Just on the road again

Title says it all :-)

Just finishing up

The long holiday weekend was perfect for finishing up the battery installation. When I last posted the batteries had been bundled and physically installed in the battery box. The next step was wiring everything up.

There are 48 individual batteries making up the pack. Each battery needs to be connected to the next battery. Batteries are connected in either blocks of 4 or 8. The blocks are then connected to make the whole pack.

Because the lithium batteries require a little more monitoring than lead acid batteries I decided to install a battery management system(BMS) with the batteries. The BMS serves several important functions. The most important function is to prevent the batteries from being overcharged and over stressed.

In order to accomplish this the batteries are monitored by a multiple circuit boards. These are pictures of the mounting boards prior to installation. The top board is for 4 cells and the bottom one for 8 cells.

These copper bars connect the cells together and are attached to the bottom of the mounting boards.

The mounting decks and copper bars installed on the cells.

A closer view showing the circuit boards on top of the mounting deck. The circuit boards are connected to each other in order to communicate with the charger.

Here the packs of 4 and 8 cells have been connected to each other to form one big pack.

A fuse in the middle of the pack. In case of a short the fuse should protect the cells in the pack.

Close up of the fuse.

With the pack wired up the car is now drivable again!

Next step is charging up. Also need to do some slight modification of the software settings since the pack voltage has changed. Final part will be to get a top for the battery box.

Just Lego blocks....sorta

Continuing from the last post I'm in the process of installing new batteries in the Vue. The new lithium batteries come in the form of a 3.2V cell. The cells are then bound together in groups of four to form a ~12V battery.

Here are pictures of four individual cells bound together using metal banding.

This is a picture of the blocks of cells in the battery box.

And here are the cells installed.

This picture show the charger mounted on the battery box. You can also see some of the holes in the box that help with dissipating any heat produced during the charging.

Next step will be starting to connect all of the batteries together.

Just a big shiny tray

Time to change the batteries on the electric Vue. I'll just go down to the Radio Shack, buy a pack of batteries, pop out the old ones, and pop in the new ones. Oh I wish it were that easy....

Let's go back a few years first to when I decided to do the conversion. At that point lead acid batteries were really the only choice for electric vehicle batteries. Lithium batteries sized for electric vehicles were just coming to market. And the other less common type of batteries were either too expensive or unavailable for the average person.

Fast forward several years. My original lead acid batteries have lost a great deal of capacity. This is expected as one of the shortcomings of lead acid batteries are their life. I got two years+, ~10k+ miles, and ~700 charging cycles from the lead acid pack. This is about average for lead acid. But now that I need to replace the batteries I'd like to do better.

Now that lithium batteries are made by several manufacturers and have come down in price I'm going to switch battery chemistry. Switching to lithium batteries has several advantages compared to lead acid batteries.

1. Weight. For a given amount of energy lithium is considerably lighter. My lead acid pack weighed about 1500lbs. My new lithium pack will weigh about 600lbs.

2. Range. Not only is the pack lighter. It will contain more usable energy. So where my max range for lead was ~40 miles my max range will be ~80-100miles.

3. Performance. Having almost 1000lbs less in weight should make the car accelerate uphill better and brake better.

4. Battery life. Lithium is rated for more cycles and mileage than lead acid.

Now for the disadvantage. $$$. No getting around this. Up front lithium is more expensive. Over the long run lithium will probably be cheaper because of the number of cycles and mileage for the pack.

So two weeks ago I made the plunge and ordered new batteries. I also took the car out of service in order to remove the old batteries and make the necessary upgrades in order to make the switch.

Because the new batteries take up considerably less space I no longer need to have batteries under the hood. So I eliminated the wiring for that portion of the battery pack.

Today I started working on a new battery box for the rear. The old box was made of plywood. The new box will be made of galvanized steel.

Below is the bottom portion of the box. It will be mounted where the old box was in the back.

The box is made out of 18gauge galvanized steel and thicker galvanized angle iron. The bottom is riveted to the angle iron. It will be bolted to the 1" square iron supporting it. More pictures to come as it progresses.

Just an article about me...

... and the Vue of course!

http://newtown-pa.patch.com/articles/no-fill-ups-required-newtown-doctor-converts-car-to-electric#c

Just glad the winter is over

It's now been two years since I've converted a 2002 Saturn Vue from gasoline to all electric. Other than a few minor hiccups, as previously documented, the Vue has been my daily commuter five or six days a week. It now has over 10K electric miles on it.

This winter was a little tough for using the Vue. Everyone who has ever driven a regular car in the winter knows that the starter battery isn't quite as "peppy" when it is cold out. Well lead acid batteries in electric cars are just as finicky about the cold.

On a nice hot summer day, dead empty for my two year old batteries is probably about 35 miles. This poses no problem since my round trip commute is 20 miles. (My wife continually reminds me that it is only 13 miles if I don't go out of my way to get coffee. But it's really good coffee!)

Anyway, I digress. During the winter my range drops to about 20 miles. That means for my 20 mile round trip I need to charge at work in order to make it home. No problem. I have an outlet behind my office. Eight hours is more than enough time to recharge to full.

So my winter routine is drive to work 13 miles one way. Charge eight hours during the work day. Drive back home 7 miles. No problem at all....except for the snow.

You might be asking yourself what does snow have to do with electric vehicle range. My answer would be nothing. Except for when it comes down....and down...and down.. and down...for a total of about two feet over a couple weeks.

You still might be asking what does that have to do with the car? Roads get plowed and the Vue is front wheel drive. So that's not a problem. And the car has a great electric heater. So that's not a problem. What's the problem?

Glad you asked:-). The problem is that all of that snow has to get plowed somewhere. And the guys at my office complex decided that the best place to plow it was in a corner...behind my office...where the outlet is located :-( Yep, several feet high and deep of rock solid plowed snow right where I need to plug in.

I thought about trying to dig it out but then the second shoe dropped...more snow. And this time the outlet wasn't the problem. You see I have to plow the snow in my drive somewhere. And after all the snow had been plowed as far off the drive as possible the only place left for me to plow it was in front of the garage bay where the Vue is stored :-( So now not only couldn't I recharge at work, I couldn't even get the car out of the house!

Luckily the snow melted, the garage door unblocked, the plug visible, and the Vue back on the road for the last several weeks :-)

Just a hiatus

Another update on the EV Vue. For the last six weeks the Vue has been out of commission. Over the winter I was having a very intermittent problem where the vehicle would "start" but was not responding to the throttle. Invariably the problem would go away in a few minutes and everything would run fine. The problem was very infrequent and intermittent enough that I could not reproduce it to troubleshoot.

Well in late March while driving home the vehicle became completely dead to the throttle. I managed to coast it into a local business and tow it with my truck back home.

Between leaving for vacation and just being busy with life it took a few weeks for me to get to work on the car. When I finally did I managed to track down the problem to the controller.

So off to the UPS store to ship the controller to the West Coast. A week later it arrived at the manufacturer. Luckily the only thing wrong was a wire inside that managed to work its way loose. Another ten days later I get the controller back. Today I managed to find the time to reinstall it.

Everything seems back to normal at this point. I'm looking forward to getting it back on the road as my daily vehicle.