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[aprssig] Prius Battery and 20 kW APRS

Bob Bruninga bruninga at usna.edu
Mon Aug 27 02:14:45 UTC 2007


APRS in a Prius:

> We all love the concept of the Prius,

I did too until I saw the price.  Never looked at them again, until I stumbled on this one at half price due to $4K door damage.  I just covered the door with a SIGN and didnt have to do anything else... see photo

http://www.ew.usna.edu/~bruninga/APRS-SPHEV.html

> The big debate revolves around battery life.

No debate really.  Satellites all the time last 10 years or more while using rechargeables.  The TRICK is, to limit the charge/discharge to only about 20% of capacity.  We do it in space, and Toyota does it too.  The Prius tries to keep the battery at about 60% charge, never ever allows it to get past 80% nor below 40%.

Any rechargable will last 10 times longer or more under those constraints.  

One has to remember that the prius only uses the battery as an energy ballast.  The real key to high mileage is its well engineered 1.5 liter engine that tries to run optimally at all times.  If it has excess energy it stuffs it in the battery, if it needs some for acceleration, it takes it back.

> The replacement cost has been quoted between $5,500
> to over $7,500.

Prius was $6K But is now down to $2.5k.  But shucks, I bought
20 brand new Lead Acid 9 AH batteries at Dayton for $350 and that should also do the same job.  As a EE, I am not worried about the battery at all.  But then that's me.  Messing around with a 250 volt battery is not for everyone, though...

> Given the high initial acquisition cost, the 
> cost/mile...will be several times higher than 
> a car with 35+mpg costing under $18,000. 

Agree completely.  A 40 HP diesel volkswagon will be much more cost effective.  I dont buy $20k+ cars, so a Prius was never in my plan either.  But then where else am I going to put all my solar panels?

Solar power at home makes little cents.  It can never repay when you can get electricity from the mains for 10 cents per KWH..  But solar power DOES pay when you can get it where you cannot get electricity otherwise.  Such as into the battery of my prius while it is parked at work...  See photo:

http://www.ew.usna.edu/~bruninga/APRS-SPHEV.html

So it was as much of an excuse to invest in solar power as it was to get good gas mileage.  AND besides, I can pull up at Field Day (or anywhere) when the sun is shining and provide 200W of GOOD DC power continuoously and peaks of 20 kW but the engine would have to start keep the battery up. . And I can take my solar power with me anywhere  I go.  Wait till you see the 1 kW solar power TRAILER I plan on building... Then I might be able to drive on all electric...

hi hi..

Oh, and a Bass boat is not cost effective either.  It drives the cost of fish up to over $100 per pound.  Yet people buy them all the time...  (But they often dont have APRS, so not realy a topic here.)...

Oh, used it today to run all my APRS radios at the Annapolis 10K at water stop 2...

Bob, WB4APR




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