower than setting and charge current 272 mA higher than setting. This cannot be seen on the display! (see explanation below).
slot#2: Small leakage in zeener diode type ZM4734 (5.6V), before input to the AD-converter IC16.pin11. Gave –0.5 mV on pin 11 (‘+’ input, normaly –0.3mV), thus a 0.2mV unbalance. This gave a charge/discharge error of 8/-8 mA.
Remedy: The two zeener diodes were replaced with selected-for-low-leakage zeeners (6.2V, as 5.6V ones had too high leakage).
Result: Still a very small error in slot#2.
ToDo: Replace with Semtech ZM4734, ordered on ebay.

EDIT: ZM4734 was too big (size LL41-5 mm) so I have ordered” ZMM5V6 (size LL34-3.5mm) instead.“:100PCS Zener diode ZMM5V6 5.6V 1/2W 5V6 LL34 | eBay

DESCRIPTION OF THE BLOCK DIAGRAM:
The MC3000 is build around a 0.025 Ohm resistor to measure the current to/from the battery. Figure this is connected with plus to the bottom of the resistor and with minus to ground.
On the top of the resistor is a discharge FET IRF3205 to ground and a DC-DC switch circuit that convert +15V to battery charge voltage by means of pulses from the uP (not at the same time as discharge, of course).

Discharge:
An 18 bit AD converter MCP3424E-SL (only 14 bits used, I think) measures differentially the voltage drop over the resistor (through a LP filter and security clipper circuit) and the uP fetches the measured voltage by I2C-bus and calculates the current. 10 mV corresponds to 400 mA. That very low voltage makes the measurement very sensible to leakage current (as told above).
The uP then compares the measurement with the set (wanted) current and outputs a corrected PWM signal at 20 KHz, filtered to DC through a RC filter. This voltage is fed to an integrating (slow start) driver for the discharge FET. Pulse width of PWM signal is around 6us for 400mA and the filtered DC is around 390 mV.

Charge:
The uP sends adequate negative pulses to a P-channel FET 4407A that pushes current from the 15V rail into a big coil in the DC-DC converter which output is the top of the 0.025 Ohm resistor. The current is measured by the uP via the AD converter so that the uP can correct the current through the pulses to FET 4407A.

Functioning of the display at Discharge/Charge in case of miscalibration or leakage error as in ‘error 2’:

  1. The current shown under CURR is not the true current.
  2. mAh is derived from the current shown under CURR, not the true current.

This means that if there is an offset in the measuring circuit (as above, in error 2), the current will be measured (and corrected) wrongly and mAh will be in error and you cannot tell from the display that anything is wrong.
e.g. The true charge current could be 1.8A when set to 1A and the Capacity cut-off would be in error or even missing at charging, or Capacity cut-off could happen without any current was drained from the battery.
In any case the use of voltage cut-off at both charging and discharging will give a good security, but cannot protect against excessive charge or discharge currents. I advice to check currents at intervals with a Amp-meter. The true current can also be checked by starting the calibration procedure on MC3000.

89

Wow, might just try the error #1 fix. Great work and info!!

90

Thanks for your analysis!! But if i choose 3000mA charge rate, the mAh should be a straight line in the graph at the beginning y=mx+b. But can you provide a graph from the PC software?

The mAh graph is curved at the beginning when the current ramps up, it takes a few seconds to reach 3000mA no? The curved graph tells me that mAh is derived from the true current, or are you wrong?

91

Ordered the MCP3424E-SL from here: https://www.aliexpress.com/item/18-MCP3424-E-SL for $3.35 USD

92

I also bought from him. 1 piece!. At 2 pieces the price for me is $8.27! check that! :person_facepalming:
he is a little slow (5-7 days for shipping), but the IC is original, the same as in MC3000.

93

Yes the current ramps up because the DC-DC converter (with large el-co’s) is “pumping up” at the charge start by pulses from the uP (this is my guess). Whether the graph software uses “true” (from the ADC) current I don’t know.
That mAh is taken from the wanted current was obvious when I had error no.2 . At discharge I had Capacity cut and there was not used any charge from the battery (Amp true = 0), (Amp set = 0.4A). mAh ticked up until Capacity cut.
But as for charging I think now that the true current is used for calculating mAh. So you are probably right.
EDIT: I have now made a trial with batteries in ch.1 and 2. With the current calibration procedure I misaligned ch. 1 to charge/discharge 477 mA instead of the set 500 mA. In spite of that, ch.1 and ch.2 gave the same values for ‘CURR’ and ‘mAh’ (starting with 0.50 A, 0 mAh) in the display at both charging and discharging. So mAh is derived from ‘CURR’ whether it is the real current or not.

94

Right now I got 6 MC3000 charging bays - 2 from one unit, 4 from a newer one. Would love to get the full 4+4 - nice for the BLF GT and the BLF Q8's, Haikelite MT03 and MT07, etc.

95

I have a bunch of Samsung LiIon 18650-28A batteries which require a specific 4.3v (+/-0.03v) charging voltage. I bought this MC3000 charger which got shipped with FW 1.10. This version does not allow me to configure the charger with this specific charging voltage (max allowed is 4.25v). I wonder if the latest firmware 1.13 solves this situation (more info on this battery https://www.bto.pl/pdf/02023/icr18650-28A.pdf).

(I have not been able to upgrade the unit to the latest firmware yet.)

96

Of course it does, you select 4.35V LiIon and adjust the voltage 0.05V down.

The 4.35V LiIon must be enabled in the configuration.

97

Found and fixed!

Thanks for the clarification! :slight_smile:

(sometimes I feel happy when I realise that my perception of the reality is completely wrong, like in this case)

98

In my repair post (#90) the ZM4734 arrived but was a little too big (size LL41-5 mm) so I have ordered ZMM5V6 (size LL34-3.5mm) instead. (Sorry, TomE).

99

No prob, let me know how it works. I'll wait til you try it before ordering

100

Great charger but I haven’t been able to get it’s included SkyRC monitor.exe PC program to work correctly on any of my PC’s video adapters and monitors.

I’ve tried several monitors and video adapters set at different screen resolutions, but so far no luck getting the monitor.exe to display correctly. Display screens are usually too large and/or cut off, no way to read and configure it’s display screens and configuration menus.

SkyRc should really invest a few more dollars to re-program it’s monitor.exe PC program for the MC3000 as one of the reason for my purchase was because of it’s PC connection and software.

Apparently the monitor.exe program is designed for one specific video resolution. If your monitor and video adapter are not configured for a certain video resolution the monitor.exe program becomes totally useless.

The DataExplorer Dex is useful for monitoring (by design has no charger control). It too has problems with configuring it’s display screens as well as e.g. reporting correct MC3000 temperatures.

101

http://www.skyrc.com/Charger/Multi-Channel/MC3000_Charger

There are 2 versions of the MC3000_Monitor software:

v1.03 (for 1080p screens) and

v1.04 (for 720p screens) (I think most laptop screens should fit 720p, but I haven’t test yet on a laptop screen)

The settings screen for v1.03 and v1.04 are slightly different in the configuration though.

102

IMHO “fixed screen size” might be an indicator of programmer’s incompetence. Even icons should be scalable in Windows OS since years …

And the android app was apparently programmed as a quick & dirty solution, too. Or by an amateur, and not a good one. Now it crashes e.g. if bluetooth isn’t activated before …

103

No, neither version displays the gui correctly either from my laptops or PCs.

I’ve owned and used PCs and various software for more than 35 years and this app sort of reminds me when gui apps first came out a long time ago. Some had problems with resizing the window boxes. Most likely it’s the programming language app their using doesn’t have any window resizing functions and it’s probably open source or freeware?

I don’t think SkyRC invests very heavily with their software. They more concerned with the hardware and it’s firmware.

To write a good windows app for the MC3000 that has user control would require a bit of low level programming. The programming language their using I suspect is very rudimentary, they would probably need to hire programmers familiar with low level programming from a more robust programming language that addresses different gui features in Windows applications. Which will usually cost more for development, licensing, etc.

Imo, this is a mistake as users would be able to better utilize many of SkyRCs charging equipment with use of PC apps. They would also be able to increase sales as many users don’t want to deal with a small lcd screen that’s difficult to read. PC connectivity is a huge selling point. However the MC3000 at this point in time doesn’t really have any PC connectivity as the app doesn’t work with very many PCs and monitor combinations.

Their monitor.exe uses a single resolution and format. I’ve tried all the various resolutions of my PC and NEC 1080p monitor and none of the resolutions work at all.

Their monitor app is totally useless running on my various laptops and pcs. The MC3000 should have never been marketed with this PC control app they have available for download.

PC control was one of the reasons why I initially purchased the MC3000.

104

[quote=albert]

[quote=d_t_a]

This is disheartening. I read so many posts full of rave reviews about this thing, so I have one incoming on top of the OPUS BT-C3100. Now I realize, maybe 5000-post-long-threads are perhaps more an indicator of bugs than of a great product.

I thought i was getting something like the OPUS, but more customize-able, with constant current charging, and with the ability to record discharge curves via PC. But now I find all these mentions of poor build quality, posts breaking, problems with connectivity, and instructions on how to alter the electronics to remedy defects? Sigh. I still can’t even figure out how to really tell whether my incoming model has the improved post-June 2016 build quality or not, without opening it up. Vendor listing says HW1.4, but FW 1.03.

105

Other than the softwares and UI (User Control) issues I haven’t found the MC3000 to be problematic. It has done a good job of charging my batteries which at this point in time only consist of NiMH AAs and Lithium 18650s.

However, I don’t find it’s built-in LCD (menus) user interface to be all that intuitive. It could use some more development to create a more intuitive less, stressful UI. It’s key-presses aren’t all that logical and/or are using a different type of logic that most likely derived from it’s low level firmware & programming. This is fairly typical for devices that have user control from a small LCD screen. The UI programming often follows the logic of the firmware’s low level programming which has less logic compatibly for a UI.

I don’t use the MC3000 all that regularly and usually can’t remember it’s keypress menu logic. So I’m usually fumbling around trying to remember the kepress logic and menus.

That’s one reason why I support a PC app as PC applications have better programming in relation to a UI and GUI.

Programming development for LCD screens has it’s limitations. For LCD screens It can sometimes take a lot of work to come up with a UI that’s even usable and the end results will usually have limitations.

The MC3000 is charging individual multi-chemistry cells. It does have the ability to save up to 30 programs, however you are required to remember or write down the program # saved for a particular battery & chemistry as the MC3000 doesn’t have any text labeling to identify each of the 30 programs.

What the MC3000 would benefit from not only to be able to ID each program from the MC3000’s LCD screen & menu(s) but would to also have access and control from a PC app where one could save and load each program with an ID and description.

You could then install a set of up to four batteries, loading a program for each battery and start charging.