I have a 2005 BMW 1200GS with a one year old Yuasa YTX14H battery. The bike is ridden three of four days a month, and stays on an Optimate 4 charger when not in use. The charger is CAN bus compatible, but I have it hooked up to charge direct through a harness. The charger has never showed any issues with this battery until this Saturday. The Optimate was blinking to show that the battery is not ready to accept a charge. I unplugged the charger to reset it, but it keeps coming back to the warning that the battery can't be charged.

Before this Saturday the bike was not connected to the charger for about a week. The bike starts easily, the battery is not laboring. I rode it on Saturday and the battery stayed strong. I took the following readings in the hopes of figuring out if it's the battery, or the charger that's giving me trouble.


Saturday 7 PM, the float charge while on the charger is 13.34 volts.
Take the charger off and turn on the ignition, 12.45 volts.
Start the bike, 14.56 volts at idle.
Shut the bile off, float charge back to 13.4 volts.

Sunday 11 AM, battery at 13.34 volts. Bike was off the charger since Saturday evening.
Sunday 11 PM, battery at 13.09 volts.
Monday 6 AM battery at 12.94 volts.

I will take another reading tonight when I get home. Any ideas?

Pardon me if I misread your post.

Have you tried disconnecting the battery from the bike and using the conventional clamps from the tender?

If not, try that to rule out any harness interference to the tender's logic.

And try the tender on another battery.

What The Monkey said.

Your voltages figures are well within normal limits. The 24 hour drop of about .5 volts is probably due to "keep alive" circuitry.

12.5 with ignition on and bike not running is okay. 14.5 with the bike idling is good.

If I read this correctly the problem isn't the battery but the charger showing it can't charge the battery.

Check the wires coming off the batter for the quick connect, is there an inline fuse, it may be blown, if not, it's possibly in the charger itself, I would connect the charger to a different battery on say your car or lawn mower, see if it reacts the same. if so it's probably a problem within in the charger itself

If the other batteries on the charge cause the charger to operate properly then it's either the inline fuse or your battery.

Sounds like the charger has an issue.
Try it on your car/truck and see if the failure to charge is repeatable.
I use Harley Davidson batter tenders for all of our motorcycles and ATV's. They are specifically spec'd for sealed AGM (absorbed glass mat) batteries. I consistently get six to seven years service life out of the AGM batteries.

HRK beat me to it. I'm betting on a blown inline fuse on the harness connection.

quote:

Originally posted by HRK:
Check the wires coming off the batter for the quick connect, is there an inline fuse, it may be blown, if not, it's possibly in the charger itself, I would connect the charger to a different battery on say your car or lawn mower, see if it reacts the same. if so it's probably a problem within in the charger itself.

I didn't even think of the inline fuse. If it's blown that would give me the 'can't charge' signal. I'll check it tonight.

"Saturday 7 PM, the float charge while on the charger is 13.34 volts.
Take the charger off and turn on the ignition, 12.45 volts.
Start the bike, 14.56 volts at idle.
Shut the bile off, float charge back to 13.4 volts.

Sunday 11 AM, battery at 13.34 volts. Bike was off the charger since Saturday evening.
Sunday 11 PM, battery at 13.09 volts.
Monday 6 AM battery at 12.94 volts. "

Everything looks fine here. Do you not like any of these results from testing?

Mine is a 2012 R1200R and I use an Optimate 4 as well.

Reset the Optimate to charge through the canbus.

See if that makes a difference.

Mine works well that way.

Ok, here's what I found tonight. Battery holding steady at 12.94 volts so it looks like the battery is good. The 15v fuse looked good, tested good, and I swapped it out for a new fuse. Optimate still won't charge. I hooked the Optimate up to my Subaru which has a six month old battery and it gave me the same 'can't charge' light show. At this point I'm assuming it's the charger. It's five years old and maybe I got a bad one or I dropped it or whatever, but at this point I'm sure it isn't the battery.

Any advice on a new charger? I use an AGM battery so I plan to use a battery harness. I'm thinking Battery Tender as I had one that lasted almost 20 years.

Edited for spelling.

This message has been edited. Last edited by: SgtGold,

Here is the one I use. Had it a little over a year with no issues. I ride about 5-6 times a month in nice weather. Stays charged all winter, not as much during warmer months.

NOCO Genius G1100 6V/12V 1.1A UltraSafe Smart Battery Charger

Once upon a time my favorite and supporting dealer got a deal on optimate. We (the sponsored racing team) all switched to them from battery tender. We need them since we don't run charging systems on race bikes so its critical. Great concept in some ways, but in actual practice eventually all junk. they are all gone. Ditch the current charger, get a current model battery tender and be happy.

https://www.batterytender.com

Hq in Deland Florida. Make a unit for agm motorcycle batteries you can get on Amazon

quote:

Originally posted by HRK:
https://www.batterytender.com

Hq in Deland Florida. Make a unit for agm motorcycle batteries you can get on Amazon

I see a Battery Tender Plus in my future.

quote:

Originally posted by Jelly:
"Saturday 7 PM, the float charge while on the charger is 13.34 volts.
Take the charger off and turn on the ignition, 12.45 volts.
Start the bike, 14.56 volts at idle.
Shut the bile off, float charge back to 13.4 volts.

Sunday 11 AM, battery at 13.34 volts. Bike was off the charger since Saturday evening.
Sunday 11 PM, battery at 13.09 volts.
Monday 6 AM battery at 12.94 volts. "

Everything looks fine here. Do you not like any of these results from testing?

No, I posted the data because I thought it looked good and wanted a second opinion.

Either of these would work

Battery Tender Jr

Battery Tender Plus

The nice thing about the Jr model is you could easily bag it and take with you on a trip in case you need it.

I ended up with a Battery Tender Plus. Battery is now happily charged.

Shouldn’t need a battery tender if your riding 3-4 times a month in my opinion

3 or 4 times a year, possibly

In the warmer months it's not really necessary. Once it gets colder it's a must.