R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric Off-Road

Reply
 
Thread Tools Search this Thread
Old 02-12-2009, 12:21 PM   #16
Tech Elite
 
joe of loath's Avatar
 
Join Date: Mar 2007
Location: Bristol, England, United Kingdom
Posts: 4,857
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by mattnin View Post
I still own many A123 packs. I wouldn't be knocking these batteries if I didn't already own them and use them myself. As matter of fact, I still use 1100mah A123 cells in my rock crawler. I have used A123 in touring car, and A123 in modified offroad racing but I have since stopped using them because of the hassle dealing with them. Hardly any battery tray fits these batteries, and forget about using A123 if you race stock.

And there are LIPO batteries out now rated at 10A or more charge current. That is just as fast as the A123 charger. So yes, you can charge a LIPO battery pretty darn fast.

A123 doesn't discharge better than 30C. And there are LIPO batteries out now like the Reedy that discharge at 35C, and tested. If you want, I can pull up some tests from rcgroups. Yes, the A123 does discharge high, but it isn't as good as some of the newer LIPOs out right now.

I take that back if the price is a 2600mah is only $50 though, that isn't a bad price at all. But for the total cost of A123, you must also factor in the special charger.

A123s aren't ROAR approved either. There are a lot of cons about the A123 batteries, more than LIPOs in my humble opinion.
its not the charge current, its the charge rating in C's. A123 can charge at 4c. no lipo can go past 2c.
__________________
HPI E-Firestorm - Tamiya TA05 racer (carbon chassis, 10.5 brushless etc) - LRP Blast S10 BX - Revo 2.5r truggy conversion (in progress)
joe of loath is offline   Reply With Quote
Old 02-12-2009, 12:23 PM   #17
Tech Fanatic
 
Join Date: Jun 2006
Posts: 872
Trader Rating: 35 (100%+)
Default

So where are you gonna get a charger that can do 4C anyway? Best chargers can do 10 amps..... unless you are hooking it up across a lead acid 12V battery.
__________________
High Desert Raceplace, Grand Jct CO, Sanwa Exzes Plus Stick Radio, Spektrum,Thunderpower 230g, Modified Tri-Nut Novak GTB2, Ballistic 4.5t 550, 5.83lb SCTE Ten, Novak Sentry Brushless Dyno, Crossweight Setup Station, Junsi 20A power supply Icharger 20A Charger,TP610C, 22B, Novak Edge, Novak 13.5, SC10, Havoc Pro SC XDrive, Ballistic 17.5 Matthew Joseph Cordova
mattnin is offline   Reply With Quote
Old 02-12-2009, 12:31 PM   #18
Tech Fanatic
 
Join Date: Jun 2006
Posts: 872
Trader Rating: 35 (100%+)
Default

Look, the poster wanted to compare Lipos to A123s. I challenge anyone here to name any benefits of A123 over Lipos, and see if I can dispute them....

A123 are safer. Yes, they are inherently safer, but if you use a lipo only charger, and use a newer lipo with discharge cutoff and a lipo sack, you are just as safe. And to be honest, if you are charging A123s, you don't want to leave them unattended either, and charge them in a lipo safe as well. And A123 batteries get pretty darn hot under charge, not so with LIPOs.

A123s have a great cycle life... This is a true statement. A123s have been known to be able to charge up to 1000 cycles and go strong. However, some of the newer lipos from respected companies also boast near the same cycle life.

4C charge rate. They can be charged this high, but they do get hot! Don't let the 4C charge claim fool you. And if you buy a standard charger, you are limited to 10 amps anyway, the same max you will find with most newer 5000mah or greater lipos.

That is it, can anyone name any other benefits?
__________________
High Desert Raceplace, Grand Jct CO, Sanwa Exzes Plus Stick Radio, Spektrum,Thunderpower 230g, Modified Tri-Nut Novak GTB2, Ballistic 4.5t 550, 5.83lb SCTE Ten, Novak Sentry Brushless Dyno, Crossweight Setup Station, Junsi 20A power supply Icharger 20A Charger,TP610C, 22B, Novak Edge, Novak 13.5, SC10, Havoc Pro SC XDrive, Ballistic 17.5 Matthew Joseph Cordova
mattnin is offline   Reply With Quote
Old 02-12-2009, 01:59 PM   #19
Tech Adept
 
Join Date: Dec 2008
Posts: 249
Trader Rating: 12 (100%+)
Default

Quote:
Originally Posted by mattnin View Post
So where are you gonna get a charger that can do 4C anyway? Best chargers can do 10 amps..... unless you are hooking it up across a lead acid 12V battery.
Actually you can zip charge A123's directly from a 12v battery...

Also you can charge the 2300mah cells at 20 amps with the correct equipment. A 3 cell pack is the same voltage as an 8 cell nimh pack.

Not being ROAR approved just proves how backwards ROAR is. These cells are cased in metal and won't start a fire even if you puncture the cells.

Some more benefits are you can charge the cells to 0 volts without any damage. You can charge the packs HOT, their is no need for the cells to cool. Hundreds of cycles I have some aircraft packs with close to 500 cycles on them without any signs of fatigue. The biggest benefit is you can charge these things faster then you can discharge them!

The C rating on these cells are totally wrong and can't even be compared to lipos. A123's hold a constant voltage throughout the entire discharge curve and drop sharply at the very end. Lipos have a much more linear discharge curve. The 30C rating is very very conservative, I have run these cells over 100 amps continuous without problems in aircraft and helicopters.

I have a 3S1P pack in a stock Firestorm Flux (sidewinder+5700kv) top speed is 50mph (GPS verified). Run time is over 10 minutes recharge time is 7 minutes...Two packs is all you need to run continuously.
My other A123 vehicle right now is a 4S2P brushed E-Revo. It's my wife's truck and she beats the snot out of it. If I were to guess 30mph top speed and about 25-30 minutes run time. Again I can recharge this pack in 7 minutes.
Linkdead is offline   Reply With Quote
Old 02-12-2009, 02:10 PM   #20
Tech Elite
 
sosidge's Avatar
 
Join Date: Dec 2001
Location: Bristol, UK
Posts: 3,865
Default

Thought I should mention that Tamiya have gone with an A123 pack instead of going down the LiPo route.

They have released a 6.6V 2200mAh pack and charger.

List price is pretty high - but it could mean a serious future for A123-type tech in RC, even if is just for Tamiya bashers or a stock class.
sosidge is offline   Reply With Quote
Old 02-12-2009, 02:47 PM   #21
Tech Elite
 
joe of loath's Avatar
 
Join Date: Mar 2007
Location: Bristol, England, United Kingdom
Posts: 4,857
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by Linkdead View Post
I have a 3S1P pack in a stock Firestorm Flux (sidewinder+5700kv) top speed is 50mph (GPS verified). Run time is over 10 minutes recharge time is 7 minutes...Two packs is all you need to run continuously.
My other A123 vehicle right now is a 4S2P brushed E-Revo. It's my wife's truck and she beats the snot out of it. If I were to guess 30mph top speed and about 25-30 minutes run time. Again I can recharge this pack in 7 minutes.
wow, recharge faster than discharge!

gotta get me some of them.
__________________
HPI E-Firestorm - Tamiya TA05 racer (carbon chassis, 10.5 brushless etc) - LRP Blast S10 BX - Revo 2.5r truggy conversion (in progress)
joe of loath is offline   Reply With Quote
Old 02-12-2009, 02:50 PM   #22
Tech Fanatic
 
Join Date: Jun 2006
Posts: 872
Trader Rating: 35 (100%+)
Default

You cannot discharge A123s to 0 volts, this will surely damage the cells.

30C discharge rate is very inflated for A123. They will not hold their voltage like you claim under that load.

You cannot 'zip charge' a 2S2P 2200mah pack across a 12V battery.

Here are some graphs that show A123 discharges

http://www.rcgroups.com/forums/attac...mentid=1948092

http://www.rcgroups.com/forums/attac...mentid=1948928

You can clearly see that at 80A, the cell doesn't even come close to holding its voltage. At 50A discharge under a cooling fan, the battery reaches 145F, this is 20A less than its 'rated' 30C. Seems like A123 Systems over-inflated the current capacity claims.
__________________
High Desert Raceplace, Grand Jct CO, Sanwa Exzes Plus Stick Radio, Spektrum,Thunderpower 230g, Modified Tri-Nut Novak GTB2, Ballistic 4.5t 550, 5.83lb SCTE Ten, Novak Sentry Brushless Dyno, Crossweight Setup Station, Junsi 20A power supply Icharger 20A Charger,TP610C, 22B, Novak Edge, Novak 13.5, SC10, Havoc Pro SC XDrive, Ballistic 17.5 Matthew Joseph Cordova
mattnin is offline   Reply With Quote
Old 02-12-2009, 11:14 PM   #23
Tech Apprentice
 
Join Date: Feb 2009
Location: houston mn
Posts: 67
Trader Rating: 10 (100%+)
Default a123/lipos

decided to go with lipos .new to lipos how do keep them balanced and in good working order thanks
Geewiz is offline   Reply With Quote
Old 02-13-2009, 01:33 AM   #24
Tech Elite
 
tom_chang79's Avatar
 
Join Date: Jul 2008
Location: Southern California
Posts: 2,591
Trader Rating: 13 (100%+)
Default

Does anyone know if you can use a LiPo-capable charger to charge A123 cells? A123 cells are LiFe based cells right?

I have a Pulsar 3 that can charge LiPo and was wondering if it's capable of charging A123 cells... Anyone know?
__________________
RIP TAP RC
tom_chang79 is offline   Reply With Quote
Old 02-13-2009, 05:58 AM   #25
Tech Champion
 
whitrzac's Avatar
 
Join Date: May 2008
Location: WI
Posts: 5,750
Trader Rating: 96 (100%+)
Default

the charger must have a specific A123 seting...
whitrzac is offline   Reply With Quote
Old 02-13-2009, 07:57 AM   #26
Tech Fanatic
 
Join Date: Jun 2006
Posts: 872
Trader Rating: 35 (100%+)
Default

To keep lipos balanced and in good working order, get a LIPO balance charger. If you want to be 100% safe, get a LIPO *only* charger, that way you don't get into an accident and charge your lipo as a NIMH. I seen a guy on the forums here selling a scorpion 2S for $50, that will charge your lipo up to 10 amps. Ask your local hobby shop for LIPO chargers, or go to Tower Hobbies and do a search. There are many for a reasonable price. It is best to store lipos about half full as well, and be sure to never leave them unattended while charging, and invest in a $20 lipo sack.

I use only 1 LIPO battery for my stock truck. I charge it before the race, then after the race I charge it again and continue on until the main. After the main, I just remove the battery from the truck and store it in my lipo sack until the next week, and repeat. I don't know of any other maintenance associated with these LIPO batteries. I do balance charge every time though.

Get a hard cased LIPO battery too, which are pretty much standard nowadays anyway. Any of the ROAR spec LIPO batteries has a voltage cutoff and current limit built in anyway, so the chance of them failing is much lower.
__________________
High Desert Raceplace, Grand Jct CO, Sanwa Exzes Plus Stick Radio, Spektrum,Thunderpower 230g, Modified Tri-Nut Novak GTB2, Ballistic 4.5t 550, 5.83lb SCTE Ten, Novak Sentry Brushless Dyno, Crossweight Setup Station, Junsi 20A power supply Icharger 20A Charger,TP610C, 22B, Novak Edge, Novak 13.5, SC10, Havoc Pro SC XDrive, Ballistic 17.5 Matthew Joseph Cordova
mattnin is offline   Reply With Quote
Old 02-13-2009, 10:00 AM   #27
Tech Fanatic
 
gndprx's Avatar
 
Join Date: Dec 2005
Location: Fort Mill, SC
Posts: 791
Trader Rating: 18 (100%+)
Default

Quote:
Originally Posted by whitrzac View Post
the charger must have a specific A123 seting...
Not entirely true.

I can charge my A123 packs on ANY charger, but I have a Hyperion LBA10 balancer that has an A123 high voltage cut-off built in.

So I have my ICE set to 8A LiPo mode (as high as it will go) and when the pack is full the balancer cuts the connection and the ICE just views this as a battery disconnected and beeps until you acknowledge it.
__________________
Carl Fisher
Team Xtreme RC
The Grove Racing Center

Last edited by gndprx; 02-13-2009 at 01:59 PM.
gndprx is offline   Reply With Quote
Old 02-13-2009, 12:44 PM   #28
Tech Elite
 
Join Date: Jun 2005
Posts: 2,570
Trader Rating: 26 (96%+)
Default

These are the cells that any car running hump packs should be running. They fit perfectly into a b44, give you 20 minutes of runtime w/ a 5.5 & can be charged in 10 minutes. You can built a plug that will wire them in series. I charged my 6.6volt 6900 pack in 10 minutes every time.
party_wagon is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Tekin RX8 1/8 Scale Brushless ESC Thread sharkman Electric Off-Road 18837 11-05-2017 05:29 AM
Electric 1/8th Scale conversion kits. DJ1978 Electric Off-Road 19923 06-12-2017 06:16 AM
RC equipments for Sale ijnek Malaysian R/C Racers 22836 09-09-2009 02:50 PM
Maxamps Life Battery packs lookieaefanboi Electric Off-Road 24 08-07-2009 06:26 AM
lipo direct charging. advanaw11 Radio and Electronics 7 07-13-2009 10:21 AM
Should A123 Lithium be allowed in stock? mattnin Electric On-Road 12 09-28-2007 10:31 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 09:07 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net