SAD CHILD <--- Help Battery issue



I’ve got a very sad child that his mekamon doesn’t work anymore. Seems like the battery is of issue and is a common one. With Mekamon going out of business, I cant seem to find any replacement batteries anywhere. Anyone out there with any knowledge on what to do?

Help is much appreciated.

Thank you


I can’t do much besides commiserate with you. My son was very sad as well that the battery didn’t work.


I have faith that someone will eventually know what to do and save the day


I to have 3 disappointed children with a dead battery robot


I can’t attest to whether this is legitimate or what the quality is, but I found this on eBay, may be worth a shot:


You really came through! And before new years too :stuck_out_tongue: Thank you so much!!! I will test the service and post findings here.


Hello there. The replacement service looks interesting. I’ll be interested to see how that goes. I’ve used an ebay fix service for a Timing Control board on an LCD TV (after twice failing to import a replacement from China for only slightly less) and I was very glad I did (TV fixed great when I got it back and it had a six month guarantee - still works great today).

re. Mekamon, I bought a cheap DOA/“for parts” one off ebay the other week for not lots, suspected of battery issues. No signs of life initially but the battery was at 0.5v :joy:

Looking good so far for the 'mon though. Have created a “dummy plug” (yes yes Evangelion reference) out of foam connected to a 3 cell battery I had lying around, via electric cable and the Mekamon seems happy (if a little behind on firmware :sweat_smile:)

Next trick on the power issue will be to crack the battery open and see what goes on inside. Looks like it might be a bit of a pain to get into though. Might make a thread on progress.


Got the battery apart. Took some pics along the way so can document later if need be. Not expecting a DIY fix to be something I’d recommend to most people at the end of the road, but it does look doable.

Cells not looking good though. I’ve asked that chap doing the repair service if he wouldn’t mind sharing what he used for replacement. It would be nice to have a mended pack at the end of this journey but could always go the “use a hobby battery and recharge with dedicated charger” route if need be. There is a backup plan at least.


How difficult was it to get into the battery casing? I have little to no experience fixing batteries, but it’s a project I considered tackling…


Great find. I’m going to get two batteries fixed by this service. I’ll try to post back the results. Thank you very much!


Hard to say on difficulty as it’s all a bit relative. But then again, first time I’ve tried to get in to a sealed battery case. Once/If I’ve successfully fixed mine I’ll defo consider making a tutorial but feel a bit uncomfortable handing out advice on something I’ve yet to prove works.

That said, from what I could tell the battery is properly sealed and was never intended to be got back into. It didn’t seem like some of the video tutorials where folks prise open say laptop batteries and there are interlocking parts that can be preserved.

As a minor preview though, the casing is about 1mm or so thick. Getting in, I had to cut in on one side of the join, enough to get a screwdriver into the gap, then I could gradually sideways levered the lid off with a bit more cutting say on corners and awkward bits.

Anyone attempting a self repair should ideally know about lipos and be careful not to cut too far when opening the case (no more than 2mm in). The cells are pretty close to the edge of the case and you don’t want to stab/cut them. There is more of a gap on the right side edge (that’s where the connecting wires are and more foam) with the thin lid on top and the contacts pointing away from you. This is where I went in.

At the moment I’d advise just going with the repair service though, he seems a decent chap and sometimes it is just easier to get someone who has already done it to sort the problem. (Note that is only speculation though).


Note will be a while till I can say more on fixing from my end. I’m going to be waiting probably a month or more for replacement parts to come from China. No guarantee it will even arrive/fit though at this stage.


I made a custom battery pack mod using 18650s in 3S configuration with a protection board.
The battery holder mod makes swapping batteries easier.
One con though is that the battery pack is a little heavier.
Other than that, it works great.

Let me know if you are interested and I can post pics and instructions. All parts can be purchased in Amazon.

Battery and Mekamon dead on arrival

Here are pics Mekamon-with-battery-mod


Very cool, I’m definitely interested in finding out more about your mod.


As always, please proceed with caution in attempting any DIY mods.
NEVER insert the batteries and/or the battery pack incorrectly.
Batteries should be seen facing up NEVER down.
It could damage the Mekamon.

A bit of a background first…
I got hold of these amazing robots just a few weeks ago when they were listed for cheap on eBay.
Bought 2, and then bought another 2 a few minutes later - for parts, just in case.
I probably wouldn’t buy them in their original price. :frowning:

When they arrived, it had the same problem as others reported, the battery has been fully discharged.
This began my journey to modding a power source.

Truth be told, this is my 2nd attempt actually.
Plan A was to replace the li-pos in the original pack with 3S 3.7V camera batteries and re-use the original BMS.
However that was short-lived as it only powered the Mekamon for a few minutes.
Voltage dropped quickly to about 7V from the fully charged 12v.
Perhaps, the batteries I used may not have sufficient power, maybe one of them is defective, or the internal BMS kicked-in and prevented the high-current drain.
I didn’t dugged much since I had a Plan B ready.

Anyhow, below is the Amazon part list I used for the battery pack mod:

  • 3pcs 12V 10A 18650 BMS Charger Module Lithium Battery Charging Board with Protection 3S BMS Module
  • Aodesy Plastic Battery Holder Case Storage Box 3 x 3.7V 18650 Black Pack of 5


  • RuiLing 1 Roll 10 Meter (393 Inches) Nickel plated steel Strips for 18650 Li Battery Spot Welding 8x0.1MM(WxT)
  • Heat Resistant Tape No Residue High Temperature Polyimide Tape 2 Rolls 10mm X 33m 100ft

The nickel steel strips can be skipped and alternatively a sufficiently gauged wire can be soldered directly to the protection board and the battery holder terminals.
Heat tape was used for insulation since the BMS mounts above it.
Other insulating tape should work.

I used metal folder fasteners for the battery terminal.

For charging, the OEM charger works well.
It trickle-charges when the battery reaches 12.5-12.6 volts.
The protection board should prevent over-charging, over-discharging, short-circuit, etc.
One thing to note though is that I cannot attest for their durability since I only have been using them for a few days but so far so good.

When charging, I temporarily just used alligator clips with magnets to connect to the jerry-rigged terminals.
I took note of the polarity of course.
With the terminals facing you, left is negative (-) and right is positive (+).

The 3S battery holder and the front battery plate requires some special trimming so they fit. The front battery plate/chest plate cover has a support lock that can also be removed without the need to cut anything.

Please see the pictures below:

Battery protection board wiring overlay (bottom view).

Note: heat tape used for insulation so the wiring doesn’t touched the board PCB.

Make-shift center channel sleave for protection and also helps with the alignment so it slides in like the original.
Foam fillers added also on the bottom and the sides.

Battery holder cuts (top view)

Battery Mod (top view)

Battery Terminal (front view)

Battery Inserted

Battery cover/chest plate

Note made some cuts for fit but the lock support can just be removed.
This will be a lose fit without a support piece though.

When done right, Mekamon lives!!!


Nice write-up! Thanks for sharing that.


Hello All!
I’m the person supplying the battery refresh service on EBay. Knelf asked that I hop in and join the fun.

So far all the rebuilds have been working very well with no issues. I was use sure to maintain all the safety features of the original design, this includes both the thermal protection and overcurrent protection circuits. I took care to match the cells with the originals in capacity so as not to stress any of the components and keep everything as original possible. These are exceptional little creatures and I am very sad they are no longer produced. Hopefully, as a community, we can keep them alive for a long time.

I would also like to apologize for the cost of the rebuilds, but when its all said and done, I only make around $10 for my labor. If anyone can find lipo cells that fit in the case for less than $10 USD each, I would gladly lower the price accordingly.

I believe I posted these before - But just in case, here a few of my Mekamon adventures! - Takes dip in the water at the end - High heels - 360 camera high jinks


Great to see folks are rising to the challenge (also “waves at Ckalkhof - thanks for coming!”). Rave thanks so much for putting the effort into the write up of your version. It takes time I know.

My order isn’t expected till end of Feb “on average” (if it shows even) but after doing a little research I have a plan B and a plan C and even a plan D. Plan C looks similar to what Rave has done. I think I have some of those cells in an old battery pack rescued that might be OK.

In the mean time I’m using my “foam battery” (it’s a slab of foam [with contacts made out of a coke can] with a wire coming out of it, connected to a spare drone battery) to have a little fun with the Mekamon while I wait.

Looking forward to trying out some of the animations I’ve seen lying around that folks here have made.

PS Rave, don’t blame you for buying a few. Very glad my friend got one. I have to admit I nearly bought a 2nd one as soon as I’d verified I could get the first one working. Alas someone had bagged it overnight :smiley: Ah well.


Thanks! Really appreciate the response!

I hope we can spark or even revive interests on these amazing robots.
There’s so much potential for them.

Thanks for sharing too!
I thought of Coke cans too for the terminals but I opted for folder fasteners since that’s what I have.

About the cool animations, check out the ‘Punisher push-up’ in the Mekamotion public share.
It’s one of the coolest I’ve seen.
Also the ‘ninja flip’.
On loop, we are playing with the idea of how many non-stop flips it could do.
It’s gonna be quite a stunt. :sunglasses:

Btw, I got 6 now. I built another custom battery pack so I can battle my 5 year old son and/or older sister(s).
I’m tempted to buy a few more since I can power them now.

Currently, I’m planning on adding a magnetic charging port to provide easy charging without the need to remove the battery pack. The idea is to position the Mekamon close enough or within proximity such that the magnetic port can engage. Dis-engaging is just a matter of navigating it away from the magnetic charge port/dock.
When it’s almost fully-charged(90-95%), an automation (using a wifi plug) can just wirelessly turn off the OEM charger plugged to it. From time to time, it can turn on the charger to trickle-charge the battery so it’s kept almost topped off(90-95%).
It’s good for keeping the batteries maintained.
Alternatively, I’ve already considered wireless charging but QI wireless charging currently is still an inefficient technology (60-75% efficiency) – high power loss.

Next stage, I’m thinking of an IR beacon so the Mekamon can home-in to the charging dock when battery gets low or instructed to do so.

There’s really a lot of potential for hacking this.
Some ideas/plans that may be down the line…when I eventually get to them… :smiley:

  • wireless camera for video streaming for remote control via the internet
    wireless video streams can also be used for machine vision/AI.
    Edge AI is better but too much time to develop for me at least.
  • Alexa/Google integration for voice control via voice skills or just plain old Alexa-enabled robot.
    e.g. Alexa, ask Mekamon to guard the house,
    Alexa, ask Mekamon to check the kitchen.
  • leveraging its 4 built-in IR transceivers for IR remote control/automation e.g. turn off TVs, Air-con, etc.
    when it can self navigate room to room.
    IR control can of course be done without it, but its cool if its one of its capability – a mechanized IR Remote
    Or when let loose, the cutest walking TV-b-gone mechanical monster. :smiley:
  • A more ambitious project, is adding some AI similar to Anki Vector for autonomous navigation, object detection and of-course, self-charging.
    Originally I thought of just mounting Anki Vector on top of the Mekamon. Integrating some sensors to translate its track movement to Mekamon motion. The best part is Anki Vector already has a rich AI personality and has some level of autonomy. With Mekamon legs, mobility is greatly improved. :smiley:
    Just albeit more scary from the head down.