I use automotive battery charger for bike batteries, 2 amps mode. But real charge is about 6-7 amps (I checked with multimeter). Is it killing my batteries?
Bike generators have about 30 amps specs and regulators keep voltage about 14. I guess if my charger keeps voltage below 14, it shouldn't hurt bike batteries, right?
Where to buy cheapest battery? I found one for $69 on ebay shipped.

 

Depends...the initial inrush when you first connect the battery can be in excess of 10A but it should drop down as the battery charges...but if it is staying constant at 6A measured with a known good ammeter connected in series with the negative cable and battery negative post for more than an hour or so, then I would suspect the battery. How old is the battery, and when it is charging, is it getting hot? If it is 3 years old or older, pulling that high current constantly, and is getting hot, then it is time to replace.

 

Get a Battery Tender or similar fully automatic charger. Open these links and see what the manufacturers recommend.

http://www.yuasabatteries.com/pdfs/TechManual_2014.pdf

http://www.batterytender.com/technical-info

 

A battery tender is not designed to charge a battery, only maintaining a top charge. Any automotive battery that is pulling 6A constant to charge needs replacing. If you ride regularly, you do not need a tender...save your $$ for bling and gas...

 

Three basic, critical things you don't cheap out on: tires, brakes and batteries. But I guess you didn't like the battery answers from your other post.

 

I buy cheapest Shinko tires, because they are soft and have excellent grip.
I buy cheapest brake pad, because I don't know difference between cheap and expensive ones.
I buy used batteries from junk yard for my cars because I have load battery tester, so I know which one is good.
I buy cheapest oil for my cars and bikes because I am a car engine mechanic(kind of) and I believe there is no difference between cheap oil and expensive one.
I install lawn mover solenoids and automotive electrical fuel pumps on my bikes.