Why LiPo and not LIon?

[spacephrawg]

Lith-ion batteries are what is used in cell phones, computers, most small gadgets, and a variety of other things, so why arent they used in RC? They're a little less tempermental than LiPos. For instance if you overcharge one, it won't explode.

So why LiPo and not Lion?

[Kmot]

Because they cannot deliver much current.

[willhaney]

The lithium ion batteries have a problem with internal resistance.

[nick_75au]

De-walt drill packs (A123) are the equivalent to Li-ion but with high current capability up to 60 amps and 15 minute recharge, 2300 mAH cells 3.6 volts, Ive got some non A123 cells on the way, not as good as the A123 but 15 c discharge and $4.00 US per cell as opposed to the $17 to $23 US per cell I was looking at (Aussie dollar sucks at the moment :mad: ), 40 cells adds up quickly :eek:
Check out the airplane batteries and chargers forum, HUGE amount of info there on every chemistry.
regards
Nick

[pmackenzie]

Lith-ion batteries are what is used in cell phones, computers, most small gadgets, and a variety of other things, so why arent they used in RC? They're a little less tempermental than LiPos. For instance if you overcharge one, it won't explode.

So why LiPo and not Lion?


FWIW, Lipo are a form of Lithium ion. So are A123.
Lipo = lithium ion polymer.

http://en.wikipedia.org/wiki/Lithium-polymer

A lot of the devices you mention that say Li-ion could in fact be Lipo.

Pat MacKenzie

[steamboatmodel]

They have to have somewhere to put the fat when they do Lipo suction!

[pkboo]

They have to have somewhere to put the fat when they do Lipo suction!
Ahhhh...... finally a good explanation they're so expensive :p Boo

[Shaun Hendricks]

Lion cells are in use everywhere but don't mistake them for not having similar issues as LiPo. They are more adept at taking over charges and a bit more armored (read heavier) than LiPo, but those relatively small chemistry differences result in not holding a charge as well as LiPo and a bit easier to charge. Some have successfully charged them on NiMh chargers as their characteristics for charging are similar on the lower end of the charge scale, but if you pump too much juice into one too fast, you get "Boom" just like LiPo. You can even do it to NiMh and NiCd but that generally gets destructive levels of heat and no "Boom", more like meltdown.

Some of the Laptop battery packs that are 'exploding' are Lion cells which are very popular in Laptops. You'll also find them in portable DVD's and such. More forgiving than LiPo but still dangerous. They could easily be used in Boats, but boats tend to be either weight insensitive (needing more ballast) or very weigh sensitve (go fast). So you are realistically stuck with Pb or LiPo. NiMh or NiCd is really only used for inexpensive battery packs over Pb or LiPo chemistry. There isn't really a good reason to use Lion when they are usually more expensive than NiMh or NiCd.

[w2jinwu]

Well, I was able to to use laptop li-ion batteries for my Pro Boat PT-109. I found li-ion is much better than Nimh/Nicd battery in my setup. I had convert the PT-109 stock motor to BL motor. I got more than one hour run time with decent speed.

[Shaun Hendricks]

Check out this possible change in Lithium Battery technology:

http://www.foxnews.com/story/0,2933,508988,00.html

Now, if you imagine that you can charge a battery in seconds, the reverse should be true as well and discharge it in seconds. Talk about amp delivery. However, the article doesn't address safety and it might be that these kinds of cells would be small bombs in a model... <poof!> :eek:

[mfr02]

The only problem should be controlling the re-charge, an opportunity for the charger manufacturers to stay in business another season. Presumably they will need the same kind of protection against over discharging as the present generation.
Any installation that can use the present ones effectively should be able to use these without any problems - if you decide to use the potential extra performance by fitting a more powerful and therefore more current-hungry motor then obviously the wiring and controller will need beefing up.
Lithiums are normally only dangerous when mechanically abused - the same can be said of any other type of battery, its just that when lithium goes off, it is much more spectacular, incinerating its surroundings rather than dissolving them.

[spacephrawg]

Well, I was able to to use laptop li-ion batteries for my Pro Boat PT-109. I found li-ion is much better than Nimh/Nicd battery in my setup. I had convert the PT-109 stock motor to BL motor. I got more than one hour run time with decent speed.


What is a BL motor? Also did the boat run faster, slower, higher or lower in the water, etc.?

[Rex R]

BL = BrushLess motor, can deliver large amounts of power, also are great for draining batteries in no-time :).

[w2jinwu]

There are currently several of Lithium battery available. I found a good website about them:
http://libattery.ustc.edu.cn/english/introduction%203.htm

The "lithium cobalt oxide" cells are commonly used in laptop and cellphone, which is very high power density, but low discharge current. A typical 18650 cell has 1.5Ah~2.4Ah. But it's only 1C discharge rate.

The "lithium manganese oxide" cells are used in power tools. The chemical that being used in varieties of power tools could be a little be different. A typical 18650 cell has about 1~1.5Ah with discharge rate less 10C and charge rate at 2C (30 minutes). I had tried the cells from Bosch battery pack. It's very powerful, it didn't even get warm after a 20-minute run.
http://forum.drc.su/cordless-power-tool-battery-capacity-rating-vt4184.html

The A123 is "lithium-ion" type cells. It has about 1~1.5AH, and can be discharge at 20C. The unique thing about it is that it can charge at 10C rate (can be charged up in 10 minute)! But I think it's way overprice.

Lipo is the best, very high power density, highest discharge rate, lightest weight. But if I want a 50000mH battery :D , it's over my budget .

[pmackenzie]

The A123 is "lithium-ion" type cells. It has about 1~1.5AH, and can be discharge at 20C. The unique thing about it is that it can charge at 10C rate (can be charged up in 10 minute)! But I think it's way overprice.


The two A123 cells available are 1100 mahr and 2300 mahr. They are rated for 30C discharge.
As far as being overpriced, if you calculate based on number of cycles the lifetime costs look much better for A123.
If you calculate based on flights per day and the number of packs you need to get they look better again. 2 packs will let you fly (or float :D ) almost non stop (or until your charging battery dies :) )

Pat MacKenzie

[spacephrawg]

BL = BrushLess motor, can deliver large amounts of power, also are great for draining batteries in no-time :).

I thought brushless motors were suposed to be more energy efficient. I inquired at my LHS and the guy told me they have higher power output and are more effecient.

[Rex R]

they have lower resistance, and when doing the same work as the equivelent brushed motors produce less heat/amp draw...unfortunatly a lot of folks seem to think of them as 'supermotors' and do not put the same load on them (usually a lot more). thats where most of the problems start. low resistance = efficient draining of batt.s(high amp draw) w/ heat being generated in the cells & esc. they can work well in 'normal' boats, one just needs to determine what 'size'/speed motor to use. a boat that would ordinally run a 27t(500 size) brushed motor, will run quite well with a 500 sized bl motor(rated at 3500kv)...and if you ran the same prop for both motors the bl motor will run cooler with less amp draw(though the boat will likely run faster :)). the key words here are; "the same size/type prop", not an oversize prop!

[spacephrawg]

they have lower resistance, and when doing the same work as the equivelent brushed motors produce less heat/amp draw...unfortunatly a lot of folks seem to think of them as 'supermotors' and do not put the same load on them (usually a lot more). thats where most of the problems start. low resistance = efficient draining of batt.s(high amp draw) w/ heat being generated in the cells & esc. they can work well in 'normal' boats, one just needs to determine what 'size'/speed motor to use. a boat that would ordinally run a 27t(500 size) brushed motor, will run quite well with a 500 sized bl motor(rated at 3500kv)...and if you ran the same prop for both motors the bl motor will run cooler with less amp draw(though the boat will likely run faster :)). the key words here are; "the same size/type prop", not an oversize prop!

Forgive me if the above explains my next question: so I have some normal props in my boat and some traxxas stinger motors (500 size?) and normal props. I run them on a pair of 4200mah nicads. if i converted to BL, would i get longer run time?

[Rex R]

hmmm, lets see stinger motors...iirc are 20t and probably something close to 4400kv. if you used 3500kv motors(36-50)...offhand I'd guess it would be a tossup, how hard/hot have you been running them? hadn't heard of that size ni-cd...

[spacephrawg]

assuming i was running them full blast the whole time i mean.

[Rex R]

well I was kinda trying to get an idea of the amp draw... well try something else :). lets see twin 500's usually means a boat in the 24-30" range...if it were mine I'd ditch the twin set-up. for a 24-27" boat a single 600 size bl in the 3500kv range(with 7.2v), from 27-30" either an sv motor or an extra long (74mm) can motor on 14.4v(1800-2000kv) running a 3/16" shaft and a 40mm prop. (see this is what sort of answer you get when you don't nail down just what kind of boat and performance you want :)).
rex

[spacephrawg]

the boat is 40" long, and i think the stingers are 500 speed but am not sure.

[Rex R]

if you had mentioned size before, and whether it was a twin prop(with gear box)...we might not have done all this dancing around :). if you want direct drive you'll want 2 540L's in either 8t or 7t. geared 540(shortcan) 8s or 10s. the motors are the 'cheap' part of the equation...the esc's will run high(you'll want 2 of them, 100amp)

[spacephrawg]

I c. hmm... I'm most interested in the projected runtime. the boat is direct drive, no gears.

[Rex R]

at 40" I'd guess that; the boat ran kinda slow, motors ran hot, or both :). ifn you didn't go wild with prop sizes...that one could get some decent runtimes. think I'd(this depends on shaft size) about x437, hmmm 4200's, my guess 5 minutes, could be more...lot of factors come into play. oh right, water cool everything :).

[spacephrawg]

the stock motors, which were a little better were 550's but i burnt them out by accident. The boat got more than 10min run time. the motors are now and were then water cooled. The boat ran relatively fast actually.

[spacephrawg]

Sidenote: if L-ion batteries arent as good as li-po's, why does the Tesla Roadster run on all L-ion's?

[spacephrawg]

The props i'm using are 35mm i believe. Three bladed.

[w2jinwu]

well I was kinda trying to get an idea of the amp draw... well try something else :). lets see twin 500's usually means a boat in the 24-30" range...if it were mine I'd ditch the twin set-up. for a 24-27" boat a single 600 size bl in the 3500kv range(with 7.2v), from 27-30" either an sv motor or an extra long (74mm) can motor on 14.4v(1800-2000kv) running a 3/16" shaft and a 40mm prop. (see this is what sort of answer you get when you don't nail down just what kind of boat and performance you want :)).
rex
FYI: I have a 40" boat. I replaced the twin 500 motors with 1800kv BL motors (56mm). 40mm prop, 1.4x pitch. The system draw about 25Amp (two motors) when supplied 7.4v battery. Since I had used the same battery package & prop for both motor, I can do a apple-to-apple comparison:
With 500 stock motor: draw about 30Amp, motors were very hot after one hour run (even with water-cooled), motors generated more noise. I guess the speed would be 12mph.
With BL motor: draw little bit less amp. motors (water-cooled) were just little bit warm after one hour run. motors are quite. Speed is much faster, I guess it's about 18mph.
I think if you go for the performance, above setup should be reasonable. But on 3500kv with 7.2v system, it would draw lot of amps.

[dcwebaccount]

power and weight, it is the most important factor, i tried a123 on my boat last week, the result was disappointed.
i used to use 3s1p 1500mah 20c (12.6v) lipo to compared a123 4s (14.4v)

[spacephrawg]

FYI: I have a 40" boat. I replaced the twin 500 motors with 1800kv BL motors (56mm). 40mm prop, 1.4x pitch. The system draw about 25Amp (two motors) when supplied 7.4v battery. Since I had used the same battery package & prop for both motor, I can do a apple-to-apple comparison:
With 500 stock motor: draw about 30Amp, motors were very hot after one hour run (even with water-cooled), motors generated more noise. I guess the speed would be 12mph.
With BL motor: draw little bit less amp. motors (water-cooled) were just little bit warm after one hour run. motors are quite. Speed is much faster, I guess it's about 18mph.
I think if you go for the performance, above setup should be reasonable. But on 3500kv with 7.2v system, it would draw lot of amps.

I"m more interested in run time than speed. What was the run time like?