# Wire Size for battery power



## russfox (Apr 11, 2008)

Hi all,
What is the recommended wire size to use from the battery to QSI board?
Thanks,
Russ


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## Greg Elmassian (Jan 3, 2008)

Russ, it would really depend on the loco, and the length of the wires. Try to keep it as large as possible if you will be pulling heavy loads or the length is long. 

Use 16 gauge as a goal, my suggestion. 

Regards, Greg


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## russfox (Apr 11, 2008)

Hi Greg,
I'm running Aristo Dash-9s and SD-45s. I want to run around 50 car trains using 16.8 volt batteries.
Thanks,
Russ


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## Del Tapparo (Jan 4, 2008)

Heavier gauge is always better, but 22 or 20 ga. works just fine for me (short trains, narrow gauge). Since you will be pulling some amps with your diesels and long trains ... bigger (smaller gauge number) wouldn't hurt.


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## Greg Elmassian (Jan 3, 2008)

Yep, you have the capacity to pull a lot of amps, especially since your voltage is lower. (for same power to motor, lower voltage will draw more amps). 

For the same power, 12 volts would draw TWICE the amps of 24 volts. Wire size is really determined by amps. Motors are very low resistance, so the resistance of the wire feeding it DOES matter and does enter the "equation". 

You did not mention the length of the wires... are the batteries on board, or in a trail car? 

I will now change my recommendation to 14 gauge wire. (and if the wires are long, like several feet, use 12 gauge) 

Using too light a gauge of wire will result in wasting energy in the wires and shorter run times.. 

Remember everyone who is reading this, there are these special conditions, long trains, big locos, low voltage.... 

Regards, Greg


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## russfox (Apr 11, 2008)

Hi all,
I plan on having the battery onboard and using 16.8 NiMH. http://www.batteryspace.com/customizenimhbatterypack168v42ah55wh.aspx

This is why I had the question about volts and amps yesterday.

Do you think 16.8 volts is too low? I'm very interested in what people suggest. I haven't bought any batteries yet but plan to do it very soon (just a few to try out).
I was considering the battery in the link above.

The main locomotives that I want to run are as follows:
(Most routes will have grades between 0 to 1/2 %) There will be 1 or 2 routes that will have 1 to 2% grades but train length will be shorter or addition locomotives added.
Freight car lengths around (50) 15” in length cars. 

3 - Aristo Dash 9s (Freight Only)
3 - Aristo SD-45s (Freight Only)
2 – USAT GP38-2 (Freight Only)
2 - Aristo E-8s (Freight and Passenger)
4 - Aristo Pacifics (2nd Version) (Freight and Passenger)
1 - USAT ABA Alco PA set (Freight and Passenger)
4 - LGB Genesis (Passenger Only)


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## Bill Swindell (Jan 2, 2008)

I have an SD-45 with 14.4 volt batteries. It is OK, not great. I'm going to change it to 18 volts. Your 16.8 will certainly work as long as you are not trying to race your engines. As for wire size, you do not need large wire since your wire lengths are very short. I use 20ga wire for almost all of my on-board motor wiring and 26ga for lighting.

If you are going to power a train from the track then bigger really is better. The HO club that I belong to uses 10ga wire for track feeders. We do NOT have any voltage drop probvlems.


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## Greg Elmassian (Jan 3, 2008)

I read your list, and thanks for the answer, I personally like to overbuild, so with long trains, I would still stay with 14-16 gauge, and really 16-18 is probably fine because you said on board batteries. 

But I see another piece of data: The Aristo E8's run very slowly, too slowly for passenger trains if you ever want to run near prototype speeds. 

You might be disappointed at top speed on these at less that 18 volts. The speed of motors is very nonlinear with respect to voltage, all the top speed is in the last 2 volts. 

On my layout, my e8's would not go over 62 smph (I have a calibrated speedometer) until I upped the voltage to the motors 3 volts, then got 92 smph. 

My best advice is to build a pack, and get your controller, and then run the loco, specifically the E8 and see if you are happy with the lower voltage pack. 

I surely would not make the decision until I had tested it on at least one loco. 

Regards, Greg 

p.s. I use 10 gauge feeders to my track too...


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## Bill Swindell (Jan 2, 2008)

Greg, do you wire the internal power circuits in your locomotives with 16ga wire?


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## Greg Elmassian (Jan 3, 2008)

Nope, I run more locos per train, and have short wires, so will not run the current (per motor) that he will. 

Since I am DCC, very little if any wire is added in DCC conversions.. in fact, I often shorten the stock wires. 

Also, I don't have the potential for the surge current that the batteries can produce... the batteries can produce more current that my system. 

Finally, I don't have to worry about loss in my wiring, it does not affect run time like it does on batteries. 

Regards, Greg 

(track power and DCC does have certain advantages







)


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