Battery Recommendations 1975 Mark III Electric Start

Finally got to the point of installing the main wiring harness and now I have to purchase a battery. I am in Texas USA and ask fellow mark 111 owners what battery rating and type do you recommend ? I will be using the standard 2 brush starter with upgraded cables (4 gauge wire). I did hear that interstate batteries carry a decent gel unit however I am not to sure what rating is recommended as I have heard that the standard OEM type battery hardly spun the motor. I know there are many upgrades top consider like 4 brush and Atlantic Startert etc however the budget is tight.

Absorbed Glass Mat is the technology often confused with "gel". There is a difference. Light reading here: http://advrider.com/forums/showthread.php?t=757934

A high quality US made AGM here: http://www.dekabatteries.com/assets/base/0278.pdf priced reasonably.

Good price here: http://www.tristatebattery.com/etx15l-d ... p-977.html

http://www.batteriesplus.com/product/40 ... 850CC.aspx

In combination with a Dyno Dave starter it spins like a modern bike. Even under the best conditions the two pole never spun so quickly.

JimNH said:

http://www.batteriesplus.com/product/40578-DURAGM--15L--US-Duracell-Ultra-AGM-Battery-Made-in-USA/558-CC/4823-Motorcycle-Batteries/146428-Norton/Commando-75/850CC.aspx

In combination with a Dyno Dave starter it spins like a modern bike. Even under the best conditions the two pole never spun so quickly.

Click to expand...

+ 1 on the aftermarket starter mentioned. This is the battery I have, I believe CNW uses them too.

http://www.tnrbattery.com/pc680-odyssey ... AiCu8P8HAQ

The OEM battery was 14ah rated and worked if kept fully charged. Anything less will be unsatisfactory. I am running a Yuasa 14ah lead acid now and it works fine, but I have the benefit of modified to 4 brush/4 pole.
Jaydee

jaydee75 said:

The OEM battery was 14ah rated and worked if kept fully charged. Anything less will be unsatisfactory. I am running a Yuasa 14ah lead acid now and it works fine, but I have the benefit of modified to 4 brush/4 pole.
Jaydee

Click to expand...

Battery technology has moved on a lot in recent years.
I have 2 electric Commandos , one has four brush conversion Prestolite and use a Motobatt MBTX 14AU and starts and runs just fine. The other though has standard Prestolite and uses a Motobatt MB 12U., this battery is slightly narrower than the 14AU and the bike also starts and runs just fine aswell. Both bikes run standard mk 111 alternators with Podtronics reg/rec mounted under the battery trays (horn resited).
sam

With the stock alternator and running at night around the city I was always kicking it. With the 3 phase alternator I just leave the headlight on all the time without a second thought. I really think the stock alternator was marginal at best especially with the anemic starter.

I'm especially happy with one of these in place of the stock charge light and assimilator :

http://www.sparkbright.co.uk/sparkright ... onitor.php

JimNH said:

http://www.batteriesplus.com/product/40578-DURAGM--15L--US-Duracell-Ultra-AGM-Battery-Made-in-USA/558-CC/4823-Motorcycle-Batteries/146428-Norton/Commando-75/850CC.aspx

In combination with a Dyno Dave starter it spins like a modern bike. Even under the best conditions the two pole never spun so quickly.

Click to expand...

Is the size of the battery the same as the standard fitment battery or is it bigger and has to be mounted on its side . Does anyone know the size of a standard fitment battery. My Norton was in boxes when i bought it and sadly no battery to check physical dimensions

thackero said:

JimNH said:

http://www.batteriesplus.com/product/40578-DURAGM--15L--US-Duracell-Ultra-AGM-Battery-Made-in-USA/558-CC/4823-Motorcycle-Batteries/146428-Norton/Commando-75/850CC.aspx

In combination with a Dyno Dave starter it spins like a modern bike. Even under the best conditions the two pole never spun so quickly.

Click to expand...

Is the size of the battery the same as the standard fitment battery or is it bigger and has to be mounted on its side . Does anyone know the size of a standard fitment battery. My Norton was in boxes when i bought it and sadly no battery to check physical dimensions

Click to expand...

Same size as the original - direct replacement, just better performance and can't leak.