result longer life
Charging
Optima max. less than 25 A (after my tough flying day -I use cca 30Ah, still 11.9 V !!!! - it is charged with my Schulze charger max. 9A within 3-4 hours)
Normal max. I=cca C/10 or better less i.e. with 4-5A double time result after 2-4 h ready for other use
Internal resistance
Optima very low i.e. low self discharge, efficiency, high charging currents (no heat, no bubbles etc.)
Traction Bat.
rel. low currents for long time and deep cycle e-flyers needs this they are expensive
Normal start Bat.
High currents for short time, no deep cycle
e-flyers DONT need this, but on my expirience 99% here are using them
rel. cheap
Semitraction
Maybe good compromise

Optima is producing even special start batteries (start current cca 750 A for 30 sec. !!), but they are not deep cycle and funny is I've seen them already with elec. cars models guys. I guess they are wrong, why they need for theirs 6 cells cars start bat. with 750 A shortcut current (and this bat. Is really expensive at least here in Czech Rep.)?
I am not a dealer nor commercial connected with Optima Battery Inc.  I'd like to give just idea to other e-flyers to think about before they spend some bucks for new lead-acid battery. Everything here are my experiences and knowledge. Everything mentioned here is for standalone batteries, I can't recommend to discharge cars battery to 20% and then at the evening try to leave airfield ....
best regards
Roman

The Pink Disk S400 drew a lot of interest.

Below: Don Belfort's lop-sided fighter.  Neat plane.  Nice work Don.

Optima Battery
Roman_Vojtìch email: rovo@medicon.cz


Hello Ken,
Thank you very much for you prompt and complete answer regarding Sanyo Ni-Cd Alpha codes.
I guess that 99 % of us use as primary energy source for our chargers lead-acid batteries, at least on the field.
I've never seen on the Internet nor in any magazine somebody from specialists (I don't count me to them)  to speak about this phenomenon regarding to e-flight.
I use Semitraction battery from www.optimabatteries.com/main.htm. It is Deep Cycle, i.e. you can discharge it to 20% to nominal capacity 52 Ah (at C/20 65 Ah) and still it has cca 350 cycles. It is complete care free because there is no fluid (water). Get detailed info on their web site.
My comparison between Optima and Normal Lead-Acid Battery
Deep Cycling to 20%
Optima cca 350 cycles (to 80 % cca 1150 Cycles)
Normal cca 10 cycles and it is dead

The OPTIMA is a sealed, zero-maintenance battery that combines proven lead-acid electrochemistry with advanced Spiralcell Technology to create the
Best Batteries in the World!

Picture and info above from the Optima battery web site for info.
Km (continue)