Battery Confusion ?
 

My 748s lives on its Optimiser when garaged and has been
spot on everytime for the last 3years 357 days.
We get a sunny weekend - role it out and the batteries as flat as a pancake.
So I bollock the kids for turning it off - (which they hadnt done but they had it coming anyway)
I put it back on the optimiser and cut the grass - it went through several charging cycles and then told me it was good. Started up OK and ran for a while.
A short check everything is all right trip - return home, lunch
go out again - Dead.
Optimiser now tells me the battery is weak.
Charging cycle ..... Battery is good, Next day Battery is weak?

I suppose I'm really looking at a new battery but I'm confused as to why its good one minute then dead the next.
I even started to suspect the optimiser was failing.

Suggestions/recomendations for a good battery retailer ?
BMF next week but I dont really fancy lugging a battery round all day.

I'm guessing your bike is at least 4 years old from your comments, what type of battery is it? the larger one where you can fill the battery yourself (usually white/cream in colour) or the newer smaller type, sealed unit?

The sealed type don't seem to last that well, well not for me and a few others, the old type seem to last longer. Have you tried cleaning the battery terminals up (sandpaper etc) couls just be that and oxidised etc.

If not probably a new battery as you suspect

If the battery is too flat so start the bike it will take an optimate at least a day to charge it fully.

Put a meter across your battery with the engine running (once you've got it charged again) and make sure the charging system's working properly.

I had trouble with my battery after last winter (on a 2003 749S) when the Optimate said it was OK one day and weak the next, sometimes it would start the bike but mostly would not. Turned out to be a dodgy earth terminal on the battery where the connection between the terminal and the cable itself had corroded through. Replaced it and it has been fine since.

Not suggesting you have exact same problem, but just showing it can be something else that gives the impression that the battery has failed.

Or you could just need a new battery, because the modern gel ones are notorious for not lasting very long (that's progress for ya!)

I don't trust optimates.

On all of my bikes I have had problems with the optimate if left on for any period of time. They supposedly 'cycle' the battery in order to check it is okay. From my experiences this cycling gives the battery a sort of memory such that it will lose its capacity. What I mean is, if the bike doesn't fire straight away you don't get many chances at cranking the bike before it is flat. If the battery gets too low the ecu will shut down anyway, so then it really is game over.

What I do now is put the bikes on charge for a week or two, then unplug them for a week or two. So far (touch carbon :lol: ) this has worked for me.

Interestingly, for the first time ever (that I've noticed) my optimate told me it was 'desulpher'ing the battery this weekend...

One final thing, I always start the bike with the lights off, just to give it more of a chance. :burn:

Im not a fan of Optimates either,seem to do more harm than good if left connected all the time.Prefer to start the bike every week or so during winter or remove battery.

Starting the bike every week or so might save your battery but it'll wreck your engine!

All this Optimate stuff! Just sales and marketing if you ask me. A lead acid battery requires a float charge of about 13.8 volts. Whenn you park your bike after running, it shouldn’t need any fancy cycling or monitoring of the battery. Due to sulphating at the base of the plates and possibly and immobilizer (yes they do kill the battery!) the battery will attempt to deteriorate itself after long periods standing

If you get yourself a cheap power supply, the sort they sell in Maplins. Make sure you get one that's cheap and got some space in the plastic case as you need to crowd some electronic in it.

De-solder the wires from the transformer & connect these to a 12volt regulator similar to this…. http://www.maplin.co.uk/module.aspx?...=8067&doy=16m5 with a couple of the essential capacitors.

Wire it up to produce an output of 13.8v by lifting the ground rail from 0 volts on a small trim pot. Slap a load of Araldite or something similar around the wires to seal everything and then connect the output to the wires you originally took off the transformer.

Add a couple of wires from the battery with a fuse and diode in line to prevent shorts and solder them to a sexy little power connector to fit the one on the power supply. Mount this on a small steel plate and a place of you choice with thermal bonding heat shrink sleeving on the back of the wires to keep everything tidy. (I’ve put mine just next to the rev counter).

An hour or so work but what you end up with is a beautifully stabilised and regulated float charger that will not annihilate your battery and hold it at the optimum voltage. I've been doing this for years on many vehicles including my old classic VW Golf Cabriolet I used to have…..Works fine

Hi Chris,

I've not much useful to say except I had the identical experience.

'02 998

Bike connected to optimiser whenever in the garage.

Never had any battery trouble.

Vanned it down to Nogaro in France a couple of weeks ago for a trackday.

Battery totally flat when I unloaded the bike.

Handy tip #287 - When jumping the bike from a diesel van for the third time to go out for a session, do not get all giddy and put the jumpers on the wrong terminals. The resulting spray of acid from the tiny vent hole will go all over your bike.

Spinoli

Optimisers - hmmmm......

Solution - new battery from French race team.

Spnioli