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Old 06-25-2011, 11:26 AM   #1
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Default To LiPo or not to LiPo

So I'm down to one good 1500 NiMH pack and a faltering 2000 NiCad pack. So new batteries are in my future but I'm torn on what to do.
I have a stock SCX-10 that has AE-2 ESC. So I've got LiPo cut-off but not adjustable (as far as I know).
Should I be able to run a LiPo battery with no other changes? I would stick with a 2S so the voltage should be close enough not to hurt the LEDs. I know I will need a new charger also. I am not planning on any comps or anything so it's pretty much just for fun. It looks like as far as batteries go there are some pretty decent prices on LiPo out there so the cost really isn't that much different other than adding in a new charger.
Do LiPos need any more water proofing than any other battery?
How dangerous are they really, I spent some time on youtube and that about totally ruined them for me. But is that really when you abuse them or just do it on purpose? How much do you have to babysit them when they are charging?
Sorry for noob questions but I have been out of RCs for a long time, long enough that I still have the NiCad pack.
Thanks for any advice.
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Old 06-25-2011, 11:46 AM   #2
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You probably have to reset your esc for the lipo cut-off, should be able to find that in the manual or online. I run 5000mah 2s lipos in my class 2 rig, so much runtime you will get bored. Pick up a good balance charger, I use a Racer's Edge 2000, this charger has since been replaced by the 2010 model. As for waterproofing lipos, the cells are already sealed, your only concern is the balance tab and power connector. You can use di-electric grease on those.

Do not be afraid of lipos. The best advice I can give you is to be sure to unplug the battery when not in use.

Hope this helps in your decision to update your batteries....
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Old 06-25-2011, 03:23 PM   #3
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Lipo's rarely (and I mean rarely) fail on their own. 99% of the time its operator error.

As long as you don't...

Hit it with something
Overcharge it
Undercharge it
Fail to balance it
Over amp it
Put it in the oven or microwave
Chew on it

...you'll be fine. Get a decent balancing charger, don't drain them down to nothing, and don't ask for more than they are capable of powerwise and they'll live a happy life.

Last edited by Duuuuuuuude; 06-25-2011 at 03:27 PM.
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Old 06-25-2011, 05:43 PM   #4
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How do you know if it's over or under charged? Do you have to check the voltage periodically while charging or will a LiPo charger let you know when you are there. I've got an old school 2 or 4 amp peak charger that you just plug it in when the pack is full it's done.
Is it smarter to run the hard case batteries? I like the other ones since they are smaller and lighter.
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Old 06-25-2011, 05:53 PM   #5
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A good LiPo charger will let you program it and will stop charging when each cell reaches 4.2v. Your stock AE-2 (assuming you haven't turned off the LiPo cutoff) will stop the motor from working when total voltage drops below 6v (3v per cell).
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Old 06-25-2011, 05:56 PM   #6
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Hard cases are for racing on ROAR tracks or when you are beating the ever lovin' crap out of them and risk a puncture. Just mount the soft shell lipos where they won't get hit by anything and they're fine.

A good lipo charger will not overcharge them. There are specific voltages that must not be exceeded, and charger manufacturers work within those specs for safety reasons. That is also the reason that they need to be balanced. A 2 cell pack holds 8.4 volts, or 4.2v per cell. Without using a balancer you run the risk of overcharging one cell and undercharging the other, which makes for a short lifespan.

Typically if you overdrain a lipo the charger will not charge it because it thinks there is something wrong. As long as you have an esc that has a lipo cutoff (or one that doesn't but you use an external cutoff or alarm) they should not get down that low. Its also pretty easy to tell when they are getting to their shut off point, as you will notice a drastic reduction in power. Lipos run at a nearly constant voltage until their capacity is drained, which is opposite of nickle batteries that slowly lose voltage and punch until they go flat. Really all you have to do is pay attention.

It is also important not to overamp a battery, meaning don't throw a load at it that it can't handle. If you take a little 1000mah crawler battery and stick it in your Slash, you just wrote its death sentence. It'll overamp, overheat, puff up, and might even let some smoke or fire out.

Last edited by Duuuuuuuude; 06-25-2011 at 06:03 PM.
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Old 06-25-2011, 05:56 PM   #7
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A lipo charger will keep it from going over 4.2v per cell and your esc with the lipo cutoff on, will keep it from going under the set voltage. I have seen a few lipo go bad, but every time it was from misuse. One was during charging the guy was not balancing the pack and it over charged one of the cells. Another was from leaving the pack connected to the esc and forgetting about it.

You can pick up Hobby King or Turnigy pack cheap that will be good enough for crawling.

I used a 2 year old SMC 5200 pack today and ran for over an hour straight and only used 3000 Mah. I did not even need my other pack.
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Old 06-25-2011, 09:49 PM   #8
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Okay one last noob question... for now. Lets say you have a full charged lipo and go run for 30 minutes and that drains half the charge and you stop for the day. Can you just unplug and continue another day or do you need to discharge and recharge? Is there any memory like the old NiCad?
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Old 06-25-2011, 10:20 PM   #9
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Quote:
Originally Posted by Big Daddy View Post
Okay one last noob question... for now. Lets say you have a full charged lipo and go run for 30 minutes and that drains half the charge and you stop for the day. Can you just unplug and continue another day or do you need to discharge and recharge? Is there any memory like the old NiCad?
There is no memory, in fact, you should store them at approximately half charge.

If you want to plug it back in later and go, you can. Won't hurt a thing.
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Old 06-25-2011, 10:29 PM   #10
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No need to discharge, just run them the next day, or the next month, whenever. LiPo's have no memory issues like NiCads. (I still have 5 NiCad packs, and about a dozen or so NiMh packs).

If you're going to store LiPo's for more than say, a week, they should be at 40-50% charged. Check on them periodically (ie. small battery checker that plugs into the balance plug, or check your charger, see if it'll display the cell voltages. Unplug after checking, store LiPo's completely unplugged from anything, and in a LiPo sack).

And that 2-4 amp peak charger you mentioned before, you didn't say what it was, please don't plug that into a LiPo until you find out if that charger's LiPo compatible.
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Old 06-25-2011, 11:46 PM   #11
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Being new to rc, I really learned something about lipo's. Great thread
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Old 06-26-2011, 12:07 AM   #12
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Quote:
Originally Posted by Trubble View Post
No need to discharge, just run them the next day, or the next month, whenever. LiPo's have no memory issues like NiCads. (I still have 5 NiCad packs, and about a dozen or so NiMh packs).

If you're going to store LiPo's for more than say, a week, they should be at 40-50% charged. Check on them periodically (ie. small battery checker that plugs into the balance plug, or check your charger, see if it'll display the cell voltages. Unplug after checking, store LiPo's completely unplugged from anything, and in a LiPo sack).

And that 2-4 amp peak charger you mentioned before, you didn't say what it was, please don't plug that into a LiPo until you find out if that charger's LiPo compatible.
I had no plans of trying it. It will be used for the packs that still run in the old RS4 Rally.

Thanks for all the information about the batteries, really seems like a good time to switch over.
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Old 06-26-2011, 12:44 PM   #13
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Okay one more last question, well a few actually.
Is anything over 20C a safe rating for scaling and playing? Can you get too high of rating?
Can I use like a 1300mAH 2S 25C and just expect fairly short run times? I'm thinking of getting a 1300 to cruise around the back yard course and as back up and getting a 4-5K for general trail runs.
I was thinking I would get the Passport AC/DC charger.
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Old 06-26-2011, 01:06 PM   #14
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I got a passport ultra charger works great for ne battery lipo/nimh/nicad/life. as far as the "C" rating a 20-30 c should b fine and sumone home in if im wrong but it doesn't have nether to do with runtimes the mah will determine the runtime I run a 1300mah 20c lipos in my crawler and get a little over 30 min from it I also have a 8000mah 20c I run in my slash and I get over 1.5 hrs from that. ur motor/gears will also change the runtimes
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Old 06-26-2011, 01:13 PM   #15
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Quote:
Originally Posted by Big Daddy View Post
Okay one more last question, well a few actually.
Is anything over 20C a safe rating for scaling and playing? Can you get too high of rating?
Can I use like a 1300mAH 2S 25C and just expect fairly short run times? I'm thinking of getting a 1300 to cruise around the back yard course and as back up and getting a 4-5K for general trail runs.
I was thinking I would get the Passport AC/DC charger.
with a lathe motor anything over 20C is fine. No you cant get to high of C rating the higher the rating from the same MAH pack the better(assuming the C rating is not bull shit)...

Depends on the motor but a 1300 2s really should give you the same or better run time then that nicad is.. your shedding a ton of weight, and you will carry a better voltage threw out the run.. I really dont thing you will need a 4-5K battery. A 2200MAH will give you a hour plus of run time with most normal setups...

If that ESC will handle 3S which I think I heard it would, I would bump up the voltage..

that charger is pretty limited. and does not look like it balance's the packs..

this is a really nice charger and priced pretty good.. plus free shipping and their packs are decent to..
http://www.hobbypartz.com/73p-ac680-accharger.html
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Old 06-26-2011, 01:16 PM   #16
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A 1300 mah @ 25c = 32.5 amps max, as long as you don't exceed that you will be fine. The higher the c rating generally the better, although they cost some more money. In my 1/8 buggy my motor is rated for 80 amps, I had an 5000mah 25c, I bought some 2200mah 40c thinking that I would fine since it was over the motors rating. While the batteries worked fine, It just did not have the punch off the line like the 5000 mah did. You should check out hobbypartz they have some decent prices. Why don't you get a charger that can charge them all like this.
http://www.hobbypartz.com/skychb6chdup.html
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Old 06-26-2011, 01:20 PM   #17
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Sloppy posted while I was typing
Yeah what he said too!!
I've only had one problem with a lipo, it was just last week. I was at the track with my buggy, And the extreme driving (jumps and cartwheels and crashes) caused two of the balance wires to be pulled out. I finished, only to find a puffy pack.

Last edited by racerfred; 06-26-2011 at 01:40 PM. Reason: addition
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Old 07-15-2011, 03:17 PM   #18
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To lipo was the answer. I got 2 sky lipo 1300 mah and a 2650 mah. I've ran one of the 1300's and got longer run time than the old 2000 NiCd and new 1500 NiMH. The truck worked a lot better too. I could totally tell the difference.
I picked up a Duratrax Onyx 235 charger, seems okay but I think it will over charge the cells even with all the info you put in. Would be nice to have a storage charge to. I just set up one of the memories for 40% of capacity charge and it seemed to work fine.
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Old 07-15-2011, 08:31 PM   #19
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I have the passport AC/DC charger. Great for at home or at the field. Has built in balancer and comes with a temp sensor for your other packs as well. I have been running a 4800mah lipo pack in my crawler since 2004. Still charges to a little above 4800 to this day. You can also get lipo packs that are in a hard case to help against impacts , tumbles , and keeping it from getting a cell poked by foregin object.

Buddy ran a pack without a hard case in buggy and it tore up the pack. But for crawling I am sure some people run hard case or no case packs.
Higher C rating is always better but for crawling a 25c willl work.

And the pros of lipo packs are the light weight , high capacity , and will you will get full power out of them til the very end and then drop off. They do not gradually lower like other battery packs.
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Old 07-16-2011, 01:12 AM   #20
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Quote:
Originally Posted by Big Daddy View Post
I picked up a Duratrax Onyx 235 charger, seems okay but I think it will over charge the cells even with all the info you put in.
I can't see why you would think that. (I use a 230 with a charge-through balancer)

So long as you're charging a 2S battery with a 2S program, you should be fine.
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