# New book published on electric cars!



## Jason Lattimer (Dec 27, 2008)

Thanks for the info and welcome to the forum. I think that is the only electric car book I haven't read yet. I have read all the others I can find. Not to many out there though.

Once I have completed my first conversion, funds willing, I will probably be the first electric car evangelist in Columbus, Ohio.

Lots of misinformed folks out there ya know,

Jason


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## Alchemist (Apr 16, 2009)

Hi 2cents!

Welcome! Thanks for sharing the info. I'm excited to read the info. I'm still in the midst of reading "Build your own Electric Car" - the second edition by Seth Leithman and Bob Brant.


"Lots of misinformed folks out there ya know,"

LOL - Jason,

I was one of them until I discovered this site! I'm getting better informed all the time because of this site!

Good luck on your conversion!

Ernie


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## Coley (Jul 26, 2007)

Obama isn't interested in doing us any favors. 
He is too busy selling the country out. 
The last thing on his mind will be helping us have better EVs, when he is investing in GM.....


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## rillip3 (Jun 19, 2009)

NiMH is dead in my opinion. It's a format that's had no development, use or competitive forces driving it for years and years now. There were also a lot of disadvantages to it that have been conquered by Li-ion technology. Could it be improved? Probably.

Is it going to be, even if the restrictions on it are lifted? I doubt it.


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## Jason Lattimer (Dec 27, 2008)

rillip3 said:


> NiMH is dead in my opinion. It's a format that's had no development, use or competitive forces driving it for years and years now. There were also a lot of disadvantages to it that have been conquered by Li-ion technology. Could it be improved? Probably.
> 
> Is it going to be, even if the restrictions on it are lifted? I doubt it.


Part of the problem with NiMH is the fact that the patent is owned by one of the major oil companies and they refused to license it to anybody but oem and charge horrendous prices to boot.

As far as Obama doing us any favors I agree. The most feared words in the English language is "I'm from the government and Im here to help."


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## 2centsebook (Jul 6, 2009)

Hey all- I was also a misinformed folk until I read a book about the subject. I've never seen an electric car on the road, although one of my old neighbors had a plug-in car imported from Europe that the DMV wouldn't let him register.

As for NiMH vs Li-Ion, I'm still new to a lot of the information, but it seems that if the bigwigs at Chevron had the GM EV-1 literally crushed, and sued Toyota, both for running on NiMH batteries, that they are more of a threat to the market share of oil companies than any other battery technology. The other advantages in NiMH batteries are that they are much less expensive, last a long time, and are made with resources much more plentiful and available than Li-Ions. I'm interested in learning more though- What batteries are most common in conversions? Is it possible / do people ever string together many NiMH batteries in a conversion car? Also, what are the advantages of Li-ion batteries besides density? do you know which type are more recyclable, and which ones recharge faster?

Also, It's true that Obama probably isn't interested in helping develop EVs. I would argue that most politicians aren't interested in doing anything for the good of the general population. I think if we raise awareness, and put pressure on the government, then they could be motivated to do more.

Thanks for the good replies


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## Jason Lattimer (Dec 27, 2008)

I don't know much about Lithium Ions, but the hot ticket now seems to be Lithium Iron Phosphate batteries. They are the slightly heavier cheaper cousins to Li Ions. They are so cheap that http://www.evcomponents.com
has them so cheap they are almost as cheap as AGM or Gel cell lead acids. And they weigh like a third what lead does and they can be safely discharged to like 80% DOD, compared to the 50% DOD for Lead without damage.


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## Coley (Jul 26, 2007)

I think developement of the NiMH batteries ia moving on, as Chevron leased them to NASA for use in spacecraft etc.

They also leased them to CHINA for everything, BUT ev propulsion use.

That should bring down the costs, when the patent runs out.


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## david85 (Nov 12, 2007)

Welcome to the forum, 2centsebook. For a second I thought you might have been a spammer, but you most certainly are not. Spammers don't carry on conversations that are on topic usually

Welcome to the forum.


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## david85 (Nov 12, 2007)

As far as batteries go, here are some of the basics:

Lead acid is still the norm for home conversions,

Lithium Iron Phosphate is currently the largest alternative to lead,

Nickel Metal Hydride is comparable to LFP in terms of performance, but there are a few differences between the two.

I'll try and put into perspective what sort of performance difference there is between lithium and nickel, and the old school lead acid.

Lead acid is good for about 20-40 Wh/Kg (watt-hours per kilogram tells you how far you can drive relative to the weight of batteries you install in the car). Cycle life is usually around 500 cycles if you don't go past 50% discharge.

Nickel and lithium phosphate are around the 100 wh/kg mark with some rare exceptions getting close to 130. Nickel has a cycle life of 300 for the smaller consumer batteries like AA cells, but bigger ones can hit 1500 cycles. Lithium Iron phosphate starts at 1500 and can go past 4000 if you don't pass 70% discharge.

This is only the theoretical difference between these chemistries. To get a better idea of what you can actually get out of them, you need to look at the peukert effect. This is basically the name for what happens when you start pulling larger amounts of amps through the cell to get the car rolling up to speed. The result of this effect is the voltage will sag proportional to the amount of current you draw. More draw, more voltage sag.

This cuts down the amount of usable energy you can store in the batteries but as much as 50% in the case of lead acid. LFP on the other hand only sags by 5-20% (depending on make and model), meaning that you get much more of the theoretical energy capacity out of the battery.

Nickel hydride also has good peukert performance, but historically, suffered from other problems. Low charge efficiency meant that the battery had to be recharged by as much as 140% to get 100% charge. Lead acid and lithium only need ~105% for slower charging rates. There was also the problem of self discharge. All batteries have this to some degree, but NiMH was among the worst.

I've been told that the NiMH chemistry has evolved to address at least the self discharge problem. One big advantage NiMH has over lithium is the fast charge (dump charge) capability. Tests carried out on some EVs showed that a 15 minute recharge time was possible, though at such high charge currents, heat and efficiency loss was a concern. LFP is closing the gap rapidly though, and 30 min recharge to 80-90% is possible right now if you have an industrial sized charger.

The final concern is the safe discharge cut off. You generally don't want to discharge batteries 100% every time as this will reduce cycle life of the battery.

The ideal cut off for lead acid is 50% DOD (DOD = Depth of discharge)

NiMH I think (some one correct me if I'm wrong) is 60-80% DOD, but 100% will not kill them if done rarely.

LFP is 70-90%. 100% discharge is not advised and will damage them.

Now lets take a closer look at the lead acid again.

If you factor in the peukert effect AND the safe discharge cutoff, you are only getting about 25% of the theoretical battery capacity.

With lithium, you are getting closer to 80% on average. When you combine that with the lower higher energy density, low self discharge, and cycle life measured in the thousands, it becomes clear why lithium is gaining favor so quickly among this crowd.

The final question about lithium is the calender life. Again, all batteries are subject to this. Calender life is how long it will last on the shelf and still be usable weather you are cycling it or not.

Lead is about 5 years (larger ones can pass 20 years, but those are too big and heavy to be used in an EV)

Nickel is about 3 years for consumer cells, or about 7 years for EV batteries like what is deployed in the prius. Some are lasting longer though.

Lithium Iron Phosphate is......not known yet. Best guess is 10 years, but because it hasn't been marketed for that long, no one can really be sure.

This is a big unknown because calender life is required in any calculation of how well an investment in these higher tech batteries will pay off. Only time will tell.

As I said, these are only some of the basics. There is much more to be said, but this is a start


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