It was rwven and Ride My See Saw who were talking about the 80%. From what I've read, if I understood it, charging a battery at a high rate of current causes the plates to heat up and excessive heat can damage the plates. A battery that is supposed to be at 12.6 volts fully charged would be close to 10 volts at 80%. An unregulated charger could put it's max current out overheating the battery while trying to get it back to 100%.
The video on the Yuasa site is worth watching
http://www.yuasabatteries.com/videos.php

 

My OEM battery was on a tender from the day I brought it home in Oct '05.
I replaced the battery purely as preventive maintenance in 2013. That battery is still going strong in my neighbors riding mower. The new battery is also on a tender 90% of the time. I've never had a battery or starting problem.

 

Bingo!

Great post. I have a 2000 F-350 diesel. Bought in '99, replaced first set of batteries in '07, just replaced those about a month ago. I took the 2nd set home and trickle charged them, 9 years not too bad. I have a company truck so my personal truck doesn't get driven daily either.

 

I learned something from this video: when the AGM battery voltage drops below 11.5V and doesn't take charge we must apply 25V during 5 minutes to bring it back to life. But for how long?
I consider myself 'well' equipped and experienced in this domain but without access to a dedicated lab who would risk such a rescue knowing that the battery can overheat or let hydrogen leak?

I chose to rely on a 100A load tester, an analog voltmeter to visualize stability of charge and a digital voltmeter to sense AC leaking out of the voltage regulator.

 

When my Brother writes: " No harm will ever come to a battery that is trickle charged, plus it only serves to prolong the battery's life span." he may possibly be in error. I'd check on that...

 

2016 will be my 6th season on this OEM battery. No issues, sat all winter on the trickle charger, fired right up after sitting all winter. Starts fine, short runs or long runs.
I have always used a trickle charger on everything that requires a battery.
Just my .02

 

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That simply means your trickle charger is working well / properly not over charging the battery therefore not damaging it allowing it to live a nice long srv'c life.

Like i said in my initial post," some not all " (with your charger falling in that category) maint /float type design chargers can in some cases lead to premature battery failure when used 24/7 or when used often left on battery for longer periods of time.

I have a strong feeling thats why some maint charger mfgs now have what they call a " Safety Timer " that " shuts the charger off post 72hrs " which IMHO is to protect the battery from being overcharged & damaged causing premature failure.

Think about this,there isnt a rash of reports of many maint/float chargers starting on fire trashing bikes & homes etc ,but i have read/seen/heard 100's of reports over past few yrs of of tracking premature battery failures on bikes & classic cars when maint/float chargers were used 24/7 or often .

So with that in mind why else would mfgs like deltran & yuasa spend the time & money to install a SAFETY TIMER to SHUT THE UNIT OFF POST 72HRS ON THE BATTERY in their maint / float chagrers?

There is no way battery charger mfg's are going to admit the maint / float chargers they have sold for many yrs advertised as being ok to leave on a bike or classic car battery 24/7 has in some cases (NOT ALL!) been overcharging & damaging batteries directly causing them to fail prematurely.

Thats why i avoid taking the chance to find out if the maint/float chargers i have would damage my bike or classic muscle car battery or not because i will never leave a miant charger on those batteries 24/7 ,often & or for long period /many hrs post reaching full charge.

Been doing that for many yrs now and get significantly longer then avg srv'c life out of the batteries in my bikes & classic muscle car doing it that way.

If it smells like a dog,looks like a dog & acts like a dog then it's very likely a dog!/LOL!!!

Scott

 

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Ensuring a new battery (including fact activated batteries most people use toady!) are properly /fully charged prior to 1st use is an importan points.

BUT,its no quite as important or damaging as is being made to be here,i say that because most people (98 of 100 that buy a new fact act battery) dont do the right thing ensuring the battery is properly/fully charged prior to 1st use so if not doing that significantly reduced srvc life or significantly damaged the battery as much as is being suggested here you would be seeing a very high rate (50-60-70%+) of those batteries failing prematurely / a lot earlier then what they should on avg which i didnt see at all while i was monitoring bike & classic battery failures.

Same thing go's for every day use replacement car batteries (std lead acid & AGM) where if they werent fully charged prior to 1st use would supposedly damage them enough to significantly reduce their srv'c which again i didnt see in my monitoring battery failures.

Again,i agree fully charging a a new battery prior to 1st use is best case for max power output & chance at longer then avg srv'c life .

But not doing that doesnt automatically mean a battery that has a proven avg srv'c life of 4.5-5yrs will then fail in 1-1.5yrs if not fully charged prior to 1st use either.

I think a case where a new fact act battery has sat long enough without charging to be down to approx 12.4-12.5 maybe 12.6v and put into srv'c without 1st ensuring its fully charged with just enough power to fire up the vehicle post installing it letting the alt take over charging duty from there is a candidate for a shorter srv'c life.

I have been wrenching cars/bikes for well mover 4+ decades and always chk batt volt on new fact activated batteries before i top them off with a full charge prior to installing them for myself or other people i do work for and cant remember the last time i had batt voltage that was less then 12.7 or 12.8 prior to topping them off with a full charge.

Just installed a new yuasa gyz32hl fact act maint free AGM battery in my hd which showed 13v when i got it prior to topping off its charge anyway.

Also got 12.9v on an new deka etx20l battery prior to topping off its charge too before i installed it in someone else's bike.

The yuasa was mfg'd 5 months ago and the deka was mfg'd 6 month ago and showed very good voltage for sitting on a shelf for 5-6 months prior to getting them.

Thats just one of the great design features of the newer gen AGM bike batteries which is they in fact " dont loss as much charge/voltage " when sitting with non use & or no charging as older gen non agm lead acid batteries do.

Depending on source i look at full charge voltage (post fully charging & sitting idle 5-6hrs w-no load) for a std lead acid bike battery is approx 12.7volts & for AGM i have seen 12.8-12.9volts as full charge depending on source.

When i took the Yuasa & deka batteries off the maint/float charger after they reached full charge and charger cut back to it's lower maint charge rate the Yuasa read 13.3volts & the Deka showed 13.1volts which drops down/lvl's off to their constant voltage 5-6hrs post removing from maint / float charger.

Scott

 

Yuasa never said that not charging a new battery would reduce it's service life, that I can see. Where did you read that? They said that it would never hold a full charge.

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Actually, I beg to differ. Batteries are maintenance free, and rarely experience shorted cell failure as was gonna in the past.

What is your reference point Mr. Doomsday?