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Discussion Starter · #1 ·
So I was considering converting a g35, mainly because with the factory aero kit it has the same drag coefficient as a model s (.26) and that's before you plug up the grill that's used for the intake.
My big problem though is trying to use the battery calculator thingy. converting ev power is way different than what im used to in converting hp and such.

So my main question is how many miles of range can I expect from let's say 1 lithium ion car battery? (or 10 if it's easier)
I know it's relative to weight, drag, and powertrain loss but ballpark would be great. Or if there's a rule of thumb im unaware of, I use to hear that 1 lithium ion pack was the equivalent to 10 miles of range, does that seem right?

I saw that the standard model 3 has a 50kw battery pack for the 200+ range, which sounds great. I want to use an optima yellow top, specifically a d51, and can't seem to find the wattage/kw. From what I've found it's maybe 9kw? that doesn't sound right though. Basically if I had 5 or 6 of the optima batteries then that's the same a the Tesla battery pack? Is that right? I'm not sure but I think im missing something.
 

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Coefficient of drag is just one part of aero drag, the other part is frontal area. Frontal area x Cd = actual drag. Lots of people just focus on the Cd and not the frontal area. For instance a Miata has pretty bad Cd, but it's itty bitty tiny so it has low drag.

Basically if I had 5 or 6 of the optima batteries then that's the same a the Tesla battery pack?
Absolutely not. I like your confidence though!
 

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Optima Yellow-Top batteries are AGM lead-acid batteries, not any kind of lithium-ion battery. Lead-acid batteries are good for starting engines, but are obsolete for electric cars.

The is no single standard size of lithium-ion battery or battery module for electric cars, so you can't assume some amount of range per battery. You need to determine how much energy would be required to drive the car the desired distance, and that is the measure of battery size. For instance, if you decide that 50 kWh is the required amount of energy, that could be held in the four very large modules of a Tesla Model 3 Standard Range battery, or the 10 smaller modules of a Chevrolet Bolt battery, or 16 of the 33 small modules in a Jaguar I-Pace battery. You really need to look at the energy capacity of the module you are considering, not just count modules.

The relevant unit of energy is a kilowatt-hour (kWh); a kilowatt (kW) is a measure of power, not energy.
 

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I want to use an optima yellow top, specifically a d51, and can't seem to find the wattage/kw. From what I've found it's maybe 9kw? that doesn't sound right though. Basically if I had 5 or 6 of the optima batteries then that's the same a the Tesla battery pack? Is that right? I'm not sure but I think im missing something.
An Optima YellowTop D51 has a charge capacity of 38 amp-hours (when discharged very slowly, much less in EV use); at 12 volts, that's 38 Ah * 12 V = 456 Wh (or 0.5 kWh). And that's kWh, not kW. You would need more than 100 of them (weighing much more than a ton and costing about $25K) to hold 50 kWh, and perhaps 200 (over two tons, over $50K) to deliver that much energy at the relatively high discharge power of an EV.

In case that doesn't make sense yet...
  • an amp of current flowing for an hour is an amp-hour of charge
  • a watt of power for one hour is a watt-hour of energy (or 3600 joules of energy)
  • one amp of current at one volt is one watt of power - you really can just multiply amp-hours by volts to get energy in watt-hours
  • when a battery is discharged quickly the power lost to internal resistance means that less of the energy is usefully extracted, and Peukert's Law explains that the voltage drops and so reduces available power (so the usual capacity rating for deep-cycle lead-acid batteries don't apply for EVs)
 

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I want to use an optima yellow top, specifically a d51...
I realize now that this battery choice came up last year in the same member's other thread:
Shouldve been more clear, was thinking about lithium ion, probably optima for the weight...
So, repeating this point:
Optima Yellow-Top batteries are AGM lead-acid batteries, not any kind of lithium-ion battery.
Classycrusader, you seem to have the impression that Optima batteries are lithium-ion, but they're not. They're a specific construction of lead-acid battery called "AGM", meaning "absorbed glass mat", which means that the electrolyte (acid) is soaking a mat of glass fibres between each pair of lead plates, rather than just being an open pool of liquid.
 

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Discussion Starter · #7 ·
all duly noted. what would be a good lithium ion battery? I'd like to use car batteries because they're more easily refurbished when they go dead.
Second, how much would, let's say, the d51 optima give?
 

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all duly noted. what would be a good lithium ion battery? I'd like to use car batteries because they're more easily refurbished when they go dead.
Second, how much would, let's say, the d51 optima give?
You say "all duly noted", but did you actually read any of the responses? You're still talking about using Optima batteries, which you have repeatedly been told are not lithium-ion. You're asking again 'how much an Optima D51 would give', but I worked that out for you already.
 

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Discussion Starter · #9 ·
calm down im just asking for reference, ill look into the real lithium ion but as stated I'd prefer lightweight car batteries because it's easier to refurbish them and coming from the ICE world I know that optima is the best in terms of weight.
I can't seem to find the exact numbers I need for the optima d51 atm. And like I said, I am not educated in electricity, I'm a mechanical engineer, not electrical. That's why I came to you for help. If I understand what kind of range I could expect (roughly of course because of factors) with one good car battery I can work out the rest through reverse engineering. That's why I came to you, for help, not flaming.
 

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calm down im just asking for reference, ill look into the real lithium ion but as stated I'd prefer lightweight car batteries because it's easier to refurbish them and coming from the ICE world I know that optima is the best in terms of weight.
I can't seem to find the exact numbers I need for the optima d51 atm.
Try reading the post that I already wrote for you a month ago, and pointed out to you again today, in response to the first time that you asked this. But don't ask for clarification if you don't understand it, because you're certainly too much of an asshole to bother helping any more.

AGM isn't "not real" lithium-ion, it's completely different.

And like I said, I am not educated in electricity, I'm a mechanical engineer, not electrical. That's why I came to you for help. If I understand what kind of range I could expect (roughly of course because of factors) with one good car battery I can work out the rest through reverse engineering. That's why I came to you, for help, not flaming.
I suggest that you burn or return your engineering degree. A first-year engineering student in any discipline knows the difference between power and energy, and can deduce the range per D51 battery from the earlier posts.
 

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Discussion Starter · #13 ·
What's this forum, here for otherwise? stroking egos? or helping each other. Sorry if I was mistaken for the latter rather than the former.
As I mentioned, I can not find accurate numbers for the d51, thank you for pointing out that it's not lithium ion but I'm more interested in car batteries. I cannot equate what you mentioned in you're post accurately because I do not have a degree in electricity so I was hoping you could help me. I do not mean to come off as an asshole, if I could ask you for help on this since you do seem to be educated in this subject, id be really appreciated.
 

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calm down im just asking for reference, ill look into the real lithium ion but as stated I'd prefer lightweight car batteries because it's easier to refurbish them and coming from the ICE world I know that optima is the best in terms of weight.
I can't seem to find the exact numbers I need for the optima d51 atm. And like I said, I am not educated in electricity, I'm a mechanical engineer, not electrical. That's why I came to you for help. If I understand what kind of range I could expect (roughly of course because of factors) with one good car battery I can work out the rest through reverse engineering. That's why I came to you, for help, not flaming.
You are totally off track. I'll try to help.

Lead is dead. If you fill up your G35 with as many Optimas that you possibly could fit it would go 20 miles range, maybe. The optima batteries or a shitty Walmart battery, it doesn't matter.

If you want to build an EV hang out on the forum and learn.
 

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Discussion Starter · #15 ·
im trying to but everyone isn't really giving any data, info, or help. What batteries would you recommend? I remember talking to someone that had a square back and they said each car battery for them was about 10 miles worth of range. Probably because of the low weight of the car and less mechanical loss being rear engine rwd
 

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im trying to but everyone isn't really giving any data, info, or help. What batteries would you recommend? I remember talking to someone that had a square back and they said each car battery for them was about 10 miles worth of range. Probably because of the low weight of the car and less mechanical loss being rear engine rwd
I use Nissan Leaf batteries. Check out my thread I have been documenting my build for the better part of a year.

Others use Chevy volt batteries. Some use Tesla or Mustang. Some people use off the shelf.

The best Optima Red Top is like 75Amp-hours at 12 volts. 75 x 12 = 900 watt-hours.

900Wh is enough to run about 4hp for 3 minutes.

So if you have 20 Optima Red Tops maybe you can move your G35 a block.
 

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if you can stuff 8 of these babies into a G35 that should give you good range and good voltage. :geek:

point being, lead acid is just to big and heavy to build anything practical. even stuffing lithium batteries into most conversions is pretty darn awkward and not practical to most people. not worth going into too much detail with the math because, as ELC was nice enough to point out, the numbers just go way off the charts really fast with even the best lead-acid batteries you can buy.

Over the next few years, at least where I live, it's looking like Leaf and Volt batteries are the most budget-friendly options. (y)
 

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Pay for a round of golf. Rent an electric golf cart. Go to the back 9 and lift the seat up. There's your Optima battery tech and the reference performance of a vehicle you can build with it. Make yours heavier than that and things turn to shit for speed, acceleration, and range proportionally. Do they teach "proportionally" in furnace duct school?

You're about 20 years late to the party with your "car battery" constraint.
 

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Discussion Starter · #20 ·
Thanks everyone, guess car batteries just aren't feasible, shame I really wanted a refurbish-able battery. nicolaskn, mind me asking how much range you get and where you put them? That sounds like a better option.
 
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