Lithium in the future?

Since the car is a part while the engineering drawings are being made, I've been researching lithium batteries. I got a message lately reminding me that the price has come down quite a bit since I first wrote my FAQ on Lithium batteries too.

It does seem that Thunder Sky may be on their way to fixing their quality issues and the price is coming down. I found a couple of retailers (Elite Power for example) that offer 52 60 amp cells (equivalent to the 13 Optimas in my car) for $6240. Not bad.

The charger Elite Power offers is a HUGE thing, but I believe my Zivan can be reprogrammed for lithium. I haven't seen a good BMS system for sale though. Elite Power has a system designed to work with that big charger and Hot Juice Electric is dropping production of their BEQ boxes so that they can focus on bringing a controller to market. I'll keep looking.

Meanwhile, I'm having the kit racks tweaked a bit so that the 52 lithium cells can be installed without modification.

On to Phase 3...

Well, the project is now officially in Phase 3.
Back when I started this project, the activities were part of three phases.

• Phase 1 was to design and build the car.
• Phase 2 was to test and drive the car
• Phase 3 was to document the conversion so that a kit could be made

The third phase was originally just to promote car conversion at shows, but making the kits became more important...

At any rate, after I pulled out #2 battery to have it tested, I thought it was a good idea to start getting the battery racks drawn up so they could be duplicated. Pretty soon, all three racks were out of the car and it was nearly completely disassembled. I had intended on testing the range and 0-60 times first, but that will have to wait.

While I'm waiting on the drawings to be finalized I've been working on the installation manual. This is no easy task, but it's coming along.

Next is to find someone to test the kit in order to make sure the shop-made parts fit properly and the instructions are right. The plan is to offer the racks and brackets at cost and provide support for someone local to convert their car.

#2 is out, service disconnect is in

I was not looking forward to pulling out the number two battery. It has been not holding a charge and keeping the pack from getting fully charged, so it's got to go.

I had to remove the Zivan (you can see it upside down in the upper left of the pic.), a bunch of high voltage cables, the high voltage box and it's wiring and the bracket that hold all this in place.

Once all of that was out of the way, the battery was pretty easy to pull out and set aside.


Once the battery was out I started on my next project - installing the service disconnect. The idea is be able to disconnect the battery pack from the driver seat to make it easy to service the car or in case of an accident. Some people call these "emergency disconnect" switches, but I like the "service disconnect" name - why not put a positive spin on it?

There are three ways to do this
1. run high voltage wires under the dash to a breaker or switch.
2. put a low voltage switch on the dash to open a contactor
3. install a mechanical cable that activates a breaker under the hood.

Though I had originally planned on using option 1 and placing the breaker under the dash, I realized the high voltage cables really don't belong under there. I went with the 3rd option as it was the simplest, least expensive and safest (compared to #1).

I bought a choke cable at Kragen for around $5. I mounted the "pull" side on the tunnel near the bottom of the dash. This position provided the most room for my big feet...

I needed to mount the cable below the breaker. I ended up bolting an angle iron to one of the top rack's mounts. The cable itself was looped through a hole in the breaker's lever. The cable then looped together where a cable clamp to hold it in place.

It works good. It doesn't take much of a pull to pop the breaker, and just a little push to reconnect the pack. The breaker is spring loaded and does most of the work.

Survey says!

I've gotten a number of questions about providing a conversion kit for the Miata so back in August of last year I posted a survey to determine what kind of kit people were interested in. The link was on all pages of the main www.evmiata.com site and asked you to vote for the components, battery and kit type that you'd like to see.

The choices were:

components

• 156v WarP/Zilla
• 144v WarP/Curtis
• 144v WarP/Belktronix
• 144v Selectria

Batteries

• AGM
• Lithium
• Flooded lead acid

Kit Type

• Basic - Battery racks, brackets, motor mount and adapter
• Standard - all the above plus motor charger, controller and associated parts
• Complete - all the above plus bolts, cable ties and pre-terminated cables

The results were pretty impressive:

• 405 total surveys taken
• 180 votes (45%) went with the 156v WarP/Zilla route
• 29 votes (7%) went with the 144v WarP/Curtis route
• 57 votes (14%) went with the 144v WarP/Belktronix route
• 137 votes (34%) went with the 144v Solectria route

Of those voting for the 156v WarP/Zilla...

• 102 votes (57%) were for AGM
• 65 votes (36%) were for Lithium
• 13 votes (7%) were for Flooded

And for those voting for 156v WarP/Zilla with AGM...

• 27 votes (26%) were for Basic kits
  
• 26 votes (25%) were for Standard kits
  
• 49 votes (48%) were for Complete kits
  

So, as they say in politics, the people have spoken.
I'm closing down the survey today.

Thanks to all of you who participated in the survey!

The Battery Story

I realized that the battery problems I've been having may not make a lot of sense unless you know the full story - so I thought I'd give you all a recap and some lessons learned so that you may avoid learning them like me.

I had 13 Optima D34M Blue tops delivered before I was ready for them to be installed. This wasn't a bad thing, in itself...
You are supposed to test the motor when it's first installed to confirm that the flywheel, clutch and the motor all all in working order. I put the car in neutral and since the batteries were there, I jumpered one of them to the motor leads. It worked fine, but I put a drain on one of the batteries and now they were no longer balanced.

Lesson #1 - use your starting battery for this test - not one of your pack batteries.

Next was a little mishap I had wiring up the batteries. The details are in a post called "the meltdown", but the end result was 5 batteries were shorted out with one of them taking the brunt of the damage. One was replaced (it was the original #4) but the others are still in the pack and now out of balance with the rest of the pack.

Lesson #2 - don't be a numskull and short out your pack - or, more correctly, don't leave loose ends of cables on your batteries. Each cable should have both ends connected before you move on to the next. Don't leave one end unterminated while you go onto the next cable.

With the pack out of balance, I began to charge each battery individually. This is the way to do it, but you should use an automatic battery charger with an AGM setting. I used a manual charger, and though it worked most of the time just fine... well you get the picture.

Lesson #3 - invest in an automatic battery charger with an AGM setting for individual charging.


I have heard people say that Optima doesn't have the best quality control and that one should expect a battery or two to fail in a pack, and I can say the 2 that have been troublesome so far (#5 and #2) were not overcharged by the manual charger. But, if I had not put the pack so far out of balance I don't believe I would still be dealing with battery issues today.
And that, I think, that is the big lesson.

Pressed into service

My wife called me at work yesterday to say her car broke. She wasn't too far from home when something went ding (her words) and her battery light came on, then her power steering was gone and then it started to overheat.
Any guesses?
Fan belt, maybe?
I got home at looked under the hood and the belt was there, and in one piece, but it was all wrapped up - looks like an idler pulley broke off.
It was 6:30 at night and I took the Miata down to Kragen for some ICE parts.
Kinda ironic, I guess...
I didn't have a chance to put them in that night, so the Miata got to run errands and drop our daughter off at school. She enjoyed riding in it, not because it's quiet or quick or emission free, but because she can sit in the front. Anyway these little trips confirmed my verdict on #2 - she's bad. So replacing her will be my project for the weekend.
Since I will have everything stripped down up front to pull the battery, I invited the draftsperson (do they still go by that?) over to start the drawings for the kit. Might as well take advantage of the situation...
I also might install the emergency disconnect cable. I bought a choke cable that I was going to connect to the main circuit breaker so that I could disconnect the pack from the driver seat. It's been sitting on the toolbench. Maybe I'll have a chance to connect it this weekend too.

Sunday driver

Friday and Saturday I charged batteries - in between running errands and watching kids. But the pack is charged - though #2 is still acting a little flaky. I noticed that the pack looses voltage over time and am starting to suspect the Zivan may be putting a slight load on it. I've been leaving it unplugged from the pack to test my theory.

So around 2:00 Today the pack was fairly charged. My SOC gauge showed 95% which is closer to 98% in the real world, so I'm off. First thing I noticed in that the vacuum pump isn't working, but no matter, I'll just stand on the brakes like we used to do in the old days. I still have the tach set to display amps, and what a difference that makes in your driving style - you can't help but accelerate slowly and coast into intersections. They need to put something like it on gas cars - like an MPG gauge. Didn't make any friends with the other drivers, though. I took a mile and a half loop and came back to the garage to check things out. #2 is at 12.35v where the rest of the pack is in the high 12.4 to 12.5. I plugged the Zivan in and gave it some juice, but #2 came up to 15.6v pretty fast - the rest of the pack was in the 14v range when I had to abort the charge to save #2 from being overcharged.

I'm thinking #2 needs to go.

I let her rest for a bit then took her out for another drive. This was about a 3 mile loop (the trip odometer isn't working - gotta add that to my list). I took some streets with bike lanes and it sure confused the cyclists having a silent car running with them. I came back home with about a 70% SOC - not too bad. #2 was the lowest about a tenth of a volt below the rest of the pack, and again I had to abort the charge when #2 reached 15.6v.

#2 is in the most in accessible place in the pack - in the front of the nose rack on the driver side. I'll need to pull out the Zivan, all the high voltage cables to the box, pull the gauge, contactor and relay connections remove the high voltage box and bracket, then pull out #1 so that I can get to #2! It's gonna take me a full day just to get her out.