The only real way to tell is use a multimeter to measure the voltage... When you plug the battery in to the charger what happens? What leds are lit and what colour are they? Do they flash?

The charger stayed all three lights green but the battery was dead. Puffy. And I don't know what that would happen given I am doing (as I wrote above) all the proper things to keep battery in tact.

So when you flip the switch on Roli (from your other thread) is there any lights or sound or movement at all? If not, it might be possible you have just blown Roli's fuse... All green lights (I believe) on the charger usually means the battery is fully charged...

Nothing at all. I replaced battery with another and all is well.

It seems quite involved to buy a multimeter to measure battery voltage. If I'm following all the directions, why is the battery "over discharging"?

There is no way to stop the battery from discharging if the device is left on... EZ Robot cuts off the fun at 7v to protect the battery and for safety... However the battery will continue to drain as long as Roli is switched on so it is up to the user to switch him off at this point and charge the battery.... Unfortunately Lipo batteries are extremely sensitive to absolute voltages... Meaning too much voltage or too little and they will die.... Just the nature of the beast for this type of battery chemistry... Anyway chances of this happening is remote with proper care...

To me it sounds like Roli just blew his fuse and not a battery issue...

I see you joined the forum in August, how long have you had your Roli? LiPo batteries (as with any battery) do have a limited life. Typically about 1000 discharge/recharge cycles, and/or 1-2 years regardless of discharge cycles. LiPo's are more sensitive than most other batteries to mis-treatment.

One important step for longer life is to allow a cool down period before and after charging, so if you go straight from getting the battery warning to charging and then from charging to using the robot again, it will shorten the life. About 30 minutes at either side is helpful, and the newest tutorials recommend this.

I am not sure if the new EZ-Robot labeled batteries are the same as the ones sold last year with private label or if they changed vendor, but you can get the same ones they used to ship for lower cost and without paying the shipping from China from Amazon: https://smile.amazon.com/dp/B016DD1GT6 The shipping estimate is long though (3/10-4/10).

I just had to replace a couple, and bought these instead: https://smile.amazon.com/gp/product/B01N082H04 but they had JST instead of DEANS connectors (at the time, the Amazon description said they had DEANS. The vendor just changed the description when I let them know it was wrong. He expects to actually have DEANS in stock in a couple of months. I soldered on new connectors myself in the mean time). They did come in 3 days even though the shipping estimate was 1 week.

I am actually planning on modifying my Roli to take a much larger battery (same voltage, more MaH) to get longer life between charges.

Alan