Introducing McDesign

4429 Views 14 Replies 5 Participants Last post by McDesign, Feb 16, 2011

McDesign

Discussion Starter · Feb 14, 2011

Hello - I see I've got lots of reading to do!

I'm a professional ME in the LED lighting industry, and long-time IC hot-rodder. As the kids are getting old enough, I've recently made a few multi-motor scooters, a boosted PowerWheels for the youngest, and a friction-drive electric bicyle that just got on the road this weekend. All just small PM motors; free SLAs and NiCads from work.

My goal is to electrify and mod my "good ol' 1/2 ton P/U truck" for a specific daily commute that will be starting in August. I understand I'll be making various concessions to style, but I understand them.

Five days a week, for two years, I'll need to go 70 miles in the morning; can charge for 8 hrs there (company will supply, they say), and then 15 miles home in the PM to charge overnight. Driving is 80% interstate; flat-ish.

Perhaps something like the EMC-SM300 & Curtis PMC1231, at 144V maybe through a 2-or 3-speed dirt-track transmission (Speedway Motors). Probably forklift batteries to start (again, a deal through work), but maybe BBs.

I first need to get a sense of the KWH I'll need for a 80-100 mile range at ~60 mph in a 6,000 lb. vehicle. Again, its term of duty is two years - no need to have any residual value after that. Target is ~$10-12K, and I have a good shop.

Looking forward to sopping up all the info here over the next few months

Here are nine 250W 24V motors at 48V, and twenty-two 6V / 12 Ah E-light SLAs -

Forrest

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Duncan

· #2 · Feb 14, 2011

Hi

Hate throw cold water but

I first need to get a sense of the KWH I'll need for a 80-100 mile range at ~60 mph in a 6,000 lb. vehicle.

Rough numbers (real rough) 600whrs/mile for 100 miles = 60Kwhrs

For Lithium keep below 80% discharge need 75Kwhrs - $380/Kwhr = $28,500
weight 750Kg

For Lead keep below 50% discharge - 120Kwhrs
weight 3,750Kg -
With all that weight the 600whrs/mile will go up - meaning more watthours meaning even more batteries
100 miles at 60mph is not really do-able on lead acid

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McDesign

Discussion Starter · #3 · Feb 15, 2011

Thanks - that's just the kind of info I need to get my head around. I'll keep reading.

So maybe a more reasonable goal would be 75 miles at 50 mph, and not run any errands on the way. I guess target life charge cycles is ~500; I could discharge the lead acids more, at the expense of life?

Forrest

VoltsCar

· #4 · Feb 15, 2011

McDesign said:
maybe through a 2-or 3-speed dirt-track transmission (Speedway Motors).

Forrest

I looked into the Lenco 2 speeds. I liked the simplicity of no clutch and only 2 or 3 speeds. The problem is the the ratio isn't wide enough. The Speedway Motors trans is a 1.34 2nd gear ratio. You'll need much wider than that in an electric application. IE Drives makes a 3:1 that is real appealing, but a little on the expensive side at 7k. If you really want a 2 speed, look at IE Drives. After I decided that 7k might be worth it, I took measurements, and the trans won't fit in my application. So now I am re-gearing the stock trans to have a 2.75 final drive.

McDesign

Discussion Starter · #5 · Feb 15, 2011

Duncan said:
Rough numbers (real rough) 600whrs/mile for 100 miles = 60Kwhrs

I did some figuring, and have to pretty much agree.

LOAD
I've loaded my truck to weigh ~6500#, and driven to Atlanta and back along Interstate-20 a few times. If I baby it, I can squeak by at 20 mpg for the 60 mile RT. This is carbureted, but I do have a wide-band O2 sensor and have been playing with jetting to optimize highway mileage. However, it still includes rear axle and transmission losses.

That's 0.05 gallons/mile. Gasoline is 115,000 BTU/gallon, so in a mile I've burned one-twentieth of that, or 5750 BTUs worth of gasoline.

An older carbureted gasoline vehicle is at best 18% efficient.

That means that in each mile, the gasoline I've burned has supplied me with only 1035 BTUs of energy to propel the truck.

1 kWh is 3414 BTUs, so ON GASOLINE, at 6500 lbs and ~50-55 MPH I've used (1035 BTUs)/(3414 BTUs/mile), or .303 kWh per mile, or 303 Whrs/mile - in the ballpark with your numbers. This doesn't include motor efficiency losses, but it does include all drivetrain and tire losses for this actual vehicle at this actual weight - even a non-lockup automatic transmission.

Further – Ignoring motor/controller efficiency, if I assume that my average range at 50-55 MPH has to be 70 miles, and I pull the batteries down 75% in that time, that makes the pack size (.303 kWh/mile)*(70 miles) / (.75%) = 28 kWhr.

So, my thinking (hoping!) was more along the lines of a 30-35 kWhr pack

BATTERY PACK
An initial look at the GB Industrial Battery site shows me battery model FS23S-6C413. It’s listed at 12 Volts / 300 Ah, or 3.6 kWhr, and weighs 324 lbs. So, if I use ten of them, that gives me a 120V pack with a 36 kWhr capacity.

WEIGHT
This pack would weigh 3240 lbs. My truck is now 4080 lbs full of gas (from the legal scale at the quarry). Engine, auto trans, radiator, and gas tank removal will pull that down ~a thousand lbs, and I’ll take out the bed and only keep the rear fenders and hollowed tailgate, so say the bare truck is down to 2800 lbs. That weight, plus 200# me, 3240# batteries, plus 250# for motor, puts me at about the 6500# target.

Such is my thinking.

Anyone please add anything pertinent!

Forrest - newbie

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major

· #6 · Feb 15, 2011

McDesign said:
BATTERY PACK
An initial look at the GB Industrial Battery site shows me battery model FS23S-6C413. It’s listed at 12 Volts / 300 Ah, or 3.6 kWhr, and weighs 324 lbs. So, if I use ten of them, that gives me a 120V pack with a 36 kWhr capacity.

Anyone please add anything pertinent!

Hi McD,

That 300 Ah capacity is at a 6 hour rate. Details of your application lead me to believe you will be looking at more like a 1.5 to 2 hour rate. So you can expect maybe more like 200 Ahr. Reference Peukert's Law.

BTW, it's nice to see a newbie doing the calcs

Most don't....just ask endless questions.

Regards,

major

ps....303 Wh/m sounds optimistic for a 3 ton truck.

McDesign

Discussion Starter · #7 · Feb 15, 2011 (Edited)

major said:
Reference Peukert's Law . . .303 Wh/m sounds optimistic for a 3 ton truck.

Thanks - Yeah, forgot about the Peukert thingy.

303 does sound optimistic, but the weight, distance, speed, and mpg are observed actuals and repeatable. My assumed efficiencies are the SWAGs.

Forrest

<edit> Oh - wait - I've taken my pipe rack off since I did those runs - that's gotta help aero like a bazillion percent. And - I'm gonna put on flush wheel discs. And lower the truck a lot. And take off the big side mirrors. Yeah!

Woodsmith

· #8 · Feb 15, 2011

major said:
ps....303 Wh/m sounds optimistic for a 3 ton truck.

McDesign said:
If I baby it, I can squeak by at 20 mpg for the 60 mile RT.

So what do you get when you don't 'baby it'?
You could put that figure in your calcs to see what the top end of your energy demand would be.

McDesign

Discussion Starter · #9 · Feb 15, 2011

Normally, commuting to work at 75-85, at 4300lbs, I get 14-17 mpg. But, I don't mind babying it while I learn about E-vehicles and learn Rosetta Stone Chinese on my daily commute for a coupla' years - I've got a play car for fun on the weekends.

Forrest

Woodsmith

· #10 · Feb 15, 2011

So that would be about 33% more energy making your 303Wh/m into 404Wh/m.

McDesign

Discussion Starter · #11 · Feb 16, 2011

Woodsmith said:
So that would be about 33% more energy making your 303Wh/m into 404Wh/m.

Okay, so if I'm using 600 (Watt*hour / mile) * 60 (miles / hour), am I correct in canceling and multiplying and determining that I'm using 3600 Watts (instantaneuosly? That seems low.

Hep' me!

Forrest

major

· #12 · Feb 16, 2011

McDesign said:
Okay, so if I'm using 600 (Watt*hour / mile) * 60 (miles / hour), am I correct in canceling and multiplying and determining that I'm using 3600 Watts (instantaneuosly? That seems low.

600 * 60 = 36000

Regards,

math police

McDesign

Discussion Starter · #13 · Feb 16, 2011

Whoops! That makes more sense. Thank god you're here.

I was gonna' say "your" so I could have a visit by the grammar police as well.

Oh - and say "grammer" so the spelling police could drop by.

Forrest - lots to learn

Woodsmith

· #14 · Feb 16, 2011

McDesign said:
Whoops! That makes more sense. Thank god you're here.

I was gonna' say "your" so I could have a visit by the grammar police as well.

Oh - and say "grammer" so the spelling police could drop by.

Forrest - lots to learn

You could have a visit anyway as it should be God but then you could get a visit for not thanking all the other deities that also may not be there.

We tend to worry less on this forum as we have an international membership separated by a common language.

Besides which, we all make typos.

McDesign

Discussion Starter · #15 · Feb 16, 2011

Not capitalizing that word is a whole other can of worms - not a typo.

Forrest - capitalizing proper nouns only

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