Best rechargeable batteries for electric motors

There are various types of batteries. The NiCad pack is the basic battery. It has great current output, but is heavy for the amount of energy it can store. Nicad packs are probably the cheapest.

Next up is the Nimh battery pack. It has slightly less current output, and doesn't last for as many charges as the Nicad pack, but it is more environmentally friendly, and stores more energy given the same mass.

Li Ion batteries are expensive, but they store alot more energy for the weight than either nicad or nimh packs. They must be charged using a special charger. Their current output is lower than the nimh battery. There are special governor cards that should be used with them to prevent them from sourcing too much current, and catching on fire!

The li poly pack is the newest thing. It has high energy density, plus high current output. Sadly (there is always a catch) they are insanely expensive. They also require a specialized charger.

You can build your own packs.

has a great deal on some 1700mAH AA sized nimh batteries right now. They are $1 each. I bought 20, and built three packs. You need the connector, but radio shack has them, or you can also get them online. These cells must be soldered together.

| Francois Begin wrote: | > Do you guys have some suggestions for long lasting rechargeable batteries | > for electric motors?

That question is far too vague to properly answer. What sort of motors? What are they being used for? How big of a factor is cost?

| Li Ion batteries are expensive, but they store alot more energy for the | weight than either nicad or nimh packs.

A lot = around twice as much here. It depends on exactly which batteries you're talking about.

| They must be charged using a special charger.

Well, a charger for charging LiIon/LiPo batteries, much like NiCd/NiMH or Lead-Acid batteries need a charger that can charge them. I'm not sure the word `special' applies anymore. `Appropriate' seems more appropriate.

| The li poly pack is the newest thing. It has high energy density, plus | high current output. Sadly (there is always a catch) they are insanely | expensive. They also require a specialized charger.

They aren't _insanely_ expensive. Perhaps 50% to 100% more expensive as some good NiCd or NiMH cells for the same application.

They're also more sensitive to abuse, and can cause fires under the wrong conditions. (Of course, to be fair, other batteries can cause fires as well.)

| You can build your own packs.

has a great | deal on some 1700mAH AA sized nimh batteries right now. They are $1 | each. I bought 20, and built three packs. You need the connector, | but radio shack has them, or you can also get them online. These | cells must be soldered together.

Our local Frys has 2000-2400 mAh NiMH AA cells for $1/each (really, a

10 pack for $10 or 4 pack for $4) on sale quite often. Or you can get 900 mAh NiCd AA cells at your local Wal-Mart, Home Depot or Lowes for about $5/4 pack (in the solar powered lawn light section) and they work well too.

But not knowing anything about what he wants to use these batteries for, we can't make any specific suggestions.

The issue with li-ion batteries is that you can set them on fire or cause them to explode with an 'inappropriate' charger. A lithium fire is fairly nasty. You may not remember the apple powerbook that kept exploding due to li-ion batteries.

The upshot is you can use nearly anything to charge nicd and nimh packs, but you have to be more careful with li-ion batteries.

Damn, you are right!

LIPO. Except Kokam

NP. You sure don't like those Kokam batteries , do you ? :-)

I think they're OK for the applications where you don't demand a lot of amperage , especially the new generation of high discharge rates. I ran tests on a number of different 1st Generation Kokams and the voltage dropped thru the floor with high discharge rates , but the newer ones are much better. I have a number that I use on my lazy slo-flyers , and they do fine.

I do agree with you if they're used in very high discharge applications , but there are other brands out there worse than Kokam. But given the choice at the same price , I will choose TP over Kokam....if I can get them at the same price. Probably others as good as TP , but I've only had personal experience with a few brands.

I wonder how many manufacturers there really are ? I'm sure many brands come from the same place , but just re-badged.

BTW , I've had trouble with Kokams , Thunder Power and Apogee giving up the ghost way too soon. Only one TP , couple Kokams and Apogee. I have a Thunder Power 3s1p 2100 that I used in my pylon racers and although it still works , it now thinks it's a 1200 ma. :-(

Think I'll do a little research and try to find out just how many mfr's are out there.

Ken Day

| The issue with li-ion batteries is that you can set them on fire or | cause them to explode with an 'inappropriate' charger.

Ditto for NiCd, NiMH or Lead-acid. Or non-rechargable batteries, for that matter.

| A lithium fire is fairly nasty.

_Any_ fire that happens where you charge your batteries (your house, perhaps your car?) or in your plane is `fairly nasty'.

| You may not remember the apple powerbook that kept exploding due to | li-ion batteries.

I remember a recall. Wasn't very long ago --

`It said the computer maker has received six reports worldwide of batteries overheating due to an internal short'

1) overheating != exploding, and 2) this is not specific to Li-ion batteries.

A better example would have been the reports of cell phones catching fire (actually catching fire) that came out a year or two ago. They blamed that on cheap aftermarket packs, but I don't know how much of that was just `spin' from places like Nokia who want you to buy overpriced packs from them.

| The upshot is you can use nearly anything to charge nicd and nimh | packs,

... only if you don't mind ruining them and maybe causing a fire.

Go ahead, put your NiCd pack onto your car battery charger, or a LiPo charger set at a high rate. Bad things will happen, and they may very well involve a fire.

| but you have to be more careful with li-ion batteries.

They're more likely to catch fire if abused, that's true. But I'd still guess that far more fires have been caused by NiCd and lead-acid batteries than Li-ion batteries. | > Our local Frys has 2000-2400 mAh NiMH AA cells for $1/each (really, a | > 10 pack for $10 or 4 pack for $4) on sale quite often. Or you can get | > 900 mAh NiCd AA cells at your local Wal-Mart, Home Depot or Lowes for | > about $5/4 pack (in the solar powered lawn light section) and they | > work well too. | | Damn, you are right! | |

Of course! Though the local store often has higher capacity packs for that price as well. Not that it really matters so much beyond a certain point.

Lithium is apparently quite hard to put out once it gets started.

Wrong example. This one was the first powerbook to use the PPC chip, in the 90s, possibly around '96. And they were catching fire... and it was li-ion batteries. And there are now special interlocks required of commerical li-ion packs, due to the problems that can occur. And these packs will cut off the output if the pack gets too hot.

Well, if you douse them in gasoline, and then throw a match at them, they will also probably catch on fire. However, most people don't do that. A simple resistor is all it takes to prevent problems with nicad packs; this is NOT true of li-ion or li-poly packs.

My nicad fast charger pumps up to 4C into 600mAH packs. Sanyo suggest

1/2 C max for nicads, and 1C for nimh. This overcharge doesn't appear to cause them to burst into flames, or even heat up much. I'm far more careful with liion packs.

Ok, be cavalier. The websites I've seen that sell single cells, without the limiting circuit, make you 'sign' a waver...

Liion cells are safe if used properly. That includes limiting the current output, and charging them according to mfgr specs. That is really all I was saying; they need a real li-ion charger, and can't be charged using a fast charger.

They are only average or less in performance, will do abouit half what they claim, and are very expensive for what they are.

Irate and Polyquest and I think Tanic are all enerland cells -

and will do more or less whayt is cliamed.

Thuunderpower are alsio good, and more or less live up to marketing, but they cost a lot.

I've had no uninduced faliures on LIPOS running them at 5-8C and never flattening them. The two packs I have had that went, were both Kokams, but in this case I woldn't say it was Kokams fault. Both spent several weeks up the same tree...and flattened themselve beyond recovery, though one still works as a partially OK sort of pack - its low on power and capacity.

True, but why pay a premium for an average piece of s**te?

The old E-tech cell is good value at 7-10C rates too. Tough as anything, if not spectacular.

There is no lithium in LIPO batteries. Its an inert non flammable salt - lithium carbonate.

Like sodium is inflammable, but sodium carbonate (baking powder) is not..

There is some urban myth about lithium being formed under fualt conditions by electrlysis, but if its so, it will be in minute qwuantitoes.

the flammable bit is the organic electrolyte - the POLYMER part of the LIPO.

Its actually true. However the rather explosive nature of LIPO fires is worth understanding.

It SEEMS that the more current draw you want, the more exp[losive an electrolyte you need to use. There are some new CVhinese cells out there that have a built in thermal effect: They do great current in shiort burst, but then they get hot and essentially shut down.

'Better' cells don't - they get hotter and go up an a whoosh of smelly white smoke and considerable flame.

Actually, that section of the message you are responding to was talking about Li-ION batteries. However, I know nothing about the chemistry, I just know about the warnings on all the mfgrs sites, the special interlocks to prevent them from flaming on, and the warnings about explosions and fires resulting from improper use of cells.

Here is a link describing the problems fedex has had with them:

Here is an article outlining the requirements for charging LiION and LiPoly batteries:

Again, they are completely safe if you charge them and use them properly. However, the RC community is into charging speed, and so tends to 'fast charge' batteries with huge currents. Who wants to wait? My little hitec charger puts more than 3C into a 600mAH nicad pack, and would probably put more in if it weren't for the external current limits I use. This is ok for Nicad or nimh packs, since it only wears them out more quickly. It's a fire hazard for liion, and possibly lipoly packs, particularly homemade packs made from free cells.

| The Natural Philosopher wrote: | > Bob Monsen wrote: ... | Here is a link describing the problems fedex has had with them: | |

From your link --

In the past several years there have been incidents involving lead acid (20), NiCd and NiMH (4), lithium primary (5), lithium-ion (1), and dry cell (8) batteries.

So, from the numbers, which battery sounds the most dangerous? Which battery sounds the safest?

In case it's not clear, lithium primary = lithium batteries that cannot be recharged. These are not what we use in our planes, though your transmitter may have one to retain it's memory when the primary battery is discharged.

Granted, these figures do not mean that lead acid batteries are 20x more dangerous than li-ion cells, but only that they (it's not really clear who `they' is, however) had 20x the problems with them recently.

| Here is an article outlining the requirements for charging LiION and | LiPoly batteries: | |

We are all pretty much aware of these instructions.

Note that many of these instructions apply to other types of batteries as well. For example, looking at these instructions, only #2, #3, #6 and #7 don't apply to NiCd or NiMH cells. (For #1, the rule changes considerably, but the gist is still there -- use only the appropriate charger.)

Some of the other rules aren't quite as important for NiCd or NiMH cells, but they are still good ideas. Like #4, #5, #9, #10.

| Again, they are completely safe if you charge them and use them | properly.

That's not entirely true of any battery. Safe perhaps 99.999% of the time (pick an appropriate number of 9's) but not 100%. And I'm not counting things like crashes which can cause fires, be it with NiCd or LiPo cells.

| However, the RC community is into charging speed, and so tends | to 'fast charge' batteries with huge currents. Who wants to wait?

I'm perfectly willing to wait if that means I don't ruin my batteries.

And the RC community is really into _dis_charging speed, not charging speed.

| My little hitec charger puts more than 3C into a 600mAH nicad pack

And you let it? Bad idea. You're ruining your NiCd pack.

SubC cells tolerate higher charge rates, and that's mostly what the RC car community uses. But your AA (?) pack should never be charged at over 2C.

| and would probably put more in if it weren't for the external | current limits I use.

Lovely. You'd abuse your batteries even more if you could.

| This is ok for Nicad or nimh packs, since it only wears them out | more quickly.

Most of the time, yes. But if something goes wrong, they can catch fire or cause fires as well.

| It's a fire hazard for liion, and possibly lipoly packs, | particularly homemade packs made from free cells.

Where did this bit of wisdom about homemade packs come from?

Are you really trying to argue that nicad packs are as dangerous as liion or lipo packs? The article above is talking about both primary and secondary cells.

Here is a quote:

"M. Sudduth of FedEx related their experience in shipping batteries. Because of the recent incidents, they require shippers of lithium batteries to go through a qualification process before accepting shipments from them. They accept only shipments from the qualified list, and they are taken as Class 9 hazardous goods. Their two recent incidents involved medical primary lithium batteries and 78 Li-ion batteries intended for HEV application. Both incidents were detected before the aircraft took off. The Li-ion cell fire melted the plastic shipping container. It was taken off the aircraft when a worker smelled smoke. It appeared that the cells were not packaged properly and were touching one another. The fire started in one cell and then spread domino fashion to nearby neighbors. He did not identify the source of the cells."

The li-ion batteries were huge ones, of course, as implied by their HEV usage. The link was mainly included to point out the danger of lithium fires. The link indicates that fires in lithium batteries cannot be put out using the typical fire extinguishers that are used on aircraft.

Even people who are asking what the best rechargable battery is, like the OP?

There are recently documented cases of exploding cellphones, and spontaneous laptop combustion, which are directly attributable to mishandling lithium secondary cells. I can't remember a similar widespread problem caused by nicad or nimh batteries.

As I've continued to assert, these batteries are safe, but one must simply take more care in using and charging li-ion and li-poly batteries than nicad or nimh batteries.

Well, no, that isn't what I said. I was complaining about the hitec charger, which was included in an ARF plane. It also included 600mAH nicad pack. The charger instructions indicates it wants a 5A, 12V supply, but I only give it 2A, using my bench power supply. The charger claims to be designed to charge 600mA to 1800mA packs.

As I understand it, commercial packs which are designed for comsumer devices are required to have current limiting electronics built into them. Since packs made out of individual cells may not have this current limiting built into them, there is nothing preventing them from producing too much current, resulting in a fire. For example, if you inadvertently cause a short in your charged, homemade, unprotected liion pack, (after a crash, or by shoving the pack into a backpack with something that might short it) the current will not cut out as they heat up, and the pack could well explode, or burst into flames.

No flight packs are equipped with any current limiting at all, either home made *or* commercial.

The discharge rates do not allow of any series switching to limit current.

Short any LIPO flight pack and it will puff, pop, and possibly catch fire quite violently.

In article , Bob Monsen wrote: | | Doug McLaren wrote: | > In article , | > Bob Monsen wrote: | > | > | The Natural Philosopher wrote: | > | > Bob Monsen wrote: | > ... | > | Here is a link describing the problems fedex has had with them: | > | | > |

The link may concentrate on LiPo/LiIon cells, but the statistics given clearly show that most of their battery incidents involve _other_ sorts of batteries.

| > From your link -- | > | > In the past several years there have been incidents involving lead | > acid (20), NiCd and NiMH (4), lithium primary (5), lithium-ion (1), | > and dry cell (8) batteries. | > | > So, from the numbers, which battery sounds the most dangerous? Which | > battery sounds the safest? | | Are you really trying to argue that nicad packs are as dangerous as | liion or lipo packs? The article above is talking about both primary and | secondary cells.

Not exactly. What I was saying was clarified shortly after. You even quoted it --

| > Granted, these figures do not mean that lead acid batteries are 20x | > more dangerous than li-ion cells, but only that they (it's not really | > clear who `they' is, however) had 20x the problems with them recently.

My point has been through this entire thread that all batteries are dangerous. Battery danger is NOT confined to LiPo or Li-Ion batteries!

In fact, lead acid batteries have many of the same dangers as LiPo cells --

-- damage them, and they release acid.

-- overcharge them, and they release hydrogen gas -- explosive. Far far more people have been maimed by exploding lead acid batteries than by lipos.

-- discharge them too far, and they'll damage themselves. (Especially if you don't recharge them quickly.)

-- Make sure you use the proper charger, or you'll damage the battery and could cause a fire.

| > We are all pretty much aware of these instructions. | | Even people who are asking what the best rechargable battery is, like | the OP?

You were responding to me. Think of my `We' as the `editorial we'.

| There are recently documented cases of exploding cellphones

I'm aware of the cases. I even mentioned them in the thread. However, they weren't exploding. Just burning. (Though I guess any fire that starts in your packet is going to be called an explosion.)

| and spontaneous laptop combustion, which are directly attributable | to mishandling lithium secondary cells. I can't remember a similar | widespread problem caused by nicad or nimh batteries.

That's because when you short out a NiCd cell and start a fire, that's called a fire started by a `short circuit'.

When you short out a LiPo cell and start a fire, that fire is attributed to those `dangerous LiPo cells'.

But don't worry that NiCd and NiMH cells aren't burning up their share of R/C planes -- they are.

| As I've continued to assert, these batteries are safe, but one must | simply take more care in using and charging li-ion and li-poly batteries | than nicad or nimh batteries.

And I've been asserting that NiCd and NiMH cells are dangerous as well, and require similar care to be taken.

| > | My little hitec charger puts more than 3C into a 600mAH nicad pack

Ahh, I misunderstood what you were trying to say. It's good that you're not really putting 3C into your pack.

| > | It's a fire hazard for liion, and possibly lipoly packs, | > | particularly homemade packs made from free cells. | > | > Where did this bit of wisdom about homemade packs come from? | | As I understand it, commercial packs which are designed for comsumer | devices are required to have current limiting electronics built into | them.

As Red said, you will not find these electronics in R/C power packs. It doesn't matter if they're homemade or commercial.

You short it, you may start a fire. Same goes for NiCd and NiMH packs.

I guess an RC aircraft is not considered a consumer product. It thus makes sense to store these packs somewhere flameproof. You never know what a crash will do.

I've not used lipo packs. I've only bought surplus camcorder li-ion packs, which DO have the current cut-off, as I found when I tried to run a 400 motor off using them. Also, I noticed that battery sites sell current cutoff circuits for use with their cells. The mfgrs all seem to warn about high rates of discharge.

Yow! That'll wake you up.

No, they don't.

They cell overcharge protection sometimes, and pack balancers.

The mfgrs all seem to

As well they might.