You can fit the G3, the P8 and the battery all in the "A with room to spare. You won’t need the second battery in the “B”. Just run a cable with a plug on it from the A to the B. This way you can run the “A” solo. Run 4 wires, 2 for the motors and 2 for the second speaker. You will want a speaker in the “B”! Be sure to change all the lights to LEDs. Running both engines, you should get about 3 hours run time depending on number of cars, track curves, grades etc… There are batteries out there that fit perfectly your FA and GP-9. Let me know if I can be of further help. Ralph [email protected]
Ralph, the “B” unit is motorized, same as the “A” unit. Shouldn’t the “B” unit have a battery in it too? Don’t you want to set both the “A” and “B” units up with the Airwire to run concurrently? Didn’t plan on changing the lighting in the engine, but the new USAT passenger cars all have LED’s in them, so there should be less drain on the batteries.
Given my test results, you may want to consider the 18.5 volt batteries from RLD Hobbies instead of the 14.8. Be sure to get the better charger. Especially if these are for a passenger train. It will be able to go faster if that is something you desire. I haven’t personally tried the 18.5 volt batteries and the summary from this thread is that there maybe reception loss by going to higher voltage but some on here have said they didn’t experience any issues with the higher voltage.
Michael Kirrene said:
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?
Michael have you given any thought to using the drop-ins instead of the G3x?
Richard
It appears that the G3 series has a 3 amp smoke driver, while no mention if that counts against the 120 watt rating or if the drop in has this… no mention for the dropin.
Interesting to note that the 120 watts is indeed 10 amps at 12 volts, but 8 amps at 14.8 volts and 6.5 amps at 18.5 volts.
People used to call it a 10 amp decoder, but it’s not really at G scale voltages. Of course, normally at higher voltages, you draw lower current, so the wattage consumed should be approximately the same regardless of the voltage input.
2 locos should be fine from one unit in my opinion, and this has been done for years with the CVP product.
Greg
Richard said:
Michael Kirrene said:
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?
Michael have you given any thought to using the drop-ins instead of the G3x?
Richard
Richard, yes I did initially. Then a gentleman who does the Airwire installs for many of the BAGRS club members here advised me to go with the G3 over the drop-in. I think he said it was because of the G3’s versatility over the drop-in board. I don’t remember the details of the conversation. There doesn’t seem to be a big difference in price between the two.
RALPH MERRILL said:
You can fit the G3, the P8 and the battery all in the "A with room to spare. You won’t need the second battery in the “B”. Just run a cable with a plug on it from the A to the B. This way you can run the “A” solo. Run 4 wires, 2 for the motors and 2 for the second speaker. You will want a speaker in the “B”! Be sure to change all the lights to LEDs. Running both engines, you should get about 3 hours run time depending on number of cars, track curves, grades etc… There are batteries out there that fit perfectly your FA and GP-9. Let me know if I can be of further help. Ralph [email protected]
Just read my e-mails from months ago and this is what the gentleman who does the installs said:
My question: “I thought it would be preferable to have a G3x (or drop-in) in both the A and B units. That way you can control the speed of both independently and have them run in sync? And wouldn’t the A and B units draw more battery power faster by running on 1 instead of 2 batteries?”
His answer: "As far as the F-3’s, I have been able to run 2 of them with one G-3 and 2 batteries in the A unit. That makes the B unit very inexpensive to convert. A G-3 in each unit is the preference. Battery usage is determined by the current draw of each engine.
I prefer to have a decoder per loco myself, it allows easy speed matching, and being able to run the loco independently. I actually have fun driving the locos together and then adding them to the consist, and then driving the consist away. Also, I cut helpers on and off the consist on grades. It’s a lot of fun, so independent control and separate sound is nicest.
But, many people are more cost conscious so they want to run a single decoder. It’s understandable.
Also, the same train uses about the same amp-hours, one loco or two… the power consumed to take a train up a hill remains constant, so two locos will each draw about half of what one loco will draw. (not counting smoke units and extra sound). So you don’t necessarily need double the battery if you run 2 locos from the same decoder BUT! this is for the same length train… most people running 2 locos will want to pull more cars than when they run 1 loco.
Greg
I received an 18.5 volt 6700 mah battery today. Put it in one of the SD70’s and ran it around for a bit. Fully charged it goes fast. Probably too fast. I found running it at a level 20 (out of 28) or about 70% of full speed it ran at a nice comfortable pace. On straight runs at full speed it looked ok but on the 10 foot curves I have, it started to have the a toy too fast feel. I’ll at some point provide a video.
Overall, my initial impressions are that I am happier with the 18.5v battery. I can adjust the throttle speeds to limit how fast it can go giving me more options to pick a suitable maximum speed. Will have to spend more time with the engine learning the feel of it.
How fast does it run with a string of cars behind it?
I was going to comment before Steve’s post but seems even more important now, the ability to have some reserve, will allow prototype top speeds with a load (like the prototype) should the desire arise.
Just because the loco is now capable of over prototype speed unloaded does not force Nicolas to go into toy train mode, as I interpret some people have implied.
Another thing to remember, if you want to speed match locos, you might need the extra speed to help “tune” a loco downwards to match another.
Regards, Greg
" Rooster " said:
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
Umm… I think we all understood that…
I tested the engine with the 18.5 volt battery both with and without pulling cars. I had it pulling 6 4 bay hopper cars, each of which is about 4 to 5 lbs I think. It still went faster at its top speed then I think looks good on my railroad. I think, in part due to 10 foot diameter curves, prototype max speeds of these engines won’t look good. I think being able to go faster then the max speed of a 14.8 volt is still advantageous.
For a little bit of Edumacation, it’s not the car weight as much as rolling resistance that will be your loads. You can use a fisherman’s scale to pull your cars and get an idea of each cars drag.
I think you’ll enjoy having the extra power, even if you don’t use it all the time.
By the way, the “max voltage” of a battery unloaded is of basically anecdotal value only. Many devices, batteries included, will “float” open circuit much higher than the nominal/true working voltage under load. A voltmeter places so little load on a circuit that it is basically measuring the unloaded value by itself.
Under load, even a freshly charge LiIon will “settle down” to the nominal 3.6 to 3.7 volts per cell.
And the effect of weight will come into play going up a grade, you are doing work lifting that weight. Luckily that effect remains constant, as opposed to the rolling resistance which varies all over the place considering lubrication, age, if you are on a curve, etc.
Greg