Wildguzzi.com
General Category => General Discussion => Topic started by: brider on August 15, 2025, 10:40:03 AM
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This has happened to me TWICE now after dis-connecting the fuel tank harness for tank removal. Removed tank twice recently to diagnose/fix fuel leak. Brand spankin' new battery. After the tank is off for 4-5, 6 days, I put it back together and the batt is stone dead, not even the dash lights light up.
Even IF the batt was "bad" even though it is new, it wouldn't dis-charge that severely from did-use, would it?
I am still leaning toward bad batt, but is there ANYTHING in the bike systems that would dis-charge the batt merely by disconnecting the fuel harness?
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No. Take battery in for Load test to any autoparts store for free testing.
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Nothing to drain battery if stock wiring. If kept on a tender it will kill a battery, they only need a charge 1 day a month. Lots of bad new batteries all depends how they are handled & set-up. Many riders add terminals to run GPS and lots of add ons. Maybe that stuff is not off, same with flashing lite on upper R/H corner of dash.
IT is not the tank plug.
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I'm always curious about negative thoughts on battery tenders. I had over 25 batteries on tenders for over 12 years and not one failure. Seasonal sports and work equipment. Wonder why my empirical experience is so different that many others.
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I have never seen any mfg say it's OK to keep them plugged in, that comes from advertising on tenders. They all say 1 day per month. Plus I changed many dead ones, that's what I do is work on Guzzi's. I didn't leave the crap for years plugged in thinking I'll ride.
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Do you have Guzzidiag cables still attached to the battery for any reason after taking the tank off?
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I would attach a temporary 5W globe to the positive terminal and see if there’s a parasitic drain when you disconnect the tank, or at any other time when you have the key off.
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I think the difference in experience is interesting as well. Not all battery tenders are "Battery Tender" brand battery tenders. I have a friend who swears by his wall wart universal charger as a battery tender, burns up a battery every year or so. He leaves it plugged in 24/7/365. I checked the voltage for him. It gets as high as 16.8 volts depending on state of charge of the battery. It only provides less 750 ma so not a full amp but voltage that high is dangerous to the life of a nominally 12v battery. I have several "Battery Tender" tenders they work just fine and can be always on without damaging a battery. The term battery tender is misused a lot it seems.
Brian
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So back to my story: As luck would have it, my favorite battery charger literally almost melted with an internal failure the week before, and my backup was old, repaired with kid's hockey tape and basically didn't work so I had no way to CHARGE the dead battery. Went out and bought one from NAPA today that I don't really like but I'm heading out for a 2-day ride tomorrow morning, so I needed something. Spent 4 hrs charging at 6 amps and the charger said "95%" charged, but I dis-connected it and read the voltage with a DMM and it read way over 13V, so..........does that happen directly after charging a battery at that rate?
Anyway, I took it for a test ride and all is well, I have a boost charger with me so if it goes low I should be OK, but when I get back I will definitely have to check for current draw.
Comparison: My Cal 2 Auto has been sitting in the garage for 2 yrs, I charge the batt about once every 6 mo, didn't do it at all last winter, and about a week ago I pulled the cover off and hit the starter and it fired up practically as I waved my hand near the switch. It's a conventional (non-AGM) 650 CCA tractor battery.
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I would attach a temporary 5W globe to the positive terminal and see if there’s a parasitic drain when you disconnect the tank, or at any other time when you have the key off.
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I'm always curious about negative thoughts on battery tenders. I had over 25 batteries on tenders for over 12 years and not one failure. Seasonal sports and work equipment. Wonder why my empirical experience is so different that many others.
While I have not had issue either I've found that there is no need to leave batteries plugged in 24/7. It does not extend or prolong battery life. During long periods of inactivity I'll connect batteries to a tender/charger for an hour or so every 4 to 6 weeks is all it takes to keep them tip top. It's what works for me.
I will say that years ago I bought a burner cell phone to be able to connect Pandora to a BT speaker in the garage. I used an old handlebar mount screwed to the wall to hold the phone and it was plugged into a charger 24/7. After a year or so one day I noticed the phone was swelled up like a poison dog and pulled it out of the holder and found the battery was swell to at least twice the normal thickness. I'm guessing it would probably would have ruptured at any point had I not unplugged it. Not sure if a fire or just stuff oozing out of the battery would have been the end result but not wanting to find out I disposed of the phone and no longer leave batteries on chargers 24/7
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I'd go over everything electrical, you may have disconnected or crossed something, it sounds like you were pretty deep into the bike as you were working on and sorting the fuel line issue.