Sat May 07, 2022 3:19 pm

Hooked
'74 rally 200; '62 LI150
Joined: 12 May 2013
Posts: 117
Location: Tacoma, WA
 
Hooked
'74 rally 200; '62 LI150
Joined: 12 May 2013
Posts: 117
Location: Tacoma, WA
Sat May 07, 2022 3:19 pm linkquote
Any recommendations for a 12v battery to sit in the Rally 200 tray nicely?

I have a lithium one which will fit sideways, but it looks a bit kooky.

My 6 v horn seems overwhelmed by the 12 volts. Is there a way to rig the 6v horn to work?

I know the other options.

thanks
Sun May 08, 2022 4:33 am

Hooked
1964 Piaggio Allstate Cruisaire
Joined: 15 Aug 2021
Posts: 372
Location: York, PA
 
Hooked
1964 Piaggio Allstate Cruisaire
Joined: 15 Aug 2021
Posts: 372
Location: York, PA
Sun May 08, 2022 4:33 am linkquote
Gazoo,

Add a resistor in series with the horn. If you know the current flow of the 6v horn, its easy:

R = (Vs-Vf)/I,
R = (12-6)/0.5 (guess)
R = 12 ohms

W = RI
W = 12 ohms *0.5 amps
W = 6 watts (round up to 10)

R=resistance
Vs=supply voltage
Vf=forward voltage
I=current
W= watts

https://www.digikey.com/en/products/detail/te-connectivity-passive-product/THS1012RJ/2366855
Sun May 08, 2022 4:57 pm

Hooked
'74 rally 200; '62 LI150
Joined: 12 May 2013
Posts: 117
Location: Tacoma, WA
 
Hooked
'74 rally 200; '62 LI150
Joined: 12 May 2013
Posts: 117
Location: Tacoma, WA
Sun May 08, 2022 4:57 pm linkquote
Thank you.

I am sketchy with electronics, so I appreciate the help and thoughtful explanation. Just to confirm, let me know if this sketch makes sense. Also, not sure how we know the current (I) of our system. Is that dependent on the battery?

With regard to Amps, I have a new battery that is rated 105 cranking amps and 45 cold amps, 18wtt hrs so 1.4 AH so not sure if that plugs into this equation for a different level of resistor or what? Perhaps I need to buy a different battery?

I am still looking for advice on which type of battery would be best for my situation. The battery I have is a Lithium Powersport Battery, which I can fit sideways into my battery holder.

I also have an old CASIL 12v 4AH battery which is a cheaper version and heavier possibly less powerful?, ( i have no idea)

I get the resistor idea, I think.... but now need to put in the proper, or possibly best battery to run a powerful horn, lighting system.

thank you



Mon May 09, 2022 2:32 am

Hooked
1964 Piaggio Allstate Cruisaire
Joined: 15 Aug 2021
Posts: 372
Location: York, PA
 
Hooked
1964 Piaggio Allstate Cruisaire
Joined: 15 Aug 2021
Posts: 372
Location: York, PA
Mon May 09, 2022 2:32 am linkquote
Your existing battery is fine. As is your drawing. The current draw is based upon the horn. I think .5 amp is pretty close.
Mon May 09, 2022 5:41 am

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11133
Location: The state of insanity, SoCal
 
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 11133
Location: The state of insanity, SoCal
Mon May 09, 2022 5:41 am linkquote
locked in that you've got two threads about the same thing.
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