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Are you wary of Li-Po batteries?
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 Posted: Tue Jul 14th, 2015 07:53 pm
   
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Tramcar Trev
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Best "tool" for the separation of batteries in a "Pack" to replace one cell or modify the pack is in your kitchen drawer.... Its a plastic egg lifter; work it in between the cells till the glue lets go.

Kari Byron (turns me on, nude pics here; http://www.nudography.com/Celebrities/kari_byron.aspx ) and she was trying to get some lithium's to "explode" on Mythbusters without much success and was having the same problem as you Herb, the foil kept tearing until she used a plastic spatula....

Needless to say if you are going to try this at home do it with a view to doing it safely, i.e do it outdoors, wear safety goggles and gloves and a canvas jacket (or similar).

I'm not advocating the practice but it can be done with reasonable safety as long as you are confident and a competent hand with a soldering iron to resolder the leads....



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 Posted: Tue Jul 14th, 2015 08:45 pm
   
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Tramcar Trev
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Tony Walsham wrote:
So smaller single cell Li-Po batteries are available with protection pcb's
How about bigger Li-Po packs with say 4 cells for Large Scale locos?
Are they available with protection circuits?
Not sure Tony. I make up my own packs and use a protection board that connects to EACH CELL rather than just one on the final output.
For cells this one works for me; http://www.ebay.com.au/itm/PCB-Charger-4-Packs-Li-ion-Lithium-Battery-Recharge-4-5A-Protection-Board-New-/221807411514?pt=LH_DefaultDomain_15&hash=item33a4c0813a
this board protects both charge and discharge and is cheap enough. It also ( I have discovered) balances the cells when being charged...
I use either hobby King cells or buy them from china via eBay viz; http://www.ebay.com.au/sch/i.html?_odkw=li-ion+battery+3.7v&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.Xli-Po+battery+3.7v.TRS0&_nkw=li-Po+battery+3.7v&_sacat=0

Advantage is that these cells come pre wired so you are not soldering to the battery tags. PLEASE WHEN YOU ARE CUTTING THE LEADS CUT THEM SEPARATELY for what are obvious reasons.

Im not sure why there is not someone making up cells commercially, certainly a demand for them and they can be made up to fit into available spaces. Using individual cells does not mean they have to be made up into one bundle....

I use an iMax B6 charger, got it via eBay at half the price of my local supplier....



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 Posted: Wed Jul 15th, 2015 12:09 am
   
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Tony Walsham
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I can tell you why no-one is prepared to make Li-Po packs commercially here in Australia.
1. Users would whinge and moan about the cost compared to the Chinese makers.
2. No insurance company would be prepared to cover a maker for the consequences of incompetent end users.



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 Posted: Wed Jul 15th, 2015 12:25 am
   
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Tramcar Trev
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Tony Walsham wrote:
I can tell you why no-one is prepared to make Li-Po packs commercially here in Australia.
1. Users would whinge and moan about the cost compared to the Chinese makers. Yes I can understand that. The cost differentials in various markets never seems to amaze me, Australia always seems to be the most expensive place onn the planet to buy anything.
2. No insurance company would be prepared to cover a maker for the consequences of incompetent end users. True, or even accidental damages. See how hard it is to claim against a lead acid battery manufacturer whose battery has internally shorted and destroyed the front end of a car.



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 Posted: Thu Jul 16th, 2015 10:39 am
   
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Bob D
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I just ordered 2 more 11.1v, 2200Mah LiPo battery packs from All-Battery to install in my last remaining steam engine conversions. I'll have 2 NiMh and 5 LiPo powered steamers when I'm done.

In another topic it was determined that LiPos have a higher voltage at the low end due to less internal resistance of the chemical makeup. I believe I can actually see the difference when I swap batteries. I know my Williams brass 4-8-4 N&W J starts at a lower turn of the knob with the LiPo than with the NiMh.

I think fast-charging LiPos is bad Ju-Ju and would never do it or recommend it, nor do I feel the need to poke around inside them to see what makes them tic.

Actually, the first thing I look at when choosing a battery pack is: will it fit, then voltage, then Mah, and lastly chemical makeup.

I haven't tried it yet but I feel a battery with 1000 Mah will probably do a home-sized layout just fine, 2000 Mah if you want to run at shows.

BobD.

Last edited on Thu Jul 16th, 2015 10:40 am by Bob D



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 Posted: Sun Jul 19th, 2015 05:32 pm
   
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Simon M
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Tramcar Trev wrote:
For cells this one works for me; http://www.ebay.com.au/itm/PCB-Charger-4-Packs-Li-ion-Lithium-Battery-Recharge-4-5A-Protection-Board-New-/221807411514?pt=LH_DefaultDomain_15&hash=item33a4c0813a
this board protects both charge and discharge and is cheap enough. It also ( I have discovered) balances the cells when being charged...


This is interesting Trev. I had a look but the specs are fairly light on in the eBay ad. I'm thinking this little cheapie board would allow 3s or 4s to be left installed for recharging. So would this board have a bridge rectifier/surge protector element on board-which would allow charging via the track?



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 Posted: Sun Jul 19th, 2015 07:54 pm
   
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Tramcar Trev
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Simon M wrote:
Tramcar Trev wrote:
For cells this one works for me; http://www.ebay.com.au/itm/PCB-Charger-4-Packs-Li-ion-Lithium-Battery-Recharge-4-5A-Protection-Board-New-/221807411514?pt=LH_DefaultDomain_15&hash=item33a4c0813a
this board protects both charge and discharge and is cheap enough. It also ( I have discovered) balances the cells when being charged...


This is interesting Trev. I had a look but the specs are fairly light on in the eBay ad. I'm thinking this little cheapie board would allow 3s or 4s to be left installed for recharging. So would this board have a bridge rectifier/surge protector element on board-which would allow charging via the track?

Its not a charging circuit as such but it will prevent over current charging as it will protect from over discharge and low voltage.
For "On Track Charging" you need a few things to be constant, every battery needs to require the same charge voltage and to prevent reversing the polarity you need an onboard rectifier, this also prevents the onboard battery discharging back through the track.
In my application I dont need that as my trolley wire is always positive but with 2 rail its feasible that the polarity could be reversed. Im going to have an onboard supercapacitor bank rather than batteries so that the power runs to them and from them to the rest of the works, this prevents power surges and glitches caused by dirty track or overhead....



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 Posted: Mon Jul 20th, 2015 03:44 am
   
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Tramcar Trev
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I have ordered 1 of these; http://www.ebay.com.au/itm/PCB-Charger-4-Packs-14-8V-16-8V-Li-ion-Lithium-Battery-Rechargeable-2-2-5A-Hot-/251937880697?pt=LH_DefaultDomain_15&hash=item3aa8aafa79
Maybe I'll be taking 1 for the team.... Reading the specs as crude as they are this one gives an input voltage of between -3 to +26 so it may be a charger on board.... For $3 it easier to get it and play around... I wish I had spent more time in the electronics lab rather than driving trams...



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 Posted: Mon Jul 20th, 2015 03:48 pm
   
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Simon M
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Will be interesting to see if there is a data sheet of some sort. Thanks for taking one for the team!



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 Posted: Tue Jul 21st, 2015 03:13 am
   
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Tramcar Trev
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One thing I did forget to mention and its very very important. Make sure you cover any bare terminals or wire. I actually use the Liquid tape it covers everything and does not add too much bulk to the battery pack. Stops shorts = less chance of any problems



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