Please see https://www.wifimodelrailroad.com/forum/installation/can-a-locofi-receiver-be-installed-in-a-brass-steam-loco-tender-wondering-if-there-would-be-issues-with-wifi-signal-reception

Hope that helps.

@Admin

Excellent! Thank you!

@coadydr

You’re welcome!

Please do let us know how it all turns out. ?

I have tried two different CurrentKeeper caps wired as shown above but each only outputs 4.9 volts when the track power is shut off. Increasing the "charging" time from the tracks does not increase the voltage. Can anyone share their experiences?

@chdiecast

Can you please make the following two measurements?

1. As seen in the picture below, disconnect the LocoFi module and charge the CurrentKeeper by connecting to track power. Once it is charged fully, disconnect the track power as well and measure the voltage.

    

   

    

2. Connect an ammeter in series as shown below and record the average current consumption of the locomotive when running at average speeds?

    

   

The 1. will ascertain the maximum voltage the CurrentKeeper is being charged to and the 2. will help in determining how long before the voltage falls below 7V (the lowest threshold voltage LocoFi will operate on). To do the calculation, we will also need the capacitance of the CurrentKeeper which should be listed in the user manual/specs of the CurrentKeeper.

@Admin

Thanks! My multi-meter only registers up to 200DCmA. So, I’ll start with an Item”0″ showing baseline specs.

0. Test — rrAmpMeter connected between the diode bridge and the LocoFi unit using the red AND black meter connections. This is with no CurrentKeeper. The loco was on rollers.

12.14V constant track voltage using a power supply.

10.3V at 0.02A between the diode bridge and the LocoFi board (static, LocoFi board not “connected” to wifi).

LocoFi connected to wifi and the motor at half-throttle. No CurrentKeeper connected.

9.4V at 0.37A.

1. Tests were done with two CurrentKeeper devices, A and B.

1A. CurrentKeeper A charged 5+ minutes with 10.3V from diode bridge. When track power was turned off, the CurrentKeeper showed 11.66V with no load.

1B. CurrentKeeper B charged 5+ minutes with 10.3V from diode bridge. When track power was turned off, the CurrentKeeper showed 11.12V with no load.

2. Can’t perform test. rrAmpMeter requires voltage to illuminate the digital readout. I can find no information online about the CurrentKeeper specs.

3. Practical tests.

   3A. CurrentKeeper A charged 5+ minutes with 10.5V from diode bridge. When track power was turned off, the voltage immediately went to 4.7V and the loco motor at half-throttle stopped in less than a second and wifi connection was lost.

   3B. CurrentKeeper B charged 5+ minutes with 9.9V from diode bridge. When track power was turned off, the voltage immediately went to 0 and the loco motor at half-throttle stopped in less than a second and wifi connection was lost. I can’t explain why B was so different from A. It seemed OK in test 1B.

@chdiecast

Thank you for running the tests. This is very useful information.

Few observations:

1. You need a beefier power supply. The fall in voltage when the loco is running is indicative that it is working hard to supply the needed current.

2. Without knowing the capacitance of the CurrentKeeper, it will be hard to do any calculations. Can you possibly reach out to the manufacturer and get the numbers?

3. What is the maximum voltage that a CurrentKeeper can take? Based on some rough assumptions about the supercapacitors capacity, if you can find a power supply that can provide the highest possible voltage that the CurrentKeeper will accept and try with that, you should see probably 4-5 seconds of life to the loco when the power is disconnected. Again, this is purely based on some assumptions, so you may not see the exact results.

@Admin

Thanks! It looks like I’ll have to get a Digitrax 14V power supply so I’ll have the same power source as my module club uses for public shows.

@chdiecast

Alternatively, you may want to consider something like the following:
https://www.amazon.com/Universal-Adjustable-Variable-100V-240V-Converter/dp/B0D91V471B

https://www.amazon.com/AstroAI-Multimeter-Auto-Ranging-Resistance-Non-Contact/dp/B08DHHJPS1

The power supply can be adjusted to a desired voltage and the multimeter can measure up to 10A. The only drawback is that the power supply cannot supply DCC power and the multimeter cannot measure DCC voltage.

@Admin

I now have the power supply and multimeter — great recommendation! Here are new test results using them.

Test 1: ...disconnect the LocoFi module and charge the CurrentKeeper by connecting to track power. Once it is charged fully, disconnect the track power as well and measure the voltage.

CurrentKeeper A: 14.1 V track power;

12.5 to 12.93 V at the CK while charging 5+ minutes

9.6 dropping to 9.2 V when track power was disconnected.

CurrentKeeper B: 14.1 V track power;

12.63 slowly drops to 12.59V at the CK while charging 5+ minutes

0.3 V when track power was disconnected.

Test 2: ...record the average current consumption of the locomotive when running at average speeds.

CurrentKeeper A: 14.0 V track power;

1/2 throttle: Approx. 300 mA (meter wouldn’t settle on a figure).

CurentKeeper B not tested (appears to not hold a charge).

Test 3: Practical test. 14.0 V track power, CurrentKeeper A connected, loco is running on rollers controlled by LocoFi at 1/2 throttle.

11.3 V at the CK while charging 5+ minutes;

Track power off: 4.5 V (LocoFi disconnects from wifi)

2nd test as above except that the track power is quickly switched off then on (about 1/4 second off): 8.0 V (LocoFi stays on and allows control of the loco).

@Admin

1. Done. See new test results using the recommended power supply and multimeter.

2. "Amp rating is based on the decoder’s motor stall current rating.  The caps will discharge immediately as needed, so as long as you do not stall your motor more than what the decoder is rated for, then your variable will be the hold up time.." from the manufacturer. The motor is a Mashima can motor but I don't know the model number or spec. I don't want to risk damaging my gearbox/connector parts by doing a stall test.

3. "The caps are rated at 13.5v collectively, but we do have a voltage regulator to help the caps from being overcharged." from the manufacturer.

@chdiecast

Hello,

Thank you so much for running the tests. It helps clear things up a lot.

Test 1: With LocoFi disconnected, there is no reason for the voltage to drop as soon as the track power is disconnected. The voltage should have held exactly at the same level the CurrenKeeper was charged to. It appears to be faulty. Do you have another (new) lying around to compare?

Test 2: Very much in line with the expectations.

Test 3: Proves the above two.

Unfortunately, at this point, all we can suggest is to try with a brand new supercapacitor based solution and see if that helps.

P.S. The motor is just fine.

Best regards,

LocoFi Team