# Batteries that will last



## skooler (Mar 26, 2011)

m_k_321 said:


> Hey guys,
> 
> I just want to know what is the best type and brand of batteries to be used on an EV. That will lass for more than 5 years


Hi,
Its hard to say without knowing how you will use them.

What is the doner vehicle?

Average daily range?

Driving style?

As a daily driver you will definately want to go Lithium. Most prismatics advertise 2,000 - 3,000 cycles at 70-80% DoD (Depth of discharge)

Cheers,

Mike


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## m_k_321 (Nov 29, 2011)

Donor vehicle is a bmw z3 or equivalent

A 60kw ac motor with regen will be installed 

It will used daily but also, sport performance is required


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## skooler (Mar 26, 2011)

m_k_321 said:


> Donor vehicle is a bmw z3 or equivalent
> 
> A 60kw ac motor with regen will be installed
> 
> It will used daily but also, sport performance is required


What about range?

I'm assuming you want to match the performance? ~6sec 0-60?

You'd definately want lithium cells, have a look at:

Calb / Calib
Thundersky
Winston
Sinopoly
Headway
Turnigy
A123
If you range is short you might want to look at having a smaller pack with a higher 'C' rate. usually the cylindrical and pouch cells (typically headway, A123 and Turnigy cells)

If you require a higher range have a look at the prismatic cells (Calb and Sinopoly)

Why have you chosen AC over DC?

What is your budget?!

Cheers

Mike


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## m_k_321 (Nov 29, 2011)

Range is a minimum of 100km or 60 miles

I chose ac because its more efficient and i heard that they operate better on hill rides.

My budget as
Over all conversion including batteries and BMS around 25k


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## skooler (Mar 26, 2011)

m_k_321 said:


> Range is a minimum of 100km or 60 miles
> 
> I chose ac because its more efficient and i heard that they operate better on hill rides.
> 
> ...


25K is a reasonable budget.

You may want to consider a Large DC motor and spend the money saved on more/better batteries. There isnt really a high performance AC option available at the moment for a reasonable price. Have a look at the Warp11HV and Kostov11. 


An 11" motor, decent controller and a large pack wont have a problem with hills.

Assuming a maximum of 350WH/Mile you will need a 28KWH pack for 60 miles. 

So 45 200AH Cells or 90 100AH cells

I would say you should look at the larger prismatics. The pouch and cylindrical cells will be impractical.

so either:

Calb
Sinopoly
HiPower
Have you read this thread?

http://www.diyelectriccar.com/forums/showthread.php?t=60127&highlight=kostov

Its for a Z4 but he DC/AC issue is discussed in some detail.

Cheers,

Mike


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## rwaudio (May 22, 2008)

m_k_321 said:


> Range is a minimum of 100km or 60 miles
> 
> I chose ac because its more efficient and i heard that they operate better on hill rides.
> 
> ...


From reading your other posts it sounds like you are going for a build like mine, good performance in a smallish light car, to keep the performance up without needing to haul around hundreds of lbs of extra cells you might want to look at the higher C rated cells if you will have a low voltage AC system, if it's high voltage 300-400v+ then 60ah Calbs might do the trick.

I think my goals aren't to far from yours and I went with a Warp11 HV, Soliton1, in an '86 Porsche 944 and A123 20ah pouches. Peak power should be in the range of 260kw (300 HP) and 300ft-lbs of torque along with 100km range. I don't need a ton of range so finding cells that would still give me peak power without destroying them was difficult. You could take the Tesla approach and pack as many low power cells as you can in the car and you get tons of power and range all at high cost (and weight), I wanted the opposite, low weight, high power, and the range that I need, (not want).

Good luck with your conversion. 
PS... 60kw of AC power (70 hp) doesn't scream performance in a car that will probably weigh 3000-3500lbs


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## ElectriCar (Jun 15, 2008)

An 11" DC motor with a 1000A controller and you can rip the transmission out of the thing! No problems climbing a hill even if pulling a boat. 

I have a Curtis controller modified for 1000A with a 9" Advance DC in an S10 truck and the torque is incredible. I've seen charts that at 1000A it's making about 240 pounds of torque.

AC though is what I want to go with next to be able to use regen and eliminate the issue of brush arc that can happen in DC motors in certain situations with high current.

For a car of that size, look at Sinopoly cells as they've reduced the volume in their 200Ah cell by 31% over the Calb cells that I use. A pack of 50 that I have in their batteries would only be 36 x 26 inches at about 11 inches tall. That size pack would take you well over 100 miles I suspect but I understand the reduced profile battery is only being made in the 200 and 60Ah size. Of course you could parallel 60's and have 120Ah equivalent which would probably get the mileage you want in that car.


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## Rational (Nov 26, 2011)

m_k_321 said:


> . . .more than 5 years


If you can estimate how many inservice hours this is and if a battery manuf. will tell you the MTBF of it's products, then you have a shot at finding a battery that will do this to some level of confidence.

Two hours/day for 5 years would be ~3700 hrs. If the battery MTBF were 3700 hours you'd have a 37% chance of having them last this long. It's an exponential relationship and there are several ways of figuring this.

Getting an MTBF for commercial products is usually easier than for consumer products.




rwaudio said:


> PS... 60kw of AC power (70 hp) doesn't scream performance in a car that will probably weigh 3000-3500lbs


My spreadsheet gives me 12 seconds to reach 60 mph [630 feet] and 18 seconds to do 1/4 mile.


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## MN Driver (Sep 29, 2009)

You won't get an MTBF from batteries, I'd be surprised if it took less than a week's worth of emails back and forth from a Chinese battery manufacturer before they even understood what you are asking. Mean Time Between Failure is extremely difficult because then you have to define failure. The cycle life to 80% DOD at a standardized discharge rate is the best we have. Probably all we need too otherwise the standards are different all over the place.


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## Rational (Nov 26, 2011)

MN Driver said:


> You won't get an MTBF from batteries, I'd be surprised if it took less than a week's worth of emails back and forth from a Chinese battery manufacturer before they even understood what you are asking. Mean Time Between Failure is extremely difficult because then you have to define failure. The cycle life to 80% DOD at a standardized discharge rate is the best we have. Probably all we need too otherwise the standards are different all over the place.


Anyone have a conversion between cycles & years? If five years is hard to achieve I guess it's less than 1 cycle/day.


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## MN Driver (Sep 29, 2009)

I don't think it would be difficult to achieve 5 years, especially if you planned your pack capacity to so you wouldn't usually use more than 70% of the capacity of the pack. Then again, these LiFePO4 cells haven't been around in peoples cars for 5 years yet or the answer would be more definitive.


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## m_k_321 (Nov 29, 2011)

As i have heard that these batteries can do 2000 cycle 

If i used 50% of energy stored than recharge the battery again to full is 1 cycle lost ? Or half a cycle ?? Or it has a different calculation


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## ElectriCar (Jun 15, 2008)

Life depends on the depth of discharge per the manufacturers . The lower you discharge it the shorter the life. Knowing that it could be the best thing to buy a large pack to minimize the depth of discharge. 

OTOH, it is likely that with the prices dropping which should happen with improvements in technology, you may be better served to keep your pack just a little larger than you need and when it goes bad, move up into the newer cells that will be smaller and cheaper with more power/kg. Actually Sinopoly has dropped their prices about 20% compared to the Calb's that I bought last December of the same size.


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## sokon (Sep 15, 2011)

maybe you can get a price tag for this motor:
http://www.evo-electric.com/inc/files/AFM-140-Spec-Sheet-V1.1.pdf
I think I read something about 6k$ somewhere (but i am not sure anymore).

U might also want to have a look at the cells discussed in this thread (better power density than the usual big prismatic cells):
http://visforvoltage.org/forum/10370-around-03m%CF%89-inner-resistancethe-best-lfp-lithium-battery-china

Of course, a123 20 AH would fit nicely, but they are hard to get.

also I heard that new thundersky (or are they called sinopoly now?) cells are much more energy dense than the older ones. See here
http://sinopoly.todayir.com/attachment/201110101246483_en.pdf


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## Rational (Nov 26, 2011)

Prelim lifespan opinions, formatting is a problem
EV BATTERY LIFE 

A	life in cycles 
B	life in years 
C	type 
D	notes 

A	B	C	D
100	1	lead acid	
300	1	lead acid	
300 lead acid	mora
400 lead acid	mora
8	lead acid	alexcrouse
1500 lithium	mora
3000 lithium	mora
2000 lithium	skooler
3000 lithium	
2000 LiFePO4	
5	LiFePO5	mn driver
10	LiFePO6	alexcrouse
350 AGM	
1000 AGM	
300 

1187.5	=average cycle life 
5	=average lifespan 

3/4ths of the batteries did worse than 
2000	cycles 
and worse than 
8	years


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## drgrieve (Apr 14, 2011)

BMW Z3
Warp 9" (170v) Soliton 1 300v 1000amp
Calb 100ah to go 60 miles safely in winter 24 kWh = 75 cells

This would be a build where people have done it all before tried and tested and all products tried and tested and well recommended and would come at or under your budget

You performance at a wild guess be similar to Z3 2.8. Consider upgrading the clutch for the 1000 amp (motor amps) starts.


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## m_k_321 (Nov 29, 2011)

drgrieve said:


> BMW Z3
> Warp 9" (170v) Soliton 1 300v 1000amp
> Calb 100ah to go 60 miles safely in winter 24 kWh = 75 cells



What do u mean in winter ? Cold weather makes them more efficient ? 

If so ! 

Will it make 50 miles in summer or less ?


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## Outtasight (Dec 8, 2011)

Cold weather (less than 0C) makes all batteries less efficient as they are chemical devices and the reactions work more slowly at low temps. You'll still get the same total energy out of a cold battery but you can't extract it as fast. In a car, that means lower top speed and slower acceleration in cold weather. This may shorten your effective range, depending on the terrain and driving style (anything that will cause you to try and pull a lot of Amps).

Of course it could just be that you get less miles in winter because you can't resist turning on the 1kW electric fan heater in the car rather than freeze to death 

In very sub-zero climates (-10C) you'll need an insulated battery box and possibly some kind of "underfloor heating" type thing in there to warm the cells up so that they can work. The problem thereafter is keeping the cells cool, as when they're working hard they heat up and then you don't want them in an insulated box that doesn't let the heat out.

In terms of what counts as a "cycle"... Yes to an extent any charge and discharge counts as a "cycle". Depth of the cycle has a big impact on the total number of survivable cycles. Humble car starting batteries can survive several hundred micro-cycles (turning an engine over only uses less than 1% of the cell capacity). So when used only for such micro-cycles they last for a good 4-5 years in daily use. But if you deep cycle the same battery to 70% discharge level and recharge it, it will be good for about 25 "cycles".

In lead cells, more and more of the active lead electrode is permanently converted to hard lead sulphate that cannot dissolve when recharged and more of the fragile paste material that the electrode is made of simply falls off the plates and ends up as sludge at the bottom of the cell.

Even lithium cells are prone to cyclic wear and tear. As you charge and discharge the cells, you're forcing big lithium ions into and out of the electrodes and this action progressivley and permanently breaks the lattice structure of the electrode materials (the lithium ion actually makes the lattice bulge). That's how a lithium cell dies - from mechanical fatigue. The deeper you cycle the cell, the more of the electrode you bust up with each cycle.


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