Large Scale Central

From NiCd to Li-ion?...I could use some advice, please

Electronics Power and Sound
#1

Hi, all

The 14.4 V NiCd battery packs in two of my locos are failing (won’t hold charge). I’d like to replace them with Li-ion battery packs, but I’ve not done that before. So I hope you’ll bear with my “newbie” questions:

  1. If a single 14.8 V Li-ion pack is physically too large for my space, can two 7.4 V Li-ion packs (each with protective PCB) just be connected in series to provide 14.8 V? Or will the two PCB’s interfere with each other somehow?

  2. Do I need to disconnect the batteries from the RC/sound electronics boards to charge them? I’m using RCS 27.MHz ESC’s and Sierra sound boards. Or can I just charge the batteries in place?

  3. Tenergy seems to be a popular (or at least well-advertised) brand for packs/chargers. I’d appreciate your comments on this vendor’s products, plus any recommendations for other vendors you might have.

  4. For one loco, I’m considering the Tenergy 31024 14.8 V 2200mAh pack and the Tenergy TLP-4000 1A smart charger. Reading the published specifications, this seems to be a safe combination. Has anybody had experience with this combination? Comments, please.

  5. You can tell I’m new at this. Any warnings or cautions or possible hang-ups you can offer will be much appreciated. I can almost promise that I’ll be back with more questions… :slight_smile:

Thanks for any help you can offer.

Steve

#2

Steve…

I can answer some of them, I think.

  1. If your NiCad batteries fit in your locos, I am confident that the Li-ion batteries will, and with room to spare. That is one of the benefits of switching to the lithium chemistry. You get the same power in a much smaller package. As to connecting two Li-ion batteries in series, I will defer to others of the battery mafia.

  2. I think it is always a good idea to disconnect the batteries from the electronics. That way there is less chance of letting out the magic smoke. There are three members of this board that supply those disconnectors, Del Tapporo at G Scale Graphics Rick Isard of Cordless Renovations and Tony Walsham of RCS. Pick any one of them, they are all good. Basically, it is just a switch that allows you to select run or charge.

  3. Tenergy has gotten some good reviews, but beyond that, I don’t know.

  4. No experience, but it will probably work, as long as the charger is specified for the Li-ion chemistry. Magic smoke, again. You should consider getting batteries that can be charged by the same charger.

I’m still learning, so take this free advice as being worth what you paid for it… :stuck_out_tongue:

#3

ANSWER TO #1 YES YOU CAN and it will not interfere. I use this method to get my batteries in some tight fits. You can even combine a 7.2 and 11.1 to get an 18 volt batt. just use a charger for the correct amount of cells.
#2 all mine are either hooked to a on and off switch for charging or physically come out of the engine or tender for charging.
#3 Tenergy is an excelent company that gives you a great value for the money
#4 good combo I supply this to a lot of our club members. I have bought the TB6B as I charge different batteries.
#5 the only dumb question is the one you already know the answer to LOL

#4

The only dumb question is the one you DON’T ASK!

Bob C.

#5

Steve,
I concur with the other comments here. I would just add that you should make every effort to charge outside the battery car or locomotive if you can. Remember treat the battery pack as if it is armed all the time, switches and electronics fail but physically disconnecting insures the system is disarmed.
Dave

#6

Dave’s suggestion of external charging, if possible, is a good one. It simplifies the charge circuit wiring to a single plug. I chose to use Tamia R/C plugs on my trail car batteries because they are nice high-current plugs and the Tenergy charger already has one.

Another advantage to removable packs is that you can swap them out when they go dead and keep on running :slight_smile:

Since it isn’t always possible to have removable packs, a coaxial charge plug with a switch activated by inserting the charger cord is good positive protection for your electronics. I believe both Del and Tony have modules that simplify wiring a charge jack.

#7

Jon is giving good advice.
A single charge jack for non removable on board batteries that need to be charged in situ is OK for most batteries. However, for batteries that must balance each cell during charging, such as Li-Po you must also figure out how to access the balance cable connections as well.
BTW. Most Li-Po battery manufacturers state that their battery packs must be removed from a model and charged in a ceramic container on a concrete floor and MUST NOT BE LEFT UNATTENDED.

#8

Thank you all for the good advice. Very helpful and informative. I’m pretty sure I can make this substitution work (safely), but Tony’s caution does raise some new questions: 1. How is a Li-Po battery different from an ordinary Li-ion battery? Or are they the same thing? 2. Obviously I need to learn something about “balancing” cells. The Tenergy 31024 battery pack only has two leads. Does this pack need “balancing?” Where are the “balancing” connections?

(http://freightsheds.largescalecentral.com/users/dawgnabbit/misc/Libattery.jpg)

  1. Tony, I’m puzzled by the requirement that the battery pack never be left unattended. Or did you mean only during charging? What’s the safe procedure if the battery pack is “built in” and can’t be removed for charging? 4. I’ve been assuming that the PCB in a battery pack limits charging to safe levels, and prevents discharging below safe levels. Do I have that right? Pretty obvious I’m on a steep learning curve here. Still, I really do want to understand what’s involved well enough to mod my locos safely. Any more hints or helpful suggestions (or warnings) would be very halpful. Thanks again, guys. Steve
#9

TonyWalsham said:
BTW. Most Li-Po battery manufacturers state that their battery packs must be removed from a model and charged in a ceramic container on a concrete floor and MUST NOT BE LEFT UNATTENDED.

(http://upload.wikimedia.org/wikipedia/commons/8/89/Bomba_atomowa.gif)

Sorry…couldn’t help it! :frowning:

#10

Thanks, David. I’ll take that one as a “warning…” :lol:

Steve

#11

Steve,
Li-Po and Li-Ion are different.
Stick with the Li-Ion and you shouldn’t have any problems.
Li-Ion batteries are in tons of consumer devices, including laptop computers.
Ralph

#12

Hi Steve -

To answer #1 - LiPo and LiIon are different chemistry. You chose LiIon which is the safer of the two because it has built-in protection and is not as unstable as LiPo. They still demand respect and proper handling, but are in common use in cameras, phones etc. The LiPo chemistry offers an even smaller package for a given voltage and are commonly used by model airplane enthusiasts due to high current to weight ratios. They are willing to add some risk as a trade for lighter weight. For model railroad purposes LiIon is a better choice.

#2 The LiIon pack you chose (same as I and others on here use) does not require balanced charging, thus only two wires. It is possible for the pack to get out of balance. When that happens the pack can be salvaged by disassembling and charging each cell individually to regain the balance. It’s rare, but it happens.

#3 Tony is referring to LiPo chemistry. It’s a good safety procedure to charge LiIons away from flammable materials and keep an eye on them, but it’s not as bad ad Dave Russell’s photo implies :slight_smile:

#4 Yes. That’s exactly how they work.

No problem with the questions Steve. We’ve all had to learn and a lot of the information out there is confusing.

#13

Okay guys, thank you! That helps. Li-ion it is for me, then.

Jon, you’re spot on about all the information (and mis-information) you can find on the web. Sorting out what’s right and what’s not right is the issue. I found directly contradictory warnings and informations. Sheesh…

Does anybody know of a good, comprehensive, and reliable primer or FAQ on Li-ion battery pack use? I’d appreciate the link, if so.

Again, thank you all for the help.

Steve

#14
Jon Radder said:
#3 Tony is referring to LiPo chemistry. It's a good safety procedure to charge LiIons away from flammable materials and keep an eye on them, but it's not as bad ad Dave Russell's photo implies :) .
I said I was sorry....;)

Steve…please post pictures of your upgrade when finished!

.

#15

Steve wrote

"Jon, you’re spot on about all the information (and mis-information) you can find on the web. Sorting out what’s right and what’s not right is the issue. I found directly contradictory warnings and informations. Sheesh…

Does anybody know of a good, comprehensive, and reliable primer or FAQ on Li-ion battery pack use? I’d appreciate the link, if so."

Steve,
This is why I made the recommendation that I did.

#16

Rick, and all…

Having a pro do it is clearly the safest and most reliable solution, I completely agree. But I’m just stubborn about learning how to do things myself. I ask lots of questions (you should know!) to minimize the risk, and then take the plunge. Usually it works out okay.

Thanks to all who offered advice. I’ll let you all know if I manage to burn my house down! :slight_smile: :stuck_out_tongue:

Steve

#17

I have switched all my locos over to LiIon batteries and have zero problems. i do use the chargers they suggest. All my batteries are fixed inside my locos mainly due to the fact that I don’t care for battery cars and for me the locos are a “pita” to open and close. I use an M type jack on the loco and modify my chargers with an M type plug. Between the battery and electronics I use a DPDT (double pole Double throw) switch. The center feed on the switch is for the battery, then one side goes to the loco and the other goes to the charging jack. That way I can charge without worrying about the electronics releasing the magic smoke and the switch creates a dedicated break in the power to safely store them.

Terry

#18

Terry, I’m not familiar with “M type” plugs and jacks. Are they anything like this UHF connector?

(http://en.wikipedia.org/wiki/File:UHF-Connector.png)

Steve

#19

Radio Shack sizes their coaxial DC connectors as K, L, M, N, etc. Maybe it’s that. I am using N.

#20

Michael is right. I get them at radio shack or supply houses. They are a DC jack/plug. I use the switchable jack because it’s size is smaller than the standard panel mount. The switching option doesn’t have to be used.
the plug: http://www.radioshack.com/product/index.jsp?productId=2103614
the jack: http://www.radioshack.com/product/index.jsp?productId=2102491

Terry