hardhittinz

wanna get my self a new electric short course truck or something and everything i see suggest lipo well ive never used or owned anything lipo only nimh.so whats it all about? i see the packs have like 2 connectors on them like a deans and some white plug i saw on one,and whats this about balancing and stuff ? do you charge it then balance ? whats charge time like? And last is there any short course truck that runs good on nimh batteries? or is anything using nimh slow?and only way to be fast is lipo? thanks for any info...

Goldenduff

Read hangtime hobbies webpage.

karlik

http://www.rchelicopterfun.com/rc-lipo-batteries.html

hardhittinz

thanks for the info guys ive learned alot now..Another question is do i need a saftey bag when charging?or no? and whats a ok charger for lipo and what brand of packs are good?

Goldenduff

When charging a lipo assume it will go on fire! This has never happened to me but has to others. I charge outside in an old oven! 

hardhittinz

dang catching on fire? what causes that?

trax de max

putting trust in a poor charger.
abused lipo,
charged wrong,
The wrong size for the RC. I'd say these four are the main culprits nowadays.

Lipo's seem to be built better now,
people have a better understanding of them,
chargers are also smarter.

Go back 3-4 year and you would hear of houses burning down / businesses burning down. You rarely hear of these now, but on some occasions you hear of a rc bursting into flames.
Most important to be nearby when charging. Some people charge outside, on my packs i think there is a 30feet warning for flames, but i charge on the kitchen bench near the door.
There's lots of old vids on you tube. When you see these you'll get scared, but these are old videos.

hardhittinz

gotcha also at what amp is a lipo 3s 5000mah to be charged at?

mehrshad

Depends on your lipo type. if it is rated for 2C charge it means you can charge it by up to 10A.
but typically 1C gives the best combination of charge time and cycle life and safety unless your pack is rated for 5C or so.

trax de max

That's the thing about lipo's, it's all about numbers. Understand these numbers and your on your way to being safer.

Goldenduff

Also 5000mah is a relatively large battery. If charging at 1C that is 5amps. At 11.1volts your charger would need about 55watts. The pitfall here is many chargers can deliver the wattage but not the amps.

For example a cheap charger and or power supply that can only deliver 2amps would limit your charging rate.

tmbatteries

Certainly smaller charging current can charge the battery more completely, but it will take longer hours. Basically the charging current is not allowed to exceed 4C, say, 1C, 2C is available. Due to security concerns, the balance connector is introduced to Lipos to avoid catching a fire.

chuckk2

Charge rate for a 3C 5000mah Lipo - - -
Most of the decent Lipo chargers are limited to 50W or so.
As a result, starting at 3.7-3.8V per cell storage, the charge current is limited by the wattage of the charger.
On top of that, as the battery charges, the current will decrease as the battery gets closer to the fully charged voltage of 4.2V per cell.
(The charger changes from a current limit to a votage limit.) (CC/CV)
Finally, at the very end of charging, it's common to go into balance mode. This will usually reduce the charge current to well below one Amp.
The last 20% or so of charge can take almost as much time as getting to 80% of charge.

Goldenduff

Erm most of the decent lipo chargers are NOT limited to 50w. In fact almost the opposite is true. I.e there are hundreds of sub 50w inaccurate chargers. Now most chargers over 500w are decent!!!?!......

chuckk2

Many of the common computerized single battery chargers are 50W chargers. (BC6 and clones)
Naturally, there are chargers of various complexity and capability, as well as price.

I try to shoot for a charger that will balance charge the lipos I use (3300 to 5000mah, 3,4&6 cells)
in an hour or less.  Discharge to storage is another issue, and I use 12v 50w light bulbs to discharge
in a reasonable time.  Currently, I'm using two BC6DXII's and one Q6320 charger.  the Q6 is limited to 80W x4
(4 port charger).

Rob2160

One extremely important thing when using Lipos..

Never drain them until they are completely discharged.. This is the fastest way to destroy your batteries and risk fire.

I have dozens of Lipos in various sizes for Helis and fixed wing aircraft.. I fly strictly to a timer on every flight and land with about 20 to 25% capacity still in the battery..

If your aircraft / heli loses power in flight due to battery exhaustion you have gone way too far with the discharge already..

Keep the charge rates to 1 or 2 C and don't discharge below 20% and they can last for hundreds of cycles with no deterioration..

The way to determine charge rate is based on capacity.. EG 2000Mah battery 1C charging will be 2 amps... 5000 Mah = 5amps etc..

There are batteries that can be safely charged much faster but they should be clearly marked as such.. if not the 1 - 2C rule is pretty safe for anything..