We have a new slogan at Plasma Boy Racing….11′s in 07!
I’m happy to report that Dick Brown (Aerobatteries) pulled through again for us this year and working with our sponsor Enersys, our new 40% more powerful batteries have arrived! This year White Zombie will again, be running on Hawker power, but instead of the 30 – 24.5 lb. 26 ahr Aerobatteries models we used last year, we will be using 60 of the smaller Genesis model 16 ahr batteries. Yes, these are nearly the same battery we ran with from ’98 through ’02, back when White Zombie had 28 of them making up an ultra-light 378 lb. 336V battery pack. Before they had been abused and super-heated to extreme hand-burning levels, we could pull 750 amps from them with very few failures. Even 800 amps was doable for less than 10 seconds. Yeah, we did blow quite a few of them up as the years were added on, but again, they only began to fail after substantial abuse. Details for those interested, can be found at the Plasma Boy web page…just click on the ‘White Zombie History’ button and scroll to ’1998 Early Version’.
There have been some changes made to these already terrific little batteries over the years, the first and most obvious is that today they are no longer labeled ‘Hawker’ since being bought out by Enersys. They are now an Enersys ‘Genesis 16 XE’. The Hawker electro-chemist at Enersys I’ve been in close contact with, tells me the already beefy inner-cell straps inside these tough bricks of power were thickened up some more (yeah!) and their plate grid redesigned for even more aggressive high current power delivery. Though still spec’ed out at 13.5 lbs. each, we weighed the new batteries on some pretty accurate scales and they come in at 14 lbs. plus some change, so it seems that a bit more lead is indeed, packed inside! Oh yeah, they’re no longer black like they used to be, and are that nice Hawker Odyssey orange color with contrasting black labels.
So why are we going to run 60 of these smaller batteries over the 30 larger ones that produced that quick 12.151 @ 106.25 mph? The answer is simple…A LOT MORE POWER!!! The Hawker guy says this battery is their #1 most powerful battery in terms of power density, lb. for lb., than any other battery in their line up. The 2nd most powerful is their little 13 ahr, 10 lb. model, and the 3rd most powerful is the 26 ahr models we have been using since ’05. He and I had good discussions and he confirmed that my observations of the earlier Hawker Genesis 16 EP batteries we used to run years ago, were correct. Back then, when warmed up they would sag to 6.9 volts at 750 amps current draw…this, out of a 13.5 lb. package. More recently, in early 2005 (check out the White Zombie History page) when thanks to Dick Brown Hawker sponsorship returned to the Plasma Boy team, I had my pick of any version I wanted. A double string of the 16 ahr models was considered. However, the sheer numbers of batteries, all the inter-connecting bus bars, plus the 70-90 lbs. of extra battery weight they would add, helped steer me away from them. I really didn’t fully understand the big difference in power density these batteries had over their larger, heavier brothers, and I chose 30 of the larger 26 ahr, 24.5 lb. models instead. Hey, it worked out pretty good….low 12s aren’t anything to be ashamed of
Of course, we’ve learned a lot since then. Try as hard we did, with the 26 ahr models we just could not get any more power from the pack and those 11′s remained out of reach. Curves plotted from the Zilla’s Hairball told the story over and over…huge battery pack voltage sag under load, especially after 4-5 seconds as the lead inner-cell straps inside each battery heated up and became near-molten resistors. Last year, those resistors became fuses as we began blowing batteries, too. At 1000 amps (yeah, I know that’s an awful lot to ask of a 24.5 lb. lead acid battery) the batteries would initially only sag to about 8 volts each (about 240V) and the power on launch and through most of the 1/8th mile was fantastic, but after that as the inner-cell straps would go near molten, the pack dropped to 180 volts (just 6V per battery), and the car’s acceleration would flatten out. Again, the Hairball curves showed what was happening, and melted inner-cell straps don’t lie. We were clearly battery limited….time for a change. To be fair, the 26 ahr Aerobatteries performed above our expectations since they were rated for 950 amps for 5 seconds, and certainly not designed to do 1000 amps for 12 seconds! However, Hawker’s electro-chemist agrees with me, that the longer runs of lead strapping inside the 26 ahr batteries we had been using the past two years were creating higher resistance under the extreme currents we were drawing, and he again, told me about the stubby thick inner cell straps and the more aggressive grid design on the newest 16 ahr models.
The switch to 60 of these new, smaller Enersys 16 XE batteries is very exciting, because the math looks very encouraging. One 26 ahr battery weighs about 24 lbs. and sags to 6V @ 1000 amps, for 6 kw of power. Two of the new little 16 XEs represent 28 lbs. but only sag to about 7 volts @ 750 amps each…that’s 7V @ 1500 amps for 10.5 kw of power! That works out to be a 50% power increase, so the claim of a 40% power increase seems very believable. At 500 amps draw, each 16 XE might only sag to 8 volts or so. Stay with me everyone….our best ET of 12.151 @ 106 mph was done with the battery current limited to 1000 amps and the pack sagged down to 180V, 180 kw of power for the last 3-4 seconds of that run. Now…a new double string of the 16 XEs might fall to 8V per battery at 500 amps near the end of a run for a pack sag of 240V @ 1000 amps….240 kw of power! That’s a 35% power increase doing my conservative seat-of-the-pants analysis. Sooooo…it seems if Tim and I take it easy when we first go out with the car and leave the current limit set at 1000 amps (even though we can now go as high as 1500 amps) we’ll still have an extra 80 hp to play with at the far end of the track! We’re thinking the car might bust into the high 11′s without even turning the screws up! Cranking up the juice eventually, to the full 1500 amps with warmed-up batteries, should only initially sag the pack to about 7.5V per battery right off the line for a pinch more than 450 ‘battery’ hp at launch! After that, the pack will get closer to 7V per battery for the duration of the run. Like I said…11′s in 07!
The new pack would have added about 90 lbs. weight to the car, but careful attention to detail and lots of planning have cut that down considerably. This past week and weekend’s efforts, along with Marko’s metal shop expertise have produced all new battery compartments for the car. The previous rear seat area compartment weighed 34 lbs….the new one? Just 14 lbs.! The rear sunken trunk area tray with hold-downs weighed about 16 lbs….the new one? Just under 5 lbs.! We’ve trimmed more than 30 lbs. just in the battery compartments’ redesign, and we’re still not done with the weight reductions. How’d we do it? Instead of 3/16 thick aluminum and a basic box with thick pedestal mounts and such, we used thin sheet aluminum with lots of bends, creases, gussets, and supports. We also cut out material where we could and used lighter weight material in general. I’m still considering an aluminum Ford 9 inch casting that will trim up to 45 lbs. weight off that heavy rear end. It’s entirely possible to get the car to weigh less than the previous version, even with 840 lbs. of hi pro lead in the car.
I’ll be adding new photos to the web page soon. OK, I’ll sit back now and take the feedback from everyone. Am I nuts, or are we on the right track? Will we fail to hit the 11s, or will White Zombie be required to be fully caged when it hits an 11.5 this year when we dial-up the full 1500 amps?
One more thing….White Zombie will be a ‘highlighted’ car at the upcoming Portland Roadster Show and will be displayed at the entrance into the main arena of the show. This is quite an honor and a step forward for EV acceptance in the hot rod world. The show promoters are encouraging us to set up and loop videos of White Zombie taking out classic muscle cars and hot rice burner imports. We are happy to accept their request! Any local geek types with a big flat screen and computer setup wanna lend us a hand? New Enersys and ‘Genesis XE’ stickers will be affixed by show time, mirrors will let show-goers see the battery packs, and NEDRA promo material will be on display and ready to hand out. Should be a fun weekend. March 2nd, 3rd, and 4th.
See Ya……John Wayland