Mail truck at end of life

[kevm14]

http://www.wsj.com/articles/postal-serv ... 1423786375

Grumman aluminum body on a modified Chevrolet S-10 platform. Wiki says the originals were the 2.5L iron duke with TBI and then later the 2.2L used in the newer S-10s. Both were known for being terrible performers.

http://en.wikipedia.org/wiki/Grumman_LLV

[Bob]

This would be a great EV application with the predictable use and most of the time spent driving at low speed stop and go.

[bill25]

I wonder about this. They have to accelerate from stop repeatedly all day, and accelerating is what drains the batteries the fastest. I totally understand that they aren't racing to top speed but they are accelerating almost all of the time. They also aren't likely going fast enough to benefit from regenerative braking either.

I would think the ideal for EV would be driving at about 30 - 35 mph without stops.

What do you guys think?

I might almost recommend diesel. They have a high reliability at high mileage, low end torque for pulling out, and not high HP which is fine since they don't drive at high speeds.

Not trying to be argumentative, just starting a discussion.

[kevm14]

An EV or hybrid is probably the best technical solution. Reasons:
1. Highway speeds not much of a requirement
2. Lots of stop and go. Regen will help add a lot of efficiency as you dump less energy into the brakes.
3. Package deliveries require shutting the engine off and restarting it. Hybrids do this all the time, and would remove the starter from the list of maintenance items.

Thinking about it more, an pure EV is probably better. The route is very well known and with a hybrid, the engine would be starting and stopping a lot.

But for practical reasons, I'm not sure someone can sell the USPS, for fair market value, EV trucks that meet all of their requirements for the $25-$35k indicated in the RFI.

Article from 2011: http://www.washingtonpost.com/blogs/fed ... _blog.html

Though most delivery vehicles incurred less than $3,500 in annual maintenance costs last year, but a handful of trucks required more than $10,500 in maintenance — or more than a third of the price it would cost to completely replace a truck, GAO said.

http://www.govexec.com/management/2015/ ... ck/105306/

[bill25]

I may have undervalued the regen at 10 mph. Do you think that would substantial? I know there would be a lot of braking, but how much regen do you get at really slow speeds?

[kevm14]

That is a good point. It becomes very hard at slower speeds. I read about this for the Volt's design and I forget what they said. I think it works to slower speeds than 10mph but obviously not at peak efficiency.

[Bob]

There is actually a speed at which the Prius switches from regen braking to convention brakes (I think 5 or 8 MPH). This isn't to say that the regen couldn't be reconfigured to work all the way down to zero for a specific application, but I think the gain in efficiency might be minimal.

Nissan already makes the e-NV200, which would work well in this application. I am not sure of the pricing, but I suspect it would probably be close to the target price (ICE NV200s start at under $21k, so it's not unreasonable to think the electric version could be around $30k, or maybe less in a high volume sale). When you factor in the value gained by lower maintenance costs and lower fuel costs, I can see it making sense to select a vehicle like this.

[kevm14]

That is also a good point. It's all about lifecycle cost when it comes to large acquisitions like this.

[Fast_Ed]

I had the same thoughts on the mail truck re predictable routes and known parking locations for charging. My main concern would be battery replacement.. Those things are never cheap..

The lack of highway speeds means little aero drag... There may be existing NEVs that are optimized for this type of travel, like that stupid looking GM one Bush used to ride around in. I wouldn't be surprised to find electric golf carts already delivering mail in small private communities..

[Bob]

The replacement cost for a Leaf battery pack (virtually identical to the one in the e-NV200) is currently $5500. By the time these vehicles need a new battery, I would expect this price to be significantly cheaper. Assuming a 10 year service life for the battery, a $550 annual cost for replacement is going to be more than offset by the fuel and maintenance savings. Also, this assumes you need to replace the entire pack at today's price. You can probably save money by replacing individual modules if one fails.