Jay, don't you just love all the experts on BROL? Ha, a battery isn't a battery unless you pay $200 too much for one! I have had mine for over a year and have had no problems with it. Getting ready to order two more before the next price increase.

 The only problem I've experienced with the Ebay-sourced battery on my trike is the Hailong plastic case and mount deteriorating due to vibration, resulting in a loose fit. The locking hole in the plastic mount has elongated, and together with the loose-tolerance locking plug, allows the battery to slip forward in the mount about 2 mm. I have to strap the battery tightly to the mount to prevent intermittent power loss.
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Some batteries have a cover over the locking plug. remove the cover and see if there are two screw you can adjust to keep the battery engaged with the contacts

I have had success with epoxying a washer over holes on plastic Jay. Or use a wide washer with the correct hole diameter and use short self tapping screws. You can even use a soldering iron or hot air gun to weld a washer over the hole. You can use the very thin metal washers so the bolt is still long enough. If you could get the case open to put the washer on the inside of the case it would be even better. If they would do that at the factory it would save us all some grief.  
 
You could also drill out the case a little to put the washer flush.

I agree Jay. Just like the crappy stuff from Japan in the 1960's and 1970's now we have the even crappier crap from China. Don't you just love it when the item says proudly designed in the USA, made in China. They would probably use lead as the base if it were metal.  
 
I was wondering if the whole bottom of the base could have a thin piece of metal epoxied to it. Something like 26 or 28 gauge. The whole could then be drilled out and a washer JB welded to the metal plate.  
 
Ace Hardware has some nice thin washers in the nut and bolt section of their store. The one I shop at they are where the automotive bolts and stuff are.

Quote from jrob_bent on Mar 22^nd, 2022, 7:29am:
 I don't own any counterbore bits, so I need to check the clearance between the base and battery bottom to see if there's enough clearance to surface mount a thin washer.  

Quote from jrob_bent on Mar 22^nd, 2022, 8:43pm:

 
I would need a counterbore (https://www.mcmaster.com/counterbores/round-shank-adjustable-diameter-counterbor es/shank-type~round/) to cut a shallow recess for a thin washer.
 
Not much material to work with, as the plastic base's thickness at the plug hole is just 4 mm.

I almost forgot about Forstner bits.  
https://www.harborfreight.com/14-in-1-in-forstner-drill-bit-set-with-38-in-shank s-7-pc-62361.html?utm_source=google&utm_medium=cpc&utm_campaign=12126402660&campaignid=12126402660&utm_content=118355023673&adsetid=118355023673&product=62361&store=3129&gclid=EAIaIQobChMIqc_Nhfjc9gIV1g-tBh2KMgEaEAQYASABEgIx9vD_BwE
 
 
I have used them to countersink in plastic, wood, and fiberglass. They leave a perfectly flat bottom. I have an expensive set but those cheap Harbor Freight ones should be up to the task.

You are welcome Jay. I hope it works for you. With plastic and Forstner bits you need to use a very low rpm. It will heat up fast if too high an rpm.