Freerails Home 
Home Search search Menu menu Not logged in - Login | Register

Because of non-railroad abuse of the site, new members MUST use their first names (at least) to join NO EXCEPTIONS!

Are you wary of Li-Po batteries?
 Moderated by: W C Greene Page:  First Page Previous Page  1  2  3  4   
New Topic Printer Friendly
 Rating:  Rating
AuthorPost
 Posted: Fri Jul 24th, 2015 03:24 am
   
31st Post
Tramcar Trev
Registered


Joined: Sat Mar 16th, 2013
Location: Gordon ACT, Australia
Posts: 415
Status: 
Offline
Ok here is a schematic how to wire up these protection pcb's. Now its as clear as spring water and I should have realised from my own meanderings why the do work as well as they do. the batteries are discharged in series and are charged individually eliminating the need for balance charging and preventing over discharge....This is a 3 cell board got one on order just to see if its the same as a 4 cell board.

http://www.ebay.com.au/itm/400935943160



____________________
There once was a man who said Damn!!
I perceive with regret that I am
A creature that moves
in predestinate groves
I'm not a Bus, I'm a tram
Back To Top

 Posted: Sun Aug 30th, 2015 08:18 am
   
32nd Post
Simon M
Registered
 

Joined: Thu Jun 18th, 2015
Location: Watson, ACT, Australia
Posts: 9
Status: 
Offline
I decided to buy one of those circuits, still waiting for it (them) to arrive. Did you have a schematic that you referred to above?



____________________
Cheers, Simon

Modelling Bradford (Exchange) platforms 1-5 C1954-1959
Back To Top

 Posted: Mon Aug 31st, 2015 05:55 am
   
33rd Post
Tramcar Trev
Registered


Joined: Sat Mar 16th, 2013
Location: Gordon ACT, Australia
Posts: 415
Status: 
Offline
Have a look at the sketch with this one, it shows how they are wired up; http://www.ebay.com.au/itm/4A-5A-PCB-BMS-Protection-Circuit-Board-for-3-Packs-18650-Li-ion-lithium-Battery-/400935943160?hash=item5d59a4fbf8



____________________
There once was a man who said Damn!!
I perceive with regret that I am
A creature that moves
in predestinate groves
I'm not a Bus, I'm a tram
Back To Top

 Posted: Mon Aug 31st, 2015 08:48 am
   
34th Post
davecttr
Registered
 

Joined: Sat Nov 9th, 2013
Location: United Kingdom
Posts: 309
Status: 
Offline
I am becoming more wary of Lipo batteries. These 8 were bought about a year ago and have varied use but only occasionally discharges to the Deltang Rx 3V low voltage cutoff. Some of the ones on the right have swelled alarmingly but all still retain their 4.18V maximum charge according to my meter. Have I stored them wrongly? Is this expected behaviour? The 220mAh ones on the left are only 2 pence per battery more expensive


Last edited on Mon Aug 31st, 2015 08:50 am by davecttr



____________________
Dave
Back To Top

 Posted: Tue Sep 1st, 2015 05:27 am
   
35th Post
Tramcar Trev
Registered


Joined: Sat Mar 16th, 2013
Location: Gordon ACT, Australia
Posts: 415
Status: 
Offline
davecttr wrote:
I am becoming more wary of Lipo batteries. These 8 were bought about a year ago and have varied use but only occasionally discharges to the Deltang Rx 3V low voltage cutoff. Some of the ones on the right have swelled alarmingly but all still retain their 4.18V maximum charge according to my meter. Have I stored them wrongly? Is this expected behaviour? The 220mAh ones on the left are only 2 pence per battery more expensive


Would not get to alarmed, lions of that size are not that dangerous, usually ooze brown muck all over the place but not enough lithium to start a fire unless all bundled together and deliberately ignited. Its Interesting that they have puffed up yet still work, maybe they are not vented? All the ones that I have had that have puffed up are dead and best used to throw on a camp-fire of some unsuspecting person.... They are not easy to dispose of here....



____________________
There once was a man who said Damn!!
I perceive with regret that I am
A creature that moves
in predestinate groves
I'm not a Bus, I'm a tram
Back To Top

 Posted: Sat Sep 5th, 2015 05:28 am
   
36th Post
Robert Comerford
Registered
 

Joined: Thu Feb 14th, 2013
Location: Glen Innes, Australia
Posts: 578
Status: 
Offline
Herb Kephart wrote: While we are on all this battery talk--

Does anyone know of a source for IiFe single cells that are flat? I find that thickness is the thing that limits whether a cell will fit, more than any other factor. LiPo cells seem to come flat, as a matter of course, but the few LiFe cells that I can find, are round.

I also understand that LiFe cells do not require protection
circuits. Consensus?

Herb
Herb I used the 700mAH soft packs for some small model plane power packs and to power  one of my train tests. I made 3S packs by prising apart one pack and adding the single cells to another 2S pack. That might be one way of getting a single cell.

 Of course if you plan to use commercial equipment designed only for a lipo it will not charge or cut off at the correct voltages for LiFe's.

They are available on this page
http://www.hobbyking.com/hobbyking/store/__218__85__Batteries_Accessories-LiFePo4.html

LiFePO4 cells do not have the propensity to go into thermal runaway that LiCoO2 ( lipo's) do with either overcharge or overdischarge but the life will be shortened somewhat if regularly used well beyond their design boundaries. We certainly discharged these cells at rates well beyond the norm but surprisingly none ever bloated like the larger soft packs do.
regards
 Bob Comerford

Back To Top

 Posted: Sat Sep 5th, 2015 08:49 am
   
37th Post
Herb Kephart
Super Moderator


Joined: Thu Jul 19th, 2007
Location: Glen Mills, Pennsylvania USA
Posts: 6135
Status: 
Offline
Thanks Bob, and bookmarked.

Last time that I tried to turn a three cell LiPo into a two cell, I managed to stab the bloody thing with an xacto knife and it had a hissy fit. If I do in again, I'll know better.

(axe?) 

Herb



____________________
Fix it again, Mr Gates--it still works!"
Back To Top

 Posted: Mon Sep 7th, 2015 07:07 pm
   
38th Post
Pete Steinmetz
Registered
 

Joined: Tue May 29th, 2012
Location: Encinitas, California USA
Posts: 75
Status: 
Offline
Swelling batteries mean there was contamination in the manufacturing process.

All of my cells and packs that were purchased from RC sources have swollen and failed within about a year.

Companies that sell to the RC market do so because they can't sell to Dell or Apple. This is due to lack of automated equipment and inprocess quality control.



____________________
Pete Steinmetz
Dead Rail Society
Back To Top

 Posted: Tue Sep 8th, 2015 09:27 pm
   
39th Post
Pete Steinmetz
Registered
 

Joined: Tue May 29th, 2012
Location: Encinitas, California USA
Posts: 75
Status: 
Offline
Rod Hutchinson wrote:
Pete,

I have picked up on your comment and similar from other sources.

Could it be that there are possibility 3 levels of LiPo quality in descending order?

1. Hi end cameras, computers etc.
2. Bricks and mortar RC shops
3. If so, what would you view be on 3rd party providers such as those on eBay?


I supposed there could be many levels of quality. I put RC batteries in the low quality. E bay is buy at your own risk. It is hard to tell from the limited descriptions and specifications.



____________________
Pete Steinmetz
Dead Rail Society
Back To Top

 Posted: Sun Mar 13th, 2016 03:42 am
   
40th Post
Pete Steinmetz
Registered
 

Joined: Tue May 29th, 2012
Location: Encinitas, California USA
Posts: 75
Status: 
Offline
Bob D wrote:
Has anyone in the model railroading world actually witnessed a train catching fire from using LiPos that were charged according to specs? My LiPo charger says to charge them at 1amp/hr. It takes 2 hours to charge a 2000Mah pack and 2hrs-15mins to charge a 2200Mah pack.

The only fires I've read about were from packs installed in planes or cars that get jostled around quite a bit or from fast charging.

I keep seeing the same folks on other forums express caution about using LiPos, but have yet to seen a train go up in smoke/flame, and of course they have provided no proof of it happening.

BobD.


Bob:

You must have a lot of space to be able to use a 2000 ma pack. At a 1 amp charge rate, you are charging at 1/2C which is kind to the pack.

I have never heard of a train catching fire.

The best way to be safe is to use a pack with a protection circuit. The RC guys are not able to use protection due to the high discharge rates.
Train guys have much lower discharge rates and are encouraged to use packs with protection.

I use 240ma, 400ma, and 450ma packs. All have protection. Protection circuits, called PCMs, protect against over charge, over discharge, and short circuits.

None of the cells I use are from the RC world. All are low discharge rate cells.

Never had a problem

Pete Steinmetz



____________________
Pete Steinmetz
Dead Rail Society
Back To Top


 Current time is 01:02 am
Page:  First Page Previous Page  1  2  3  4   

Top



UltraBB 1.172 Copyright © 2007-2016 Data 1 Systems