I just got my brand new 1/8 Summit with 2 Traxxas PowerCell 2S LiPOs(5000 maH). After going through the warnings for the LiPo battery care, I am pretty much freaked out since I dont understand how to operate them safely. My entire house is carpeted and I dont know if I can charge them indoors safely. Can somebody enlighten me on some LiPo dos and donts?
Can I keep driving the truck until the low voltage shut off kicks in?
Also are the LiPos water proof? Is there any precaution I need to take to operate in wet conditions?
Welcome to the forums, and LiPo 101!
1. 1C is the standard industry charge rate (read: it's safe!) Depending on how far discharged a pack is, charging at 1C only takes 45-60 minutes.
To calculate a 1C charge rate, simply divide your pack's mah by 1000. A 3000 mah pack should be charged at 3 amps, a 5700 mah pack at 5.7 amps, and so on.
2. Don't OVERcharge (no more than 4.2v per cell at end of charging). Set your charger properly. It should read "2S / 7.4V" for a 2 cell LiPo, "3S / 11.1V" for a 3 cell LiPo, etc.
3. Don't over DIScharge (no lower than 3v per cell when battery is done being used). You must set your ESC's LVD (Low-Voltage Detection) to LiPo mode before using these batteries. Green on the ESC = GO for LiPo. If the light is still red on your ESC, press and hold the EZ-Set button for about 10 seconds, until the light stays green and an ascending tone is heard.
4. Check the voltage of each pack before and after each use, and before charging. Use an inexpensive cell checker. This one works great (or search for one on eBay):
5. Always balance charge! If your cells become too unbalanced, the pack will be ruined.
6. A puffed LiPo is TOAST. Dispose of it. Don't try to charge it, unless you like visits from the fire department.
7. Never leave LiPo packs fully charged for longer than 24 hrs. It's a sure-fire way to puff them, or at the very least shorten their life span. Charge 'em, use 'em! Some guys will disagree with me on this, but the only LiPo I've ever puffed was fully charged.
8. Follow the above advice, and a LiPo fire will be extremely unlikely. But use a LiPo sack and keep a fire extinguisher handy when charging, JUST IN CASE.
Make it idiot-proof and along comes a better idiot
charging anywhere indoors is risky, the flames could travel 30 feet.
Depending on the cut off voltage you want to be aiming for 3.6v when removing the packs. If the cut off is higher that's ok, if it is lower you should not be getting to the cut off point all the time. Aim for 3.6V it will make the packs happy and give a longer life.
A happy pack is a safe pack, dont throw it, puncture it, overcharge the pack, don't let the voltage go too low. saving a few $ on a charger is a bad investment.
Google search trumps Wiki. Refer to user guide.
For your packs, as zippogeek stated, charge at 5 amps, but I charge my 5000mAh packs at 3A to charge a little slower. As long as you follow the guidelines and tips here, you will be fine. Congratulations on your purchase!
Don't drive in water on you summit.
Make sure there's a balloon on it
Slash 2wd, Slash 4x4, 30th digger, Rustler VXL
Due to how LiPo's are assembled, they are somewhat water resistant. The cells themselves are completely sealed... but water can get in between the cells within the pack and start to corrode the cell material.
I have done absolutely nothing to further protect my LiPo's from water damage and have gone through countless 1-2" puddles and miles of wet grass. Now, if you were to submerge your packs I suggest doing something... either preventative measures to keep water out or something to dry the pack out afterwards.
Zippo's post has some very good information... the only thing I would change is that LVC should not be set for lower than 3.4v/cell. 3.0v/cell is the lowest you want to go... but the ESC/motor can make volt dip below 3.0v/cell if LVC settings are too low.
Whatever it is I just typed... could be wrong.
Thank you so much for all your replies. They are very helpful.