Hi Steve,
Originally Posted by Ragmanx
battery Tender charger
The BSA is different, as you know, because or the positive ground.
Nope, no different. Electrons go the same way 'round any DC circuit; "ground" is an imaginary concept, nothing to do with Physics.

The only reason you'd experience difficulty is if you didn't connect the battery Tender leads to the actual battery terminals, you were connecting either BT -ve or +ve lead to somewhere else on the bike.

Originally Posted by Ragmanx
last week I forgot to disconnect it before starting the bike, That move destroyed the charger.
Curious ... suggests the alternator was working and the BT doesn't have any protection against being connected the wrong way 'round (which is effectively what starting the bike's engine/alternator did)? confused

Originally Posted by Allan G
tried starting bikes up when they are on an opti-mate before now, usually the optimate just cuts out until you unplug and plug it back in again. It hasn’t damaged the optimate,
+1; protection against being connected the wrong way 'round.

Originally Posted by Ragmanx
Perhaps better asking for comments before you ordered it? Since you asked:-

. Several previous posts from people who bought and fitted them say they don't give any more power at low rpm than standard RM21.

. Those particular Wassell pattern stators are available in the US, curious why you'd order from GB? confused

. Otoh, available from another British dealer are original Lucas RM23 stators, that do make more power than RM21 at all rpm, for less money than Feked have relieved you of.

Originally Posted by Allan G
shame you didn’t know this before, you could have bought a 3 phase high output stator and regrec and never had another battery issue again.
3 phase kit is you reach max output at 2000-3000 revs,
single phase I believe max output is something like 5000+
Not so.

All alternators generate more with increasing rotor rpm just, at higher rpm, for the same given rpm increase, the Amps increase is less.

5,000 rpm was just a comparison point 'original Lucas' happened to choose. Afaik, Wassell Lucas haven't ever published rpm/Amps plots for any of their pattern stators.

'Original Lucas' rated both the aforementioned RM23 and the RM24 high-output 3-phase for 14.5A @ 5,000 rpm, but the 3-phase's output increases faster at lower rpm - 'original Lucas' advertised 75% of rated @ 2,400 rpm for a single-phase like the RM23, but 85% of rated @ 2,400 rpm for a RM24 3-phase; i.e. a gnat's under 11A from the RM23 but over 12A from the RM24.