battery question - optimate

On Optimate will keep even a duff battery charged especially if its connected just after a run. That doesn't mean the battery can hold a charge, a battery is considered 'discharged' at 12v - one hit on the starter can easily drop a fully charged but duff battery to that level. You really need to get that battery load tested as zimtuff says before trying to make sense of anything else, imo.

willtill said:

Stick a multimeter on your battery, set it for DC volts. Disconnect your coils and then turn over the engine. If you drop under 9.6 volts, you may have a bad battery.

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Where does the figure of 9.6volts come from,is it in the manual?

zimtuff said:

Where does the figure of 9.6volts come from,is it in the manual?

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No, when I was researching this, I found several sources via Google, that stated that a voltage drop of 9.5 or 9.6 is the determinate value for diagnosing a bad battery

One source: http://autos.yahoo.com/maintain/repairqa/battery_electrical/ques029_3.html

From the above link:

If load testing with a carbon pile, apply a load that is equal to half the battery's cold cranking amps (CCA) rating. A good battery should be able to supply half its CCA rating for fifteen seconds without dropping below 9.5 volts.

that looks interesting - how do I disconnect the coils?
Mike

mike5100 said:

that looks interesting - how do I disconnect the coils?
Mike

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Can't look under the tank at the moment (bike's not near); point of the procedure is to keep the spark plugs from firing while it's turning over. I'd wager you could pull the leads to the plugs as well.

You could also test your own battery with something like these,Ive been meaning to get one for a while.

http://www.ebay.co.uk/sch/i.html?_f...battery+load+tester&_sacat=See-All-Categories

I fought a weak battery problem for over a year. Off and on problems starting, even in nice weather. I even had to pack jumper cables cause I never knew when it would strike. I finally bought a hYTX20DHL battery from BatteryStuff.com for $99, including shipping . I have not had a problem with it starting, even in the 30' weather we have had here. I am impressed!!! to say the least. They make a regular model of this battery for the RIII and they make the same battery for the HD, I thought if they make one that will start a Harley it ought to be perfect for me and I bought it. The description is 'YTX20HDL 12V HVT-1 HD AGM Battery Powersport.
Try it, you will like!!!!!
Bob

Don't get hung up too much on batteries. They all die eventually.

Optimates etc are fine for keeping a GOOD battery at it's best. If the battery is old then it's best is less. If you start using an Optimate etc from day one - I'll guess teh battery will last longer - but alot of us tend to only make recourse to one when teh battery is giving trouble - may well be too late then.

Just about every lead battery uses acid. AGM is just a way to pack the lead plates closer together without risk of shorting. This increases (pure physics) the capacitive value. BUT the acid does dry out in "maintenance free" batteries. And unless the acid liquid covers the plates 100% you loose power CCA and fast. Worse still it is not always recoverable even if you find a way to get in and top up the liquids. GEL batteries also dry out. And when they do you chuck'em.

I had issues with batteries in my ex-softail - The battery is encased in an oil tank and gets warm. On average I was adding water every 4 weeks in summer. My Buell (same battery) has always been fine for years. The R3 we have to see. My guzzi eats batteries - but this I believe has more to do with it's rather antique charging system.

We've just had a similar battery related issue on the missus car. Friday she returned home fine. Satuday . went down open car - switched on and NO START. The starter turned over OK but the volts dropped enough for the ECU to lose RFID communication with the chip in the ignition key. Result immobilised car. End result new battery and ECU re-flashed.

Might have to get a load tester - mmmmmm

All good advice and I think I'll order a new battery. But .... this morning - so 3 days after I started the bike and ran it for 10 minutes - it started fine. And yet the temperature has been low all week. It had been on the optimate for the 3 days.
Mike

I've always been impressed with the Optimate charger.Back in cold Blighty, they kept my old dodgy batteries going ok for years!( had to leave them on permanently when garaged tho)