My two in sequence NiMH batteries in my Bachmann 3-truck shay have become tired and I’m replacing it with a new Li-ion. This is an RC/Battery install with help from TOC back a few years ago.
Question…do I need to keep the yellow capacitor installed with the new battery??
Thanks,
Richard
You should probably ask TOC.
Steve Featherkile said:
You should probably ask TOC.
I agree, but unless he has changed his tune he will recommend against Li-Ion due to his fear of fire. I disagree with his fear so long as proper protection circuits are used and only a proper Li-Ion charger is used. I prefer the programmable smart chargers, but have used the simple ones as well with no issue.
Richard,
I’d check with Dave… That said not sure where/why a capacitor would be employed on a battery powered engines power supply. Perhaps your looking at a Polyfuse. More often than not; their known to be yellow, round, square or rectangle. If it is a auto resettable Polyfuse/PolySwitch its protecting the battery from short circuits and/or excessive current draw.
Michael
I was thinking that too Michael. Polyfuses look a lot like disk capacitors. The obvious physical difference is they are not as thick and the leads are clearly visible through the coating. Got a picture Richard?
Jon, you may be correct that it is a polyfuse. I took a picture and uploaded it but when I tried input in a post I got the message that “this document is supported to be previewed”. It is a jpeg taken with my cell phone…so not sure what’s up with it.
BTW…TOC has not responded to my email about this issue…He may have written me off…(http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-tongue-out.gif)
I guess there’s a difference between 'jpeg" and “jpg”…but here is the pic of the tender.
thanks,
Richard
The CVP (AirWire) website has articles about using the two different batteries, I think from what I read, using the correct charger is most important as you want your battery protected from overcharging, which can lead to a disaster if not done correctly.
trainman
That looks like a Polyfuse. Also looks like it’s the first thing, connected in series with the battery on the left which is logical for a fuse. So, yes - leave it in the circuit. You will probably need a different charger for a LiIon pack.
Thanks Jon…when I purchased the Li-ion batteries I also purchased a Tenergy TB6B Multifunction Balance Charger.
I was hoping you would post that!
Rooster, thank you…I feel so much better now!
Welp…my new Li-ion is a tad to big to fit in the 3-Truck Shay tender. It runs into the speaker just enough to not allow the tender shell to close.
so question… can I series 2 7.2 volt Li-ions safely?
Richard
Welp…my new Li-ion is a tad to big to fit in the 3-Truck Shay tender. It runs into the speaker just enough to not allow the tender shell to close.
so question… can I series 2 7.2 volt Li-ions safely?
Richard
Yes. I do this in my side tank Porter, with one of the two cell packs in each water tank. Each pair has it’s own PC Board. The battery packs are wired in series and charged as a single 4 cell pack. This is not an ideal situation since during run or charge, one board may cut off before the other. If you never run the loco until it stops (the way you always should with LiIon) and use a programmable charger like you have purchased, the charge should cut off well before the PC board trips as “full”.
Better would be to split up a 4 cell pack and keep the single PCB. That will do a better job of keeping the cells somewhat balanced, but still not perfect. Since you bought the balancing charger, the best wiring would be to include the individual cell leads or the balance charger’s input and then charge with the balancing program. This requires a bit of wiring and a connector that fits the charger.
I am far from the expert here. If Michael Glavin. chimes in again I would take his advice over mine! He has taught me a lot over the years.
EDITED to clarify a few statements and to add this picture of a balance charge in progress on Frankenbattery…
Richard,
Yes, you can series connect two 2-cell Li-Ion batteries. That said the are caveats. What size, capacity and make battery did you purchase? I’m not suggesting you attempt to modify a Li-Ion battery yourself! If this the only way you see fit to make this happen let us know. Some of us have the proper equipment and experience with battery assembly and the knowledge to get-er done. Purchasing two separate two cell batteries is an option, but you’d have to charge them separately.
Michael
Michael Glavin said:
Purchasing two separate two cell batteries is an option, but you’d have to charge them separately.
Michael
Hi Michael - Thanks for adding your expertise. When I did my Porter install Tenergy Customer Service told me that it was OK to charge two 2-Cell packs wired in series together as a single 4 cell pack. I have been doing it that way with my Porter for years. I understand that there are limitations and disadvantages to doing it this way, but so far (5+ years) both packs are holding up well. What are the disadvantages besides possible imbalance?
Jon,
Perhaps my assertion requiring separate regimen’s was to matter of fact!
Each of the two batteries should have a simple PCB or battery protection circuit board. Cell imbalance is inevitable, series-wired-charged cells suffer imbalance by design and the charger sees the average voltage of the two batteries through the PCB’s. Each PCB acts independently if need be as well. In the scheme of things as you’ve realized it works; best scenario, NOT! The consideration/inconvenience of two charging regimens is doable, but why? You can purchase a 4 cell, 30A, 14.8V, 4S Li-ion, 18650 Battery BMS-PCB Protection Board with cell "Balancing" for $3.00. Or use the original protection board and remote wire the two cells.
Michael
