4 ms·

NiCd is actually more capable than NiMh, but suffers from memory issues (capacity decreases significantly if not carefully discharged and recharged; ie you cann

NiCd is actually more capable than NiMh, but suffers from memory issues (capacity decreases significantly if not carefully discharged and recharged; ie you cannot “top them off” without sacrificing capacity. Again, speaking from my lived experience, NiCd pushed to the limit resulted in many gnarly fires in high performance RC use, NiMh was never a contender given low output (again low discharge rates). LiPo is king here, both in terms of output and weight/power, but overcharging or excessive discharging results in thermal runaway. Lithium ion is far safer, but less effective.

xoa 6y ago
As a non-performance (including weight) practical matter as well, cadmium is just plain a rather toxic heavy metal. IIRC the EU has outright banned NiCd batteries entirely with a few very minimal legacy exceptions (medical devices I think?). Even though in principle part of the price is supposed to cover proper disposal EOL, people being people plenty got tossed and it's nasty stuff to have in a landfill even let alone elsewhere. There isn't any real treatment for it either as far as I know, normal heavy metal treatments like chelation therapy don't really work with Cd. So I think yet another benefit of lithium is also that it's relatively easier to deal with over its whole life cycle. Elemental lithium is of course quite reactive, don't want to be directly exposed to it, but it doesn't stay that way in nature. That it's extremely abundant and distributed doesn't hurt either. While for economic reasons it makes sense to get it initial from naturally highly concentrated sources, and to recycle lithium packs, it'd be perfectly viable to pull it right out of the ocean with solar power if there was ever a need.
Hnrobert42 6y ago
What about lithium and memory? Do lithium batteries have big memory issues, or is all the stuff rattling around in my head about batteries having memories mostly because I grew up when NiCd and NiMh were all the rage?
- Robotbeat 6y ago
  Lithium doesn’t have any memory effect.
- usrusr 6y ago
  If you grew up with both you must remember how NiMH was initially championed as "no memory effect". It was still there, but so weak compared to NiCd that the claim wasn't really disputed. Lithium are at least another step of that size better than that, if they have memory effect at all. If they do have a tiny little memory effect left it's probably smaller than the extra cell aging one deep cycle would cause compared to to two smaller cycles of the same total capacity, as least as long as the smaller cycles are taking place somewhat close to nominal voltage. That would at least make memory effect irrelevant for all practical purposes.
ksrm 6y ago
LiPo is a type of Li-ion battery and they have much the same safety characteristics. Lithium iron phosphate (LiFePO4) batteries are much safer, they don't tend to run away.

xoa 6y ago

As a non-performance (including weight) practical matter as well, cadmium is just plain a rather toxic heavy metal. IIRC the EU has outright banned NiCd batteries entirely with a few very minimal legacy exceptions (medical devices I think?). Even though in principle part of the price is supposed to cover proper disposal EOL, people being people plenty got tossed and it's nasty stuff to have in a landfill even let alone elsewhere. There isn't any real treatment for it either as far as I know, normal heavy metal treatments like chelation therapy don't really work with Cd. So I think yet another benefit of lithium is also that it's relatively easier to deal with over its whole life cycle. Elemental lithium is of course quite reactive, don't want to be directly exposed to it, but it doesn't stay that way in nature. That it's extremely abundant and distributed doesn't hurt either. While for economic reasons it makes sense to get it initial from naturally highly concentrated sources, and to recycle lithium packs, it'd be perfectly viable to pull it right out of the ocean with solar power if there was ever a need.

Hnrobert42 6y ago

What about lithium and memory? Do lithium batteries have big memory issues, or is all the stuff rattling around in my head about batteries having memories mostly because I grew up when NiCd and NiMh were all the rage?

Robotbeat 6y ago
Lithium doesn’t have any memory effect.
usrusr 6y ago
If you grew up with both you must remember how NiMH was initially championed as "no memory effect". It was still there, but so weak compared to NiCd that the claim wasn't really disputed. Lithium are at least another step of that size better than that, if they have memory effect at all. If they do have a tiny little memory effect left it's probably smaller than the extra cell aging one deep cycle would cause compared to to two smaller cycles of the same total capacity, as least as long as the smaller cycles are taking place somewhat close to nominal voltage. That would at least make memory effect irrelevant for all practical purposes.

ksrm 6y ago

LiPo is a type of Li-ion battery and they have much the same safety characteristics. Lithium iron phosphate (LiFePO4) batteries are much safer, they don't tend to run away.