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Old 06-19-2008, 03:51 AM   #31
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I've noticed a massive difference between SMC4000's and the Yeah Racing 3200's

Even with a 540 motor there was a very noticeable difference.
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Old 06-19-2008, 06:22 AM   #32
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10A, really? I was under the impression that you cant go above 1C per pack, because the Lipos just can't handle it. What type of charger are you using for this?
I have this charger:

http://www.fmadirect.com/new_applica...0s_charger.htm

It has a few features that are pretty cool and it will balance charge with a full amp difference between the cells if they are way out of balance. I would only charge at 10 amps (or about 3C) with really good cells like the Orions or SMC's. Been running my Orion like this for over a year now and it's still fine. I only charged at 7 amps last year but I didn't have the balance charger then.

FMA also has a small balance charger that's capable of 7 amps and is under $100 with the balance adaptor.
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Old 06-19-2008, 06:38 AM   #33
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I rum mostly stock tuck and I have tried a bunch of diff lipos and they have all been pretty punchy.

The Trackpower 4900's and Orion 4800's feel pretty close with the trackpowers getting a slight edge.

The best has been the SMC 5000 packs they have a slightly lower IR and seem to have the most punch but all were pretty close.

I have also found than warming the packs to about 120deg F. helps lower IR about 10%.
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Old 06-19-2008, 07:01 AM   #34
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I have had really good luck with the Reedy 5000 w/12ga wire, great runtime and excellent punch.
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Old 06-19-2008, 08:13 AM   #35
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You can charge a LiPo pretty fast with some of the newer high end balance chargers. I've been charging at 10 amps with my FMA balance charger and it's working out fine. Takes about 40 minutes to charge a 4800 or 5000 LiPo (Orion or SMC). A good LiPo on a balance charger won't even get warm to the touch charging at 10 amps. Be careful with those charge through balancers (some only balance at a quarter amp between cells and that may not be enough with an older pack).

My Orion 4800 is over a year old and it still works great. Been charging hard since day one without any problems.
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My point was that w/ lipos and the recommended charge rate (5400 = 5.4A), they just take longer than NIMH. You can't crank up the amperage like with NIMH to charge faster if needed. Of course a pack will charge faster at a higher amperage, thus the reason I used 8A w/ NIMH.

I also noticed that the lipo packs start off the same way as you posted they finished. With a low amperage at first, then ramping up to 5.4A, and then back down as the pack "peaks". I use a balancer (Checkpoint) each time I charge.



10A, really? I was under the impression that you cant go above 1C per pack, because the Lipos just can't handle it. What type of charger are you using for this?
I have tricked my ICE into charging my checkpoints at 6a, they got warm though so i got worried about my 100$+ investment and let the charger figure out what amperage to charge at since i have two and i can get just about 3, 5 minute runs out of each from a full charge i figure i'm good for practice, heats and a main w/o even recharging.


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+1


not home is our new resident experts on all things RC, and he weighs in on all sorts of things and makes a whole lot of very ridiculous, odd, and bizarre claims. But this is a regular occurance this time of year on all discussion boards as kids get out of school for summer.

Then again, all sorts of people have been making those stupid claims since LiPOs first came on the market but they're always as a result of being slowpokes that finish many laps down from the leaders or just the uninformed that can't rationalize that amp hours are amp hours regardless of which it's a nimh or a lithium battery.
+2 on checkpoints 5400, i have 2 of them and changing nothing else i took a second off my lap times. The scary part is they are only 17c (info straight from tracpower who make the cells for checkpoint no "friends" involved) and they are releasing 25c 4900's (again trakpower cells) very soon.

Apparently Thunder Power is supposed to be coming out w/ a hard case, once they do i'd bet they are gonna be at the top of the heap. My buddy (real friend and i DO have photo!!) uses these lipo's in his planes and he threw away every other brand he had, there is a racer at the 'bowl that tried them in his car (soft sided) he said they were, and i quote "friggin sweet".

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in my friends tc, he got like 50min on the drivers stand or maybe even longer with a 10.5. it was a trakpower 4900? i think it was.
Oh he forgot to mention that his buddy had 2 10,000's in series and his 10.5 had liquid cooling, my one friend had the same setup and he got like 2 hours once ... ..... .... for real .. i swear! My memory stick crapped out when i tried to take a picture tho and he moved away .. and he said his phone doesn't take pictures anymore so ....
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Old 06-19-2008, 12:02 PM   #36
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I have never had lipo in a car before...I have had them in planes and heli's. I just bought two lipo packs, a Reedy 5000 and a Trinity 4500.

I have my lipo charger from my planes but it only charges at a max of 2a. As I understand these two packs can be charged at 5a and 4.5a correct?

Is there anything that I am going to loose (besides time) by charging them at a lower rate? Or should I just buy another charger?

Thanks.
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Old 06-19-2008, 12:12 PM   #37
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Originally Posted by cherokee View Post
I have never had lipo in a car before...I have had them in planes and heli's. I just bought two lipo packs, a Reedy 5000 and a Trinity 4500.

I have my lipo charger from my planes but it only charges at a max of 2a. As I understand these two packs can be charged at 5a and 4.5a correct?

Is there anything that I am going to loose (besides time) by charging them at a lower rate? Or should I just buy another charger?

Thanks.
5A and 4.5A would be 1C, so yeah, that's ideally where you'd like to charge them. Doing it at a lower rate will only cost you time. You can get a quality LiPo charger + balancer for under $100 these days, so it's something to consider, 'cause you're going to wait around for a long time at 2A.
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Old 06-19-2008, 12:15 PM   #38
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The 0606i is priced around $99. If you want one with a built-in power supply, the 0606i AC/DC is priced around $140. Both very nice chargers.

http://media.hyperion.hk/dn/eos/
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Old 06-19-2008, 12:42 PM   #39
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A car lipo charger is on the list. I have not bought a RC battery in over 11 years. So I just dropped some money and bought two from well known suppliers. I will have to wait till next month for the charger, the wife will be unhapy with what I have spent already....but I keep telling her it is cheaper then a set of Carillo rods.
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Old 06-19-2008, 12:52 PM   #40
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Why are people so afraid of charging a lipo at higher then 5amps? The lipo chargers are setup so once the pack reaches the set voltage they start to crank back the amperage until its done. So all charging at a higher rate has done for me is get the pack charged faster.....thats it. The battery comes off the charger at the same temp if I charge at 5amps or 8amps or 10amps. Heck my lipo is hotter when I take it out of the car then when I put it in.

This is a nice little DC only charger....http://www.rchover.com/inc/sdetail/121015 It works great and will do everything.

Syndrome....where did you see that charging at a higher rate ruins the pack...I want to see who said this? Or have you ran a pack enough times to see this yourself?
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Old 06-19-2008, 01:20 PM   #41
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Quote:
Originally Posted by Kevin K View Post
Why are people so afraid of charging a lipo at higher then 5amps? The lipo chargers are setup so once the pack reaches the set voltage they start to crank back the amperage until its done. So all charging at a higher rate has done for me is get the pack charged faster.....thats it. The battery comes off the charger at the same temp if I charge at 5amps or 8amps or 10amps. Heck my lipo is hotter when I take it out of the car then when I put it in.

This is a nice little DC only charger....http://www.rchover.com/inc/sdetail/121015 It works great and will do everything.

Syndrome....where did you see that charging at a higher rate ruins the pack...I want to see who said this? Or have you ran a pack enough times to see this yourself?
Kevin..Syndrome...others...
I have been doing testing with SMC and running their lipo packs in my cars the past few months. You are correct. Pack life after 120 charges and discharges at 12 amps, is showing better numbers than when I originally cycled it. Their is no harm in charging faster than 1C as long as you have a reliable charger. If you overcharge at 1C or 3C the result is the same, its overcharged and will be a problem.
I also warm the pack to 140 degrees before running it. The results are vastly noticeable when heated versus room temp on the track and when cycled. The voltage jumps almost a tenth, IR gets cut in half, and runtime extends about 15 seconds.
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Old 06-19-2008, 01:38 PM   #42
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Why are people so afraid of charging a lipo at higher then 5amps?
probably in the warnings that come with so many lipo batteries, that nimhs started blowing up right and left when they got larger than 3300, and the fact that they cost more
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Old 06-19-2008, 01:54 PM   #43
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The only thing I have heard about charging over 1C is that it will shorten the life of the pack. Not sure if anyone has data on this but...
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Old 06-19-2008, 02:05 PM   #44
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probably in the warnings that come with so many lipo batteries, that nimhs started blowing up right and left when they got larger than 3300, and the fact that they cost more
Have you looked at what they say about NIMH cells they should be slow charged at 1amp right on the cells.....yet I dont know anyone who charges them at 1 amp. Do you think the amperage was blowing up NIMH cells or was it the crappy cells that were blowing up?
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Old 06-19-2008, 02:16 PM   #45
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Kevin,

Linger has made a number of posts on the subject here on RCTech, including graphs with hard data. Whether or not you trust his expertise is entirely up to you, but ROAR trusts him enough to be their resident expert. You can find some good discussion on the topic here and here, with related graphs.

There is a ton of discussion on the topic in the R/C flight world as well. Some people think 2C is okay for some cells, but you have to balance every time. Anybody that's interested can read and search further, but the flight crowd also seems to gravitate toward 1C charging.

I guess my point is, while it's not a safety issue, per se, there's an overwhelming amount of evidence that suggests charging at 2C will reduce the life of your pack. It's certainly a real enough possibility that I wouldn't recommend charging at 2C to everybody that comes along, and would only suggest it if there's a real need to charge quicker.

But that's just my opinion based on what I've read from people that are smarter about it than myself, and have done more testing. I don't have the time or desire to test it on my own, so I can only rely on data gathered by others. I would encourage others to do the same, and come to their own conclusions.
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