It's that time of year when we start reaching for the battery charger/tender.  What are we looking for?

I use a traditional maintenance-free sealed lead acid (SLA) battery.  Fresh off the charger/tender, I get a reading of about 13.4-13.6V.  Let it rest for about 1 hour, and  it's around 12.8-13.0V.  That sounds good - fully charged.  My understanding is 12.6-12.8V is 100% fully charged.

AGM batteries usually read .15 - .25V higher when fully charged (so maybe 12.75 - 13.05V).

Lithium Ion - somewhat higher yet....

My question - with an automatic shut-off charger/tender, why is it loading up the battery to the 13.5V range?  Is this okay?  Or should I monitor my automatic charger/tender and unplug it when it reads about 12.8V?

I know a 12V battery is the "nominal" rating value and each cell is like around 2.2 - 2.4V.  So a 6-cell battery might be considered fully charged at 6 x 2.2 = 13.2V ....or 6 x 2.4 = 14.4V hot off the charger. ~somewhere in between before resting~. Yes/No?

The alternator working with the regulator/rectifier charges at around 14.4V, right?  Probably designed this way to be at the upper limit of what the battery can handle?

I've used this charged/tender for 2 winters without babysitting it or overcharging issues (that I know of).  I leave it on for 24 hours and then disconnect it so I'm not tripping over the extension cord on the garage floor.  I only use it when I can't ride for more than like 10 days (bad Houston cold spells when it might touch freezing at night and it stays under 50.  Glad I live in the south - lol).

I just don't want to overcharge it.  Too much of a good thing ain't a good thing.

I’ve had good luck with basic SLA batteries sold on Amazon for $40-$50 (Pirate, Chrome, Weize) for my Honda Shadow and several LS650s.

Just took mine off after having it on the charger maintainer for few weeks and it was at 13.6 volts and it's a 3 year old battery that is holding up good last winter it was charging up to 14.2. It's a cheapy amazon chrome brand.

Off the charger for few days it's holding at 13.1 I think where most ppl go wrong is assuming a new battery is fully charged. When I got mine fresh out the box new it was 12.6 and i charged it up before putting in the bike and voltage has held up nice. No way would it of lasted if I just threw it in the bike at 12.6. I've looked at mounting a voltmeter as well but all are digital and might not last. If you do mount one let us know how it holds up. I seen someone on here I believe had a old looking analog one that would be cool to have mounted but they don't make them like that no more.

I'm not The Guy who Knows, but IIRC there is some Warning that is to be considered when the charging system is being asked to recharge a low battery. I'm not sure where I heard that or if it's really a Thing, but sucking the guts outta that part of the electrical system is an expensive problem.

JOG wrote on Yesterday at 05:33:28:


A motorcycles charging system is quite able to recharge a low battery so I suppose you mean a external charging system.  You have to consider what that system is designed to do, trickle chargers are not designed to fully recharge a battery, only a low rate meant to upkeep the battery.  It might be able to but will take months and what will months of full capacity do to something only meant to provide only a fraction thereof.

My decomp is long gone , only other suspect is the GPS. When I hard wired it in I made sure not to power the standby/live all the time so it does take a minute to locate. The standby wire is optional and does not affect its operation. I need to find the fuse and pull it see if problem goes away.
Someday , right now it’s my daily !