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I am on the hunt for budget ex Toyota/Nissan/Mitsubishi etc EV batteries for my 700kg Sandrail.

With an guess of 250wh/mile for a 40 mile range that's a 10kW/hrs pack I need.

So when a car battery pack is advertised as (Leaf for example) 24kW/h does that mean that is what you can actually get out of it or is that before DoD/ fast discharge effect etc. (1.32 I think is the multiplier for LIPO but I could be wrong)
 

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I am on the hunt for budget ex Toyota/Nissan/Mitsubishi etc EV batteries for my 700kg Sandrail.

With an guess of 250wh/mile for a 40 mile range that's a 10kW/hrs pack I need.

So when a car battery pack is advertised as (Leaf for example) 24kW/h does that mean that is what you can actually get out of it or is that before DoD/ fast discharge effect etc. (1.32 I think is the multiplier for LIPO but I could be wrong)
Hi sparks,

LIPO typically refers to hobby RC type batteries which are often high C-rate. As such internal resistance loss will subtract from usable energy. Perhaps that is where your multiplier comes from.

The Lithium batteries used in OEM EVcars should deliver the rated energy on a 1C rate (1 hour). I've got 40,000 miles (nearly 5 years) on my factory EV with a 24 kwhr pack. Think I've seen up to about 23 kwhr into the charger. But I hadn't run it down to "dead". Although I haven't noticed it with my Think EV, they say capacity decreases with usage and calendar life.

So throw it all into the mix, I'd count on maybe using 90% of the rated energy on a used buy. Less in the cold.

major
 

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... that's a 10kW/hrs pack I need.

So when a car battery pack is advertised as (Leaf for example) 24kW/h ...
Just for clarity, that should be kW-hrs - or better just kW-h or kWh - not "kW/h". The slash means division, and as you know it's not kilowatts per hour, it's kilowatt-hours.
 

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Just for clarity, that should be kW-hrs - or better just kW-h or kWh - not "kW/h". The slash means division, and as you know it's not kilowatts per hour, it's kilowatt-hours.
Yes, I agree, kWh is the correct unit.

I used kwhr in my reply. That should be kWh. I have been doing a fair amount of fact checking lately on units. About a month ago I read that you should not use upper case letters, hence I switch from a long time usage of W to w for watt. And along those lines thought that h should represent Henry, unit for inductance. And since h was used for Henry, I started (or switched) using hr for hour. "hr" is an acceptable abbreviation for hour. But abbreviations and unit shorthands are not the same.

So I'm back to kWh. And H for henry.

Regards,

major
 

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Yes, I agree, kWh is the correct unit.

I used kwhr in my reply. That should be kWh. I have been doing a fair amount of fact checking lately on units. About a month ago I read that you should not use upper case letters, hence I switch from a long time usage of W to w for watt. And along those lines thought that h should represent Henry, unit for inductance. And since h was used for Henry, I started (or switched) using hr for hour. "hr" is an acceptable abbreviation for hour. But abbreviations and unit shorthands are not the same.

So I'm back to kWh. And H for henry.

Regards,

major
My understanding is that the SI convention is to use a capital if and only if the unit is named after a person. So Watt, Henry, Tesla, Ampere etc. are all capital and gram, meter, second etc. are not.

I also think (less clear on this) that for prefixes if there are ones with the same letter on "both sides" of the unit, then you capitalize the one on the multiplicative side, so Mega (vs milli) and Deka (vs deci) are capitalized but kilo is not since there isn't a "k" on the other side.

:confused:
 

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I have been doing a fair amount of fact checking lately on units. About a month ago I read that you should not use upper case letters, hence I switch from a long time usage of W to w for watt. And along those lines thought that h should represent Henry, unit for inductance. And since h was used for Henry, I started (or switched) using hr for hour. "hr" is an acceptable abbreviation for hour. But abbreviations and unit shorthands are not the same.
Hmmm... whatever you read sidetracked you, since you had it right to start. The term you need is "symbol"... it's not just an abbreviation.

My understanding is that the SI convention is to use a capital if and only if the unit is named after a person. So Watt, Henry, Tesla, Ampere etc. are all capital and gram, meter, second etc. are not.
Close. There is the unit name, and the symbol. Units named after people use a capital symbol, but do not capitalize the name (because it is not a proper noun):
  • The unit of power is the watt, named after James Watt; the symbol is "W"
  • The unit of inductance is the henry, named after Joseph Henry; the symbol is "H"
  • The unit of energy is the joule, named after James Prescott Joule; the symbol is "J"
  • The unit of force is the newton, named after Isaac Newton; the symbol is "N"
  • The unit of electrical potential is the volt, named after Alessandro Volta; the symbol is "V"
  • The unit of electrical current is the ampere, named after André-Marie Ampère; the symbol is "A"
  • The unit of magnetic field strength is the tesla, named after Nikola Tesla; the symbol is "T"
  • The unit of magnetic flux is the weber, named after Wilhelm Eduard Weber; the symbol is "Wb"
  • The unit of temperature is the kelvin, named after William Thomson, 1st Baron Kelvin; the symbol is "K"
  • The logarithmic relative unit for power and field quantities is the bel, named after Alexander Graham Bell; the symbol is "B"
(I had forgotten how many of these there were until I started listing them!)

I also think (less clear on this) that for prefixes if there are ones with the same letter on "both sides" of the unit, then you capitalize the one on the multiplicative side, so Mega (vs milli) and Deka (vs deci) are capitalized but kilo is not since there isn't a "k" on the other side.

:confused:
Yes. :)
 
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