R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Radio and Electronics

Reply
 
Thread Tools Search this Thread
Old 09-24-2008, 07:05 PM   #1
Tech Adept
 
rc4fun's Avatar
 
Join Date: Mar 2008
Posts: 249
Trader Rating: 3 (100%+)
Default I need ur help charger set up for lipo pack 4 cell 3300 mah 14.8 volts, ice charger

Hi' guys i need ur help im new bie with electric, i bought this lipo pack the brand is thunder power rc, 3300 mah, 14.8 volts, 4cells, 25c cont, 50c burst(82a/165a), im using ice charger with duratrax, i set the charger to lipo 14.8volts, 3300mah, chrg 3.3mah and when i start charging the lipo pack, the voltage already start with 15.63 and after 15 seconds still going up' is that supposed to be like that? Lhs told me if it is 14.8volts when you fully charge it is not go over 14.8volts, i dont wanna blew the lipo so i cut it off' any help i really appreciate it'
thanks'
__________________
301raceway' onroad track "Eastcoast proud"
Blue Diamond on-road track
Hobbyworks Fairfax________Brooklyn hobbies
rc4fun is offline   Reply With Quote
Old 09-24-2008, 07:12 PM   #2
Super Moderator
R/C Tech Elite Subscriber
 
Join Date: Oct 2007
Location: Rochester Hills Michigan
Posts: 7,232
Default

14.8v is the nominal voltage rating, 3.7v per cell. The charge will go to a maximum of 16.8v, 4.2v per. It's fine.

But I would suggest a balancer, chances for mayhem go up with higher cell counts like 4s.
Dave H is offline   Reply With Quote
Old 09-24-2008, 07:22 PM   #3
Tech Lord
 
Join Date: Jul 2008
Location: Houston, TX
Posts: 11,530
Trader Rating: 21 (100%+)
Default

Fully charged is 4.2v/cell so for a 4S lipo, fully charged voltage will be 16.8v. I think you misunderstood the lhs - or they were wrong. If you're using the lipo charge on the Ice charger, it will charge at constant current (your input 3.3a) until the voltage reaches 16.8v. Then it will finish the charge holding that voltage constant (CC/CV type charge for lipo) until capacity is reached. You can watch as current goes down til it quits in this 2nd stage.

Stop worrying about blowing it up, you'd have to hit with a lot, lot more voltage and current to make it do that - thats mostly just misinformation about them blowing up. Follow precautions, charge like recommended and you will not have probs.

Confusion is over way lipo is rated - there is a nominal voltage of 3.7v/cell - thats the 14.8v nominal voltage for a 4S. Fully charged is 4.2v/cell. Minimum is 3v/cell. Go find your Ice manual, look at pg 11 part 1b. Wouldn't hurt to read items 2 - 13 for any comments about lipo either.

My 2S lipos charge to 8.4v, not 7.4v nominal. My 3S charges to 12.6v not 11.1v (again, 11.1v is nominal voltage).
Duster_360 is offline   Reply With Quote
Old 09-24-2008, 07:43 PM   #4
Tech Adept
 
rc4fun's Avatar
 
Join Date: Mar 2008
Posts: 249
Trader Rating: 3 (100%+)
Default

guys thanks for the info' do i really need a balancer for charging a 4cell lipo?, and how about the voltage cut-off do i really need it to save my servos?
thanks'
__________________
301raceway' onroad track "Eastcoast proud"
Blue Diamond on-road track
Hobbyworks Fairfax________Brooklyn hobbies
rc4fun is offline   Reply With Quote
Old 09-24-2008, 09:07 PM   #5
Tech Fanatic
 
harjo's Avatar
 
Join Date: May 2005
Location: OK
Posts: 972
Trader Rating: 114 (100%+)
Default

i use a balancer after i charge the pack at least 10 times just to equalize the cells again. they're usually not far off. a balancer is a good thing to use to take care of your batteries and help them last for a long time.

the voltage cutoff is more for the batteries sake in that if you run it below a certain point, you can damage the cells in the lipo, possibly cause swelling and maybe even a fire (worst case scenario). if possible, i would definitely look into one.

lipo's are great. as long as you treat them right, they'll last for a long time.
harjo is offline   Reply With Quote
Old 09-25-2008, 05:04 AM   #6
Tech Lord
 
Join Date: Jul 2008
Location: Houston, TX
Posts: 11,530
Trader Rating: 21 (100%+)
Default

Balancing is to protect the batt - the individual cells that make uo the lipo. If they start off out of balance by much, while you're running, the lowest voltage cell can get pulled below the 3v/cell minimum. An lvc just looks at the total voltage, not individual cell voltages - so you can have 3 that are over minimum, 1 below minimum and still be above a 12v lvc typical of 4S and potentially damage your lipo even though you haven't hit the lvc.

How wll the cells stay in balance is related to the quality of the cells. My most expensive lipo, NeuEnergy rarely shows more than .02v diff in cells. The less expensive lipos, balancing is more problematic. Do you have a dvm? You can figure out how to ck cell voltages off the balance tap failrly easily and see what they look like - how close are they?. Charge and recheck they again - is same cell still reading lowest? Quality also shows up in how the cells tolerate being run under the min voltage. Better ones will tolerate an occasional dip below min voltage and others will swell or puff at the slightest exposure to minimum voltage.

I would consider getting a balancer.
Duster_360 is offline   Reply With Quote
Old 09-25-2008, 09:14 PM   #7
Tech Adept
 
rc4fun's Avatar
 
Join Date: Mar 2008
Posts: 249
Trader Rating: 3 (100%+)
Default

any suggestion for balancer,right now i have the ice charger by duratrax, those charger that have a built in balancer are they good? or im just getting it separate'
Thanks'
__________________
301raceway' onroad track "Eastcoast proud"
Blue Diamond on-road track
Hobbyworks Fairfax________Brooklyn hobbies
rc4fun is offline   Reply With Quote
Old 09-26-2008, 04:52 AM   #8
Tech Lord
 
Join Date: Jul 2008
Location: Houston, TX
Posts: 11,530
Trader Rating: 21 (100%+)
Default

Depends on what you feel like doing. The one thing I would advise - a setup that charges and balances, rather than one that balances after charging - that just discharges all cells down to the voltage of the lowest cell.

I've had the Ice charger for almost 5yrs and about a yr ago, bought a Hyperion charger, 0610iNet, with the builtin balancer. I tried using a separate balancer with Ice made by DualSky, but was never satisfied that it worked right - main prob there was the DualSky balancer was a poor choice. There are much better separate balancers available now, Hyperion LBA-10 or the Great Planes Equinox are examples ofgood choices, there are others. Simply wire them up correctly, follow instructions and you're charging and balancing.

Most problems revolve around the balance tap connector, but thats a prob even with a builtin balancer - everything's got to be connected correctly. Hyperion sells 4 adapters that mate prob 95% of the lipos out there. They also have the one that adapts the hard case lipos to their balancers/chargers.
Duster_360 is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Race Results! Exterminator Northwest Racers 4712 07-09-2017 05:58 PM
over 210 used extra tc3 parts new&used parts plus hop ups mint MORE ADDED TODAY MONDA jason cheng R/C Items: For Sale/Trade 13 04-01-2004 07:05 PM
over 175 used extra tc3 parts new&used parts plus hop ups mint shape look jason cheng R/C Items: For Sale/Trade 6 12-22-2003 11:07 AM
Which 1/10 gas car to get? x_man Malaysian R/C Racers 45 06-30-2003 04:19 AM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 09:13 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net