R/C Tech Forums

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

Reply
 
Thread Tools Search this Thread
Old 01-13-2015, 05:31 AM   #631
Tech Apprentice
 
Miholc's Avatar
 
Join Date: Oct 2011
Location: Slovenija, Europe
Posts: 66
Default

Quote:
Originally Posted by Skiddins View Post
Why not get the usable voltage test to stop at 7.5V etc for the pack?
No-one will be running a pack below as low as 6.6V unless they've forgotten to change it from the last run

3.3V under 200W load.... the voltage bumps back at rest to about 3.6V/cell... meaning it is more or less empty

Why 3.3V/cell -> to see how much cells are matched in a pack. Poorly matched cells can differ up to 0.2V! Good come under 40mV.
__________________
https://www.facebook.com/mholctuning
www.lipo.si
Miholc is offline   Reply With Quote
Old 01-13-2015, 11:06 AM   #632
Tech Fanatic
 
Join Date: Aug 2008
Location: Floresville, TX
Posts: 810
Default

Quote:
Originally Posted by jedi View Post
John, are you using a 24 volt power supply to charge 2s batts at 25amps or will a 12 volt power supply do? If not, what is the maximum charge rate using a 12 or 14 volt power supply? Thanks.
12V Car Battery so I can discharge at over 20 amps (cannot do that with a power supply on the ICHARGER). Don't know what the max charge rate is for a 2C pack with a 12V input power, but I've done 25 amp and no problem from the charger point of view (just make sure your battery has enough C rating to take that charge rate), but I usually charge at 20.
John Wallace2 is offline   Reply With Quote
Old 01-13-2015, 11:53 AM   #633
Team EAM
 
EAMotorsports's Avatar
 
Join Date: Dec 2001
Location: Murfreesboro, TN
Posts: 9,006
Trader Rating: 79 (100%+)
Send a message via AIM to EAMotorsports
Default

Quote:
Originally Posted by John Wallace2 View Post
12V Car Battery so I can discharge at over 20 amps (cannot do that with a power supply on the ICHARGER). Don't know what the max charge rate is for a 2C pack with a 12V input power, but I've done 25 amp and no problem from the charger point of view (just make sure your battery has enough C rating to take that charge rate), but I usually charge at 20.
Sure you can discharge at 40 amps on the icharger using the power supply if you use a resistive load such as bulbs or resistor bank. I do it all the time.

With my 12v power supply I can charge 2 2S packs at 40 amps each with no issues either. 24V is not required.

EA
__________________
Contact Us
Team EAM, Our Facebook
Xray | RCAmerica | Hudy | Apex RC | RC Mission | Killer Concepts | AVID | Hobbywing.
EAMotorsports is offline   Reply With Quote
Old 01-13-2015, 12:37 PM   #634
Tech Adept
 
dave-man's Avatar
 
Join Date: Jul 2010
Posts: 243
Trader Rating: 14 (100%+)
Default

Quote:
Originally Posted by Miholc View Post
Capacity winner of 2S HC pack: LRP 7500, 7200mAh usable from 4.2-> 3.3V/cell @ 200W constant discharge.
This may be a silly question but how can you measure capacity?
dave-man is offline   Reply With Quote
Old 01-13-2015, 03:35 PM   #635
Tech Regular
 
jedi's Avatar
 
Join Date: Nov 2002
Posts: 422
Trader Rating: 2 (100%+)
Default

Quote:
Originally Posted by EAMotorsports View Post
Sure you can discharge at 40 amps on the icharger using the power supply if you use a resistive load such as bulbs or resistor bank. I do it all the time.

With my 12v power supply I can charge 2 2S packs at 40 amps each with no issues either. 24V is not required.

EA
Thanks EA and John. That's the info I was looking for.
__________________
It's better to be lucky than to be good......when it comes to getting a clean run in qualifying!
jedi is offline   Reply With Quote
Old 01-13-2015, 04:19 PM   #636
Tech Elite
 
Skiddins's Avatar
 
Join Date: Feb 2006
Location: Windsor, UK
Posts: 4,655
Default

Quote:
Originally Posted by dave-man View Post
This may be a silly question but how can you measure capacity?
Fill it up, then discharge it, measure how much comes out.
__________________
Xray T4'17, T4'14 (Wet Car)
Xray X12 2017
Xray X1'16
wlrc.co.uk (West London Racing Centre)
RCDisco.co.uk
Skiddins is offline   Reply With Quote
Old 01-13-2015, 05:35 PM   #637
Tech Fanatic
 
Join Date: Aug 2008
Location: Floresville, TX
Posts: 810
Default

Quote:
Originally Posted by EAMotorsports View Post
Sure you can discharge at 40 amps on the icharger using the power supply if you use a resistive load such as bulbs or resistor bank. I do it all the time.

With my 12v power supply I can charge 2 2S packs at 40 amps each with no issues either. 24V is not required.

EA
Of course Eric, with enough light bulbs you can discharge at very high rates and don't even need the ICharger (just like we did with Nicads and NIMH cells). But with only the ICharger, the max discharge rate in the non regenerative discharge mode (at least on the 306B that I have) is 20 amps unless you attach additional light bulbs and/or resistors. I just bought a car battery and use the regenerative discharge mode and I discharge at as high a rate as I'm comfortable with. BTW Those light bulbs came in handy one night when I was racing in Ohio and the power went out during my race. All the NiMH batteries being discharge with light bulbs provided enough light to find all the cars that were racing when the lights went out.

Last edited by John Wallace2; 01-14-2015 at 04:14 AM.
John Wallace2 is offline   Reply With Quote
Old 01-13-2015, 07:24 PM   #638
Tech Regular
 
slowpoke68's Avatar
 
Join Date: Dec 2008
Location: Moutains near you🤔
Posts: 381
Trader Rating: 28 (100%+)
Default

Quote:
Originally Posted by Miholc View Post
You are obviously not understanding how 4010 charger measures the IR.

IR can only be measured on the 4-wire Kelvin method, you can see more here: https://www.youtube.com/watch?v=N8QhXewcAXY

http://www.allaboutcircuits.com/vol_1/chpt_8/9.html

If you read instructions carefully you will note the charger gives you few different IR readings :-)


Now the answer what causes the IR to change. It is the temperature! Generally - more temperature gives lowe IR, but not all LiPo chemistries have the same behaviour. If you can controll the temperature you can heat up the cells from room temperature up to 110 F you will definately see IR decreasing.

Charging at higher amps heats up the cells, thus IR goes down. You can also cycle the lipos fast in sync mode on 4010... 1S goes nice with 40Amp discharge

Edit: Yes, you need to have also balancing conector setup for 1S to have IR measured correctly. Sorry...

I measured a lot of LiPos lately. No time for report yet :/

So far:
IR winners: LRP 7500 big mama at 40C only 0.7/0.9 mOhm/cell on the test sample.
Capacity winner of 2S HC pack: LRP 7500, 7200mAh usable from 4.2-> 3.3V/cell @ 200W constant discharge.
great info thanks.ido have the balance plug set up for my 1 cell.i was told you need it for the icharger 4010
__________________
coyote hobbies raceway,tq raceway,kenon hobby.apex speed shop
Airtronics m12s,hobbywing,schuur speed,associated b6 b5m t5m sc5m,mini z,ta05 v2,some rock crawlers,and still counting....
slowpoke68 is offline   Reply With Quote
Old 02-09-2015, 12:38 PM   #639
Tech Elite
 
JayL's Avatar
R/C Tech Elite Subscriber
 
Join Date: Mar 2006
Location: Ca
Posts: 2,831
Default

What are the optimal volts for:

Storage
&
Discharge right before recharge before run
__________________
MOD: A800 R1 Digital-2 HW G2 4.5T|||VTA: A700 Orca VX3 R1 25.5V16 |||F1:
Roche 2016 R1 Digital-2 R1 21.5V16|||Sanwa M12S|||iCharger 406Duo
JayL is offline   Reply With Quote
Old 07-16-2016, 03:14 PM   #640
Tech Rookie
 
Join Date: Jun 2016
Posts: 5
Default Great info

Quote:
Originally Posted by Outlaw 44 View Post
All that high charge/discharge rate hoopla is bull**** if you ask me.

Been racing oval for 22 years now. I think I have a decent feel for what actually makes my car go faster, that stuff isn't one of them.

I race in St-Hyacinthe Quebec, TOUR Spec class with the Salvas Brothers every two weeks, 146 foot runline on new CRC carpet. Two Sundays ago I was part of a 5-car field which all finished on the same lap (an average lap is about 3.6 seconds) after a 100-lap race. The race lasted about 6 minutes.

This past Sunday at the New Year's Dash in Oneida NY, Steve Salvas finished 2nd in the TOUR Spec A-main against some of the best drivers in the business, Eric had a 2nd or 3rd place car before getting involved in a wreck. this is just to give you an idea of who these guys I race against are.

I charge between 6 and 8 amps between qualifying and feature rounds, and never discharge between runs. I'll charge at 12 amps during practice just so I can hit the track again faster. There's no point in charging at a higher rate, my battery will just be done charging before my motor gets a chance to cool down from it's last practice run or before I can finish making changes to my chassis.

I've been running the same SMC 7000mah battery for all my practice/heat/main runs since I bought it new in June. I don't see the need for high charge or discharge rates period, I truly believe that the life span you lose in the battery isn't worth the infinately small extra ''punch'' I can't even feel on the track anyways. The battery still feels like it did back when I bought it, I think a less aggressive approach to charging has helped me keep it in good shape.

Before June 2014 I was running a used battery I bought from a fellow racer. When I went to the new battery, I couldn't feel any difference in speed. What helped me is working on the chassis, and managing my tires. Some hints from the Salvas brothers helped me on the chassis setup end of things.

Don't give into the hype
That is the best info and true to the point.I don't see a big difference in ridiculously high charge rates either.I race 17.5 TC class and charge at my SMC 2s 6000 mah cells at 2c and I place in the A mains consistently at Club races as well as state and national events.And I race a against some big names that totally just heat the packs up charging at 5c discharging at 5c. Just to get a tiny bit more punch.And lower ir readings. Man I'm pulling the same lap times as these big name factory guys lol.So I back up the statement don't believe the hype!

Last edited by matt2810; 07-16-2016 at 03:24 PM. Reason: Add more
matt2810 is offline   Reply With Quote
Reply



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 09:58 PM.


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