# Opinions Regarding Boston Power Batteries

I just heard a story on NPR about the quality of these batteries. They are a new design of the Li-Ion technology which makes them not explode like previous designs. I asked for some samples but they only sell them in packs of 12 (at the time of this post \$250). Does anyone have experience with these products?

The technology seems promising but the price tag is a killer IMO.

<><><><> COST ANALYSIS <><><><>
initial assumption:
4400 mAh at 3.7v and 12 batteries cost \$250

determine kwhr per battery:
4400 mAh = 4.4 Ah
4.4 Ah * 3.7v = 16.28 whr = 0.01628 kwhr

Assuming you want storage on the order of 50 kwhr, compute cost:
50 kwhr / 0.01628 kwhr = 3071 batteries
\$250 / 12 = \$20.83333 (cost per battery)
3071 * \$20.83333 = \$63984 (roughly)

so around \$1280 per kwhr… ouch

I can drive my grand am 400,000 miles for that much dough

This technology becomes useful when the price is on the order of \$10000 for ~50 kwhr of storage IMO. So that is \$6.40 / battery instead of the \$20.84 quoted.

If someone would kindly verify my calculation I’d appreciate it.

Jebnar

Wow! That is insane (and not realistic). I’ll see if I can get a quote on quantities.

[QUOTE=Jebnar;4942]The technology seems promising but the price tag is a killer IMO.

<><><><> COST ANALYSIS <><><><>
initial assumption:
4400 mAh at 3.7v and 12 batteries cost \$250

determine kwhr per battery:
4400 mAh = 4.4 Ah
4.4 Ah * 3.7v = 16.28 whr = 0.01628 kwhr

Assuming you want storage on the order of 50 kwhr, compute cost:
50 kwhr / 0.01628 kwhr = 3071 batteries
\$250 / 12 = \$20.83333 (cost per battery)
3071 * \$20.83333 = \$63984 (roughly)

so around \$1280 per kwhr… ouch

I can drive my grand am 400,000 miles for that much dough

This technology becomes useful when the price is on the order of \$10000 for ~50 kwhr of storage IMO. So that is \$6.40 / battery instead of the \$20.84 quoted.

If someone would kindly verify my calculation I’d appreciate it.

Jebnar[/QUOTE]

Is 50kwHr the benchmark for about 80 miles range at 65MPH?

Well it’s mostly an arbitrary number I’ve come up with to assure good range in the project I was considering, to convert a full size pickup. It seems to me that after doing a bit more reading, most of the people on this site who have done a conversion are running something similar to 12 batteries with ~50 Ahr capacity. That being said, the Saturn conversion that uses this setup (I couldn’t verify the storage capacity of his batteries) can travel on the order of 57 miles on that storage at what seem to be highway speeds. I would expect that most are really interested in a range in excess of 100 miles. That being said I’d double the 12 battery energy storage requirement (7.2 kwhr x 2 = 14.4 kwhr) So these would be your bare minimums for a tiny and light car like a saturn.

Running 15 kwhr through my spreadsheet produces \$19,200 / pack. Closer, but still awfully expensive.

Edit:
your 80 mile range would similarly produce a price tag of \$12,928.99 (620 batteries = 10.1 kwhr)

Jebnar

:oI’m just talking as a novice here so excuse me if I sound naive. :o
(I saw the Saturn and I couldn’t verify the Ah neither.)

50 Ah of lead acid or even flooded are going to weigh at least 30-40 lbs.

50Ah/4.4=~11 cells, 11 cells *92=~1000 grams ~2.2 lbs for Li-Ion

A good Marine Optima is about 120Ah @ ~43lbs

120/4.4=~27 cells ; 27*92g=2484g or about 5 1/2 lbs. For the same weight, (measuring current only) I would assume:

43lbs/.2lbs (92g=~.2lbs)=215 cells

215 Li-Ion cells * 4.4 Ah=~946 Ah. That’s over 9 times more current. Nice energy density, the problem would be the construction of the cells.

So the question now is, how much current do I need for my 50 mile (round trip) commute? I go up a 10 % grade hill every day. Going down the grade will charge me up (assuming I have regenerative braking).

You’re wanting to run a pick up truck (much heavier), so you need crazy large current. I don’t mind rolling a Civic or Corolla

Jeb - If you’re converting a full sized PU don’t compare it to driving a Grand Am. It’s still obscenely expensive per mile.

In a PU you could start with a 1 ton and fill it with lead and still have a little payload weight left over.