Replacement battery pack or battery model number

Hi John,

Man, this is a tough one! I didn't have any more luck than you in locating a replacement battery for your toy.

We do know this much; the battery is specified as a 7.4V 1200mAh Rechargeable Lithium Battery. I grabbed a screenshot from the battery installation video here.

This gives me a fair degree of confidence the battery pack is most likely made up of two 18650 standard Li-Ion batteries. You'd be looking for a pair of batteries with individual ratings of 3.7V (7.4V / 2) and 1200mAh current output. The only way we can get any more information would be for someone to disassemble their battery pack and post the pictures so we can see what's inside. It may or may not have a circuit board called the BMS, or Battery Management System. If it does have one, then you'd want to reuse it if you cared to try replacing the battery cells.

I couldn't get a good look at the connector from the video, so I'm not sure what that takes, but that's something that should also be reusable in terms of rebuilding the battery pack. Most likely the two cells are connected with a strip of nickel metal, which is generally spot welded on.

If you take a look at my Ember Mug Destructive Teardown, you'll see where I opened up the packaging on the battery pack of my Ember Mug; that would give you an idea of what you'll probably find inside your battery pack.

Note that if you want to replace the cells, you have a few options. The best choice is to purchase spot welder; that inflicts the least amount of heat on the battery, which can be deadly to it. You could get away with soldering, but you need to be very quick about it and use the minimum amount of heat possible. The last idea I had would be to purchase replacement cells with the tabs already spot welded on; that way you can solder onto the tabs and not subject the battery itself to the heat of the soldering iron. Here's an example of what I'm talking about.

Tenergy 30005-1 ICR 18650 3.7V 2600mAh Li-Ion Unprotected Rechargeable Battery - With Tabs

You'll note that the voltage is correct at 3.7V, but the current capacity is much higher; this one is rated at 2600mAh vs the 1200mAh your original pack calls for. It's perfectly fine to use a different capacity; that just means your device will run for a shorter amount of time if you use a replacement with a lower mAh number, or it will last longer if you use a higher capacity battery like this one.

Once you're done you can buy fancy polymer tape to wrap the battery back up, but to be honest some wide packing tape would do the job just fine, assuming the battery doesn't get too hot during operation.

Sorry I don't have better news for you; it's possible some of our other experienced members may know other places to look for an exact replacement. If we can get a good look at the connector and what's inside the battery pack, that would give us a better idea of what to look for.

Good luck, and let us know how it all turns out!