Wattflyer RC Network: RC Universe :: RCU Magazine :: RCU Forums :: RCU Classifieds :: RCU User Reviews :: RCU YouTube
Home Who's Online Calendar Today's Posts RealTime Post Spy Mark Forums Read
Go Back   WattFlyer RC Electric Flight Forums - Discuss radio control eflight > R/C Electric Power - Batteries, Chargers, ESCs and More > Batteries & Chargers
Register Members List Wattflyer Extras Articles Search Today's Posts Mark Forums Read Social Groups

Batteries & Chargers Discuss Li-P, Li-Ion, NiMh, Nicad battery technology and the chargers that juice 'em up!

Thank you for your support (hide ads)
Reply
 
Thread Tools Display Modes
Old 12-05-2013, 03:35 PM   #1
FlyWheel
Ochroma Lagopus Tekton
 
FlyWheel's Avatar
 
Join Date: Jul 2007
Location: Blackstock, South Carolina
Posts: 2,511
View FlyWheel's Gallery5
Thanked 70 Times in 68 Posts
Club: Lancaster County Fliers
iTrader: (0)
Friends: (3)
Question Basic question about field batteries

How do you determine the amp/hour rating of a deep cycle battery? I was at Wally World yesterday looking at batteries and not one (marine, car, motorcycle, none) were rated in amp/hours, milliamp/hours or any other understandable fashion. At least not by us 'normal' electrical folks. How does one determine the capacity of these batteries? Is there some sort of special code I should be looking for, and how is it translated into something that makes sense?

"Give a man a plane and he'll fly for a day.
Teach a man to build a plane and he'll fly for a lifetime"
FlyWheel is offline  
  Reply With Quote
Old 12-05-2013, 04:39 PM   #2
Yakfishingfool
Member
 
Join Date: Sep 2012
Posts: 155
Thanked 2 Times in 2 Posts
iTrader: (1)
Friends: (1)
Default

FYI - A new apples to apples system??


http://www.batterystuff.com/kb/tools...oup-sizes.html
Yakfishingfool is offline  
  Reply With Quote
Old 12-05-2013, 04:40 PM   #3
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 5,187
View solentlife's Gallery47
Thanked 211 Times in 208 Posts
Club: Founder Member Ventspils RC Club. Ex Waltham Chase and Meon Valley Soaring.
Awards Showcase

Scratchbuilders Award  Scratchbuilders Award  Outstanding Contributor Award  125mph Speed Demon 
iTrader: (0)
Friends: (8)
Default

Originally Posted by FlyWheel View Post
How do you determine the amp/hour rating of a deep cycle battery? I was at Wally World yesterday looking at batteries and not one (marine, car, motorcycle, none) were rated in amp/hours, milliamp/hours or any other understandable fashion. At least not by us 'normal' electrical folks. How does one determine the capacity of these batteries? Is there some sort of special code I should be looking for, and how is it translated into something that makes sense?
I have a simple answer : I would not buy such an item at Wally World. The better place to go especially in USA is an RV or Boat dealer who sells support and spare parts gear. Get the proper article.

Anyway - if you insist ... they MUST have a label somewhere saying A/hr .... it's usually listed separately but also in the overall spec name ...

ie : 12v80A/hr120a or similar ... meaning 12V .... 80 Amp.hr ..... can sustain 120 Amps for xxmins .... etc.

Nigel

222kph PKJ,EDF Concorde, Mini4,Mig3,T45,PKJ twin,ME109,Edge540,Cessna182,Skymaster Biplane,F15,F16,Badius,Ultimate,SE5,Qbee10,450 Heli,V911,J3 Cub Founder 9x forum: http://groups.yahoo.com/group/Flysky_RC_radio/
- Subscribe my Youtube: "solentlifeuk"
solentlife is offline  
  Reply With Quote
Old 12-05-2013, 05:37 PM   #4
kyleservicetech
Dennis V
 
kyleservicetech's Avatar
 
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 7,419
Thanked 655 Times in 638 Posts
Club: www.racinercclub.com (I'm the newsletter editor)
Awards Showcase

Outstanding Contributor Award  3kW  2kW  100mph Speed Demon 
iTrader: (1)
Friends: (18)
Default

Originally Posted by FlyWheel View Post
How do you determine the amp/hour rating of a deep cycle battery? I was at Wally World yesterday looking at batteries and not one (marine, car, motorcycle, none) were rated in amp/hours, milliamp/hours or any other understandable fashion. At least not by us 'normal' electrical folks. How does one determine the capacity of these batteries? Is there some sort of special code I should be looking for, and how is it translated into something that makes sense?
The question is - how many amps are you planning to pull out of your deep cycle battery while charging your models batteries?

IMHO, and from personal experience, those deep cycle batteries, even the 120 Ampere hour rated units should not be discharged at more than about 20 Amperes. Any higher, and you'd better plan on replacing your deep cycle battery once or twice a year.

I've purchased deep cycle batteries from Wally World, didn't have much good luck with it. If the battery doesn't indicate how many ampere hour capacity it has, go elsewhere! Also, if the battery has "Cold Cranking Amps" stated on it. You're likely looking at a plain lead acid battery with a "Deep Cycle" name plate on it.

Here is a bit more info on this subject:
http://www.wattflyer.com/forums/showthread.php?t=65723

DennyV
Retired and the days are just too short, busier than ever!
kyleservicetech is offline  
  Reply With Quote
Old 12-06-2013, 12:09 AM   #5
FlyWheel
Ochroma Lagopus Tekton
 
FlyWheel's Avatar
 
Join Date: Jul 2007
Location: Blackstock, South Carolina
Posts: 2,511
View FlyWheel's Gallery5
Thanked 70 Times in 68 Posts
Club: Lancaster County Fliers
iTrader: (0)
Friends: (3)
Default

Thanks. I have a small charger and will only be charging 3 cell LiPos at a time. I just want to be able to figure how many times I can do this before I start draining the battery too low (I may not even need a very large capacity battery).

Last question on this: I never intended to get a relabeled no-name brand at wally world, but where would I get a better deal? I know both boats and RVs use these batteries, but would a battery for one cost more (waterproofness?) that the other, even though they both may have the same capacity?

"Give a man a plane and he'll fly for a day.
Teach a man to build a plane and he'll fly for a lifetime"
FlyWheel is offline  
  Reply With Quote
Old 12-06-2013, 01:23 AM   #6
hayofstacks
Super Contributor
 
hayofstacks's Avatar
 
Join Date: Jan 2012
Location: Utah
Posts: 1,475
Thanked 110 Times in 109 Posts
iTrader: (0)
Friends: (4)
Default

I used to charge 3-6 3 cell lipos at a time in my station wagon when I went flying. I just popped the hood and hooked up 3 clip on chargers under the hood, and had 3 cigarette lighter chargers in the car. one in the front cigarette lighter plug, and one in each rear door. I had 7 1800 mah batteries charging at 1-2 amps each, and I could fly 2 planes continuously very rarely waiting for batteries. I always went out for 2-3 hours or more. I think my record was 9 hours.

no special battery tricks or anything. just an old 88 crown vic with an interstate battery. I never even started the car to charge up the battery. I did have a small harbor freight jumper box for the just in case I did over charge or left my head lights on.

one time I was running a junk battery and only had my spare keys, which didn't have a trunk key, where I kept the jump box. I had my 4000 mah 3 cell on me, so I hooked some alligator clips to it to the battery to pop the trunk. I couldnt help but try to crank it just to see what happened.it did crank the car over once or twice, but it also melted both alligator clips. ill bet with a thicker jumper it would have started it.

slow stock prop reversal. it flies! easily! 543 watt dual motor bipe slow stick. push-me-pull-you. 242 watt 3 channel slow stick. 365 watt mini ultra stick. 415 watt mini contender. 810 watt ultra stick .25e. 220 watt alpha 450 sport (retired).
hayofstacks is offline  
  Reply With Quote
Old 12-06-2013, 05:36 AM   #7
kyleservicetech
Dennis V
 
kyleservicetech's Avatar
 
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 7,419
Thanked 655 Times in 638 Posts
Club: www.racinercclub.com (I'm the newsletter editor)
Awards Showcase

Outstanding Contributor Award  3kW  2kW  100mph Speed Demon 
iTrader: (1)
Friends: (18)
Default

Originally Posted by hayofstacks View Post

one time I was running a junk battery and only had my spare keys, which didn't have a trunk key, where I kept the jump box. I had my 4000 mah 3 cell on me, so I hooked some alligator clips to it to the battery to pop the trunk. I couldnt help but try to crank it just to see what happened.it did crank the car over once or twice, but it also melted both alligator clips. ill bet with a thicker jumper it would have started it.
Yeah
Somewhere in youtube, a guy has a car with a completely dead battery. The video shows him connecting an A123 pack to the dead battery, waits for a minute or so, and starts the car. This was in Canada, in very cold weather.

Our LiPo and A123 batteries do have a very high current capability, if only for a few seconds. At any rate, my old Chevy S10 starter pulls about 120 Amps, not that much over what some of these higher powered electric motors pull.

DennyV
Retired and the days are just too short, busier than ever!
kyleservicetech is offline  
  Reply With Quote
Old 12-06-2013, 05:45 AM   #8
kyleservicetech
Dennis V
 
kyleservicetech's Avatar
 
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 7,419
Thanked 655 Times in 638 Posts
Club: www.racinercclub.com (I'm the newsletter editor)
Awards Showcase

Outstanding Contributor Award  3kW  2kW  100mph Speed Demon 
iTrader: (1)
Friends: (18)
Default

Originally Posted by FlyWheel View Post
Thanks. I have a small charger and will only be charging 3 cell LiPos at a time. I just want to be able to figure how many times I can do this before I start draining the battery too low (I may not even need a very large capacity battery).

Last question on this: I never intended to get a relabeled no-name brand at wally world, but where would I get a better deal? I know both boats and RVs use these batteries, but would a battery for one cost more (waterproofness?) that the other, even though they both may have the same capacity?

H'mmm
Lets see. Lets take a three cell 2500 Mah Lipo battery. Safe charging current would be 2.5 Amps for one hour. And, at 4.2 Volts per cell, and three cells, charging power would be 2.5 Amps times 4.2 Volts times three cells, or 31.5 Watts. Most chargers have about 85% efficiency, so the watts out of your deep cycle battery would be 31.5/0.85 or about 37 watts.

Watts equals volts times amps, or Amps equals watts/volts. For a 12 volt battery, that would be 37/12 or just over 3 amps. If you pick up a 70 Ampere Hour deep cycle battery, and never draw over 50% of its capacity, that would be about 35 Amp hours. And at a 3 amp draw, that would be about 11 hours of discharging time.

So, a standard 70 Amp Hour deep cycle battery would provide a full days flying, at one flight per hour that is. This is the main reason many folks using LiPos have several battery packs available. It's also the reason all but one of my models use the heavier, larger, lower voltage A123 cells. These cells can be recharged in 10 or 15 minutes. But for the bad news, if you've got a 12S2P A123 pack, my experience shows that charging one of these battery packs as a 6S4P pack at 30 Amps with a 120 Ampere Hour deep cycle battery will kill that deep cycle battery in a few months. (The A123 battery charger is pulling about 50 Amps out of the lead acid battery!)

DennyV
Retired and the days are just too short, busier than ever!
kyleservicetech is offline  
  Reply With Quote
Old 12-06-2013, 08:06 AM   #9
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 5,187
View solentlife's Gallery47
Thanked 211 Times in 208 Posts
Club: Founder Member Ventspils RC Club. Ex Waltham Chase and Meon Valley Soaring.
Awards Showcase

Scratchbuilders Award  Scratchbuilders Award  Outstanding Contributor Award  125mph Speed Demon 
iTrader: (0)
Friends: (8)
Default

Originally Posted by FlyWheel View Post
Thanks. I have a small charger and will only be charging 3 cell LiPos at a time. I just want to be able to figure how many times I can do this before I start draining the battery too low (I may not even need a very large capacity battery).

Last question on this: I never intended to get a relabeled no-name brand at wally world, but where would I get a better deal? I know both boats and RVs use these batteries, but would a battery for one cost more (waterproofness?) that the other, even though they both may have the same capacity?
If you really want to go this route ...

Get yourself to a Junk yard .. where they scrap old cars / trucks etc. You can pick up good batts cheap ... and if it only lasts a season or 2 - what have you lost ?

Even though I know about Lead Acid batts .. family having boats and RV's all my life - I don't buy over-rated over-priced gear ... I buy my batterys from scrap yards ... for my boats. My present cruising yacht has 2 100A/hr batterys and they are now over 4yrs old and still in excellent condition .. starting a 43HP diesel ... powering domestic and navigation gear for days ...

Next is to find a Truck Dealer who supplies batterys for trucks ... they do types that not only start diesels, but also power the hydraulic tail-lifts. Designed for both low and high power demand.

Next is to find a Golf Cart dealer and the supply of 6v packs that get put in series to provide 12v .. they are designed to carry fat b*****ds around 18 holes all day !

Then we get to normal retail outlets .... RV and Boat shops - they deal in this everyday for keeping Mum and Kids happy in their trailers / boats etc.

Bottom of the list is Wally World and similar - who sell the compromise form battery that will soon give up under stressed loads. I know there are probably loads of people out there still using their WW battery after xx years ....

One avenue that is forgotten ... a small battery can be used - even one that has given up starting your car ... for small - medium packs at less demanding rates ... by connecting up a relay charge circuit .. so when you have engine running - it is being charged up. Stop engine and relay drops out ... you use for charging lipo's.

A good book on all this : >

http://www.amazon.co.uk/Practical-Bo.../dp/0713661496

It may be about boats ... but has a wealth of easily understood information about battery types, charging .. discharging ... etc.

Nigel

222kph PKJ,EDF Concorde, Mini4,Mig3,T45,PKJ twin,ME109,Edge540,Cessna182,Skymaster Biplane,F15,F16,Badius,Ultimate,SE5,Qbee10,450 Heli,V911,J3 Cub Founder 9x forum: http://groups.yahoo.com/group/Flysky_RC_radio/
- Subscribe my Youtube: "solentlifeuk"
solentlife is offline  
  Reply With Quote
Old 12-06-2013, 08:46 PM   #10
FlyWheel
Ochroma Lagopus Tekton
 
FlyWheel's Avatar
 
Join Date: Jul 2007
Location: Blackstock, South Carolina
Posts: 2,511
View FlyWheel's Gallery5
Thanked 70 Times in 68 Posts
Club: Lancaster County Fliers
iTrader: (0)
Friends: (3)
Default

Thanks peeps. Living in the Southeast as I do, junk yards are NOT in short supply neither are repair shops or are places that service trucks. And of course we'all know The South is the uncontested RC capitol of the world!

"Give a man a plane and he'll fly for a day.
Teach a man to build a plane and he'll fly for a lifetime"
FlyWheel is offline  
  Reply With Quote
Reply

  WattFlyer RC Electric Flight Forums - Discuss radio control eflight > R/C Electric Power - Batteries, Chargers, ESCs and More > Batteries & Chargers

« Previous Thread | Next Thread »

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
question on battery size and composition to attain c & mah rating tobydogs Batteries & Chargers 10 11-10-2012 06:01 AM
Charging field batteries? FlyWheel Batteries & Chargers 3 07-24-2011 07:07 PM
Another micro(or batteries in general) battery question earthsciteach Indoor & Micro Electric Planes 1 05-08-2011 10:04 PM
How do you charge your field batteries? FlyWheel Batteries & Chargers 12 05-05-2011 05:24 PM


All times are GMT +1. The time now is 10:48 PM.


Powered by: vBulletin
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 2005 WattfFlyer.com
RCU Eflight HQ

Charities we support Select: Yorkie Rescue  ::  Crohn's & Colitis Foundation



Page generated in 0.20877 seconds with 39 queries