Here are real numbers off the 14 I use. So say you're in being close or match them. You can watch the 3 charging loop components by using a voltmeter at their battery posts and begin as such:
12.8v or more is a well charged battery. Battery volts means PUSH. So think plenty of reserve PUSH.
12.8v with key on, no start is the read. Shows reserve and can hold this number.
11.1v is when the starter motor is at its load test or cranking [pushing] some amps out.
12.8v is immediately recovered to its static number is showing a good battery.
10.1v is the load test of the battery and static [returned] number is under 12.8v is battery going key-put.
14.4v is the next read, keeping eyes on the meter and watch 12.8v be shown as a blip in the night from its load of 11.1v. As the engine starts so shows a good stator and rectifier working perfect numbers at 14.4v.
BS means: battery acid supplied when buying a new battery. So acid in and let saturate into the pleats before charging. So say it sits for an hour.
12N14a means: it's a 12v battery with 14 rated amps. N is for cable post positions on top of that box. So you now know you need at least a 1.4amp rated charger is the formula, and 14 hours of it sitting at that charge rate.
I would not use a 1.2amp rated charger for a 14a battery. A 12N12a rated battery, yes. Formula is for at least a 1.2a rated charger cooking it for 12 hours straight.
A one time charge to get a battery up for service is the dealer level. You'd be lucky to get 4/5yrs out of a new battery. Want to try for 9yrs is this type of charge pre-prepping:
1. Acid filled and cap off. Let sit for an hour at least.
2. Charge for the 1st 14 hour charge.
3. Drain the battery down to 1 or 2v. and charge for 14 hours rated. This is 2nd charge.
4. Drain for the last time of the 1 or 2v range. This is the 3rd fully charged battery and is now for service.
5. Check every charge loop to be charged past the 12.8v aim or at 12.8v.
6. A volt checked in the static that sits for days, weeks, must be charged when the battery read 12.6v. Time to recharge. Do go under that number, remember.
I've tried this and it works for me. Takes a long time to drain and charge so last battery I only charged it twice and the static read was set at 12.4v. Have to commit next time is the prep time.
Signed,
NOLTT
Tormenting the motorcycling community one post at a time