The difference between a 2amp, a 4amp and a 6amp battery charger is the speed at which the battery will be charged. The numbers represent the maximum amperage output at a specific voltage at which the battery will be charged.
No.
First the maximum charging current for the battery should be checked. If that is unknown it can be taken as one tenth of the capacity, e.g. 2 amps max for a 20 Ah battery
Yes it has a 2amp trickle charge
No.
yes
Yes
Use a battery charger with a 2amp charge. Takes a few days. These small batteries don't like to be charged too fast with high amps.
First the maximum charging current for the battery should be checked. If that is unknown it can be taken as one tenth of the capacity, e.g. 2 amps max for a 20 Ah battery
Yes it has a 2amp trickle charge
Remove the battery, or disconnect it, and with any 10 amp/ 2amp, charger, pos to pos, neg. to neg. and charge it at 2 amp, till it is full. If you need to add water, add only distilled water to top the battery up. Use a charger with auto-shut off.
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Kills alternator? don't you mean kills battery? Installing a new alternator without first charging the battery well (2amp for 8hrs) will quite likely burn up a new alternator as well as being hard on the battery.
Charging time varies greatly, dependent on the batteries condition at the beginning of the charge cycle. Most modern battery chargers are automatic and will reduce charge amps as the battery becomes fully charged. If your charger is a manual type, there are two ways to know when the battery has reached its storage capacity. If you have a volt meter, the battery is at full capacity when it reaches 12.6 volts with the charger disconnected from the battery. Alternately, you can purchase a battery tester, very similar to an anti-freeze tester, which checks the specific gravity of the acid in the battery. Those can be purchased at any auto parts store for a couple dollars. You must have a battery with removable cell covers to test the fluid, most all lawn tractor batteries have removable covers. As a side note, ensure each cell has enough "water" to cover the lead plates by 1/4 of an inch or so.
18 guage will do you ok unless you need to run it a mile or two.
12 2amp programmable and 3 30 amp (start, run, and prestart)