A Trip to Greenshed Conversions

Posted by admin February 5th, 2011

Loaded ready to transport to Fort Pierce

I was having some problems with my battery pack and needed some expert help.  To get that help I traveled to Green Shed Conversions to get the help from Steve Clunn.  Green Shed Conversions in Fort Pierce, Florida is the home of Steve and Audrey Clunn.  Steve has been doing conversions and putting together electric cars for more than 15 years now.  He has a wealth of experience and knowledge on electric cars.

Unloaded and ready for inspection

Steve Clunn looks over the EV GT-40

Steve's Volt Meter with multiple inputs

Batteries wired to Steve's meter

Once we had the car all wired up, Steve and I took a ride in the car.  While I drove, Steve carefully monitored the suspected batteries.  Sure enough, upon acceleration two of the batteries were dropping to less than 7 volts and creating a lot of resistance in the pack.  These few batteries were pulling down the whole pack.   The issue seems to be that the batteries were not being charged at a high enough amperage.  Over time they have developed higher resistance which prevents them from giving up their charge.  To fix this, these batteries were charged at a very high amperage very quickly.  After driving the car a second time, they were showing at least a 10 percent increase.   The process is going to need to be repeated a few times before they come back up to 100% efficience.

Steve had a number of battery packs at his shop.  We tooks some time to look at the Thunder Sky Lithium Ion batteries and compared them in size and capacity to the AGM batteries I was currenlty using.  The battery I have in my hand has about the same energy capacity as the large AGM battery.  The Lithium battery weighs about 8 lbs. verses the 80lbs of the AGM.  Though expensive, the price on lithium batteries is coming down.  A pack with almost half the weight of my current pack could easily deliver four to five times the capacity.  My current pack has about 8kwh of capacity and weighs about 1,000 lbs. .  A 24kwh pack could be done in lithium ion batteries with a wieght about 400lbs.

60 ah Lithium Ion Battery. 4 of these has more usable energy than Hawker Odyssey AGM. The 4 cells would weigh about 24lbs vs. 80 lbs for the AGM battery.

100 ah Lithium Ion vs AGM with about 50ah usable

One of the dangers of lithium batteries is that they are not very forgiving to abuse.  Without a proper battery management system a pack could be killed pretty quickly by allowing them to drain to 0 volts or over charging.   The pack below was removed from a car that was used by an owner who let them all drain to 0 volts.  Steve is going through them trying to revive some of the batteries, but 80 percent will end up unusable.

a killed battery pack

Steve and Audrey’s property is filled with all kinds of electric experiments and projects like the motorcycle below.

Electric Motorcycle

Zap Electric Car

Zap Electric battery pack and controler

Electric Bike

An electric Lamborgini

Electric RAV 4 - This is Audrey's daily driver

I want to thank Steve.  He is one of electric vehicles heroes and was gracious enough to spend the day with me to find the problem in my pack.

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