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Discussion Starter #1
2018 SAS here (bought new on deal in 2019) running a GPS tracker. If I don't use a battery tender the bike battery will go flat in 4-5 days because of the tracker. This happened to me last week when I didn't ride for a week and forgot to hook up the tender. The battery was showing 11.2volts on display when I got the bike out. Bike did not start until I used jump leads from car.

But I've noticed since that time when the bike comes off the tender or after a ride and the battery is at rest the display is showing 11.6 or 11.8volts. When I'm riding the display shows 14.1volts. This feels a bit low and I'm sure it always used to say 12.something volts at rest. The battery terminals are clean and fully tight.

Tonight I hooked up a different charger that shows the battery voltage with the mains power off and it was reading 13.2volts at rest.

Is the bike display just not that accurate or is my battery on the way out? Its only a year old. No problem starting bike yet but it won't crank at 11.2volts so is only 0.4volts away from that. Thanks
 

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How many times has that battery been allowed to go flat?
Generally speaking, any lead acid battery that has been allowed to full discharge will have had it's life & capacity reduced. By how much depends how often it's happened and how low the voltage actually got down to. Lead acid batteries don't like to be discharged.

A simple way to test a battery is to disconnect it from your bike so there is no load on it at all. Charge the battery fully and then leave it for a day to settle. Then test the voltage at the terminals.

12.8v or above is good.
12.6v is probably still ok but is getting weak.
12.2v or below is bad and will likely result in slow cranking.
 

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Thanks for that. It's only happened the one time. The issue I have is the bike display is reading 11.8v and my mains disconnected battery charger is saying 13.2v at rest. Which one is more accurate... . I have got a voltage meter somewhere which I'll try to find and dig out. My battery charger has a 13 hour pulse repair mode so I might try that overnight if the voltage is too. Failing that, battery recommendations?
 

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Managed to find voltmeter, it needed a new 9v battery but found one of those too. At battery rest the meter is showing 12.9v across the terminals. My unbranded intelligent ebay charger is more accurate than the bikes display! I don't know why the bikes display is so far out... but it seems the battery is okay for now. Be interesting to know what others readings are.
 

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The one on my 1190 seems pretty accurate - 14.1v when running and 12.6v (ish) when not.

With your "at rest" measurement are you comparing like for like?
By that I mean having the voltmeter on the battery terminals while the ignition is turned on, that way you can do a live comparison between the dash and the voltmeter.
 

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Discussion Starter #6
The one on my 1190 seems pretty accurate - 14.1v when running and 12.6v (ish) when not.

With your "at rest" measurement are you comparing like for like?
By that I mean having the voltmeter on the battery terminals while the ignition is turned on, that way you can do a live comparison between the dash and the voltmeter.
I'll try that! Thanks ??
 

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Discussion Starter #9
12.7v at rest using meter. With ignition/display on 12.03v meter versus 11.7v display. Maybe that's ok....
 

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I haven't checked mine to compare the display verses a DVM.... but 0.3 volts seems close enough so as not to be worried about its reading accuracy. The fact that it is actually being dragged so low with just the ignition on could mean the battery has been hurt.

Thing is.., the hardest start your bike does is the first start of the day, so if that one works you are very unlikely to get stranded whilst out. That alone would re-assure me enough not to worry about the battery too much and just to enjoy the bike. You'll probably get a few more years out of that battery before the cold start might fail.
 

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I haven't checked mine to compare the display verses a DVM.... but 0.3 volts seems close enough so as not to be worried about its reading accuracy. The fact that it is actually being dragged so low with just the ignition on could mean the battery has been hurt.

Thing is.., the hardest start your bike does is the first start of the day, so if that one works you are very unlikely to get stranded whilst out. That alone would re-assure me enough not to worry about the battery too much and just to enjoy the bike. You'll probably get a few more years out of that battery before the cold start might fail.
Cheers and ride safe ??
 
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