Pre-orders for LiFEPO4 packs
12/20/07 21:53 Filed in: Sales
Please drop us a line if you would like
to get on a waiting list for the new PHET
LiFePO4 battery packs. We will only have a few
packs come in on the first shipment, and we
expect these will sell quickly based on pent up
demand for this great new technology.
We will post pricing information here as soon as possible.
We will post pricing information here as soon as possible.
PHET LiFePO4 E-bike pack update
12/20/07 20:36
Here is a bit of additional information on the
LiFePO4 packs we'll be carrying. These are packs made
specifically for electric bikes by PHET (Phisiang
Industries) that make the highest quality C-coated
lithium iron phosphate (C-LiFePO4) cells available,
based on the Phostech chemistry. For pictures of the
packs, see this blog
post.
We have been testing the pack for about two weeks now, on our Xtracycle/Currie USPD high-power drive setup (600W+).
At an average 1C rate, the pack does appear to have the rated capacity of 7.5AH. This is just enough for a 15 mile trip with the loaded Xtracycle, in our moderately hilly area. When the pack voltage drops to about 25V, the battery management system will turn it off temporarily until voltage recovers.
The voltage curve on these is flat. They stay above 36V until about 7.1~7.2 AH of use. This is really nice in comparison to a lead acid, it allows use of nearly all the battery capacity. There is more information on the PHET batteries here (this is a large PDF file).
The charger is built very solidly. We haven't measured the efficiency yet, but we will do so and post here.
Earlier, we posted that there was a current limit at 20A. Based on conversations with the manufacturer and our own further testing, this isn't true. Instead, the BMS system is set up so that if cell voltage drops below around 2.5V/cell (maybe a bit less) it cuts out power for a few seconds until the voltage recovers. The only time this seems to happen is when we are accelerating uphill on the Xtracycle/Currie/BMC setup, which can easily drain 30A. We've tested at a relatively constant 20A current for 1 minute or more, and it doesn't seem to cut out.
About the only negative so far about this pack is that the plastic handle on the end is a bit flimsy. It is solid enough for carrying the battery, but we cracked ours when we dropped the pack on it from a few inches height. A bit of duct tape fixed that right up!
All in all, this is a solid performing pack! We don't use our NiMH or SLA packs anymore (drop us a line if you want to buy a lightly used SLA or NiMH pack in a nice case).
We have been testing the pack for about two weeks now, on our Xtracycle/Currie USPD high-power drive setup (600W+).
At an average 1C rate, the pack does appear to have the rated capacity of 7.5AH. This is just enough for a 15 mile trip with the loaded Xtracycle, in our moderately hilly area. When the pack voltage drops to about 25V, the battery management system will turn it off temporarily until voltage recovers.
The voltage curve on these is flat. They stay above 36V until about 7.1~7.2 AH of use. This is really nice in comparison to a lead acid, it allows use of nearly all the battery capacity. There is more information on the PHET batteries here (this is a large PDF file).
The charger is built very solidly. We haven't measured the efficiency yet, but we will do so and post here.
Earlier, we posted that there was a current limit at 20A. Based on conversations with the manufacturer and our own further testing, this isn't true. Instead, the BMS system is set up so that if cell voltage drops below around 2.5V/cell (maybe a bit less) it cuts out power for a few seconds until the voltage recovers. The only time this seems to happen is when we are accelerating uphill on the Xtracycle/Currie/BMC setup, which can easily drain 30A. We've tested at a relatively constant 20A current for 1 minute or more, and it doesn't seem to cut out.
About the only negative so far about this pack is that the plastic handle on the end is a bit flimsy. It is solid enough for carrying the battery, but we cracked ours when we dropped the pack on it from a few inches height. A bit of duct tape fixed that right up!
All in all, this is a solid performing pack! We don't use our NiMH or SLA packs anymore (drop us a line if you want to buy a lightly used SLA or NiMH pack in a nice case).
Folding bikes!
12/08/07 19:24
Folding bikes are a great niche for those who do
multi-modal transport, such as combining bike/bus or
bike/train trips. They're also great for those who
travel a lot by airplane and want to take a bike
along, without paying baggage fees. We did a two-week
long cycle trip in Italy on folding bikes recently,
and we had a lot of fun! And the bikes were easy to
take on the train with us to get from one place to
the next (if it was too far to practically bike). A
couple pictures from our tour of Volterra on the
bikes are shown below.
It looks like we'll be carrying a brand new style of folding bike, that folds in 1 second to a neat little package! We will be evaluating the bike for durability and quality. As soon as we've had a good look at it, we'll post some pictures here.
It looks like we'll be carrying a brand new style of folding bike, that folds in 1 second to a neat little package! We will be evaluating the bike for durability and quality. As soon as we've had a good look at it, we'll post some pictures here.
New LiFePO4 batteries!
12/08/07 19:07
Batteries are the lynchpin of an electric assist (or
Pedelec) bike. We're excited to now be testing a new
Lithium Ion Phosphate pack that is the slickest one
we've seen in this new chemistry. For more
information on battery chemistries, have a look at
our FAQ. The short story is that
these batteries are light, safe, they last a
very long time, and they are environmentally
friendly. They have a big upfront cost, but they
will more than pay for themselves in trouble
free operation for many years to come. For those
still using a sealed lead acid pack, these
batteries are so much nicer (I hate putting the
SLA's on my bike now). Our 36V lead acid pack
weighs over 30 lbs. The new 36V Li-Fe-PO4 weighs
9 lbs. For those running 24V systems, we'll have
a 24V pack too.
One thing we've discovered is that these are
limited to about 20A, or about 720 Watts for the 36V
version. [See new
blog entry]. It is a self-resetting circuit
that cuts out power for about 10 seconds. This
is much better than a fuse. For most systems
(Crystalyte 400 series, Goldenmotor, Currie
USPD, Lashout, etc), this shouldn't be a
problem, but for the really high power hubs
(e.g. Crystalyte 5000 series/Phoenix) the limit
might be too low.
Some pictures are below. We may be taking pre-orders at a discount once we do further testing and set the final price. Please contact us if you are interested, and we'll let you know when the batteries will be ready to roll.
Some pictures are below. We may be taking pre-orders at a discount once we do further testing and set the final price. Please contact us if you are interested, and we'll let you know when the batteries will be ready to roll.
Side view showing pack
and rear rack mount
Front view, pack plugged into mount
Front view of pack with charging port and discharge
port
