# Battery Lifespan



## frodus (Apr 12, 2008)

depends on batteries, lithium can go over 1000 cycles, lead is much under that.....

also, you recycle lead batteries, so they don't get dumped into landfills..... and you get a core charge back.


----------



## WarpedOne (Jun 26, 2009)

> What have I missed here?


You missed the importance of your own statement:


> somewhere in the neighborhood of 400ish cycles out of a decent battery assuming reasonable DoD


It all boils down to what a "reasonable DoD" is. A starter battery in my car lasted for 7 years, that is about 7 (years) x 250 (days) x 2 (cranks per day) = 3500 cycles. There is a whole world of difference between 70%, 80% DoDs and 40% DoDs. Regular 70% DoDs will kill the battery much faster than occasional 80% DoD and regular 50%.


----------



## tomofreno (Mar 3, 2009)

Go here: http://www.diyelectriccar.com/forums/showthread.php?t=669
Look under selecting parts, battery technology.


----------



## Guest (Mar 3, 2010)

Go look here for more excellent information on batteries: http://www.evdl.org/lib/index.html


----------



## BMI/LiFeTech (Aug 12, 2009)

valkenar said:


> I'm just beginning to look into electric car conversions, so I apologize if I'm being an idiot here. From looking at various faqs and analyses of car battery life, it seems that people seem to agree that you get somewhere in the neighborhood of 400ish cycles out of a decent battery assuming reasonable DoD.
> 
> This number to me seems shockingly low. If you drive the car every workday (260 per year), that means you're only getting a couple years out of the batteries. From a cost perspective, replacing $1000+ of batteries every year cuts pretty deeply into the saving. From an environmental perspective, dumping a half-ton of lead-acid batteries every year seems like a pretty terrible thing to do. And that doesn't count anything except a work commute.
> 
> What have I missed here? I'm picturing a typical use pattern of driving to work and back (60 miles round trip) then charging it up overnight. Does this somehow constitute less than a cycle? Or have I been looking at the wrong information and the batteries can go for something more like 5-10 years (1300-2600 cycles) when used as described?


Lead acid batteries only have a life of a few hundred cycles if deeply discharged. LiFePO4 batteries have a cycle life of thousands rather than hundreds of cycles. Even the 1300-2600 cycles which you are quoting is quite low when it comes to LiFePO4. For example LiFeTech LiFePO4 battery packs come with a factory warranty of 3-5 years / 3000 cycles to 100%DoD. This is the warranty alone and if looked after properly will have a much longer life than this.
Lead acid will always be the cheapest option initially but LiFePO4 is cheaper long term and has been shown to cost around 70% of the cost of lead acid over its working life when all factors are taken into consideration.


----------



## SimonRafferty (Apr 13, 2009)

I think the trick is to fit enough battery capacity that you generally use less than 50% of it - just with the occasional longer run.

I'm using previously used Optima LA car batteries which were replaced having reached 3 years old - and presumably having completed a few hundred if not thousand cycles.

I've now completed 500 cycles to 40% DOD and my range is within 5% of what it was originally (exactly 1 year ago). three times they have been run to 100% and maybe 50 times to 70%. On that basis I would expect to get between 2000 and 3000 before the range is reduced to the point that I cannot complete the round trip.

Undoubtedly, I would get more life and range out of Li - but my batteries cost me $3 each (bought as scrap) so I don't think I'll be changing soon! Maybe in 10 years or so when Li comes free with breakfast cereal! 

I guess a decent charger and BMS help a bit too.

Si


----------



## ZEVUtah (Apr 10, 2008)

BMI/LiFeTech said:


> Lead acid will always be the cheapest option initially but LiFePO4 is cheaper long term and has been shown to cost around 70% of the cost of lead acid over its working life when all factors are taken into consideration.


I was looking at your web site and could not find any price list.

KJD

http://www.evalbum.com/3175


----------



## BMI/LiFeTech (Aug 12, 2009)

ZEVUtah said:


> I was looking at your web site and could not find any price list.
> 
> KJD
> 
> http://www.evalbum.com/3175


I love your EV album page on your Toyota pickup. Where you say-
" The Trojan batteries are really poor choice. Trojan battery warranty is 30 feet or 30 seconds whatever comes first".
That made me laugh! 

Speaking of Trojan batteries the owner of one of my largest projects to date was originally considering fitting Trojan T105 lead acid batteries to provide the propulsion power for the triple electric motor set up on his large electric boat. The weight of the Trojan battery bank would of been well over half a ton and I suspect would not of performed too well at full power.
The owner then found out about our LiFePO4 batteries and as a result of using BMI batteries the total battery weight is now under 200kg (440lbs). 
From the owners point of view I am sure he has much more peace of mind knowing his batteries are now covered by a full factory warranty of 3 years / 3000 cycles (100%DOD whichever comes first) which is somewhat better than a warranty of 30 feet or 30 seconds!

Below is a photo of the boat which I took last week on my most recent site visit as well at the battery bank. The boat should be finished its electric conversion in about 2 months. The boat has RS-232 monitoring of all batteries from a central location by laptop computer.

Since you are in Utah you might be interested to know that I have supplied BMI LiFePO4 batteries to Utah Valley University. The batteries were supplied to Associate Professor Paul Bean for teaching students battery technology in the Automotive Technologies Dept. I am sure Paul would be happy to show you the batteries if you are ever in the area.

We don't have a price list as such and provide quotes for total systems since we cater to the professional battery users market rather than the DIY market. Since we deal directly with large OEM's we provide prices based on quantity ordered. All our batteries are shipped directly from our factory to the customer by airfreight so it is impossible to be able to provide a price for a battery without knowing the total shipping weight (and therefore the shipping cost). 
In addition we have several different options for batteries depending on the complexity of the battery. For example if we use the example of a 24V 90Ah battery. This battery can be supplied with either Voltage Management System (VMS), Battery Management System (BMS), VMS or BMS with either RS-232 or CAN bus monitoring and diagnostics. Multiple batteries can be supplied with Battery Control Unit (BCU) as well as User Interface Touch Screen (UITS). 
So as you can see there are several battery options we supply depending on the manufacturers requirements and how critical the battery application is. A battery which performs an auto test of every cell every 12 hours and notifies the owner by either SMS or email should any cell become out of specification/tolerance will cost more than a battery with a basic VMS or BMS and no external monitoring.

So when you ask me what is the price of our batteries it is a bit like saying "how long is a piece of string".

If you would like more information on our Total Battery Management solutions please feel free to email me at [email protected] and I would be pleased to send you the technical documents which explain our batteries and monitoring/diagnostics systems in more detail.


----------



## Tesseract (Sep 27, 2008)

BMI/LiFeTech said:


> ...
> We don't have a price list as such and provide quotes for total systems since we cater to the professional battery users market rather than the DIY market. Since we deal directly with large OEM's we provide prices based on quantity ordered. ...




You do realize that this is *DIY*electriccar, _not_ *OEM*electriccar, don't you?


----------



## BMI/LiFeTech (Aug 12, 2009)

Tesseract said:


> You do realize that this is *DIY*electriccar, _not_ *OEM*electriccar, don't you?


You might be surprised the sort of people who check out this forum. I have supplied batteries and cells for applications which are in no way related to electric cars. This includes people interested in battery technology for solar power applications who frequent this forum and I have supplied cells to a manufacturer of very specialised electrical equipment for a power standby application which is not related in any way to DIY electric cars.

Having said that we are different to companies like A123 Systems who have a policy of not supplying their product to end users. A123 deal exclusively with OEM's (like Dewalt). How often do you hear about DIY users who are forced to buy Dewalt tool packs just to have a source of the A123 cells.
A123 is further tightening its policy of not supplying to end users / DIY users by preventing any further "leakage" of cells from their official supply channels to OEM's which has occurred recently.

LiFeTech don't mind supplying battery products to competent end users who have electrical, electronics or similar technical experience and understand the requirements of building LiFePO4 cells into battery packs and the requirements for battery protection.

So it is not only DIY users who read this forum to gain information on the latest battery products.


----------

