But, You Shouldn't Do That...
An electric scooter claims a range of 20 miles, but if the owner constantly rides up to that limit, the batteries wil degrade very quickly since these batteries are not designed to be deep-cycled.
So, yes it can go up to 20 miles, but we suggest not traveling more than 4 ?
Being upfront about battery life will not sell many scooters.
Why doesn't the scooter come with batteries designed for deep cycles?
Good quality deep cycle batteries with proper charging will last at least 300 cycles at 100% DOD or 500 cycles at 70% DOD (to 60% capacity). You should look into the possibility of having the scooters delivered without batteries, and installing your own - with battery balancers.
As far as your last remark, you _can_ be upfront if you sell products you can stand behind. So I would look for such a product. Simple human ethics and integrity would demand it if nothing else.
but if the owner constantly rides up to that limit, the batteries wil degrade very quickly since these batteries are not designed to be deep-cycled.
I'm almost 100% positive that all scooters you can buy even the small cheap xtreme scooters come with deep cycle batteries. Actually, most all of the AGMs available are suitable for deep cycle applications. There are a few it seems that are specially constructed for more power, but this isn't necessary for most applications because deep cycle AGMs can deliver high power if need be.
And even if your specific AGMs are not designed for deep cycle applications they still should last at least 150-200 cycles. Compare this to say a car battery which I bet you'd be lucky to get 50. I think this is because in an AGM battery the plate material is held in place much better by the glass matting. In a flooded battery the plate material is much more susceptible to flaking off (not sure if this is 100% accurate but something like that). This means for a deep cycle flooded lead-acid you need much thicker plates and a place at the bottom of the battery for the material to settle so it doesn't short the cells. Also the plates in a flooded battery need to be strong enough to support their own weight and aren't as pure lead. In an AGM however, the lead can be as pure lead as practical, which I think factors in how the material degrades with battery cycling.
What is really the problem is cell imbalance. If you look at a discharge curve for a battery you will see that the voltage drops very steeply the last 5% DOD. This means that if there is even a marginal imbalance and the batteries are drains until the scooter will not move, than its very likely that one or more cells in a battery will be reversed. In real-world use without any sort of balancing system, battery balance can get very bad, and this is why it is best to not ride past 80% DOD which would mean 16 miles in your case.
If I was a dealer I would look into a battery balancing system, especially for the larger more expensive scooters with more batteries. If you are upfront about battery life than maybe the customer would be willing to buy a battery balancing system and give you more money.