# Li-Ion with protection circuit



## Dave Ottney (Jan 2, 2008)

In another thread title Battery Trouble, one other poster and I mentioned using 14.4V Li-Ion from all-battery.com
http://www.all-battery.com/li-ion18650148v2200mahrechargeablebatterypackwithpcbprotection.aspx

These packs have a* protection circuit board (PCB)* on them to keep the pack from being over charged or over discharged. The voltage density and size of the packs make for a very useful setup. But I've run into a problem and hopefully someone might have an answer.
Here's the background-

We have three different locos using the packs- a old Bachmann Porter, an Aristo RS3 and a USA NW. All manufacturers' electronic boards have been removed and RCS EVO E3 systems have been put into place to run the locos. My freind's diesels started having problems when just puttering around his and my layouts. We'd set the speed using the transmitter, turn the transmitter off(you can do this with the RCS system) and let the loco go motoring along. After a while (at least 15 minutes) the loco would take off at full speed. (you can do this with the RCS system). Control can be regained but its pretty hairy for a bit there.


I've been testing one of the diesels this morning and noting the pack's voltage and its well above 15V. At no time has the pack been overamped (pack rated at 5A output and the loco drawing under 1A). I've even put the loco on its side on the bench, run it up and stalled the wheels and it pulled only a bit over 1.5A. So I know the loco isn't beating up the pack.


After having the loco go crazy a couple of times and checking voltages to make sure that the it wasn't suffering from a voltage drop (it still is at 15.7+V under load) I figured I'd drop it (the PCB equipped pack) into my Porter. The Porter has never done this. I have been running the Porter NiMh's and just started using some Li-Ion's that I put together with no PCB. 
Sure enough after a couple tours around the layout it took off like a shot. 

Now I need opinions. It seems that the PCB might be causing the problem. I'm sure how but my Porter has never took off at full throttle and I've run packs down pretty low it. Has anyone using one of these packs with the PCB had a problem. I know Bill Sharron mentioned he's using them with no problems..

I am running the Li-Ion I made that has no PCB to make sure it runs the loco ok. The RCS system worked perfectly with NiMh's so I'm confident its not the problem. The only other thing I can think of if the battery is not the problem is that I have not put chokes into the system to clean up signal. 

Any ideas will be greatly appreciated. 

Dave


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## Greg Elmassian (Jan 3, 2008)

The board in the battery pack does not "generate" electricity itself. The fact that you measured 15.7 volts under load means that that's how much voltage the pack produces. Is there any problem with this voltage with your RCS system? (I really cannot believe that).... sounds like you are getting some radio interference that is being interpreted as "go fast". 

Regards, Greg


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## Road Foreman (Jan 2, 2008)

Dave, 

If you are using the battery pack that you have listed it is only good for 2.5 Amps.. What will make a RCS EVO E3 system go full speed?? That will give you a good clue as to what is happening.. Also could your locos be coasting & then trying to go full power again.. This could cause the PCB to turn off because of over current.. What will this cause the RCS system to do?? 

BulletBob


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## Dave Ottney (Jan 2, 2008)

Bob, you're right the link went to a 2.5A pack and I'm using a pack rated 5A amps (rate at 2.5C), but even if it was rated at 2.5A I'm only pulling something like 1.9A with the wheels almost stalled. I had the loco on the bench and throttled up while grabbing the wheels on each truck. The coasting thing is interesting, though I don't think that's the case as I have only one very slight grade on my layout and my friend's layout is pancake flat. 

I'm also going to try some chokes on the motor leads to see if that might help. 
Thanks for the ideas, 
Dave


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## TonyWalsham (Jan 2, 2008)

The RCS system Dave is using actually an EVO-E3 although the hardware is exactly the same as the RCS ELITE-3.
One thing that will make the system behave erratically is if the voltage drops below 12 volts in under load. The LMD 18200Tsolid state motor driver I use becomes unstable at too low a voltage and can suddenly take off at full speed.
This has happened to a customer of Don Sweet who was running two USA locos with 16.8 volt batteries. To prove it I built a low battery voltage detector that flashed an LED when the voltage dropped too low. Sure enough the batteries were dropping below the threshold and the locos suddenly changed direction almost immediately after the LED started flashing. Left in that state the locos stopped completely shortly afterwards. This proved the batteries were being allowed to get too low.

I am not very familiar with Lithium batteries. They seem to be very successful with other hobbiests.
However I do know some batteries, such as AA size NiMh and NiCd cannot handle a continuous high load and drop voltage to compensate.
Part of the reason why I still only use NiCd Sub C cells where they can be fitted.
As there are electronics in the Lithium battery packs they could of course be causing "noise" to get into the micro running the system.
Also, if you haven't already installed RF chokes in the motor leads I would recommend you do so.


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## Dave Ottney (Jan 2, 2008)

Tony has been great again. He's been answering questions and checking things on and off all day long for me. 
I've taken all the Aristo boards out. I thought I did that with this installation but found I had left them in and was powering through them. 
I've got the loco running around the layout right now and so far its running well. I plan on going to get some chokes for it. As far as voltage drops go that was my first thougth but the pack is holding at just below 16volts right now. This is after using it on and off throughout the day. I shouldn't be surprised by this as Li-Ion don't dump voltage like a Nimh or Nicad. They drop slowly as they are used then dump out quickly at the end of a charge. 
Heck we'll see. Right now its been running for about a 1/2 hour with no bad behavior. 
Thanks to all who offered opinions, 
Dave


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## rpc7271 (Jan 2, 2008)

Tony, how about posting info on your low battery voltage detector in the forum. I am tired of rescuing my trains after they run low.


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## Dave Ottney (Jan 2, 2008)

I think I've found the problem!!! Yahoo!!! 
I completely disassembled the loco and redid all wiring. I installed capacitors on the motors and put in a choke board that the motor wires connect to. I put the bugger on the track after putting things back together and it was motoring along when it took off like a jack rabbit again. 
Scratch the head, cuss a bit and decide to remove the speaker. Maybe its magnet is causing problems. Put it on the track and it putters along, I smile, them wham off it goes at full speed again. 
Now I decide to disconnect the lights. Eureka!!!! Its been motoring around with no problems for at least 45 minutes now. There are little pc boards that the lights connect to that must have something on them that generates some noise when current is applied to them. I can't see what's on these boards because they're hot glued in. 
I now have to figure out how to get the lights and those pc board out. When I get them out I'll remove the LEDs wire them in parallel with appropriate resistors and connect them to the RCS unit. 
So I'm pretty sure the problem has been solved. 
The Li-Ion pack is working very well. After running for this 45 minutes its still above 16V. 
Again thanks to all who offered ideas. 
Dave


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## TonyWalsham (Jan 2, 2008)

The low voltage detector is a kit # KG9000 sold by Jaycar here in Australia.

http://www.jaycar.com.au/productView.asp?ID=KG9000&CATID=25&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=821

All I did was replace the LED supplied with a flashing one.
It could also be made to trip a relay to cut off power. That would be a bit sudden though.
One word of advice. Set the trip limit with a suitable voltage battery. Not a DC power supply. You will get a false reading.

Dave.
I do not recommend wiring the AC lights direct to any RCS/EVO lighting output. I don't know why, but they do disrupt how the output works.
The best and simplest way is to leave the AC wiring and lights in place and run them from the traction battery voltage via a# RELAY pcb that switches the battery polarity voltage according to the direction of travel. 
It will give you constant brightness lighting.


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## fildowns (May 17, 2008)

Gosh. Ordered one of these on the 17th and it turned up on my doorstep in the UK on the 24th. Not bad considering the distance AND the time of year! Sometimes these things catch the plane just so. Good, I will be able to complete my latest battery project over the holidays!

Thanks for that link Tony!


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## Greg Elmassian (Jan 3, 2008)

Many AC locos use a PIC microprocessor to be a voltage regulator. It makes nasty noise, don't know if it is the processor frequency, or the PWM output or both. 

I re-read the thread, and you did not say which loco does this... by the way, the Aristo RS-3 has boards everywhere, and the voltage regulator circuit is on the top side of the board that has the switches for the motor, lights, smoke, etc, so you said all boards were removed, but I'm guessing that was not really true for the RS-3. 

See my site on the RS-3 for pictures of the boards, and the voltage regulator... 

Regards, Greg


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