Flat Battery/Voltmeter

[nclifford]

Hi Guys,

A few weeks back a few of you may have followed my thread to get advice to fit a voltmeter to the AT. I have had a repeated problem with my battery going flat as I’m a fair weather rider.

I fitted the voltmeter and it worked fine showing 13 volts with the new battery. I watched it for a couple of week to ensure the battery wasn’t discharging and it looked ok with no change. Then this week I look at the voltmeter and its gone to 0 with the new battery being completely flat! It was fine a few days before.

Does anyone have any idea what would have caused the battery to drain so quickly?

Needless to say the new battery won’t accept a recharge so I’m back to square one!

Any help much appreciated.

Regards
NC

[iswoolley]

Voltage isn't that good an indication of battery charge. If you start with a fully charged battery and draw a constant current, the voltage will decrease very slowly until it reaches a certain voltage (dependant on battery type, capacity, etc.) at which point it'll decrease very fast. A short in the bike's wiring is unlikely, as it'd drain the battery much quicker. If you've got a multimeter on hand, whip the positive lead off the (new!) battery and measure the current draw through the multimeter.

Some rough calculations; if you've a 50Ah battery that runs down over 20 days (3 weeks) then a current drain of about 100mA would be expected.

Do you have an alarm, or heated grips, or GPS, or other electric device permanently wired into the battery?

[nclifford]

Hi thanks for help

No alarm, or heated grips, or GPS, or other electric device permanently wired into the battery.

Amazed at how fast the battery drained!

[fergus1964]

if no accessories are draining the battery, next suspect is the rectifier/regulator, or alternator itself (very rare, though, for the windings to be defective).
next time suggest you leave battery disconnected, and see if it holds a charge.

[GSPD750]

Hi Guys,

A few weeks back a few of you may have followed my thread to get advice to fit a voltmeter to the AT. I have had a repeated problem with my battery going flat as I’m a fair weather rider.

I fitted the voltmeter and it worked fine showing 13 volts with the new battery. I watched it for a couple of week to ensure the battery wasn’t discharging and it looked ok with no change. Then this week I look at the voltmeter and its gone to 0 with the new battery being completely flat! It was fine a few days before.

Does anyone have any idea what would have caused the battery to drain so quickly?

Needless to say the new battery won’t accept a recharge so I’m back to square one!

Any help much appreciated.

Regards
NC

Was your new battery charged properly? A new battery should not go flat like that. Sometimes a shop or dealer will fill your new battery with acid and not charge it properly or not charge it at all.
I recall you installed your voltmeter to the hot circuit of the battery which is not advisable due to the parasitic draw it will always have. Albeit milliamps...it is still a draw. Try it on the switched side of the ignition where you mentioned earlier that your voltmeter light is connected to.

[BobA]

NC

I'd try all of the above, and the following to try and pin the fault down.

1) The new/charges battery, leave it standing disconnected, and prove it doesn't lose excessive power after, I dunno, a week lets say.

2) After that, if its OK, bolt in and connect the battery terminals, BUT remove the Master Fuse under the Solenoid connector. Again, check it after a week.

3) If all is still well, replace the master fuse, and remove all of the dash fuses except one. Check everything again, and if still OK, remove that fuse, put one of the others in, then leave it a while and test again.

All this (time consuming admittedly) investigative work should reveal what, or atleast what circuit ,the component that is dragging the battery down is on. Once and if you find which circuit it is, it's time to break out a multimeter (if you have one) and start to dig deeper.

I'm sure it's nothing much, probably something really stupid, so persevere and you'll get to the bottom of it.

Good Luck

Bob

[BobA]

P.S

I'm suspecting something like the solenoid, or the circuit through the ignition switch back to the solenoid. Unless that solenoid is activated (by the ignition being switched on) everything else on the bike will not be live (I Think!)

Failing that, how about the ignition switch itself? Have you jetwashed, or got water in it, possibly causing a short or high resistance fault?


Good Luck


Bob

[nclifford]

Thanks for the help guys.

I'll try all of the suggestions and get back to you.

Regards
NC

[HelmetHair]

"Any voltmeter has a resistance of several kilo-ohms so will only ever take a few microamps so will not drain the battery."
this advice was given to you before, sadly, it is not correct.
a dripping tap in my bathroom will empty the water tank in my loft, a voltmeter will discharge a bettery if left connected. Fact.
your voltmeter drained your battery.
put a switch in line, when you want to check the voltage, flick the switch, then switch it off after.
job done.

[GSPD750]

"Any voltmeter has a resistance of several kilo-ohms so will only ever take a few microamps so will not drain the battery."
this advice was given to you before, sadly, it is not correct.
a dripping tap in my bathroom will empty the water tank in my loft, a voltmeter will discharge a bettery if left connected. Fact.
your voltmeter drained your battery.
put a switch in line, when you want to check the voltage, flick the switch, then switch it off after.
job done.

HelmetHair is also correct, and it has now been suggested many times
...your new voltmeter needs to be connected to the switched side of the ignition due to the continuous parasitic draw when wired direct to your battery.

Sorry for shouting.