The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: ShaunMac on 23.03. 2013 21:42

Title: Positive earth?
Post by: ShaunMac on 23.03. 2013 21:42

Hi guys,

May seem like a really daft question, but as I got my Super Rocket with no battery on and there's been a bit of bodging on the wiring, which I'm in the process of sorting, can I ask, does the bike have a Positive earth?
Is there a way of checking?

Thanks, Shaun

Title: Re: Positive earth?
Post by: trevinoz on 23.03. 2013 21:43

Certainly would have been from the factory, Shaun.

Trev.

Title: Re: Positive earth?
Post by: ShaunMac on 23.03. 2013 21:59

Thanks Trev. Looking at the wiring diagrams there's a few bits different on mine, mainly the wires from the light switch but will connect the new battery positive to earth and hope I don't get any smoke!  *warn*

Title: Re: Positive earth?
Post by: a10 gf on 23.03. 2013 22:06

Quote

hope I don't get any smoke!

If not already done, use a fuse when experimenting, something like 15 A should prevent anything from frying if there's a short, if it burns out start some investigations. btw, good to always use a fuse on the battery side.

Title: Re: Positive earth?
Post by: ShaunMac on 23.03. 2013 22:13

Going to fit a blade fuse in-line. I take it it would be best on the negative line or on the positive between earth?

Title: Re: Positive earth?
Post by: a10 gf on 23.03. 2013 22:16

Quote

on the negative line or on the positive between earth

Either side of the battery will work (IMO). But I 'would somehow' choose to put it on the battery's 'regulator side' (negative in your case), with the battery connection to frame (positive in your case) unfused.

Title: Re: Positive earth?
Post by: KiwiGF on 24.03. 2013 05:56

Just a little tip if you dont know which way around the bike was earth wise make sure you flash the dynamo as it might otherwise try to charge the wrong way around....at least with an electronic reg anyway.

Title: Re: Positive earth?
Post by: Billybream on 24.03. 2013 07:37

I would recommend you consider fitting 3 fuses, and site them for easy access.
Use the car type and you can gang them together, each side of the battery  at 15Amp  and one on the feed wire from the regulator to the lighting switch 20Amp. Mine came off Ebay for pack of 3 @ £6.20.

Title: Re: Positive earth?
Post by: BSA_54A10 on 25.03. 2013 12:22

On magneto bikes I use 3 fuses,
Both sides of the battery & the power wire from the regulator ( the one that goes to the ammeter ).
I also use blade fuses and despt beint told that they are not waterproof and will fail, Some of the bikes I did have been running over 20 years with no problems.