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Thread: What is the difference between LiPO NiCd and NiMH batteries

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Old 08-07-2011, 05:07 PM   #1
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Default What is the difference between LiPO NiCd and NiMH batteries

Okay long story short the Hobbytown near where I live sold me a a few things that I should have not bought. I know or knew nothing about RC's and I guess I should have done more home work. Not blaming them or mad they just did not know much about the RC crawlers.

They sold me a 4-7 cell Onyx NiCd and NiMH battery charger and a Onyx battery. The battery was way to big and I could not fit it anywhere, so I just bought a couple of LiPO batteries not really thinking that my charger won't charge them. So now I need a new charger and I just am thinking maybe I need a better understanding of all this battery stuff.


What is the difference between them all? Even a good link or something to read about would be great.

And what is the different cell counts?

Sorry for another noob battery question.
TIA
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Old 08-07-2011, 09:30 PM   #2
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As a new guy to this battery stuff too I can say that i feel for you. That is something i probably would have done too. I cant really offer you any help but there are a ton of posts on here that go through all that. Good luck and i will be watching your thread to see what they say.

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Old 08-07-2011, 09:38 PM   #3
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contact the guys over at Holmes Hobbies, they're 100% experts on the matter.
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Old 08-07-2011, 09:46 PM   #4
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I am no expert on this, but please tell us what kind of rc rig you have and what kind of speed controller. Some ESC (electronic speed controllers) can use NiMh/Nicd packs OR Lipo's, and some can't. I used to run a 6-cell NiMh pack, and liked it, but switched to Lipo. New battery is much smaller/lighter, and lasts just as long. But it also requires more care (possible explosive fire-hazzard) and a different charger. So what are you driving, and someone will tell you what's best for your needs.
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Old 08-07-2011, 10:35 PM   #5
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http://www.rchelicopterfun.com/rc-lipo-batteries.html
http://www.rccartips.com/rc-car-batteries.htm
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Old 08-07-2011, 11:13 PM   #6
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NiCD: And old technology that is not used very often today. They have a 'memory', so if you only use don't discharge the battery 100%, the next time you charge it, you will less capacity and that will keep on happening till there is nothing left.

NiMh: Still used today, and it for people who don't want to go the LiPo route or often recommended for beginners. Chargers and batteries are quite cheap, and are generally considered safer so long as you use a good charger. These are generally sold at 6 cell packs, which puts out 7.2v.

LiPo: The bees knees at the moment. They are lighter, have a higher voltage for the weight, and can give the motor more amps. Precautions do need to be taken when charging because if they are charged incorrectly, they can catch on fire. So long as you are careful and use an appropriate charger with the right settings (such as charging a 3 cell as a 3 cell, not a 4 cell) and have a voltage cut-off on your ESC you will be fine. If the voltage gets down to under 3 volts per cell, then you damage the batteries which is why you need the voltage cut-off set up on your ESC (most have this built in), which turns your cut power when it detects around 3 volts per cell.

That was a VERY basic explanation, and you will need to do more research with the links provided above but I hope that helped.
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Old 08-10-2011, 08:22 PM   #7
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Ok here is how I learned. There is a lot of info out there on this subject but I will give you what I know.
A lipo batteries voltage does not drop off like the others do. Look at it as a graph. A lipo graph is straight across the scale until it get to the mh value. Then it drops off quickly to 3.4v per cell. You dont want it to get below that because it will damage the battery. Ok the Nicad batteries start losing voltage as soon as you pull the trigger. That is why people use the lipo batteries for racing because they never drop in voltage until they get to that mh value. Ok if you look at a lipo. EX: 5000mh,2s,35c discharge.
What all that means is the 5000mh is like a gas tank. That is the capacity of the battery. The 2s is the amount of cell there is. 2s=7.4 volts, 3s=11.1 volts,4s=14.4 volts. Ok now to the 35c is discharge rate. The higher the C the more of the Volts you acually get when you pull the trigger, it also known as burst . The higher the C the more $ the battery. For crawling you need to look at a high mh,2s lower C discharge. Now for racing you would want a High mh,high voltage (which ever your ESC can hold most of the will only hold a 2s battery) and a High C rating. Hope this helps.

Last edited by mudjunkie05; 08-10-2011 at 08:28 PM.
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Old 08-10-2011, 09:28 PM   #8
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Quote:
Originally Posted by mudjunkie05 View Post
Ok here is how I learned. There is a lot of info out there on this subject but I will give you what I know.
A lipo batteries voltage does not drop off like the others do. Look at it as a graph. A lipo graph is straight across the scale until it get to the mh value. Then it drops off quickly to 3.4v per cell. You dont want it to get below that because it will damage the battery. Ok the Nicad batteries start losing voltage as soon as you pull the trigger. That is why people use the lipo batteries for racing because they never drop in voltage until they get to that mh value. Ok if you look at a lipo. EX: 5000mh,2s,35c discharge.
What all that means is the 5000mh is like a gas tank. That is the capacity of the battery. The 2s is the amount of cell there is. 2s=7.4 volts, 3s=11.1 volts,4s=14.4 volts. Ok now to the 35c is discharge rate. The higher the C the more of the Volts you acually get when you pull the trigger, it also known as burst . The higher the C the more $ the battery. For crawling you need to look at a high mh,2s lower C discharge. Now for racing you would want a High mh,high voltage (which ever your ESC can hold most of the will only hold a 2s battery) and a High C rating. Hope this helps.
This, my friend, is one heck of an explanation. I think i understand this whole concept a lot better now than i ever have. Thank you for that.

Otis
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Old 08-11-2011, 10:44 AM   #9
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For Crawling you don't need a high mAh (mH in the aboved post) its milliAmpHour. For crawling 850 to 2000 is a good ballpark, I have 1300mAh and get lots of wheel time...also want to get a high discharge rate...I went with a low (cheap in price) discharge rate and puffed every one I had...with lipos, don't go cheap..go with a good known lipo..Holmes Hobbies, Killer Krawlers, MaxAmps...and such.
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Old 08-11-2011, 08:38 PM   #10
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Wow awesome thank you everyone I really appreciate all the replies. This helps me a lot.

I have a much better understanding in with these batteries now.


I was running a 7.2V Onyx 5000mAh in my XR10 with a Novak M2 dig. I just grabbed a couple 11.1v 1300 mah batteries and there a ton smaller and pack a better punch for sure. The Onyx battery lasted a solid 2-3 hours but it was huge and very heavy.


Thanks again everyone for the info.
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Old 08-11-2011, 08:49 PM   #11
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Well on the MH the high this is the more time you have to run. JMO
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Old 08-14-2011, 09:46 AM   #12
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Quote:
Originally Posted by squatch71 View Post
For Crawling you don't need a high mAh (mH in the aboved post) its milliAmpHour. For crawling 850 to 2000 is a good ballpark, I have 1300mAh and get lots of wheel time...also want to get a high discharge rate...I went with a low (cheap in price) discharge rate and puffed every one I had...with lipos, don't go cheap..go with a good known lipo..Holmes Hobbies, Killer Krawlers, MaxAmps...and such.
I would skip MaxAmps, add CheapBatteryPacks.com
Yes, get a MINIMUM 35C rated battery, this value has an effect on "punch" when you peg the throttle.
While you can run a 20C or lower, you WILL run into issues at some point.
Make sure you have a charger that does LiPO as well as a balance port.
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Old 08-14-2011, 12:37 PM   #13
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Some of the info above regarding NiCd and NiMh batteries is totally and completely incorrect. Basically it's interweb misinformation perpetuated by people who don't know what they are talking about. I could explain, but it would be a big waste of time.

Just go Lipo. Far superior in every way. Just don't over charge them, or over discharge them.
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Old 08-14-2011, 01:18 PM   #14
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Like you, I was SWIMMING in info a week ago about all this stuff...and do yourself a favor, stay away from Hobbytown, I made my LAST visit there last week here in MN.

Anyway, I went with a Thunder AC6 charger...great charger and inexpensive. It will charge both NiMH and LiPo. Got mine here:
http://www.hobbypartz.com/thac6smbachw.html

For batteries, I got a pair of 3300 LiPo 40c's here (I also scored a $6 LiPo bag to charge and store the batteries in):
http://www.hobbypartz.com/77p-sl3000-2s1p-40c-2222.html

I am new to this, too, but the reviews on that charger are great and there are some good vids on YouTube on how to run it. And so far, the batteries are great.

And, if you order at Hobby Partz, the shipping will be free, too, I think.
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Old 08-14-2011, 01:28 PM   #15
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Quote:
Originally Posted by Manning View Post
Some of the info above regarding NiCd and NiMh batteries is totally and completely incorrect. Basically it's interweb misinformation perpetuated by people who don't know what they are talking about. I could explain, but it would be a big waste of time.

Just go Lipo. Far superior in every way. Just don't over charge them, or over discharge them.
I agree with going LiPO.

Other than that, I may have missed what you consider incorrect.

I started back when the yellow SC's were around, then moved up from there.
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Old 08-15-2011, 09:56 PM   #16
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Quote:
Originally Posted by Manning View Post
Some of the info above regarding NiCd and NiMh batteries is totally and completely incorrect. Basically it's interweb misinformation perpetuated by people who don't know what they are talking about. I could explain, but it would be a big waste of time.

Just go Lipo. Far superior in every way. Just don't over charge them, or over discharge them.
Yep..just like Charlie..go Lipo.

as for the rest, please explain. My first pack were sanyo matched cells back in 1987. The cost...right around 70 bucks. What info have you seen in this thread concerning the other batteries incorrect.


and to add..Charlie-III is spot on. I checked my lipos and they are all 35C discharge rate...would never go below this again. Two 25C cost me 25 bucks...they are both gone now, and replaced by one 35C that ran me 20...way better deal.


and I said.......and such....... I like cheapbatterypacks.com, for nimh, not to keen on the lipos....jmho.
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Old 08-16-2011, 05:09 PM   #17
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OK. And just for giggles, I was racing back in the day when Sanyo 1200 SCR's first came out. Also worked at a military/aerospace battery manufacturing facility as an engineer for 8 years.

Memory effect in NiCd cells. It is the repeated charging and discharging EXACTLY THE SAME WAY (charge rate in amps, dishcarge rate in amps, charge time and discharge time) for many, many cycles. This happens in automated industrial applications, such as a power backup application for a machine. And the cutoff point is well prior to the maximum capacity of the battery. When the battery is discharged past the point it was dischaged for the many cycles, there is a measurable dip in the voltage. The battery has a "memory" as to where it was discharged to over the many cycles. The act of discharging past the previous end point wipes out the "memory". Capacity is not lost to this phenomenon as stated above. That being said, in the RC or consumer electronics world, one could never charge/discharge exactly the same way for enough cycles for this to happen. This is described in detail in one of the GE battery manuals.

Not sure what marketing genius caught on to this and perpetuated the "memory effect" myth when NiMh first came out, but it sure has sold lots of NiMh batteries. What people are claiming to be memory effect is simply that the batteries are getting old and losing capacity, or that the battery is a cheap POS and wasn't very good to start with.

Then the generality of Nickel batteries having a sloped discharge curve is simply not true of all Nickel batteries. Cheap POS's, sure, but not all. The latest generation of high discharge NiMh have a very flat discharge curve. Intellect 3800 and 4200's were amazing in this regard, they would hold 1.25ish volts per cell under a very high current load from start to finish. Lipo's have just as sloped a discharge curve as anything else, especially cheap low C rated ones. They start out at 4.2 volts, then quickly drop to 3.7ish under load then go down from there.

See, it was a waste of time to write and to read, don't worry about old school Nickel batteries. Just go lipo.

Other words of wisdom......Batteries wear out just like anything else, and will go bad just sitting there doing nothing, so don't buy used batteries ever, and don't buy the cheapest, and don't buy any that have been sitting on a shelf for a long time, even if unused.
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Old 08-17-2011, 12:18 PM   #18
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The memory effect was always blown out of proportion....it basically became the term used for a pack that was losing capacity.

By RC standards..........NiCAD, NiMh and LiPo all have the rc worlds term of memory effect....but in reality, its just packs losing capacity as they are used and abused.

The last of the IB cells to come out were nutty on voltage....we actually had cells spec out on the matchers at 1.3 at 35 amps over the standard curve to .90 a cell....big problem was though, they were a very unstable cell, so we had lots of failures with them.

Like you were told though, just go lipo....buy a nice charger and call it a day. It won't be long before you won't even be able to find a Nicad or Nimh pack for an rc car.

Later EddieO

Quote:
Originally Posted by Manning View Post
OK. And just for giggles, I was racing back in the day when Sanyo 1200 SCR's first came out. Also worked at a military/aerospace battery manufacturing facility as an engineer for 8 years.

Memory effect in NiCd cells. It is the repeated charging and discharging EXACTLY THE SAME WAY (charge rate in amps, dishcarge rate in amps, charge time and discharge time) for many, many cycles. This happens in automated industrial applications, such as a power backup application for a machine. And the cutoff point is well prior to the maximum capacity of the battery. When the battery is discharged past the point it was dischaged for the many cycles, there is a measurable dip in the voltage. The battery has a "memory" as to where it was discharged to over the many cycles. The act of discharging past the previous end point wipes out the "memory". Capacity is not lost to this phenomenon as stated above. That being said, in the RC or consumer electronics world, one could never charge/discharge exactly the same way for enough cycles for this to happen. This is described in detail in one of the GE battery manuals.

Not sure what marketing genius caught on to this and perpetuated the "memory effect" myth when NiMh first came out, but it sure has sold lots of NiMh batteries. What people are claiming to be memory effect is simply that the batteries are getting old and losing capacity, or that the battery is a cheap POS and wasn't very good to start with.

Then the generality of Nickel batteries having a sloped discharge curve is simply not true of all Nickel batteries. Cheap POS's, sure, but not all. The latest generation of high discharge NiMh have a very flat discharge curve. Intellect 3800 and 4200's were amazing in this regard, they would hold 1.25ish volts per cell under a very high current load from start to finish. Lipo's have just as sloped a discharge curve as anything else, especially cheap low C rated ones. They start out at 4.2 volts, then quickly drop to 3.7ish under load then go down from there.

See, it was a waste of time to write and to read, don't worry about old school Nickel batteries. Just go lipo.

Other words of wisdom......Batteries wear out just like anything else, and will go bad just sitting there doing nothing, so don't buy used batteries ever, and don't buy the cheapest, and don't buy any that have been sitting on a shelf for a long time, even if unused.
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