Lipo Batteries (yes or no)

[Chris Doughty]

Originally Posted by jimmy

Surely they can make these packs in saddle formation ? so the X5 might not be out of luck.. rebalance it properly with lead (which it would probably need anyway to bring it back up to weight)

[sim]

Originally Posted by sefton

what are these cheaper Orion lipo's about? are they just lower capacity?

also what can this advantage charger to that others can't (except the obvious)!

I think the 3200 mah Orion lipos are 2s1p or 2 (3.7volt 3200 mah) cells linked in series. The old 4800 Orion platinum lipo are made up of 4 (3.7volt 2400 mah) cells linked in 2s2p (2 parallel sets of 2 cells in series, if that makes sense).
The newer 3200 one should be lighter and since the two actual cells take up less space than the four older ones inside their respective casings, the new box can afford to have those ridges on them to sit better into slotter chassis. I'm guessing that is the idea.

Also, 2s1p batteries might need to be balanced less often. Not sure about this. Any plane or heli guys know about this kind of thing? Do 2 cells in series still need balancing?

[neiloliver]

From my point of view (as the technical manager of a company that manufacturers lithium polymer cells), all batteries consisting of lithium polymer cells should have a protection circuit for both over chare and over discharge. The cells should also be inside a plastic case to protect them from physical damage. The "hobby" argument does not work for this technology.. it is far too volatile.

Lithium polymer cells (like lithium ion cells) do not like being overcharged. They contain highly active materials and a non aqueous flammable electrolytes Charging cells >4.2V can be dangerous and this is what can cause them to explode during charge. Over discharge is more of a performance issue rather than a safety one.

I think that high drain cylindrical lithium ion cells would be a better long term move rather than lithium polymer. A cell size of 26 dia and 70mm length is emerging as the new standard for high drain lithium polymer cells - these are 3.7V and 3Ah, capable of 30A drain rates - they are currently being designed into professional power tools (the market that drove the development of the high drain capable NiMH cells we are using today)

And to cap all of this.. if you modify any lithium ion or polymer battery in any way.. you CANNOT take it upon an aircraft.

I will stick with GP4300SCHR for now... although i am currently working on a design for a 24V 3Ah lithium ion battery for power tool applications... no that will have a kick!

Neil

[yin]

just for all the with the horror stories of lipo.what do most of us walk
around with in our pockets.
mobile phones,what do you think powers them.

[albertobdq]

Not me, I still used Ni-Cd on my Nokia 3210.

[neiloliver]

Your mobile phone has a single cell battery which has a protection circuit fitted. You mobile phone regulates that charging voltage and current for you when you plug the little 5V wall brick into the mains... same with your ipaq pda etc etc... what we are talking about with RC cars is a far higher energy cell, with little or no protection, being charged and discharged at high rates.

[albertobdq]

Yeah, for sure, tell Dell about lipo batteries... Really useful that you can use your laptop to light a fire... just in case you take it to the forest and forget the matches at home.

[neiloliver]

The Dell issues were not Lithium Polymer batteries, they were Lithium ion Cylindricals.. but those incidents do show how the cells can fail under worst case conditions. I am not saying that lithium polymer is a bad thing for RC.. all things fail.. and all things will fail badly given a high enough population.. from your kitchen toaster to the space shuttle... sh1t happens, but with lithium ion and lithium ion polymer, the abuse that RC cars (and their owners) increase the chance of this happening, and the outcome can be 'worse' than with NiCd and NiMH.... but lithium ion polymer is here to stay in one form or another...

N

[andys]

Just ran a Lipo in my touring car for the first time and i'm totally sold.

The battery never became hot, no even warm. I put it on to charge Immediatley after each race and everything worked fine. The car was much faster than with my best batteries and the speed and punch as still there at the end of each race. All in all i'd rather have all the convenience and benefits this technology has for the buggies outdoors next season. Anyone know when / if they will be allowed in the Offroad regionals ? personally i'd rather spend my cash on Lipo's now than NiMH cells.