Used Prius Primes traction battery SOC loss

Hello,
I'm in the market for a used Prius Prime and have seen two cars and have seen an odd thing happen.

One 2018 and one 2019 Prius Prime. Both were charged fully per my request before the test drive. One showed 30 miles the other 23 miles ev range when I drove them. On both occasions I didn't buy right away and came back 3 days later. They were sitting on their lot, outside, with night temps about 45-50 degrees.

When I test drove them again, one Prius showed 5 miles range, the other 0. Both started up the ICE engine in hv mode to charge the battery.

Is it normal for a fully charged Prime to lose ALL it's charge in only three days sitting unplugged??

 

That sounds right - it's a battery after all and should hold a charge. At the one dealership with the 30 mile ev range prius, the manager and salesperson said definitely not - no one else test drove it. The other one, the salesperson said maybe but he wasn't sure. He said he owns an EV truck that loses some range if it sits. But that's not ALL its EV range.

A test drive is maybe 4-5 miles. So in there days five people would have had to test drive it. And the dealership is a small, independent one out on the Olympic Peninsula of Washington State.

I find that hard to believe that there would be enough test drives in 3 days to deplete them to zero.

 

I did ask the salesperson - he did not know if it had been driven since and the second place said it had definitely not been driven. So the cars sat for 3-4 days and lost all or nearly all charge. Yes, most Prime's - those that are still owned by the original buyer - don't have battery problems. These are trade-ins or sales to a dealership or auction, not the pool of ALL Primes, so more likely to have battery problems.

This could very well be a "reverse survivorship bias" issue. Those that have batteries that "survive" are those that owners keep and those that are traded in are more LIKELY to be those that have bad batteries. There are other reasons to trade in a car of course, but the probability of a Prime with a bad battery in the pool of traded-in cars is higher than those still owned.

There's a new private firm called Recurrent that provides a kind of Carfax for PHEV/EV batteries, but again, without a federal law defining what is acceptable (like for MPG or safety features on ICE cars) I'm still a bit hesitant.

These Primes do not have Recurrent reports.

I talked to the salesperson at the second dealership and he said he has an EV truck that loses some battery life when it sits for several days unplugged. So he said it is completely expected that this Prius Prime's battery will completely drain when unplugged and sitting for several days. Is that your experience? Because he says that's normal.

This is just a frustrating experience to get reliable information on the battery on a used PHEV/EV.