Saturday, April 19, 2008

Batteries!

The batteries arrived yesterday - over 1500 pounds of them. They were nicely strapped & shrink-wrapped to a pallet:


Here is one of the batteries unboxed. It is a 12 volt, 80 amp-hour, 56-pound bundle of lead, acid, and plastic - the Concorde Chairman AGM-1280T:


And here are all 26 batteries, nicely stacked up and waiting for their Rudman regulators and Manzanita Micro charger:


I bought them from EFI Technical - Scott and John were extremely helpful - I give them an "A+" for customer support and service. They gave me a prompt quote, kept me informed of the manufacturing progress (these batteries are manufactured on-demand), and were very diligent about asking whether everything arrived correctly. Thanks!


EFI Technical
300 South Harbor Blvd., Ste 810
Anaheim, CA 92805


8 comments:

Flyblog said...

1500lbs of batteries... are you sure that something like Lifebatts wouldn't work out better on both life cycles, weight, and be no worse on costs in the long run?

Joe said...

If you don't mind; I'd really like your thoughts on my 914 conversion. I'd really like the idea of moving to the AC24LS motor.
Oddly they have move the minimum voltage spec on the AC24 to 156 not 144.
If I use 12volt batteries instead of 8volt; I will go from 144 to 216 total.
Do you have any thoughts on that 'upgrade'?
Joe

Ross Cunniff said...

Joe,

I like the idea of the AC24LS motor. I think you'll appreciate the extra "oomph" - between that and a 156V (or more!) system you'll see a 20-25% increase in power.

My thoughts on batteries are of two minds:

1. Stick with 8 volt and drop in some saddlebag or lower engine bay batteries (2 more) - gets you to a 160-volt nominal system. If you use AGM batteries it won't matter if you can't reach them easily to water them (but you'll definitely need a battery management system!)

2. Go to 12V but find some high-capacity (Group 31 maybe?) batteries and only use 13 of them for a 156-volt system.

I *suppose* you could go to 18 12-volt batteries (216 volt nominal as you say). You'd have to talk with Azure to see if they can tune up the controller for this (I would expect so).

The advantage of going to 216 is not more power (you'll be capped by the motor at ~156v), it's fewer amps. A typical group 24 12V battery is roughly 85 Ah nominal, giving you 85*216 = 18Kw system (vs. the 23Kw system that 18 US8VGC batteries gives you). So, your 25% greater power would be almost exactly balanced out by about 25% less range...

You may want to consider going to 3/0 cable if you go to 216V.

Flyblog,

The cost of even Lifebatts is so prohibitive that it's worth waiting until those prices drop before going that way. I'd spend $30000 or more on batteries that way - pays for a lot of lead-acid :-)

Ross Cunniff said...

Err, minor correction. I said, "you'll be capped by the motor at ~156v". I meant to say, "you'll be capped at the same horsepower that the motor would produce at ~156v".

Flyblog said...

Ross, Joe,

I've recently ordered an AC24LS from AD (it's on its way in fact). Please excuse that I'm only talking theory here...

On the graphs Beth Silverman sent me, the LS is not a major change - 25% maybe for torque, but only a little extra acceleration at the lower speed range.

What might be a better option is just change to the Wye configuration (312V) but then you'd need more batteries in series. However according to the graphs you'd get faster 0-60mph. No need to change the motor, though.

You can find the graphs on my blog.

Flyblog said...

And the blog is here. Whoops. http://web.mac.com/simon.kay/blog/EV/Entries/2008/6/3_AC24_normal_or_AC24LS.html

Ross: take your point on the battery (cost) but I calculate that lifetime cost is not so different. Lifebatts have a warranty of 1500 cycles. Optima's don't even carry a warranty (here in Italy) for an EV application... and seem to be 300cycles (your experience of what one can expect from LeadAcid appreciated). That ratio is the same as the price.

Besides, since I've decided to go high voltage, I'll need some kind of LiPo pack I guess. I'm aiming for a 10kWh pack - relatively short range, low weight.

rheuckeroth said...

How much did these batteries cost delivered? What is your expectation of the range that you will get from full charge to 20% charge?

Flyblog said...

rheuckeroth, 1) I didn't buy them yet but list price seems around $3000/€1800 per kWh. But add up the cost of the lead acids over the lifetime (in cycles) and it's about the same 2) the same range as for lead acids, I'm aiming for a pack to get 40km/25miles so not too big 3)I put an excel file on my blog if you want to see the comparisons. Any advice much appreciated since I didn't buy them yet so not too late to change my mind...