Greg, see my above post. After cleaning up and verifying the data, the engine performed quite different at full capacity. I do not know how discharged it was but it took hours to charge it. I will do some more tests with my GP38’s for which I have one that is fully charged.
The graphs above disappeared, but I ASSumed that you had the batteries at a reasonable charge level, perhaps they were down more than you realized.
I’ll refresh again, but right now the graphs disappeared.
Greg
I tried to embed and it didn’t work. You should be able to click on the link in the post and see the graphs.
Same link as https://public.tableau.com/profile/nicolas.teeuwen#!/vizhome/USATrainsBattery-VoltageSpeedTests/Everything
I have recorded fully charged GP-38’s. Speed is now in the high 50’s to almost 60.
I also figured out how to measure the voltage on the batteries. I hooked an extra cable up to the charging port of the engines and put a volt meter on it. You can see results now in the charts, but I’ll sum up my findings.
- The max battery voltage of the 14.8 v batteries is apparently ~16.75 volts. My SD70’s when running for the first round of tests were apparently in the 13ish volt range.
- Traction tires actually appear to slow down the GP38’s. One more test here once I remove another one of the traction tires from one of the engines.
- The voltage of the SD70’s with battery perform better than equivalent track voltage, at least when near max voltage.
Nicolas Teeuwen said:
I have recorded fully charged GP-38’s. Speed is now in the high 50’s to almost 60.
I also figured out how to measure the voltage on the batteries. I hooked an extra cable up to the charging port of the engines and put a volt meter on it. You can see results now in the charts, but I’ll sum up my findings.
- The max battery voltage of the 14.8 v batteries is apparently ~16.75 volts. My SD70’s when running for the first round of tests were apparently in the 13ish volt range.
- Traction tires actually appear to slow down the GP38’s. One more test here once I remove another one of the traction tires from one of the engines.
- The voltage of the SD70’s with battery perform better than equivalent track voltage, at least when near max voltage.
This is a no load rating
Yup. I just looked up the specs and that is correct. Perhaps when i was measuring the voltage from track i got no load as well. I was measuring it at the point of contact with the wires.
I did a preliminary test for traction vs no traction tires pulling cars up a hill. Without traction it struggled to pull up 7 4 bay hoppers. With traction it could pull 10 of em and barely struggle. Both GP38’s. As expected, going up a hill, traction tires make quite a diff. Its a shame it puts too much strain on the motors, or I would have liked to keep them on.
Nicolas Teeuwen said:
I have recorded fully charged GP-38’s. Speed is now in the high 50’s to almost 60.
The voltage of the SD70’s with battery perform better than equivalent track voltage, at least when near max voltage.
Poor conductivity between the track and wheels acts as a resistor. The higher the speed, the higher the current requirement and the more impact this resistance has on the speed.
Also, you loose current at the rail joints so if you are reading voltage at the track terminals, that’s not what gets to the motors.
Todd,
Right on. Most people do not understand that it is the CURRENT available that is important. Remember when your car won’t crank? If you were to check your dead battery it will read 12volts, but does not have the amperage to crank the engine. Voltage is the potential, amperage is the power! (https://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-wink.gif)
Nicolas you said " I can’t measure the batteries as they are tucked away." But you can with the airwire drop in’s came the charging wire so you have extras take one pull the wires apart so they are not able to touch, plug it in take your volt meter and get your reading. Repeat do not let the wires touch or you will blow your battery. You can make a meter up buy a small cheap 30 volt meter and hard wire it. Now you can use any time you need. I bought a cheap auto lighter meter and wired it up and use it.
I guess I have to put a disclaimer if you do this.
Richard
Yeah. I was able to measure voltage. I realized the same thing. I pulled the two wires apart and made sure they didn’t touch and was able to measure voltage. Its how I realized full is 14 volts. Apparently the batteries will go down to about 10 before the low voltage kicks in and it stops discharging. Ideally I’d like a nice hardwired small voltage meter that I can use any time to keep an eye on the batteries.
I really wish the drop in decoders didn’t put the charging port where they did, specifically on the SD70 where its rather challenging to get at.
Nicolas here is a small meter put heat shrink on soldier wires slide heat shrink down over and you have a portable meter. https://www.allelectronics.com/item/pm-123b/3.3-30-vdc-blue-digital-meter/1.html
Also my battery’s when full charge are 16.8 drop down slowly to 12 volt kick off. they are 14.8 lipo.
Richard
Or a gadget like this, put in the cab, it had piezo alarms, programmable, shows overall voltage and apparently can show per cell voltage too…
https://hobbyking.com/en_us/hobbykingtm-lipo-voltage-checker-2s-8s.html
under 3 bucks
whole bunch of different units: https://hobbyking.com/en_us/batteries/battery-accessories-adaptors/battery-voltage-indicators.html
Greg
Greg Elmassian said:
Or a gadget like this, put in the cab, it had piezo alarms, programmable, shows overall voltage and apparently can show per cell voltage too…
https://hobbyking.com/en_us/hobbykingtm-lipo-voltage-checker-2s-8s.html
under 3 bucks
whole bunch of different units: https://hobbyking.com/en_us/batteries/battery-accessories-adaptors/battery-voltage-indicators.html
Greg
All those are nice but none will work with our battery’s. Our battery’s don’t have a wire for each cell with what I use I only need one for all of my battery locs plug in cheek and unplug done.
Richard
I was figuring with the difficulty to reach the charge jack that Nicolas mentioned, dedicating a unit to the loco and perhaps putting in the cab would be an option.
Yes, I realize that not everyone has a pack with a balancing connector.
Did you notice the second link with about 10 more options?
Greg
Greg Elmassian said:
I was figuring with the difficulty to reach the charge jack that Nicolas mentioned, dedicating a unit to the loco and perhaps putting in the cab would be an option.
Yes, I realize that not everyone has a pack with a balancing connector.
Did you notice the second link with about 10 more options?
Greg
Yes I did but for any of them to work you would have to wire into the airwire board because the on off switch for the battery is built into board
Richard
Yep, I understand, it’s another way to go, but if it were me, a nice audible alarm, and being able to peek into the cab window to check status would be nice.
But that’s just me, I want my trains to run on my schedule, not theirs.
Greg
I did come up with a potential way to handle a few things I would like to do with the drop ins. The way the drop-ins are made, the charging port ins on the board. It is also set up so that when the unit is turned on, the charging port is disabled so you can’t charge it while its running (which is fine).
I could wire something in between the batteries and the board including my own switch and charging jack. I could then put these in a much easier to get to spot, like the side of the fuel tank, (I am not doing sound). I would leave the Airwire switch on all the time and never use its charging jack. If I wanted to get even fancier I could set it up an additional jack (or figure out how to re-use the charging jack) to supply external power, in the case of a battery that is drained. I have very limited knowledge of this at the moment and would not want to accidentally supply power to the internal battery when I mean to supply it to the engine.
I use a meter like the one in the link.
I put a plug on the wires. I could probably fit it into the loco and see it through a window.
Cheap enough to have one for each loco.
Tom
So…I have a USA Trains FA and FB unit. I also have a USA Trains GP-9. I plan on going with the Airwire system to operate both. One T5000 transmitter (w/backlight), one G3x decoder, one Phoenix P8, and one battery in the FA unit and one G3x decoder and one battery in the FB unit. USA Trains passenger cars (new w/LED’s) in the future. I intend to install one G3x decoder and one battery in the GP-9 unit.
It has been recommended to me that I use 14.8v 6800Mah Li-Ion batteries all around. Do any of you have other recommendations?