[ausev] Converting a vehicle

[Chris Robison]

MLAB wrote:

> Bear in mind that an electric pickup truck will have much of its cargo 
> capacity taken by the batteries.  That ready battery space is apparently 
> one of the things that makes pickups so practical for conversions. So 
> don't figure on having much cargo capacity, though you'll likely have 
> enough for hand tools.

In most cases, this is not true. Any properly converted pickup truck 
will have no reduction in useable cargo space, unless the conversion is 
a special case where compromises have been made for range or other reasons.

A pickup truck is valued as a convenient candidate for conversion 
because of the rectangular volume of space available between the frame 
rails, under the bed. Unbolt and remove the bed, and you'll see that 
there's space underneath, especially in the large area behind the 
differential. Forward of the differential you'll have space to either 
side of the driveshaft, and the amount will depend on how wide the frame 
is spaced -- for example, there's more room in an S-10 frame than a 
Ranger frame.

Weight is a different issue, but it's still something that can be dealt 
with. Truck frames present a multitude of opportunities for increasing 
weight capacity beyond stock, by adding leaf springs, air bags, coilover 
shocks, etc. Of course, you'll want to consider upgrading your brakes as 
well.

There have been pickup trucks converted to go over 45-50 miles on 
lead-acid batteries (not talking about OEM vehicles here, just 
conversions). These involve putting some batteries in the bed in 
addition to those underneath, reducing or eliminating cargo capacity. Of 
course in this situation, you will be turning the truck into a rolling 
battery with seats -- not much of a truck anymore.

In general I would advise against having batteries in the bed unless 
you're going into it understanding all the problems involved, with the 
safety issues with batteries mounted behind the occupants instead of 
underneath, high center of gravity, etc. And if you're putting them in 
the bed *and* under it, then obviously you're going to need suspension 
and brake upgrades plus some work done to reinforce the frame.


> Fast starts will drain you batteries much faster.  Wind resistance is 
> proportional to velocity cubed.

Wind resistance is proportional to velocity squared.  Horsepower 
required to overcome wind resistance is proportional to velocity cubed.

 > Slowly coasting down to a stop sign is
> better than powering up to it and braking.  Slow driving is generally 
> better for society, in my opinion, as it mixes better with pedestrians 
> and bicyclists.  Also, while it may frustrate drivers who are out 
> looking for the thrill of speed on a crowded public roadway, it results 
> in more predictable, less stressful traffic for all users overall.  You 
> can focus on speed or on range, but not both.

Frustrating drivers who are out for a thrill ride isn't a cause for much 
concern, but if your vehicle is causing a significant proportion of 
other vehicles to have to slow down and/or move around you (defined in 
the Texas transportation code as the "normal and reasonable movement of 
traffic"), then you're creating a hazard:

Summary (NHTSA):
http://www.nhtsa.dot.gov/PEOPLE/INJURY/enforce/speedlaws501/toc/txspeed.pdf
Official Texas document:
http://tlo2.tlc.state.tx.us/statutes/docs/TN/content/htm/tn.007.00.000545.00.htm#545.363.00




> Yes, the more you spend on batteries, the farther you go.  If you buy 
> fancier batteries they will be much lighter, and vehicle weight is a big 
> concern when considering range.  NiMH batteries are an improvement over 
> the affordable SLAs, and might do the trick if you are keeping your 
> driving really mellow.

NiMH batteries are a difficult issue in EV packs due to their exothermic 
behavior during charge and high-current discharge. On smaller packs for 
bikes and some small scooters it's not such a big deal, but for larger 
vehicles that have NiMH packs, the Ranger and I believe the EV1 used 
redirected air conditioning output to keep them cool. The large Vectrix 
scooter spins up a noisy fan to maintain its battery pack temperature 
during recharge. Building a NIMH pack for an EV will require an 
understanding of this situation. Of course, methods required to keep the 
batteries cool will reduce the pack's effective charge efficiency, which 
will slightly increase operating cost.


   Lithium batteries are plenty good, but you'll
> spend more thousands on them than you anticipate.  Whichever way, your 
> batteries might just cost more than the rest of the vehicle combined.

Lithium is going right now for a price that's between 5 and 8 times the 
price of lead, per watt-hour. It's coming down quickly, but it's still 
extremely expensive.

   --chris