battery drain

[adriangsmith]

Hi All,
I have an issue with my 400/4 where the battery will become discharged if left unused for more than 3 days.
Brand new motobatt battery, aftermarket regulator/rectifier fitted.
Good voltage from regulator when running.
Not sure where to start looking!
Any ideas?

[hairygit]

If you're not using it as a daily hack, charge the battery, but take it off the bike, and see if it still discharges. Sadly motobatt products are not as good as they used to be, and just because something is new, it can still be duff.

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[adriangsmith]

Thanks Hairy
pretty much used every day apart from a couple of days a week or over the weekend.
Did the same with previous lucas battery.
May splash out on a new loom and fuse box in case a short has developed somewhere.
Connected to optimate charger but never seems to reach full charge on the bike.
Also had issues when riding that despite good voltage out of the regulator after 30 miles of hard riding if it cuts out the battery will not have enough power to turn the electric start.

[hairygit]

Is the battery voltage actually running down, or are the starter brushes worn/sticking? Are all earth's clean and tight? If the frame is powder coated, was it scraped away where the heavy earth lead attaches to the frame?

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[K2-K6]

Disconnect the main lead from starter solenoid down to starter motor and assess it like that,  you'll have to kickstart it though.

Edit:- this test is trying to remove the function of the starter solenoid as it could be both causing drain and resistance that won't fully power the starter motor when asked.

If you've got an ammeter you can disconnect the main positive battery lead and put the meter across between the lead and battery terminal which will tell you if it's drawing current when all is switched off. That's a seperate test from above.

[Lobo]

If you haven’t got a multimeter...
(As you noted... the ‘400 fuse holder can indeed be the problem...)
On a dead bike, ie ignition off, lights off etc, when you disconnect / reconnect the battery you shouldn’t get any spark - small or otherwise. If you do get any kind of spark... there is indeed a small short / earth leak somewhere.
So... assuming there is a wee spark at battery connect..
Keep the bike ‘dead’.
Then pull all 3 fuses, and replace singly, reconnecting the battery to check for tiny spark ... to narrow down which fused circuit is the culprit. Assuming you can narrow it to one circuit, then, using a circuit diagram disconnect items singly... eg coils, starter solenoid, horn, left indicator blah blah ... and so on until that wee spark returns at battery connect.
Then check / clean the offending wiring / connections / earth etc.
Good luck!

[SteveW]

Motobatt batteries are a pain in the arse. I have had a couple replaced under warranty on my Fireblade.

If they go flat they never seem to fully recover afterwards.

The only way to use one successfully is to have one connected to a trickle charger when not in use.

[flatfour]

Different story with Motobatt for me, used them extensively over the past five years or so on a variety of bikes and found them to be first class, holding a charge for long periods when unused and spinning a cold engine over reliably every time.