[Closed] Motorbike battery drain ... what to look for?

And should've added, no alarm, no electrical accessories

Elaborate on the drain, what starting figure and how much per hour ?

do you have a 2nd battery you can try to see if it may just be a duff battery ?

How about if you remove the battery completely from the bike ? is there still a drain then ?

What does it drain down to ? How long does that take ?

You say no accessories - you mean at all or plugged in? Are there any USB sockets wired onto the bike?

Where do you keep it? Somewhere damp? Maybe just damp in cables causing a drain?

Rachel

I had this on a car once. I went through all manner of auto-electricians, new alternator, the works. Ended up taking it direct to Lucas who diagnosed it inside of about 30 seconds, it was a faulty rectifier (the electrical block that plugs into the alternator).

Thanks - and bear with me as I'm not a mechanic!

The bike is stored under cover but outside, and in recent weeks, jas got very wet at times. No usb sockets, no extra electrical stuff added to the bike - it's a pretty simple bike with the only electrical mod-con being heated grips (standard) and a digital clock (standard), no LCD display. It's an 2002 bike.

weeksy - I'm assuming a drain as I disconnected the red bike lead from the batter, stuck my simple multimeter onto the red battery terminal and then the red bike lead, multimeter on ACV50 setting and it read 4V (I think I'm interpreting it right?).
The drain takes about 24hrs.
This is a replacement battery that I have also charged overnight.

Not sure how to check a drain if I remove the battery completely?

Help v much appreciated as it's causing me chaos with work!

I had this on a Vespa. Changed the battery, but the problem persisted. Checked and double checked everything and it drove me nuts, and had almost convinced myself that it must be the regulator/rectifier (as Cougar says). Turned out the replacement battery had exactly the same fault as the original one! A 2nd replacement battery sorted it.

Put the multimeter on the bike after it's charged... it should read say 12.8v....

Come back 3 hours later with it in the house... .see what it reads... if it's still 12.8 there's no battery issues... it's a bike/drain.. If it's lower than 12.8 then it's a batter issue.

Probs rectifier.
stick meter on battery and start engine. voltage should go up.
if not. bike not charging it.

"Not charging" and "draining" are not the same thing. If it's flat immediately after riding it's the former; if it's fine then and not the following morning it's the latter.

Oh, re: the rectifier (is that the right name? Could be regulator now that someone mentioned it - I remember it being a block of resistors, a rectifier would be diodes so there's a part of this I'm misremembering) - the problem was intermittent, it'd be perfectly fine for a couple of days then dead as a doornail.

The other symptom I've just remembered is that the battery warning lamp sometimes came on very very dimly, almost too faint to see. Probably of no use if your lights are LEDs though, this was a 1985 MkIII Escort.

Great car when it worked, but it was the unluckiest car I've ever owned. The day I bought it it was vandalised (by my new girlfriend's jealous ex), all four door panels kicked in. It kinda went downhill from there really.

marrv - just tried what you suggested and voltage did go up on starting the bike.

And, my multimeter's quite basic (so hard to see accurately), but looks like:
- voltage across battery 12V
- on starting, 13V

My monies on the rectifier.

I'm off to try and find where the regulator is now!

And, my multimeter's quite basic (so hard to see accurately), but looks like:
- voltage across battery 12V
- on starting, 13V

Not good enough answers 😉 Go to Maplins/Halfords and spend £10 on a better one..

we need the bit after the decimals... that could be 12.0v and the battery is rubbish with 13.9v when running and the rectifier is fine.

Ir could be 12.9v and the battery is fine... with it running at 13.0v and the rectifier is knackered...

Without the details... you'll struggle for answers.

Regulator rectifyer is a weak point on the f650 as its under the seat. If it has died it will have killed the battery too

Is the bike in regular use? It's sitting idle that kills them more then anything (Apart from alarms). I sold my Speed Triple at 7 years old with 34,000 miles on it still on the original battery, and that lived outside, but it was used regularly and didn't have an alarm
The only bike I've ever bought with an alarm, I ripped it off the second day I had it. Useless things! 🙂

- voltage across battery 12V
- on starting, 13V

If I recall correctly a car battery should be about 14.5v when the engine is running shouldn't it?
That sounds low to me.

EDIT
My Honda's giving 12.9v at rest.
Battery is nearly 4 years old, bike is used 250 miles a week every week....

Bike will be anything from 13.9 to 14.5 to be acceptable on a running positive throttle.

Regulator rectifyer is a weak point on the f650 as its under the seat. If it has died it will have killed the battery too

This is what I think. Reg/rec has killed the battery. Fairly common thing on lots of bikes and those BMWs are't the best from what I gather

I'd also suspect the same... but without any numbers it's pure guesswork.

Thanks again all.

Appreciate getting a digital multimeter, but it does look as though my voltages are a little low?

The rectifier plugs/connections all look OK to the eye.

Am I right unthinking that if the bike is drawing voltage with keys out, then something is draining the battery? And if so, can a rectifier be the cause of this?

Thanks

I would sort the meter so I can see it while faffing about. you may need a helper.
it might be 13 volt at tick over, but you want something like 14.5 volt when revs go up a bit. then see what happens when you turn lights and grips on and off and together. prod wires and stuff. If full beam is allover the place when you rev, usually means charging circuit fault.
Or it might be that in this cold weather with grips on and lights if your doing short journeys. the battery is not getting enough charge.

Am I right unthinking that if the bike is drawing voltage with keys out, then something is draining the battery? And if so, can a rectifier be the cause of this?

Possibly... it could be draining purely because it's a knackered battery, hence why i was telling you to remove the battery, then do the same tests.

The rectifier cannot drain the battery when the bike is switched off, it's a charger (essentially speaking), it will enable the battery to charge via the electrical system... Or not... It does not affect the battery unless the engine is running.

The heated grips though, they can drain batteries, hence why i told you to also do this with the battery removed from bike.

Your voltages look potentially low yes... however, without the actual numbers, not just something rounded up, it's impossible to say.

weeksy - thanks. Sorry to be a numpty - how do I test with the battery removed?

Put the multimeter on the 2 terminals. It will say somewhere between 12 and 12.9v generally.

Wait an hour.... see what it then reads.... wait overnight... do it again....

You're not a numpty, some of us have had experiences like this before, that's how we learn the answers/processes, nothing wrong with not knowing.... you're only a numpty if you don't read what we're saying 🙂

Ah, I'm with you now - will do

The rectifier cannot drain the battery when the bike is switched off,

What if it went (partially / intermittently) closed-circuit?

What if it went (partially / intermittently) closed-circuit?

I'll bow to anyone with superior knowledge than me though.

You really should test for battery drain with the ignition off.
You can isolate a limited number of circuits by pulling the fuses out until the drain stops.

battery drain check - measure amps passing though circuit.

Google is your chum

Voltage test will tell you 2 things - health of battery , and if the battery is charging.

OK, leaving the battery unplugged and will check it again in a few hours. When I unplugged it it was showing exactly 11V (which seems low as it's been on-charge overnight). actually, my charger is an Optimate which has a light showing condition - I recall this morning that after 24hrs the 'Good' health light was not showing. This is a new battery (internet purchase) ...

11v or 11.0 ? Does your multimeter not do anything after the decimal point ?

In simple terms, the lowest your bike will start with is about 12.2v... Any lower it's not starting... at all. It really should be reading about 12.8v

We're making the assumption here that your charger is working correctly... you can check that too by putting the multimeter on when it's turned on and off on the charger.

weeksy - it's a 'clock face' style analogue multimeter so some guesswork going on! However, it should be good enough to show any change to the unattached battery after a few hours! Got a mate with a proper meter popping round later.

And when the battery was connected, the meter showed a higher voltage once the bike was started (how much higher was hard to say!)

yep 12.8v or more just after charging

11v suggests one cell in battery is not working - I would return the battry
if you can.

Tayna is an excellent online battery company.

can you borrow a different charger ? not a fan of Optimates .
Lidl were selling their charger with a voltmeter in it recently £13 and
worth checking if they still have one if you have such a shop locally.

Forgot the standard answer to all electrical problems on a 650 single....check the terminals are tight!!

+1 for checking the rectifier, had a similar problem on my street triple a few years back. Leaving the (charged) battery indoors (indoors will have a more constant temp for testing) and checking it every few hrs to read the charge should tell you if its the battery or not. Nothing worse than following electric wires around to check faults....oh, and invest in an electric multimeter, much better imo

You should be using the DC, or VDC setting on the multimeter, if it doesn't say DC it'll have a solid line and underneath, a dotted line.

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If you are using meter where you can't see 0.1v differences, they are easy to get for £10 or less (Halfords, Screwfix etc)

To measure current drain, connect as you did before (disconnect red bike lead and bridge the gap with the probes) but use the highest DCA setting, and you will need to unplug the black probe from the meter and plug it into the ADC socket. Most cheap meters will do about 10 amps before they pop the internal fuse.

You are looking for a drain measured in Amps, or Milliamps (mA), not volts.

If you get a reading that is significant, start pulling fuses and you might be able to work out what is causing the drain.

OK, so now with a proper multimeter.

Battery held charge overnight when disconnected, sitting at 12.68
Connected to the bike, starts fine and settles at 13.3 idling, and up to 14.4 when revved
Disconnecting negative lead and placing multimeter between the battery and the lead with ignition off, shows a drain of 66MA (I think)
If I disconnect the rectifier/regulator, the drain figure remains unchanged

So am I right in thinking something's draining the battery? Can I discount the regulator? I don't have an alarm on the bike.

Any pointers please?

Thanks

Start pulling fuses, maybe?

shows a drain of 66MA (I think)

mA, I would hope!

OK, more stuff. After a couple mins testing the drain, it fell from 66MA to 1.5MA I think because the clock/speedo was calibrating.

So now I've a drain 1.5MA - is this significant?

And no change when I pull each fuse independently.

Trying to find the battery earthing point - a challenge!

Its not sounding like the regulator. I also don't think its the battery now.

I'm not an expert but it doesn't sound like 1.5mA would cause any issues.

I'm feeling stumped. I've reattached the battery, checked voltage and will review it later today to see if any significant voltage change. 😕

can you discoonect the heated grips at a plug?

1.5 mA is tiny.