Not wanting to revive an old thread I thought I'd post a new one.

Old thread here for previous electric problems : viewtopic.php?t=32504&p=232910

So here is whats happened now.

Yesterday I saw a break in the weather and went out for a 20-30 mile blast with the bike not missing a trick.
Came home, put the bike in the garage and went to have dinner etc.

Then I decided I'd go over to my gf's, got kitted up, went out to the garage, went to start the bike like normal and the starter kicked off like normal then just got weaker like it had no power.

So I connected my trickle charger and it told me that the battery was discharged.

Now after a 20-30 mile blast I'm guessing the battery shouldn't be drained, it should be charged.



So today I've done some multimeter testing.

Voltage across battery bike OFF = 13.4
Voltage across battery bike RUNNING= 13.8 (idle)
Voltage across battery bike RUNNING= 14.1 (5k rpm)

Alternator resistance readings : Windings to earth = infinity
Windings to each other = 1.2-1.4

Alternator voltage reading at 5k rpm = 47-50 volts.

If you read the previous thread the problem was found to be a faulty CDI.

So I disconnected the battery earth lead like before and tested:

Amps from battery to earth Ignition ON killswitch ON = 0.43
Ignition ON killswitch OFF = 0.35
Ignition OFF killswitch ON = 0.0
Ignition OFF killswitch OFF = 0.0


From what I can remember this means my alternator is working fine, so is my CDI and my reg/rec.

So anybody any ideas on why it discharged yesterday?

All the reading look good, could be just a dud battery. Was this the battery from your earlier problems, if so has it not already gone flat a couple of times. After a full charge try a load test. Headlight ON until battery voltage falls to 11 volts, should take 20-30 minutes for a good battery. N.B. turn OFF the headlights before the battery voltage drops below 11 volts.

Its the same battery yeah, its a lithium one too, might explain why I have had to charge it before but it's not gone dead on me.

Shall do the load test and see.

What brand of battery?

bikemonkey wrote:http://www.ebay.co.uk/itm/Honda-VFR-400 ... 231b11546b

Just read the description on the e-bay link, it says these batteries are not good at low temperatures, more specifically sub zero, and are not suitable for year round use.

I know the weather has been appaling lately but not sub zero, however have you had it in the bike over winter?

I bought the battery in the middle of march this year and I think fitted it not long after.

Can't remember the weather in march being too bad, but it was a bad winter.

From reading your other post regarding earlier starting problems, I was left with the concern that you had not found an explanation as to why after you left the battery standing the engine started at the second try. Not an outcome that would suggest long term reliability.

If you have a lithium-ION battery then from the data I have seen, together with bikemonkey's comments, it is not the type of battery technology that is suitable for a normal use motorcycle. May be ok for total loss track bike with a dedicated charger, lithium-ion batteries need very specific charging pattern to maintain performance.

Lithium-IRON technology is considered suitable substitute for motorcycles and they are not cheap.

However, data regarding the low temperature performance of lithium-iron batteries may be of relevance to your situation. At low temperatures, lithium-iron batteries can be poor performers at the first attempt to start. Second attempts are apparently likely to get satisfactory results. The battery gets warmed up internally by the first try and then works better at the second and third attempts.

This may explain the strange outcome you described in your earlier post. You tried once and failed but it worked the second time. Try this procedure again if, after charging the battery, it fails to start the engine on first try or turn ON the headlight to draw some current from the battery to warm it up before trying to start your bike.

Thing is it isn't cold here today at all, and wasn't yesterday.

The battery is Lithium-ION from what it says.

When I went to start the bike yesterday after the ride I had, it just seemed like the starter motor wasn't getting the power it needed, which was worse the second time I pressed the starter button 5 seconds later. As I mentioned I whacked my charger on it and it fired up today like normal. Full choke no throttle not even half a second of holding the starter button down.

Could you be saying that because the battery is lithium ion that the alternator is charging the battery suitably? And therefore the battery will not get a proper charge resulting in low battery when it came to next using the bike?