An400x eating batteries.

[Old scooterist]

Weird one;

1999 AN400X, 13000 miles.
New battery. Filled and left an hour before use.
Initially started bike straight away but rapidly died after two days.
Zero parasitic drain.
Tried Varta, Exide, and cheap batteries but all the same.
Charger shows 14v and drops to 12.8 on install. Doesn't start bike, just groans and clicks and drops to 9v but using a booster starts straight away.
Bike charging, headlights and all electric okay.
Bike runs okay on road but down on power and doesn't respond to throttle above 75%, backing off it picks up and cruises at 90kph.
Possible iffy carb' it is 23 years old after all.
Going to change to mosfet regulator on Monday.

[Data]

Don't forget you must charge any new battery "off the" bike for several hours after commissioning it to allow it to accept a full charge & condition the battery. Not clear you did that. So let it stand for an hour after adding the chemicals then start a slow charge with something like an Optimate that controls the charge. Just leave it on overnight! This will genuinely take it to full charge. Adding chemicals won't produce anywhere near a full charge. Normally it's at about 70% charged on just chemicals but a test may show more due to battery excitement. But that's a false reading which fades fast. It's imperative NOT to start the bike with the battery in this state.

Don't let the bike charge a new battery either as it won't do a proper job & stresses the battery. A new battery to start with needs a slow consistent charge to the full mark otherwise it can & often will fail early. As a tech I've commissioned hundreds & hundreds of batteries over the last 50yrs without issues. But you must charge it first before putting it on the bike.

Have you tested the regulator? It's easy to do. It does sound like you have an issue there somewhere. If the starter motor is on its way out it draws huge amounts of current & will hammer a battery. Is solenoid ok? Check also the connections directly to the starter motor. They tend to corrode on the Burgmans.

FYI: I've completed the Suzuki factory courses for the 400 Burgmans. I can probably help if you get into a pickle over this issue. Just let me know how you get on.

[Old scooterist]

Thanks Data,
I always give a new battery a charge before using and I have just bought a new Autoxel 'intelligent' charger on Amazon and will try that. I have also changed the regulator for a Mosfet one as they have zero leak down. Bit of a pig getting it to fit as its bigger but it's in.
Currently debating the pros and cons of 'wet lead acid' versus 'gel battery' cost about the same but gel seems to have better 'specs'.
When running holds a steady 13.8v with lights off and about 12.5v lights on.
Starter is fine.
But newer K2 engine now so I wait and see but turned it over no problem so far.

[Data]

Hi mate, good, sounds like you are on the right track. Suzuki like many manufacturers recommends only the gel type of battery as they are much safer especially when mounted on their side or at angle. The Burgmans also have a 12amp/hr capacity battery after a certain year but cannot recall what year they changed off hand. Hopefully your issues are over now. Let us know how you get on.

[roadster]

When running holds a steady 13.8v with lights off and about 12.5v lights on.
Starter is fine.
But newer K2 engine now so I wait and see but turned it over no problem so far.

If you have changed the engine you have probably got rid of the problem but the voltage reading with lights on is barely adequate, unless that was just at tickover of course. It is also possible that an old starter motor could put excessive demands on the battery which are only satisfied when jump starting with an extra battery. One cause of this, which plagued one of my Piaggios, is oil contamination of the brushes through a bad oil seal on the starter pinion end.

[Data]

Oh yes roadster, I missed that reading of 12.5v with lights on. It should be bit higher for most of the time unless the battery has just been in a big charge cycle & the regulator has dropped the charge rate for a limited time to prevent overcharging.