I'm wondering if I'd get a decent flight time using a Canon camera battery - NB-6L, and additionally a neater and much faster replacement time. They are 3.7 volts, 1100 mA/h. I already have a number of these batteries which I use on my camera, plus the charger of course.
I get an amazing number of shots before a recharge is necessary. Before experimenting though, I need to know what the third connection is on the battery. The other two are marked + and - but the centre connection is unmarked. The camera uses the centre connection. Can anyone enlighten me please ?
You could try but it depends on the output C rate if it has any. It may only get you to a hover & then no power for full forward flight, it will just gradually lose altitude.
Worth a try if no battery though.
Watch out for amps aswell although it may not be a problem.
I'll solder a Syma lead onto the tags of a NB6L and let it hang. do a steady flight (no stunts !), and see what kind of duration we get. If it's an improvement on the original battery, then I'll do some surgery and fit the battery receptacle from a charger into the body of the copter and make a retaining clip. No more pulling fiddly plugs apart !
I doubt it will be better. They are Li-Ion rather than Lipos. Li-ion has the ability to discharge to a lower voltage, but the Syma probably can't take advantage of that due to the low voltage cutoff. They are also pretty heavy for their size, the required socket won't help that either.
Reguardless of those possible drawbacks this is going to be an interesting experiment. Might also try some simple lightweight 3D printed designs for a battery case and dock. Something you could put Lipos in and that would weigh less.
... Also of note is that Li-Ion batteries are more unstable than Li-Po batteries and usually require some sort of external regulation; which is what that third terminal is for.
While the energy density of a Li-Ion is higher, it's unregulated discharging (like say a quad trying to pull higher "C Ratings" than the battery would normally allow) and
not having an active limiter engaged (that third terminal hooked up to some limiting circuitry) could possibly lead to catastrophic results
Li-ion is a general term for at least 6-different major lithium-battery chemistries that are used for different applications (LCO, LMO, NMC, LFP, LTO, LNA).
For now, it's sufficient to know that most cell phones (and Cameras) use the LCO chemistry (LiCoO2); because it offers the highest Wh/kg or specific-energy
(some call it gravimetric energy density).
C-rating = ratio of charging or discharging current from a cell or pack compared to its Ah rating. For example: a 6Ah cell means it can discharge 6-amps for 1-hr. So, 1C
means it is discharging at 6A; or 2C means it's discharging at 12A, etc. Typical charging C-rating of 0.5C means it is being charged at 3A. Quad batteries are formulated
differently, in order to provide the higher C-rating capability without catastrophic degradation. All Li-ion chemistries are capable of high (regulated) C-rate discharge, and
all will (when unregulated) experience accelerated degradation with fire and explosions in extreme cases (except LTO, my favorite Li-ion chemistry for experimenting with),
also LFP heats up less than LCO, LMO, NMC and LNA from it phosphate component. Internal chemical heating from overly high discharge rates is why bats "puff up" or explode.
Syma batteries may only have about 800 mAh BUT they're rated around 25C.
The Canon's battery may be 1100 mAh BUT I'm betting it not rated anywhere near 25C.
I'm not saying that the battery (and therefore the quad too) will burst into flames or anything, BUT IT COULD !!