Some of you may have seen the thread I hijacked in the tuning section about backfiring when starting. I have resolved the backfiring issue with help from a very helpful fellow member, and then complained of slow cranking after I modified the map. I think that was just a coincidence, and actually had nothing to do with the changes I made. I mentioned how I had recently had my battery load tested only a few weeks ago and it was fine, but now the first crank is very slow. I decided to check the connections before I went spending hundreds on a new battery and found the ground cable on the battery slightly loose. I tightened it with no change to the slow cranking. So I thought while the seats off I'd put the multimeter on it and see what it does. With the bike just sitting there it read a constant 12.78V. 12.28V with the ignition, headlight etc on. Then on the first crank it dropped down to 7.25V. I shut the bike off and retried and got around 10.5V (The bike ran for about 10 seconds between starts)

So now to my actual question, can someone tell me if there is a certain voltage where you decide the battery is no good???
Sorry to make it so drawn out, just trying to provide info!!
Thanks in advance, Matt.

 

Dropping to 7.5v when cranking is not good. You say you tightened connections. Try removing and actually cleaning them bright and shiny then recheck voltage while starting. But it really sounds like a new battery is in your future.

 

Ok, thanks cobra. The connections were clean, no sign of corrosion at all, but not 'shiny' clean! I'll give them a clean up and try again, but I think you're right, I think I'll be off to get a new battery tomorrow! Thanks mate!!

 

Also check the other end of each main battery cable. They may be clean at the battery, but if they are dirty/rusty at the other ends the poor little electrons will get all confused when you ask them to turn the engine over! Often apparently electrical problems are actually mechanical, in other words simple stuff.

 

As suggested, be sure that all of your connections are clean and tight, as poor connections will give false readings. It sure sounds as though your battery is "kaput"

 

New battery and she now cranks at 10.5V. Starts and runs like a dream now! Thank You all!!!