Daniel A wrote:
> I recently read a post about some LIMNPO4 batteries and tried to post a query
> about them. I guess I did not edit the reply very successfully as I received
> one reply saying to edit my replies.
Sorry, the EVDL server will bounce your message back if you try to reply to
a digest and let your email program tack the entire digest onto the end of
it.
Regrettably, this is what many popular email systems do by default. I
suggest that, if possible, you turn off quoting in your email system's
configuration. Then, copy and paste the passage you want to reply to.
The reason the server is configured this way is to prevent annoyance and
inconvenience for your fellow EVDL members. For one thing, it's a matter of
"netiquette" to edit your reply and not include the entire message, much
less an entire digest. For another, it costs a few EVDL members real time
and money to download a large amount of irrelevant text.
Remember that we have members all over the world, and some of our members
still have to use slow dialup connections. Be nice to them. ;-)
> I am trying again to gain some info on the batteries and not include
> everything else in a paticular digest. Does anyone know anything about
> those batteries or are the same as the Lithium Phosphate batteries?
Here is a message from a couple of weeks ago which compares LiMnPO4 with
LiFePO4 batteries.
http://evdl.org/archive/#nabble-td2274441%7Ca2274441
My take on this - for what it's worth - is that using any kind of lithium
batteries makes for a more expensive and riskier project for an EV hobbyist.
Experience with lithium batteries is growing, but there are still many
things that can go wrong and damage an expensive battery pack - or the car,
or even you.
I may have missed something, but it appears to me that what's still missing
is an affordable, pre-engineered, drop-in solution.
Valence makes a lithium battery (LiMnPO4, I think) that emulates a 12 volt
lead-acid marine battery and is almost trivial to substitute for the latter.
It's pre-engineered and drop-in, and has a fairly long history now, but it's
hardly what I'd call affordable.
There are also several pre-configured lithium battery systems, aimed at
scooters and e-bikes. These are typically 24 to 48 volts and 10 to 20 amp
hours. They almost meet the qualifications above, but AFAIK none of them
is big enough and powerful enough for a 2500-3500lb, 4-wheel EV.
I sometimes wonder though if one could use several of these in a series-
parallel array. A 48 volt, 20 amp hour LiFePO4 battery from the most widely
recommended seller costs around $800, shipped from China (I know of no one
making these in the US), with a C/10 charger. Each of these little e-bike
batteries is good for nearly a kWh, so 8-10 of them might have enough energy
for respectable range with a car EV.
Other than this, nearly every lithium battery system for a car type EV
requires substantial engineering work. This is fine if you're an electrical
engineer with access to ample support and data, and plenty of time. For
many hobbyists, though, there's a substantial risk of financial loss. With
some types there are also physical dangers and risks.
Folks with lots of EV building experience and good electronics chops are the
ones who might want to forge ahead with lithium right now. However, if
you're an EV beginner or intermediate hobbyist, I'd recommend staying with a
more mature and less risky battery technology. That almost certainly means
lead-acid. NiCd is another possibliity; check out what some folks here have
done with BB-600 mil-surplus NiCd cells.
Others may have different views, so let's hear from you.
David Roden - Akron, Ohio, USA
EVDL Administrator
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