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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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Discussion Starter #3
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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Discussion Starter #11
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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Why is that 62 Ah battery there?
With that in circuit (with such a low current charger) you have stopped your bikes battery from actually being fully re-charged.
 

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That setup would work great to maintain the bikes battery & alarm for an "off grid" type solar setup, but the timer would then be redundant.

When you have 24/7 mains available a smart / intelligent charger is better for the battery as 13.6v isn't enough to fully charge a lead acid 12v battery.

800mA on a small bike battery would be considered a bulk charge rate so should't be left on all the time, though if the charger was actually limited to 13.6v then it wouldn't be able to push 800mA in for very long.
14.3v is the approx peak voltage required to supply that amount of current as the battery nears full charge.

When used on a much larger capacity battery (car battery) 800mA would be just a trickle charger so would be safe to leave on all the time.

This is the charge program that Optimate use, 13.6v is just the maintenance voltage level once the battery is fully charged.

Capture.JPG


So your setup wouldn't cause any harm and it is preventing the battery from becoming discharged by the alarm but it isn't the best way. Lead acid batteries like to be fully charged every now & then (maybe twice a year), and an external smart charger is the way to do this as even the bikes own charging system doesn't go high enough (on purpose to prevent over charging on long journeys).

Smart chargers aren't that expensive, you could probably have bought one for not much more than the cost of your setup.
I run my optimate once every few weeks, and allow it to do a full cycle (charge, test and then report battery as good).
If I had an alarm on the bike I would probably run it once a week but it is safe to leave these chargers on all the time.
 

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Discussion Starter #16
I have the Oxford Oximiser 900 Anniversary Edition which cost me 30 quid last year. My gps tracker does drain my battery making it tricky to start after 4 days and impossible after 5 if I leave the charger off so its hooked up all the time with the the battery dongle. I have let my battery accidentally go dead flat once but I think it has recovered. Won't do that again. The charger does a smart bulk charge then auto switches to maintain. Turn on and forget.
 

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I can't bring myself to leave the charger on all the time, but then the garage is closed by (attached) and I'm a control freak.
Also I keep our small fleet of bikes batteries topped up with just the one charger so I have to keep swapping over which bike it's connected to anyway.
 

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That setup would work great to maintain the bikes battery & alarm for an "off grid" type solar setup, but the timer would then be redundant.

When you have 24/7 mains available a smart / intelligent charger is better for the battery as 13.6v isn't enough to fully charge a lead acid 12v battery.

800mA on a small bike battery would be considered a bulk charge rate so should't be left on all the time, though if the charger was actually limited to 13.6v then it wouldn't be able to push 800mA in for very long.
14.3v is the approx peak voltage required to supply that amount of current as the battery nears full charge.

When used on a much larger capacity battery (car battery) 800mA would be just a trickle charger so would be safe to leave on all the time.

This is the charge program that Optimate use, 13.6v is just the maintenance voltage level once the battery is fully charged.

View attachment 33183

So your setup wouldn't cause any harm and it is preventing the battery from becoming discharged by the alarm but it isn't the best way. Lead acid batteries like to be fully charged every now & then (maybe twice a year), and an external smart charger is the way to do this as even the bikes own charging system doesn't go high enough (on purpose to prevent over charging on long journeys).

Smart chargers aren't that expensive, you could probably have bought one for not much more than the cost of your setup.
I run my optimate once every few weeks, and allow it to do a full cycle (charge, test and then report battery as good).
If I had an alarm on the bike I would probably run it once a week but it is safe to leave these chargers on all the time.
I had the one amp charger direct to battery on the timer. Cost of this setup was a tenner, works perfectly until the plug go knocked out and the battery was completely flat. The charger isn't restricted to charging at 13.6V, if the internal resistance of the battery is high then the charger may raise to 15-16V, that's what old fashion bulk charger do, with no load cos its just a 12v transformer it pumps out 12.3V, the resistance makes it climb to 13.6V. Its like a hose pipe with your thumb on the end, as the resistance rises the tap needs to opens more to force more pressure, therefore voltage rises to complete its circuit. As I said before, adding 12V batteries in parallel just adds them, like extra plates making a larger battery. This setup shows a constant 12.8V and because the car battery is a larger capacity the alarm feeds of both not just the 11.8 Amp/hr bike battery, so proportionately it feeds of the car battery more.

Now, electronic chargers. Ive owned two, maintenance charge, cold weather setting, de-sulphate.....in my experience they've a load of shit. The don't sit pumping out like a bulk charger, having said that they've not been Optimates and for the money the Optimate are a good chargers, if you want a decent electronic charger, well they are a few quid.

So my post was tongue and cheek, i.e. my expensive setup. If you want an in-depth breakdown of chemistry and charging of batteries read this post. Motorcycle Batteries .. AGM, GEL, Wet, Lithium Iron Phosphate (LiFePO4)

ISTR the charger that's worth its salt is around £250. Mine £10.
 
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