I have been noticing that when starting my 2012 FB after it has been sitting a couple days it just doesn't want to turn over quite as well as when I have been riding every day.

So I take a VOM and check the battery voltage after I have been riding and it reads 12.71 V. which is considered 100% charge, OK this is good.
Then I let the bike set for 24 hours and take the same reading and I am getting 12.60 V which according to the Harley service manual is 75% charged.
And then I go out 48 hours after the last time I run the bike and I am getting a reading of 12.58 V.

So my questions, how much discharge should a good battery have after setting a day or two? Is dropping to 12.60 V after 24 hours and down to 12.58 after 48 hours considered normal?
Could I have a bad battery, as it seems the bikes charging system is doing OK and charging the batt. to full.

I know all batteries will discharge a bit as they sit. But I just wonder if my battery is discharging at a higher rate than normal.
I want to take it to the dealer to have them check it out, but if they don't find an issue then they will charge me for diagnosis as my bike is still under warranty.
Thanks

 

Before I would spend money at the dealer, I'd go to batteries plus and buy a new one. Then if it does it again, then take it to the dealer to find out what's draining it. Then take the original Harley battery and sell it to recoupe some of the cost of the new battery.
Then crack open a beer and kick back.

 

Mine is the same. In fact in cold weather 48 hrs is enough for the battery to drain to a point of no start. Cheap battery and alarm on = high drain.

Had dealer check battery and they gave me a print out to say it was good.

Just stick it on an optimiser when you park it for more than 24 hrs, in fact I've got in the habit of connecting mine up each night now, have a quick connector tucked away out of sight that means I don't have to take the seat off.

 

My bike doesn't have the security alarm, so I am not too sure if anything could be causing a parasitic drain on the battery.

 

a tenth of volt drop isn't squat in my book and shouldn't cause any slow cranking.. now if you're dropping 2 or more volts, thats another story. i can let my bike sit for weeks without a tender and it'll crank over with no problem. make sure you're in neutral when starting. i don't know where you live but temps play a big part in the oil thickness factor. cooler temps may cause a slower then normal crank speed, but unless its really cold out, i don't think you would notice that much of a difference.

just to make sure, check the battery cables and ground strap at frame.

don't overthink any perceived issues, it may well be normal.

 

Yeah I also thought a tenth of a volt isn't anything until i checked the service manual and that first tenth of a drop from 12.7 to 12.6 volts reduces the battery charge state from 100% to 75%.

 

Something has to be draining it as these new AGM batteries really hold a charge. On my 99 Softail Custom I have an Adventure Power battery that is 7 years old, and I leave it parked for up to 3 months in the winter and when I go to start it it starts right up. And I have never used a tender on it. I know the newer bikes have computors that do drain them a little, but that sounds like to much to me.

 

i'm not disagreeing with what the book says, i'm just saying 1/10 of volt shouldn't make any difference in cranking speed of engine.

i would consider that a normal amount of drop. check your cager once the same way, it will most likely have similar conditions. a lot of times i check batterys and theres 13.2 or more on it after a road test. i like to knock the surface charge off by turning the lights on with the eng off for a few minutes before testing the battery. I've had numerous batterys pass a load test with a midtronics tester showing 11.8 to 12.5 volts.. its the amps that really count.

 

I had the same issue. I would have slow start or failed starts everytime I left the bike sit for a couple/few days without running it or having it on the charger. I changed batteries to an aftermarket (Odyssey) battery and thought, great, this issue is gone. NOPE, it might have turned over faster when it was fully charged but I still got slow / no starts at times.

I called EarthX batteries and replaced the old lead crap with a Lithium Iron battery. Saved 6 LBS, got tons of extra room in the battery box under the seat and now even after 6 weeks without a start (I was traveling) it starts like there are no spark plugs in it.

I will never go back to the old acid batteries again. I wouldn't care if it cost 10x more, this is the best battery experience I have had.

 

Well I just removed the battery from my FB and will be taking the battery to the dealer tomorrow as they said they would do a load test to determine if the battery has any issues.
I guess the tester they have is pretty comprehensive as they say it will take anywhere from 30 to 90 minutes to complete the test. They say it will then give a printed readout as to the total state of the battery. BTW I noticed my bike didn't have the red plastic positive cable cover at the positive battery terminal.
Is Harley so cheap that they quit including this positive cable cover?