I am no expert, but my standard is this:
A rule of thumb is to divide the capacity of your battery by 10 (this is called the C/10 rate) to arrive at an appropriate charge rate
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(f.ex. a 4A battery would be very safe with around 400mA, an 8 amp battery would do fine with 400mA as well, but the charging time would in practice more than double).
If one tries a 4A car bat charger damage can be done to any small battery (yes, I managed an explosion once
), therefore use a so called "motorcycle charger", which is usually rated at around 0,5A (500mA). This can not damage anything, but the charging time will be longer than with a suitable electronic charger, which adjusts the charging current relative to the condition of the battery, and ramps down the current as the battery gets "fuller", ending in a low maintenance current when done, ie one can leave it on all year.
Applies to any type of battery as far as I know. Corrections are welcome.
And must write it, even if all know about it, lead\acid batteries produces explosive hydrogen gas when charging, I friend experienced that this was not just a theory, charging a batt inhouse, he used an electric tool close by, booom, fortunately there was no fire, and the acid only destroyed his clothes and sprayed all over the room, he did not get any in the eyes.
e.