[BruceRoper]

Hi. It's chilly in Pennsylvania and my 2013 GT is now mostly sitting with the battery tender plugged in. Mid December there was a nice day so I went to go for a ride and the battery was dead. The light on the battery tender was red (instead of green). I don't know how long it was like that. The battery tender has a 7.5 amp fuse and it turned out it had blown. I replaced it with a new one and all seemed well. Last weekend I noticed the light was red again. Fuse was blown again so I replaced with another 7.5 amp one. It is stored with the ignition off and the key out so as far as I can tell, nothing is on. It's been two days now and so far the light is still green.
I know it's not fixing the cause of the problem, but can I replace the fuse with a 10 or 15 amp fuse? I just wouldn't want any damage to occur to the bike by having a higher fuse. I don't care nearly as much if something happens to the battery tender. It's wired to the battery with the plug coming out of the side faring so to replace the fuse I have to take the top panel off every time. Easy, just annoying.
Thanks for any advise!
-Bruce

 

[Sundog52]

How old is the battery? What brand is the battery tender? Most tenders "throttle" the amps during charging to 2-3. It's possible the battery contains shorted cells causing excessive current draw. Try your tender on a known good battery as a test.

 

[BruceRoper]

Hi Sundog, the battery is a sealed AGM, bought in Oct of 2020, so a little over 2 years old. The battery tender is a Battery Tender Junior (also from Oct 2020). I'll be the first to admit I am the village idiot when it comes to electrics, so you lost me with the amp throttling. But I have the exact same tender on an old Yamaha in the garage so switching the two would be easy enough.

 

[Sundog52]

Is it possible to measure the voltage across the battery's terminals w/o the tender?

 

[BruceRoper]

I have a power adapter/phone charger that plugs into the power outlet on the right side and it also displays volts. It is not plugged in while bike is sitting but I just plugged it in now and it read 13.2. I put the key in and turned the ignition on with the battery tender off and it pretty quickly went down to 11.8 and seemed to settle there. To use a real volt meter on the battery would take me a couple days to get my brother over here. He has one.

 

[Richard230]

My Deltran Battery Tender Plus! did the same thing last month while charging a spare motorcycle battery that I keep around to run my computer if the power goes out. I have been using that battery tender for about 20 years without any problems. I didn't have a 7.5 amp fuse, so I replaced fuse with a 10 am one. So far no more problems.

 

[BruceRoper]

So then back to my original question; no harm to the GT if next time I replace the Battery Tender's 7.5 amp fuse with a 10 amp? (I expect there will be a next time, but hopefully not)

 

[Pat H]

Normally the fuse it to protect the cable and the device. Its unlikely the wires are only rated to say 8 or 9 amps
so going from 7.5 should be ok.
But its possible that allowing say 9.5 amp to flow could damage something not designed to support that current inside the charger. And worse case a wire heats up and catches fire. So generally its not recommended to uprate fuses.
I'd be curious to know what's causing it to blow. If the battery tender can supply more than 7.5 amps then why as that would cause the fuse to blow if the battery was dead flat and taking all the current the charger could give.
If the battery tender can't supply 7.5 amps then how is the fuse being blown?
There could be a diode in the charger that normally prevents the battery feeding back into the charger and that could have shorted. So if the battery is fully charged and the mains goes off the battery is reverse feeding through the charger and blowing the fuse.