crazyvwobie

not sure what forum is best for this but since its related to my 1/18 here it goes.im new to electric rc i need some help with batteries.I just bought a vendetta Im going to go brushless in the near future mamba pro and an ammo 3900.I want good batteries but not sure I want to deal with lipos,mostly because I know nothing about them and to me seem pretty high maintenance and im trying to be realistic .can someone explain the charging and balancing of lipos? What is an alterative to lipo that will give me the power I need for brushless?I also notice most high end chargers seem to be just dc,whats the reason for that?

thanks

Snipin_Willy

Some good questions. I was into nitro for a long time before getting my Vendetta ST. The setup you described that you are going for is exactly what I have right now: Vendetta ST, Mamba micro pro, and Ammo 28-25-3900 motor. I'm running a 16T pinion with the stock spur and it accelerates great and has more than enough top end for any track. But back to your questions about batteries and the chargers. LiPo's and Li-ions have been around a long time being used in laptops, cell phones, PDAs, and other highend portable devices that need a high capacity storage device that could be charged and used repeatedly. Li-ion batteries aren't nearly as volatile as LiPo because of the differing chemistries used in them. LiPos need a special charger that does both constant current and constant voltage charging depending on the state of the battery (someone correct me if I'm wrong). They also don't peak charge like NiCds and NiMhs. Basicly they use and entirely different charging process. A good charger with the correct built in safety measures will charge LiPos without any problem, but still does mean you should charge one in your living room while you go out to walk your dog. Personally when an if I get into LiPo I'm going to charge them in something that can protect the surrounding area in case something happens. I have a 20mm military ammo box that is plenty big and tough enough to contain a LiPo gone mad that was charging. Balancing lithium battery cells is a process that slowly drains cells that contain more charger than the other cells connected to it to bring them down to a level where they are all even and then slowly bring them all up to their max capacity without over charging any 1 individual cell. Suppose to increase performance and life of the battery, by how much...I don't know.

And about most of the higher end chargers you see being DC input: Alot of higher end chargers also have high current output for charging larger batteries than just RC car batteries. Electric planes use LiPos too you know and some of them are big enough to fit some massive packs. Larger packs with 3000+ mAh (most mini size lipo packs dont have more than 1500 mAh) are able to charge at higher rates. I dont know if you know about the charging rates for batteries but you can't just plug in a battery to a 10A charger that's on it's max charge rate and expect your battery to live (unless it's a A123 LiFe battery but those are another story). Alot of people wont charge a battery past the 1C or 1.5C mark. The C rules are based on the capacity of the battery. If you have a 1500 mAh battery then 1C charge rate is 1.5A, or 1500mA. Likewise 1.5C charge rate for that same battery is 1.5 x 1500mA or 1.5 x 1.5A. Getting back to chargers...alot of high end chargers have the ability to charge these 3000+ and 4000+ mAh battery packs (sometimes in parallel increasing the capacity even more) at the 1.5+C rate. That's ALOT of current. A power supply that has enough "umph" to feed a charger like that is going to be too large to fit into a battery charger without making it the size of a large lunch box and the weight of a few bricks. Now say you dont have plans on charging those hig capacity packs and don't need more than 5A of DC for the charger. The Onyx 230 has an AC to DC power supply (looks exactly like an older external laptop power supply) sitting inside of the charger housing. If you look at it, the large area behind the LCD screen that's fatter than where the buttons are is where the 5A power supply is. It takes in 110AC, feeds the charger up to 5A DC.

Yeah I've been reading on batteries for a while.

Snipin_Willy

Oh 2S LiPo (2 cells in series) puts out more voltage than 6-cell NiCd or NiMh battery pack. They also have a lesser internal resistance and allow more current to flow without cooking the battery while in use. Put those two things together and you can see why LiPos have such a power advantage when it comes to running brushless motors.

I good NiMh battery pack will make you happy with a brushless setup. I'm running the ammo 3900 with the DTX 1200 packs and it's plenty for me at the moment.

crazyvwobie

wow thanks for the info.I think I will stick with NiMh for now I just wanted to make sure everything will run right.Lipo seems a little more involved for me since im not racing thanks for you help.what brand NiMh and where is the best price for them and will they fit into the vendetta?

calvino

the "bulk" elite 1500 mah cells from www.cheapbatterypacks.com is very good, they can also "custom make" a pack for you if you desire

crazyvwobie

thanks guys

crazyvwobie

ok need some more help.I checked out cheapbattreypacks.com just need some recomedations for a custom pack (elite 1500)what gauge wire? and with deans connectors does the battery pack get the male or female??

fusebmx13

it gets female and about 14 or 16 gauge wire is fine. I would go with 14. It is bigger.