Range Test

When people ask me what is the range of my electric truck, I tell them 40-50 miles.  Now that is an estimate based on how many Ah per mile I use and 80% of capacity of my battery pack.  I consider the full use to be 80%, always keeping 20% in reserve.  The 20% reserve serves two purposes.  First it give me additional "emergency" range in case I get in some situation where I have to drive more than planned, and secondly, it extends the life of the battery pack to avoid fully discharging it routinely.

Up to now, I have never actually measured the range, only estimated it.  Short answer is 60 miles.  Click below to read the details:

A couple of weekends ago, I needed to haul my tandem bicycle from my house in Austin out to Cedar Park for a ride (Atlas ride).  The tandem is too big to take in a car, I need to put it in the back of my truck.  Google maps tells me that the one-way distance is about 22 miles.  So that means if I do the round trip, I will need to drive 44 miles on one charge (I considered trying to charge somehow in Cedar Park but that was not practical).  Previously, the most miles on a single charge has been about 32 miles.

I was a little nervous about this idea just because I had never pushed it that far, and I really didn't know what happens as the battery pack runs low.  But I decided to go ahead because I need to know.

Then end of that story is that it ended up being about 45 miles round trip, and my gauge showed 27% remaining (43 Ah).  So that was no problem and gives me confidence in the 40-50 mile range estimate I have been using.

Now that I had drained it that far, I decided that I wanted to run it down, both to see what happens, and to see just how far it really goes.  So I drove it around my hilly neighborhood until the remaining capacity showed 0.  At no time did I hit a low-voltage alarm.  I was pushing it up the hills to put a good load on the battery to see if the alarm would go off.  Since my battery state-of-charge meter does not go below 0 Ah remaining I decided to stop at that point since I had no way to know how much more I was using.  When I got home I had gone 62 miles.

My conclusion from this is that the Thundersky batteries I am using have a capacity of more than the rated 160 Ah and that they are able to deliver full power for at least that much capacity.  I think I will repeat this test once per year so that I can see when they start to degrade below 160 Ah capacity.  Hopefully that will be many years.