How about Hipower lifepo4 cells?

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Hey guys, does anyone has experence with Hipower lifepo4 cells? I got some test feedbacks of Hipower cell recently, it seems hipower cell’s performace is good. Hipower cells have less weight than TS cells. And recenlty they claim that their new cells can stand 3C continuous and 10C burst discharging rate. I am discussing with them to have a large quantity purchasing, hopefully we can get 1.05/ah or better. Any one is interested in it? They said they can offer 2 years warranty.

This page covers the decisions and choices made concerning batteries.
Which technology?
There was never really any doubt - it really had to be LiFePo’s of some sort. Weight and life-time duration were the most critical duration, which rules out lead acid.

Since the choice also was made thinking about the motor - AC induction, running at 300V was the target - the pack had to give voltage and current - a small car really cannot handle the mass of lead acid batteries needed for that. It would have probably meant at least 250kg of batteries extra… too much (440kg instead of 170kg).

In the end, after about 3 months of enquiries, I settled on HiPower 50Ah units, using 95 of them to get 304V nominal. These will output (in theory, not managed this yet!) 2.5C to 3C current, so 150A - which is as much as the AC24LS motor can handle. And the price is right, and the guy dealing with this is straight and honest.

I’ve put the numbers in a spreadsheet, and in any case include it below as a graphic. Note that the pricing in Euro was correct when I put this together in the summer of 2008 - exchange rates have varied a lot since then! Prices are also what I would have paid, EU VAT (sales tax), import duty and delivery included. My purchase of HiPower was made in Sep 2008.

Note that the packs are not all the same size - I have tried to configure what was possible for the vehicle. Consequently, I have made a few unit level comparisons:
• cost for 1500 cycles: lower is better, this is a real value in € (in fact the HiPower warranty is 2000 cycles/3yrs)
• power (Wh) per kg of pack, bigger is better
• power per buck (€1,000), bigger is better.
I’ve also estimated the charger cost (except for HiPower, that’s the real cost) and I don’t know all the warranty info: indeed most lead acids seem to have no warranty if you put them in EVs.

It’s absolutely clear that the lifetime cost (based upon 1500 cycles) of HiPower is half that of lead acid, on the cycles which seem mostly reported by others or offered in the guarantee, and much better weight/performance ratio where only the MesDea seems to beat the HiPower (but look at the cost of the MesDea!).

On the kWh/€1000 - calculated on a 1500 cycle basis - the HiPower is 50% better than ThunderSky, over 3 times better than the LifeBatts, about 4 times better than the lead acids and 6 times better than the MesDea battery, which basically suffers from a poor guarantee (I have no real idea how long it lasts so maybe this figure is wrong, but even so…).

Clear to see that not just from a financial, ecological and mechanical basis, HiPower has to be the choice here (with ThunderSky 2nd). I plan 200 to 250 cycles per year (7,000 to 10,000km/yr), so 5 to 7 years of use is the current target. Only time will tell if this wasn’t a good choice, but it certainly looks the best on paper and given what others have reported. It’s the way I have chosen to go.

Hipower 10C rate cells

Andy
evisfuture@gmail.com

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Iron Phosphate or LiFePo batteries have some advantages and disadvantages that one needs to note. Same can be said for any Lithium technology as they are not ready for economical EV power.

Advantages:
[ul]
[li]Safety, they do not have the thermal problems of other lithium chemistries
[/li][li]Lower toxicity
[/li][li]Can be charged and discharged at high rates needed for EV’s but…
[/li][/ul]

Disadvantages:
[ul]
[li]Low energy density compared to other Lithium chemistries which means larger and heavier packs for a given watt-hour capacity.
[/li][li]Cannot be deep cycled without damage. Deep cycle is critical for EV’s.
[/li][li]Short cycle life and compounded by deep cycles
[/li][li]Expensive
[/li][/ul]

Personally I think Litium technology is the key to EV’s, and I think a chemistry will be developed within 5 years that will over come all the disadvantages except maybe expense which can be justified if they can last for 10,000 cycles or 10 year life span without significant capacity losses. We are just not there yet.

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short cycle life of lifepo4 battery?
I don’t think so, it says that lifepo4 can achieve 2000 times cycle? What is other mature battery technology can do this so far? And Price, it is good to see lifepo4 battery price is keeping lower.