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Following on from Richard mishap while on today run I have made some enquiries regarding the charging of a run down battery
It would appear that unlike a car the electrical system on a bike is finely balanced and therefore the alternator does not have a lot of excess charging capacity over what is required to run all the standard electrics.
It would also appear that a bike would have to travel a lot further than 30 miles at minimum drawdown to replenish lost power to start the the bike via a starter.
It now looks as if we will have to pack a set of jump leads.
I have fitted an extra socket to my bike so as to be able to use the tyre pump. I will now make a set of suitable jump leads. I hope this is of help.

More information
The alternator should be putting out about 13.7-14.5 volts. More than enough to charge the battery normally. If he left the ignition on for half an hour with the heated grips on it may have knackered the battery or rectifier/regulator as either could have overheated. Try a trickle charger and if you have one put a multimeter across the terminals to see what charge is getting to the battery with the bike running. Then turn it off and try starting the bike while checking with the multimeter. If the volts drop much below 9.5 volts the battery is probably knackered.
If the alternator is charging the bike should run but if the battery is low it may not start.

Some more information.
The usual rule of thumb is 14 miles plus to replace one start while running lights only, no grips, nav etc.

Not sure what happened on the run. For general information, because of the problems turning over the KTM on cold mornings, I always carry a compact boost battery and leads in my top box. Powerful enough to get an HGV started (they say). Works well for bikes.

Like Chris not sure what happened but I also have bought one of the small battery boosters off eBay, they are anywhere between £30 and about £70 depending on capacity. When I recently had problems with the battery on my GSA it worked like a charm. I have also used on several cars some with completely discharged batteries and it has started every time. Well worth the investment.