Author Topic: A10 convertion to 12v negative earth  (Read 391 times)

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JOHNSTONE

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A10 convertion to 12v negative earth
« on: 14 July, 2019, 12:03:41 »
I am considering converting my 1958 A10 to 12v negative earth electrics. Is this likely to be an expensive job and what will it involve? Hope the members can help and await your answers in anticipation.

Regards Rich

A10 JWO

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Re: A10 convertion to 12v negative earth
« Reply #1 on: 14 July, 2019, 15:35:36 »
What is the advantage of negative earth ? Read about many people doing it. Will follow thread with interest.

chaz

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Re: A10 convertion to 12v negative earth
« Reply #2 on: 14 July, 2019, 15:59:16 »
I always wondered what benefits?  some components are easier to find for neg earth.
I had heard its better for corrosion prevention but
http://www.rrec-northeast.co.uk/positive_negative.pdf

Trev

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Re: A10 convertion to 12v negative earth
« Reply #3 on: 15 July, 2019, 15:42:42 »
Quote
I am considering converting my 1958 A10 to 12v negative earth electrics. Is this likely to be an expensive job and what will it involve? Hope the members can help and await your answers in anticipation.
It's a relatively inexpensive thing to do. You will need an electronic voltage regulator. I would strongly recommend the DVR2. Others are available but this one is generally accepted by most people as being the preferred option. The 6v horn should be OK on 12v because it gets very little use. Ammeter will be OK that just leaves battery and bulbs. I use two 6v Cyclons in series. They fit perfectly into the period dummy battery battery cases that you see widely advertised. Not absolutely vital but a dynamo belt drive kit speeds up the dynamo a bit so that the charge characteristics for 12v operation are the same as for 6v. If you convert to LED lamps that will not be so crucial. I have all LED lamps fitted. Headlamp, pilot, speedo, rev counter, and stop and tail. That's about it really. Negative earth is the best option because some lamps are only available in negative earth, although dual neg/pos lamps have started to appear on the market of late. As an aside Cyclon batteries are fit and forget. They require no maintenance even over winter. Simply remove the fuse and they will hold their charge with no problems. Other advantages of negative earth are that the circuit is more efficient because 12v draws less current than 6v, and you can if you so wish charge your phone, and operate a sat nav. Try not to use an H4 BPF headlamp bulb (an E3L can handle it) but LED lamps demand far less current and as such it is far less stress on the battery and dynamo.

JOHNSTONE

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Re: A10 convertion to 12v negative earth
« Reply #4 on: 15 July, 2019, 22:58:00 »
Many thanks for your advice Trev. I assume the DVR 2 comes with full fitting instructions and that I would have to specify whether it was required for negative or positive earth ?  Would I also be right in thinking that some re-jigging of the wiring would be necessary to change from positive to negative earth including changing the pollarity of the dynamo?

Trev

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Re: A10 convertion to 12v negative earth
« Reply #5 on: 16 July, 2019, 09:11:23 »
Johnstone, the only alterations that you will need to make to the wiring will be: 1) Reverse the battery terminal leads, and 2) reverse the ammeter connections. The dynamo is re-polarised by flashing. This done with the green lead that connects the dynamo to the regulator (F) terminal. Disconnect the green lead from the regulator and dab it on the battery positive terminal a couple of times. You should see a little spark when you do that. Reconnect green lead to (F) terminal on regulator. That's it job done. The DVR2 when you order will need to be specified as to which polarity you require. It comes with full fitting instructions, and the unit itself is marked clearly showing the correct connections.

JOHNSTONE

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Re: A10 convertion to 12v negative earth
« Reply #6 on: 16 July, 2019, 11:56:00 »
Once again Trev many thanks for you help and advice.

Regards Rich

STAR TWIN

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Re: A10 convertion to 12v negative earth
« Reply #7 on: 16 July, 2019, 13:38:42 »
Be careful with your choice of headlight bulbs if you go down the LED route. Some (most?) are good at lighting up the countryside but not the bit of road you are trying to see. I use a BPF 50/40W bulb and LED stop/tail.

RogerSB

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Re: A10 convertion to 12v negative earth
« Reply #8 on: 16 July, 2019, 15:16:27 »
On my 1960 G/Flash with DVR2, positive earth and keeping the Ah low (see below) I'm using:-

Headlight: 12v BPF Quartz Halogen 35/35w (2.92Ah).
LED stop / tail: 4w (0.33Ah) & 1.25w (0.105 amps).
LED pilot bulb: 1.5w (0.125Ah) Note: Pilot bulb does not come on when headlight is switched on.
Speedo bulb: 2.2w (0.18Ah).

When the DVR2 kicks in at moderate revs it keeps my 12v Motobatt MB9U AGM, 11Ah battery charged.

« Last Edit: 16 July, 2019, 15:18:37 by RogerSB »
BSA Golden Flash, Plymouth, UK

JOHNSTONE

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Re: A10 convertion to 12v negative earth
« Reply #9 on: 16 July, 2019, 16:51:46 »
Thanks for the info Startwin and Roger.

Rich