BSA Rocket 3 Battery and Electric start

[Poole]

Hi all

Due to getting older and a right Knee problem, I have fitted an electric start to my 1971 Rocket 3, not too difficult really, the biggest problem has been the battery, it was my initial plan to fit a L Ion battery but after investigation this is difficult as the Lucas alternator output is not regulated at an acceptable standard so I will need to squeeze a YGZ14HBS 240 CCA battery into the space, but I would really like to fit a L ion battery, my question is has nay body found a Mossfet regulator rectifier that will work and if so how do you change the wiring.

Regards John

[Allan G]

You can fit an RM24 stator, they do a 180w version. This will charge the battery up in good time.

The original Lucas starters used a lot of power and were slow cranking the bike. Look at the electric starters from Dave Madigan much smaller, use less power and spin the motor over really quickly.

[limeyrob]

Lion batteries and charging can go very wrong. I've had a bettery fire with small battery on charge, they really burn.  Yes there are people selling kit for campers but the reviews are very mixed the LION battery life can be poor, especially in relation to the cost.
LION batteries are not ideal for starters, why do you want one?
Allan is right, starter tech has come on a lot with high rpm geared and permanent magnet units that don't draw the huge initial current.  You are spinning a 250 cc cylinder so I would be looking to re-purpose something off a Japanese 250-350.  I was surprised how good Harley starters are, I had Sportster with 442 cylinders and that started fine with a 20 size (18AH / 270 cca) battery 173mm x 90mm x 155mm.
You didn't get many goes but it worked.
The morning cold start is the hardest but you are at home and can boost the battery. Once you are out on a ride its a warm start with a topped up battery.