Thanks Bob,
Excellent data !
Best regards
-James
On Mon, Jul 13, 2015 at 6:43 PM, Bob Feretich <bob.feretich@xxxxxxxxxxxxxxx>
wrote:
7.4V LiPo (Li-Ion) will work in 95% of all 9V alkaline battery
electronics.
The rated voltages are confusing because that 9V alkaline battery
advertises its starting voltage and the 7.4V LiPo battery advertises its
discharged voltage.
Compare the discharge curves...
http://www.feretich.com/Rocketry/Resources/lipotests.html
http://www.feretich.com/Rocketry/Resources/Pdfs/7v%20Li-Po%20vs%209v%20Alkaline.pdf
Assuming your electronics draw 100 mA of current, the cross-over point is
at 30 minutes of use. After 30-minutes, the voltage of a 7.4 V LiPo is
greater than a fresh 9V Alkaline.
A fresh (newly manufactured) 9V alkaline battery starts at 9.25V, drops to
9V after about 7 minutes of use (at 100 mA), and to 7.4V after about 2
hours. (If the battery has sat on the shelf for a while, it may start at
8.4V.) See the discharge curve at the provided link. One alkaline battery
was freshly manufactured the other had one month still remaining before its
expiration date.
A fully charged 7.4V LiPo starts at 8.4V and declines slowly to 7.4V.
Below 7.4V, the voltage on LiPo (and Li-Ion) batteries drops quickly.
Given that at the end of its rated life, a 9V alkaline battery is only
sourcing 7V, electronics designed correctly to use 9V alkaline batteries
will work fine with 7.4V LiPo batteries.
Regards,
Bob
On 7/13/2015 3:02 PM, Mike Hubble wrote:
Manual says standard 9v is all you need.
On Mon, Jul 13, 2015 at 2:39 PM, Peter Hackett <
peter.hackett@xxxxxxxxxxxxxxxx> wrote:
I've always used a standard 9V alkali battery. Never had any battery
problems with it.
On Mon, Jul 13, 2015 at 2:07 PM, Steve Sawyer <steve@xxxxxxxxxxxxxxxx>
wrote:
I've been using 180mah 3S 25~40C Lipos.
For the stratologger CF required protection of the FETs (i.e.,
short-circuit or 1 Ohm pyros), I use series 3 Ohm resistors on each output.
Lots of flights are possible.
Steve
*From:* tccrockets-bounce@xxxxxxxxxxxxx [mailto:
tccrockets-bounce@xxxxxxxxxxxxx] *On Behalf Of *Ben Sandoval
*Sent:* Saturday, July 11, 2015 11:01 AM
*To:* TCC Chat
*Subject:* [tccrockets] battery for stratologger CF
Which battery are you using for your stratologger cf. I'm getting ready
to order a few batteries and I'm still on the fence. Appreciate your input.
