I am have a battery capacity of 9 Amps 12 V. Factory electrical system of the bike is DC (horn, indicator, etc.) + AC (head light).

Now I have changed the remaining AC to DC. (light system with relay to DC from AC).

The factors light is an HS1 35/35 W and I have changed to HS4 Philips Extreme Vision plus 60 W, and this one will an additional 2 Amps which is the root cause of the entire problem.

So, now running all the electrical systems at once (horn, indicator, head light, daytime running light, dashboard light), is likely to draw more than 10 Amps, and the horn is not doing its best work. I can hear the reduced output of the horn.

Is there any way to increase the battery capacity in Amps. I have seen that, a 10 Amps battery is a different size than my battery, so I cannot accommodate it.

I am not willing to degrade the head light either back to AC or to 35 W.

May I know, is there any way/work around to make this work.

  • 1
    I hope you upgraded the headlight wiring to deal with the additional current. If not, then a weak horn will likely be the least of your problems.
    – TMN
    Commented Jul 6, 2016 at 14:39
  • Hi @TMN, Horn is in good state, and they are doing well (producing the correct sound) when there is enough current. I have checked this without turning on the light... Commented Jul 6, 2016 at 16:25
  • What I meant was, if you're now pulling 60W through wires that were only designed to carry 35W, you're likely to overheat them and cause a fire.
    – TMN
    Commented Jul 6, 2016 at 16:29

1 Answer 1


One option might be to change alternators to one with a higher output, the battery really should only be there to handle starting and intermittent loads (like your horn). The bulk of the electrical load should be handled by the alternator.

Another question I'd ask is how much are you loosing by running the headlight on DC (which I think you're converting from an AC output)? The headlight should run find on AC.

  • Hi @dlu, Thanks for the reply. I have a thought of having a steady light beam and so I just turned to DC. Commented Jul 6, 2016 at 5:09
  • The beam comes from the heating of the filament in the bulb. AC and DC should do pretty much the same job. Think of your home lights which run on AC.
    – dlu
    Commented Jul 6, 2016 at 7:29
  • Hi @dlu, Thanks for the reply. I forgot to write one thing. I even want to turn the lights on, without turning on the bike. And also I have seen that, when the light is on AC, then , when I have reduced the throttle, then the light beam is also reduced. Seems they are proportional. So I planned it to run on DC. Commented Jul 6, 2016 at 9:29

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