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GoKart Trailer Power, Solar and Switched Battery Selection

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Forum Name: General Discussion
Forum Discription: General Mobile Electronics Questions and Answers
Printed Date: October 15, 2021 at 7:52 PM

Topic: GoKart Trailer Power, Solar and Switched Battery Selection

Posted By: williamhamilton
Subject: GoKart Trailer Power, Solar and Switched Battery Selection
Date Posted: August 07, 2020 at 9:51 PM

I have been asked by a friend to help setup the power in his GoKart trailer. I am looking for some guidance and double-checking if I can ask here.

Current Scenario:
    Std car battery mounted inside the trailer which is used to run a tyre compressor.

Future Scenario:
  • Solar panel on the roof of the trailer (150W panel or thereabouts is what I think they have, along with a controller)
  • Ability to top up GoKart batter between races
  • Run a small number of accessory power outlets cigarette lighter and USB style
  • some LED strip lighting
My plan at this stage is:
Solar panel -------> controller --------> trailer battery ---- lights, outlets, compressor etc
trailer Battery ----- switch/plug ---- diode ----- Kart Battery

What do you think about adding a manual switch out of the Solar controller such that if the trailer battery is low then Solar charging can be directed tot he Kart batter to top up. Is there an automated switch on the market that can monitor voltage levels if and automate this?

Like most jobs there has been some feature creep due to "What if..?" and "Could we...?" Any suggestions on a better way to set this up to allow for easier expansion?




Posted By: eguru
Date Posted: August 08, 2020 at 10:17 AM
If the effort is to make sure that the Kart battery is always charged, why not have the solar controller connected directly to the Kart battery? Basically swap the 2 batteries in your setup.
Use a battery saver switch to disconnect the trailer battery if the Kart battery voltage is too low.

Posted By: williamhamilton
Date Posted: August 08, 2020 at 6:10 PM
Thanks for this feedback. The Kart will be topped up between races, my logic was that it will be able to take more current from the trailer battery (much larger car style pack) than the solar panel (it may not always be super sunny) therefore top up a bit baster. A switch to directly connect the Kart to the solar when the trailer battery is down sounds like a good backup or would you suggest a three-way battery switch to isolate each battery or combine but connected directly to the solar controller?



Posted By: eguru
Date Posted: August 09, 2020 at 9:53 AM

Automating the process so that the best charging source (trailer battery or solar controller) gets connected directly to the cart battery is decidedly major "feature creep".
Determining which source is the best input requires a whole bunch of measuring and control circuitry.
I think a couple of $10 digital voltmeter modules connected to the two batteries and a 2PDT (ON-OOFF-ON) switch allows the simplest human controlled solution.

The switch will select whether the kart battery gets connected to solar controller and the trailer battery, just the solar controller, or the no connect center switch position.
In the center off position the batteries are isolated from each other and you can read the two voltmeters to determine how to proceed.

Wire one side of the switch so that center terminal connects to kart battery and the outer terminals connect to the controller and trailer battery.

Wire the other side of the switch so that center terminal goes to the controller. Connect the outer terminal adjacent to the one you previously connected to the trailer battery to that terminal.


Posted By: williamhamilton
Date Posted: August 10, 2020 at 5:41 AM
Thanks eguru, that sounds very logical. shopping trip this week for a switch.

I appreciate your input, thanks again.


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