The 150w heater was rewired to make it 300w. Here's a look inside the heater(before the change) to show you how easy that was to do. I just moved one wire and it now only powers one of the elements.
Then I replaced the filter with window screen to increase flow. Once I get a less restricting filter made, I'll change this. Now we're ready for test two.
The air coming out is now significantly warmer, but not hot. The flow rate is also much higher. I think if I left on the more restricting filter the air would be much warmer still. I may keep that in mind for a future test.
Yes, I know I would need to dry more persimmons to properly compare this test to the last, but there are no more ripe ones on the tree yet, so I used an apple. Again it was sliced to about 7mm and placed on the second from bottom rack. About 20 hours later the slices were nicely desiccated. They were about 2mm thick with a flexible leathery feel. Again, I can't properly compare the drying performance with different fruit, but it does seem faster. On the other hand, it uses twice as much power.
Testing Plan - Science is good, so I'll have to set up some proper experiments. Once the persimmons ripen and I have buckets full of them, which is one of the reasons I wanted a dehydrator in the first place, I'll do some proper comparisons using a scale to measure moisture loss over time with different configurations. We'll just have to wait a few more weeks. In the meantime, here is an apple.