What a great trip! Spain is wonderful! You do know helmets are compulsory?

My first tip would be to look for a more general biking forum, or even an E-bike forum. No disrespect to CT but this is a pretty low traffic area.

I know little about E-bikes but I've had the very good luck to explore a lot of Spain (and a bit of Portugal) on my trusty old acoustic bike.

You don't say if you're planning on camping or not. Campsites do have electricity but you'll have to pay extra. This summer it was running at €4-5 per site per night. In some places you may have to pay extra for the pitch to have access to electricity. And some campgrounds will only have sockets for the bigger plugs that camper vans use. Perhaps your battery can be charged at reception for less, but that can mean limited departure times.

If in a hotel there should be no problem to charge in your room, presuming the battery is removable.

During the day may be trickier as there are very few places open during the siesta hours (typically 1/2 pm - 4/5 pm). It may take some wandering to find an open café (there's normally one) because there's generally no-one out to ask. 

Given the (current) high cost of energy and the absolute beating hospitality businesses have taken in the past couple of years I'd encourage you to offer to pay for charging, especially in the smaller towns and villages. A wonderful menu del Día can be had for as little as €10. A tasty, leisurely meal, a copa de vino and your battery charged for a decent tip sounds pretty good to me!

In Portugal I found the roads to be narrower and traffic a tad less respectful. And they do like their cobbles! 

I'd imagine that battery anxiety could detract from your enjoyment  so I'd encourage you to get comfortable with the range carrying the load you intend to carry, paying attention to climbing. I know batteries can lose charge in very cold temperatures. Do you know what happens in high temperatures?

You give no information on what types of surfaces you plan to ride. There are some wonderful "camino rurales" to really immerse yourself in the country.  Other options are to look at the Via Verdes. There is an app you can download that will show (most of) them.

One right on your route is the Via Verde de La Plata. You can see what it's like here: https://photos.app.goo.gl/5rPGcMi3vqozw5A1A

If staying on roads, Spanish drivers are excellent towards bikes. 

I used CT to guide me around Spain and it chose excellent routes, often not the "official" bike routes. 

For more information head on over to CrazyGuyOnABike.com, a treasure trove of bike journals. There won't be many ebike journals, but there are lots about Spain. (Just stay away from the forum - it's poisonous)

 My own work in progess effort is here: https://www.cyclechat.net/threads/spanish-figary-other-stories.289707/ although I haven't got to where you are going yet. 

Spain is one of the closest places to perfection for bike touring. A constantly changing, very diverse landscape, great people, wonderful food and drink, friendly dogs, history everywhere, great coffee and have I mentioned the food? :-)

Oh! Lots of time to pick up a bit of the lingo. I can recommend Duolingo (although that focuses mainly on the Americas) and SpanishDict. Lots of Youtube videos too. A little Español can go a long, long way! 

Have a great trip!

Hobbes, thank you so much for taking the time to offer that advice. I’m going to use hotels but battery anxiety is my major concern atm. Heavy bike anyway and loaded with travel gear I’m not sure how it will affect range so I was hoping for the sort of lunchtime boost you describe. I’ll do some trial runs here with and without loaded panniers and compare the range. Maybe even look at carrying a spare emergency battery if I can pick up a decent one second hand but weighing in at >2kg it’s quite a penalty.

Thanks again, David

Trial runs are the way to go to manage anxiety.

I may be odd, but if 2kg gave me peace of mind, I'd take it. But that's me and I'm no weight weenie.

Worst case scenario, you may need to wait an hour or two in a small town waiting for a bar to open. Spanish towns are great for exploring or just sitting and relaxing. Remember, the best food is served late in the evening so there's no mad rush to get to your destination. 

You could avoid making hotel reservations and play it by ear, at least during the week. Something like BookingDotCom will give an idea on availability. (I was mainly camping but if I found a nice place with no camping options I'd look for a room. Consistently I got a better price at the desk than offered on the app but sometimes a room that was available was gone by the time I arrived). I admit that might cure the battery anxiety and replace it with bed anxiety! :-)

You may be interested in Timmy Mallet's recent book on his Ebike Camino, cycling from the UK to Santiago on an Ebike. 

Thank you again. After looking at the pictures you posted I’ve modified my route to add in the via verde south of Salamanca. And you’re probably right about an extra 2kg as insurance given the range extension that would give me. I love the planning, it’s all part of an adventure isn’t it.

"I love the planning, it’s all part of an adventure isn’t it."

We're all different! I spent 8 months wandering around Spain with pretty much no plan at all and no preparation, other than some experience under my belt. There is a wonderful freedom and spontaneity to it. You do yours - Spain is great for bike tours!

Ha ha, but it’s snowing here atm so this is as good as it gets.