View Full Version : LiPo Batteries
I know nothing about LiPo batteries, but have some questions.
What is if any the advantage over nimh batteries?
Can you leave them in the car for 3 heats and main just repeaking them? That being said can you get by with only one battery?
Can you charge them with a I.C.E, or that type charger?
What charge/discharge rates?
What about "balancing" cells?
What abour fire hazards with charging?
Thanks
OakHillspeedway 08-01-2007, 06:18 PM Q.1 no peek charging no discharging just charge and go
Q.2 yes
Q.3 yes
Q.4 yes i do
Q.5 6.5 for 4800 do not discharge
Q.6 we balancing after 100 charges and did not need it
Q.7 we have not had any problems with theme
McLin 08-02-2007, 07:28 AM Just to be sure you understand:
The ICE charger is fine but be sure it is in the LiPo mode. Never try to charge a LiPo pack in the NiMH mode.
6.5 amp charge for a 4800 pack is a bit stront. The rule of thumb is; pack rating devided by 100. 4800 pack / 100 is 4.8. Over charging is not as forgiving with LiPo's as it is with NiMH batteries.
Never discharge your pack. There is a safety cut off built into the pack, if it gets below it (about 6 volts) you can not recharge it.
There are a lot of other threads on this forum that go into a lot more detail about these new batteries.
brian0525 08-02-2007, 08:18 AM 2c charge rates for these packs are a fairly standard practice.
nicholcgn 08-02-2007, 08:44 AM If you charge at 2c rates some compamnies say that you will decrease the total number of charges that you get on the pack. Lipos seem to take the most wear from the last 10% of charge and discharge at each end. I think that Kokam has some good information on this.
Also all batteries of any type should be stored and charged in a safe container. I do not care what anyone will tell you. When you have an incedent with any energy storage device and it malfuctions that energy is probably going to go somewhere. You want a containment device. They are cheap over time and well worth the investment.
I have a pyrex plate and a ziplock back of sand on my lipo. If it was to have an issue the bag melts and the sand poors on the lipo. Lets see that is what about $15 max for protection? The new things like lipo sacs are great and I would recommend something like this.
Benefits - Well lipos seem to be more consistent to me throughout the pack. That is what I like. That being said I use an 8000 mah lipo inmy truck and I can run over 20+ minutes. I can charge it at 8 amps (1c) and if I have 2 of these batteries I can run about as fast as I charge. I have placed well over 150 cycles on some of my packs with minimal change. NIMH would see changes in 25 cycles or so. Now top end racing guys will always want the latest NIMH and they swap out every couple of races. But I do not have that type of wallet. NIMH will have more voltage at the front of the pack if you are using the latest ones.
Chargers - The ice is nice. There are others that can balance the pack as they charge. I use an asttro flight 109 and love it.
I guess my other question, is will LiPo's take the "have", and "have nots" battery issue out of the mix in 4 minute oval racing?
garyrcdoc 08-02-2007, 04:55 PM JNOR
I have enjoyed the change to LiPo and will continue using them until something else better is offered. I love the ease of use (i.e. no discharge or extraordinary maintenance ... other than the minimal disadvantage of taking care NOT to discharge too deeply..).
I have been charging my 3200 orion and my 4800 peaks at 6.4 and 9.6 amps respectively since, (as has been mentioned), they are certainly able to take a 2C recharge rate.
I've found a favorite brand in the max-amps and have bought at least 6 of the max-amp 6000 mah lipos (for $99 ea now) and they've been absolutely wonderful and I charge them at 8 amps simply because my charger won't charge at a higher rate.
I use ICE chargers and have had a good experience with the three I have other than the buttons sometimes malfunction and I have to clean the buttons on the electronic board out with motor spray sometimes and they will then start working again. (all three of my ICE's have done this...). Still, for the money, I'd buy another ICE before another charger at this point.
I do not deep discharge by attempting three races in a row on the 6000 mah (they might do ok....I've just never tried) since the batteries last a LOT longer if you donot deep discharge them according to the info on the kokam site...
Good luck in learning more about lipo.
gary
kevinm 08-02-2007, 05:49 PM ... There is a safety cut off built into the pack, if it gets below it (about 6 volts) you can not recharge it...
I don't think this statement is correct. There isn't anything built-in, it's just the way this battery chemistry works. Go below 3V/cell and they die. Either use an ESC with built-in LiPo cutoff, add the Novak external one, or just NEVER drive the car until it visibly slows down.
robiwon 08-11-2007, 09:53 PM Very new to LiPo's. Why two plugs?
swtour 08-12-2007, 02:54 PM Robi,
There are so many combinations of LIPO's, and they are just a bunch of batteries all connected together to create different voltages and mah ratings.
They are hooked in series or parallel to create different numbers...so each individual 'cell' has it's own plug from what I've seen.
That being said - for OVAL RACING we've chosen to go to the Peak and/or Orion brand 3200 Carbon Edition "lipo" . It comes in a sealed case, uses banana plugs and is less complicated.
I know a lot of people are confused when dealing with the 'other' types of LIPO packs...
gezer2u 08-12-2007, 10:01 PM Also, one plug is to hook to a balance charger to charge and the other is hooked to the speedo.
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