[bjfreeman]

at the time I bought mine in 2005 was the high charge and discharge rate, along with the number of cycles, about 5,000 at the time.
look at the open source 10KW in the charger section.
if you want a starting point to learn BMS you can use the ZEVA BMS Circuit. do a search on it.
then you can decide if you want to buy a manufactured on.

[EVfun]

You are a bit optimistic on the Watt hours per cell. They up to 4.0 volts at the end of charge, but when the charger is removed they will fall back to 3.4 volts. The nominal cell voltage (no load cell voltage) falls with the state of charge, down to 3.3 volts before 10% of the charge is used, and then almost steady at 3.3 volts until the last 20% where they start falling again. They also sag some under load. I'd recommend using 3.1 volts for just shy of 2 kWh from your proposed pack.

[PStechPaul]

Originally Posted by EVfun

You are a bit optimistic on the Watt hours per cell. They up to 4.0 volts at the end of charge, but when the charger is removed they will fall back to 3.4 volts. The nominal cell voltage (no load cell voltage) falls with the state of charge, down to 3.3 volts before 10% of the charge is used, and then almost steady at 3.3 volts until the last 20% where they start falling again. They also sag some under load. I'd recommend using 3.1 volts for just shy of 2 kWh from your proposed pack.

In that case, then, I'd need even more of them. But the LiPo batteries may be able to provide a lot more of their stated A-Hr capacity (as translated to W-Hr) than a similar Lead-Acid battery. For automotive use, I think the LiPo batteries are the best way to go, if you want to use the vehicle for the usual everyday commuting and household use.

But for homeowner tractors, or for inexpensive conceptual automotive prototypes, the lead-acid batteries may be OK, especially if you can get by with no more than 4-6 of them and boost the voltage.

I found a thesis paper that mentioned new research on aluminum batteries that have the potential to provide 10x the storage capacity of Lead-Acid. But it seems they are not rechargeable, although there are still possibilities of using replaceable electrodes:
http://en.wikipedia.org/wiki/Alumini...%93air_battery

I'd hate to invest a pile of money in LiPo that will last for 5-10 years and then two years doen the road there's a huge breakthrough!

[JRP3]

If you wait to build something expecting a breakthrough you won't ever build anything. Even if something appeared in a lab in the next few years it would probably be another 5-10 years before it went into volume production. Moderate improvements here and there are to be expected, major breakthroughs are not.

[ndplume]

PSTech,
I completely agree about the buy now and a breakthrough product will come out. So take one for the team, sink about $12K into a nice pack ASAP so that in 2 years (or 6 months) the rest of us can get the same capacity for $4K and 1/2 the weight. You'll still have 10yrs of enjoyment from the pack, especially the 1st 6 months :^)

[DanGT86]

I tried to get an answer from balqon as to why the price jumped from 85 to 99 in three days. They are still willing to honor the original quoted price but did not give a reason for the price increase. If I had to guess I would bet that the batts in the online store were leftover from their non retail business(vehicles they build?) and they probably sold at a loss to get our attention. Now that the qty are running low they probably need to raise the price before the next shipment. Worst case they take a loss on what they have in stock. Having to honor .85/ah on an entire new shipment would be a big loss I would think. Still have no reason to believe they are a bad company to deal with. Communication has been great so far and ricklearned seems to be happy with his purchasing experience.

[Baldbruce]

And now the price is at 1.1 per Ah.
Because they can......

[ricklearned]

Originally Posted by Baldbruce

And now the price is at 1.1 per Ah.
Because they can......

Or maybe they were naive as the the retail/diy market. If they are the sole distributer they are undercutting their dealers. $1.10 per Ah is still the best price I could find and I also saved freight but that is unique to my circumstances. They came packaged well for a delivery service, but the 30 cells in the wooden box would have to be shipped via freight.

[bjfreeman]

I can't get rid of the feeling there is a lot of hype to purchase their batteries from those that have not really bought any.

[ricklearned]

Originally Posted by bjfreeman

I can't get rid of the feeling there is a lot of hype to purchase their batteries from those that have not really bought any.

Not from me, I am happy with the value that I got for $3,800. It was a better value than I could find anywhere else on this side of the Pacific Ocean.