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Batteries, how many mAh?

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  • Batteries, how many mAh?


    How many mAh for HO sized diesels should I be looking at? 3s 11.1v Li Po batteries seem to range from 1300 ($13.35) to 4000 with the 4000 only being $38.50. Is more better?

  • #2

    Larger mah will give you longer running time; hours. Lower mah, smaller the battery is in physical size.
    Tom M.


    • #3
      You can also get 3S LiPos down as small as 250mAh is space is tight.


      • #4

        Figure an HO diesel will draw between .5 and 1 amp. 1300 mAH would theoretically run for about 2 to 1 hours. LiPo's seem to give all they have, and then drop dead. At least this in RC cars and planes. Depending on how easily you could recharge them is probably a sizable consideration. If you can "pop them out", I'd go with the smaller value, buy an extra one or two to keep on the charger. I'll admit to having zero knowledge of how "deadrail" techniques are implemented, but I do understand electronics.
        Take the red pill


        • #5
          Thanks guys--There is a local RC speciality shop in Madison so I think I'll head over there sometime today. With sound I would like to be able to run about an hour before recharging. So, I think I'll try a few of the batteries and see how they fit, if they fit and how long they will run.

          I've decided if they are too big for a single locomotive i will consist with one carrying the battery.


          • #6

            If you could bring the intended locomotive where they/you could actually measure the current draw, that would probably get you a lot closer to the estimated need. Also remember that the current amount will vary as you add cars behind that engine.

            Take the red pill


            • #7
              Jim thanks I'm heading to a RC shop--should they be able to figure the draw--what tools would I need to measure the draw


              • #8
                A V-O-M (volt-ohm-meter) They should have one. Like I said, I'm clueless when it comes to dead rail. Do you use DCC decoder in this setup? If you do, how are you controlling speed, direction, sound effects, etc? You'll have to make the engine do all of that to be able to measure the current draw. They will probably only be able to do those things in DC mode.
                Take the red pill


                • #9

                  I am leaning towards CVP


                  wireless Throttle and decoder for battery.

                  I was orginally thinking that I liked Rail Pro and I still do but its much more expensive.

                  I went to an RC shop today and they weren't real helpful, so I did not buy any batteries. The boss/owner is off today and should be in tomorrow. The kid behind the counter said to call and talk to him because he does know they sold some product to Model train guys.

                  I am going to HD now and will get a meter along with some more stuff for my valance.

                  Thank you for your input.


                  • #10

                    From what I read, it looks the mobile decoders are for 'G Scale' locomotives. That battery pack for the SD-70 is a whopping 4.4 Amp Hours. That's 4400 mAH. I didn't see the physical dimensions, but it looks fairly large for the proposed HO scale diesel.

                    Hope someone who has dealt with this, jumps in.

                    Take the red pill


                    • #11
                      Hi Jim

                      The size of the batteries is going to be an issue. I measured an empty GP-35 and its going to be tight--doubt I'll be able to fit anything beyond a 25c battery. Most of the battery sizes are metric so I need to get out my metric conversion table.

                      Size of the decoders--CVP has a mini air and that should fit with no problem. I realize until things really get smaller, I will be housing all battery equipment in a trailing unit.

                      Thanks again


                      • #12

                        Read all the other topics under dead rail. I posted a while ago size comparison of the Tam Valley receiver to a dime. You can also use a "step-Up" to get a larger voltage.
                        Tom M.


                        • #13

                          Only 3 yrs and now posting...better late than never?

                          Well anyway, I've been operating dead rail in HO for the last 7 years. The short answer to your question is, yes, the more mAh the better.

                          Without getting into what I'm using and how I use it, which can be discussed later, the reasons are:

                          * I like very much not to run out of power during a run

                          * I'm good for several operating sessions that last 2-3 hrs each

                          * I run at shows which sometimes go 6-8 hrs.

                          * Voltage regulators, sound and lighting take additional power

                          * More mAh = more battery power = cooler running batteries

                          So I recommend as much battery power as you can fit in, consistent with all the other components you want or need. I try to get around 8-12 Wh capacity in a road diesel, 15-25 Wh in a large passenger diesel or mid-size steam engine.

                          I prefer a 2S Li-ion battery configuration with 9V step-up voltage regulator for my 12V engines or a 6V step-down regulator when rebuilding an engine with coreless motors, which I like very much. With sound equipped locos, I step up the voltage to 12V.

                          I'll post a photo as soon as I learn how.



                          • #14

                            Originally posted by DanT

                            I'll post a photo as soon as I learn how.



                            I host my own pictures. I use the "img" tag in the Post Form. It's to the left of "envelop" picture in the line that says "Format:

                   This is where my picture is stored. I use the URL from that and place it between the image tags.

                            That's my project that I'm working for battery power. I'll post more once it's done.

                            New York, Vermont & Northern Rwy. - Route of the Black Diamonds


                            • #15
                              Dan, my feeling is never too late! Here is my experience:

                              Started out wit the Bluerail board on battery. The battery was 800ma, 11.1 volts. Boards wOuld not fit a GP35 or F45 diesels. Used a dummy for both, meaning a locked consist as I placed the battery and boards in the dummy with wire connections. Ran very smooth but the size of the board was too big for diesels. That experiment was discontinued.

                              Tried the CVP micro air board, fit great in SD60’s by Walthers and Kato dash 8’s with the 800ma battery in a dummy. Had to buy the throttle from wireless CVP. These have been sold. Worked great though, but you needed the board and a decoder.

                              Next up was and currently is the RailPro system, using the throttle HC2 and decoders LM3S with sound and the non sound LM3. Batteries again are 800ma in dummies.

                              The 800ma battery running sound gets me a good 2.25 hours of switching on my layout and there is battery power still useable. The non sound in my experience is in the same time frame. These are my experiences. I have just let the engines run but I rarely do mainline free running for more then an hour.

                              Costs are what you make of it, expensive depends on your budget.

                              800ma 11.1v batteries are $40 from deadrailinstalks

                              The Battery charger I went way overboard at $200. Hitec X4 AC pro available at But safety with LiPo batteries is extremely important.

                              The throttle I am currently using for Dead Rail is the RailPro HC2 available with free shipping and no USA taxes from Bill @ for $224 or many USA distributors of RailPro.

                              The decoder is the RailPro LMS for $73 at or the non sound LM3 for $46. No additional decoders needed as RailPro is direct to the decoder. Battery power works great.

                              My feeling and I know I preach to the choir but Dead Rail to me is great. No frog juicers or keep alive needed or wiring to the track.

                              I have six sets of 11.1v battery packs for 2 consists of engines. I feel the 2+ hours of run time is good enough for my switching layout. I have not experimented with more MA’s nor have I played with the volt boosters. Using the dummies to hold the batteries is good enough for me at this time. I plan to experiment this fall with a 3 engine consist with one dummy holding 2sets of batteries to the powered


                              Bernd is very very knowledgeable both on this forum and at the MRH forums. He likes to experiment and documents his information very well. I like to play at it if that makes sense. Anytime he writes up something I soak it up. He loves his steam.

                              There are many systems out there but batteries drive the system and they will get stronger and last longer. I like the 800ma LiPo packs.

                              Dead rail is here to stay, but it may never be mainstream. Enjoy!