R/C Tech Forums

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

Reply
 
Thread Tools Search this Thread
Old 12-07-2007, 01:10 PM   #241
Tech Regular
 
Shawn Palmer's Avatar
 
Join Date: Sep 2003
Location: Speed Passion USA Support HQ
Posts: 498
Default

That's the only one I've looked at so far.
__________________
Shawn Palmer
Speed Passion USA Sales Manager
USAsupport <at> King-Golden <dot> com
www.SpeedPassion.net
www.SpeedPowerrc.com
Shawn Palmer is offline   Reply With Quote
Old 12-07-2007, 05:50 PM   #242
Tech Champion
 
JayBee's Avatar
 
Join Date: Mar 2004
Location: 12TH-MAN COUNTRY
Posts: 6,813
Trader Rating: 31 (100%+)
Default

Quote:
Originally Posted by Shawn Palmer View Post
Skiddins:
Can you ask him exactly and in detail how the cutoff is supposed to work please? I'm intimately familiar with the several different voltage averaging software methods currently being used to measure on and off loaded voltage at the ESC.

ESC's are all merely "on and off switches" where the "switch" is being manipulated thousands of times per second. When the switch is "on" the ESC is drawing full throttle power, and when it's "off" it's drawing zero. At half throttle, the "on" full power pulses equal the "off" power pulses to get the observed result - half power to the car. Reto is correct in that occasionally the full power pulses under heavy accelleration loads dip the pack voltage below 6v, but the next off pulse allows it to rebound back to the point where the "average" voltage remains above 6v. The point where the pack resting voltage (motor not running) was at 5v in my test was the real killer - the ESC allowed the motor to run even when the "average" voltage was WELL under 6v!

ESC and motor were installed in my mi3 with an AstroFlight Whattmeter in line with the battery to give me real time (average) voltage between the on and off pulses of the ESC. I put the car on a slick surface and gave it varying loads from no pressure (about 5A of load) to heavy pressure (15A of load) and watched the voltage. When it came down to 6v, I released all pressure to alleviate the disparity between on and off pulses as much as possible, and in order to protect lipos from failure the ESC should have cut off at that point PERIOD. But it kept running it down to 3.5v where it simply stopped becuse of lack of voltage to the ESC - NOT because it was protecting the pack. The pack only rebounded voltage to 5v (still WAY UNDER SAFE LIPO VOLTAGE) and then the ESC allowed it to run the motor again! This behavior is unnaceptable for a "lipo safe" ESC.

If someone in a technical dpt. @ LRP would like to contact me and discuss, please feel free:
813-889-9691
[email protected]
Quote:
Originally Posted by Shawn Palmer View Post
Test #2 just complete:

Ran the car with Whattmeter attached to keep track of voltage.

When the resting voltage came all the way down to 6.0 (already too far) that's when the power reduction came in (from just the pack being depleted, or software on the ESC???). If you run it this far on a lipo, you've just damaged it.

The car would still run until the under load voltage started to flirt with 4.5V. MAJOR lipo damage happening at this level. The ESC stopped the motor, the pack rebounded to 5.5v, and it allowed the car to run again for a few seconds.

So the results are not as bleak as last night, but still the same - the voltage threshold is TOO LOW to be safe for lipos if you run all the way to the "slowdown point".

Still more to do.
Right On Shawn...THANKS!!
__________________
R C 3 G R A F I X _ F U S I O N . G R A P H I X _ S E A T T L E - R/C - R A C E R S _ E M E R A L D C I T Y R C . C O M

A E - 12R5.2 _ S M - REV8 PRO
JayBee is offline   Reply With Quote
Old 12-09-2007, 08:49 AM   #243
Tech Elite
 
Skiddins's Avatar
 
Join Date: Feb 2006
Location: Windsor, UK
Posts: 4,762
Default

Shawn, can the remaining capacity be estimated after a run buy measuring the voltage of the pack?

i.e. running 19t in the wet today the charger said it was putting 1280mAh back into the pack after a run. The voltage of the pack right now is 7.96V

What would the voltage be if the pack was at 80%, 50% etc? is there a common set of 'rules' for all LiPo's?

Thanks
Skiddins
__________________
Xray T4'18, T4'14 (Wet Car)
Xray X12 2018
Xray X1'16
wlrc.co.uk (West London Racing Centre)
RCDisco.co.uk
Skiddins is offline   Reply With Quote
Old 12-10-2007, 05:01 AM   #244
Tech Master
 
Join Date: Jun 2005
Location: Brisbane. Australia
Posts: 1,820
Trader Rating: 5 (100%+)
Default

hey guys looking for a new charger, i want to do lipo and nimh iowned and ice and found a few flaws.
it doesnt have the peak sensitivity i found my ep4200 cells would temp cut 46'c at 3 mv most times.
doesnt tell u time since peak eleapsed.
and lipo charge at 1c. though shawn made some points that this doesnt make much difference but say u have a 3200 pack and charge at 5 amps wont it take on more mah in 15 min than 3.2 amps or does the cc/cv cancel this out?
just trying to get some opinions on a good alround charger.
cheers
__________________
Josh P
to make Keith happy
Corally phi
M11
SP GT
SP 5.5,17.5
aus jd 2703 is offline   Reply With Quote
Old 12-10-2007, 07:58 AM   #245
Tech Regular
 
Shawn Palmer's Avatar
 
Join Date: Sep 2003
Location: Speed Passion USA Support HQ
Posts: 498
Default

Skiddins:
Remaining capacity and resting voltage do have a loose relationship, but it's a little different among each brand and size of pack.

From fully discharged going "up":
6.6-7.0v = basically empty. The voltage difference between 5% full (~7.0v)and 0% full (6.0v) is pretty dramatic.

7.5-7.75 = the "middle area" of anywhere between 20% and 70% full

7.75-8.0 = about 80-90% full

Anything over 8.0 = 90% or more full.

Again - loose rules here, and each type and capacity of pack will be a little different.


aus jd:
5A charge rate on a 3200 pack:
The charge time/rate are both slaves to the CC/CV lipo charging parameters. Once the pack voltage gets to 8.4v, the current ramps down to maintain 8.4v and no higher. So if you started with a 1/2 charged pack, you'd be charging at some figure over 3.2A for maybe 5 or 6 minutes.

From fully empty, you'd be able to be above 3.2A for about 15 min yes. And yes, it would be taking in more Mah than if it was set for 3.2A, but the reduction in charge time would be small. Maybe 5-8mins less.

So again - you're trading a few minutes faster charge time for an overall reduction in cycle life/performance of the pack. In my opinion, that's just not a trade I'm willing to make.
__________________
Shawn Palmer
Speed Passion USA Sales Manager
USAsupport <at> King-Golden <dot> com
www.SpeedPassion.net
www.SpeedPowerrc.com
Shawn Palmer is offline   Reply With Quote
Old 12-10-2007, 12:04 PM   #246
Tech Elite
 
Skiddins's Avatar
 
Join Date: Feb 2006
Location: Windsor, UK
Posts: 4,762
Default

Thanks

Used my Core 5000 for the first time in anger today in 19t and was very pleased.
Car was as fast as the NiMh's in a straight line but I couldn't get my setup right (it was cold, wet and slippery all day)

After each 5 minute run it only needed 1280mAh to fill the pack back up.
It will be interesting to see how much more power I use when it's dry.

Skiddins
__________________
Xray T4'18, T4'14 (Wet Car)
Xray X12 2018
Xray X1'16
wlrc.co.uk (West London Racing Centre)
RCDisco.co.uk
Skiddins is offline   Reply With Quote
Old 12-11-2007, 11:25 PM   #247
Tech Regular
 
Shawn Palmer's Avatar
 
Join Date: Sep 2003
Location: Speed Passion USA Support HQ
Posts: 498
Default

I doubt it'll be much more even under dry conditions. Most of us running stock 13.5t with them here are charging back 1100-1400mah after a 5 min run.
__________________
Shawn Palmer
Speed Passion USA Sales Manager
USAsupport <at> King-Golden <dot> com
www.SpeedPassion.net
www.SpeedPowerrc.com
Shawn Palmer is offline   Reply With Quote
Old 12-12-2007, 01:53 AM   #248
Tech Champion
 
heavy's Avatar
R/C Tech Elite Subscriber
 
Join Date: Jul 2002
Location: Brisbane
Posts: 5,136
Trader Rating: 20 (100%+)
Default

If it onlytakes 1400 after a 13.5 5 minute race can I use mine for 2 races before I top it up - will there be much drop off in performance in the second race ?
__________________
Honorary Life Member Logan RCCC -Mi6EVO and Serpent F1
Honorary Life Member Chargers RCCC -Cat K1 Aero
Life Member Bayside RCCC -Schumacher Mi6EVO
Boondall. SuperShot, XX, SVR,Schumacher Storm BigWig
heavy is offline   Reply With Quote
Old 12-12-2007, 05:41 AM   #249
Tech Elite
 
Skiddins's Avatar
 
Join Date: Feb 2006
Location: Windsor, UK
Posts: 4,762
Default

Anyone else done any 'real world' comparisons between NiMH and their LiPo's.

I.e. is one or the other noticabvly faster?

Skiddins
__________________
Xray T4'18, T4'14 (Wet Car)
Xray X12 2018
Xray X1'16
wlrc.co.uk (West London Racing Centre)
RCDisco.co.uk
Skiddins is offline   Reply With Quote
Old 12-12-2007, 07:01 AM   #250
Tech Regular
 
Shawn Palmer's Avatar
 
Join Date: Sep 2003
Location: Speed Passion USA Support HQ
Posts: 498
Default

heavy:
Not much if any at all, but check your lap times to be sure :-)
__________________
Shawn Palmer
Speed Passion USA Sales Manager
USAsupport <at> King-Golden <dot> com
www.SpeedPassion.net
www.SpeedPowerrc.com
Shawn Palmer is offline   Reply With Quote
Old 12-14-2007, 10:13 PM   #251
Tech Champion
 
Join Date: Nov 2002
Location: Chicago, IL
Posts: 7,664
Trader Rating: 37 (100%+)
Default

Shawn,

Since you like Hyperion chargers do you know about this one...

EOS 0610i NET


What does this mean...the 300mA balance thing. Also to plane/heli guys not discharge much. I don't see any discharge feature on some of these or they are low like 1amp :P

'Built-in Hyperion LBA10/300 Balancer with 10A max rating and 300mA max balance rate per cell."


===

Was looking at some of the chargers you mentioned or just an ICE for the Core 5000.
Nexus is offline   Reply With Quote
Old 12-15-2007, 12:43 AM   #252
Tech Elite
 
andrewdoherty's Avatar
 
Join Date: Jan 2005
Location: ★Wylie, TX★
Posts: 3,776
Trader Rating: 47 (100%+)
Default

Quote:
Originally Posted by Skiddins View Post
Anyone else done any 'real world' comparisons between NiMH and their LiPo's.

I.e. is one or the other noticabvly faster?

Skiddins
Depends what you mean by noticeably. From what I have seen when fresh NiMh's with good #'s are compared to the Orion 4800, the NiMh has up to 3 tenths a lap on the Lipo. We haven't had enough track time with the Core or any of these other new high capapcity/hard cased lipos to know much. I am hoping they show a little better performance than the Orions.
__________________
"Whether you think you can, or think you can't, you're right." -Henry Ford
"[Driving] Genius is 1% inspiration, and 99% perspiration" -T.A. Edison
|◤Hobbywing◢|◤SpeedzoneUSA.com◢|◤Pro-One◢|
|◤ReflexRacing.net◢|◤Protoform◢|◤AVID R/C◢|
andrewdoherty is offline   Reply With Quote
Old 12-15-2007, 02:12 AM   #253
Tech Champion
 
JayBee's Avatar
 
Join Date: Mar 2004
Location: 12TH-MAN COUNTRY
Posts: 6,813
Trader Rating: 31 (100%+)
Default

Quote:
Originally Posted by Nexus View Post
Shawn,

Since you like Hyperion chargers do you know about this one...

EOS 0610i NET


What does this mean...the 300mA balance thing. Also to plane/heli guys not discharge much. I don't see any discharge feature on some of these or they are low like 1amp :P

'Built-in Hyperion LBA10/300 Balancer with 10A max rating and 300mA max balance rate per cell."


===

Was looking at some of the chargers you mentioned or just an ICE for the Core 5000.
That's a really good charger there Nexus I could try and explain the 300mA balancing rate thing but I'd get my thoughts all wrapped around each other and wouldn't make a damn bit of sense IMO though, it's an important feature in a balancer.
Shawn chime in anytime......
__________________
R C 3 G R A F I X _ F U S I O N . G R A P H I X _ S E A T T L E - R/C - R A C E R S _ E M E R A L D C I T Y R C . C O M

A E - 12R5.2 _ S M - REV8 PRO
JayBee is offline   Reply With Quote
Old 12-15-2007, 03:38 AM   #254
Tech Addict
 
Skill's Avatar
 
Join Date: Apr 2003
Location: Doncaster, England
Posts: 537
Default

Put my Core lipo on a balancer yesterday after running it for about 6 meetings, it was still that well balanced that the balancer didn't even need to kick in.
Skill is offline   Reply With Quote
Old 12-15-2007, 03:49 AM   #255
Tech Champion
 
JayBee's Avatar
 
Join Date: Mar 2004
Location: 12TH-MAN COUNTRY
Posts: 6,813
Trader Rating: 31 (100%+)
Thumbs up

Shawn have you received my package?
__________________
R C 3 G R A F I X _ F U S I O N . G R A P H I X _ S E A T T L E - R/C - R A C E R S _ E M E R A L D C I T Y R C . C O M

A E - 12R5.2 _ S M - REV8 PRO
JayBee is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
SMC Lipos 7.4 5000mah wfdfiremedic Electric On-Road 624 08-27-2008 10:09 AM
CORE 5000MAH LIPO FOR SALE jsfrcfrk R/C Items: For Sale/Trade 5 08-05-2008 11:09 AM
Core R/C 5000mah 2s 7.4volt LiPo SchuMi2 Australia For Sale/Trade 2 06-08-2008 04:24 AM
New SMC Lipos 7.4v 2s 4000 and 5000mah HardCase IOwNMkeG R/C Items: For Sale/Trade 4 03-30-2008 01:54 PM
Core RC 5000mah Hard Cased LiPo - Brand New!! XACDesigns R/C Items: For Sale/Trade 8 01-08-2008 11:25 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 10:39 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