Stupid battery charger question
01-05-2006, 08:19 PM
#1
Racer
Thread Starter
Stupid battery charger question
OK, dumb question.....my '87 911 sits....alot more than I'd like it to, but.......it has a tendency to drain the battery. Not sure if it's a short (doubt it) or just the alarm (I leave it armed when stored), but I want to hook it up to my battery charger to maintain it (the charger shuts off whenever the charge is complete).
The charger has two slow-charge settings - 12volt/10amp and 12volt/2amp. Which would be best, and why?
The charger has two slow-charge settings - 12volt/10amp and 12volt/2amp. Which would be best, and why?
01-05-2006, 09:13 PM
#2
Rennlist Member
Neither, get a Battery Tender + as it is designed to -maintain- a full charge properly.. Read up here - http://www.batterytender.com/
01-05-2006, 10:48 PM
#3
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A battery tender sounds like a good choice, lead-acid batterys like to stay topped up all the time.
When recharging:
- check the voltage first(12.6V is fully charged, 12.2V is 50% charged, below 11.8V'ish and you want to start shopping)and plan the length accordingly.
-check the water level if it has the removable cell caps. Refill to the correct level only with distilled water, but this is usually a bad sign of an overcharging alternator.
-do not smoke, or hook up backwards, or short the positive to chassis.
-disconnect the battery so the cpu/alarm/etc doesn't get spikes. Quick disconnects for the negative terminal are handy, but removing is better (because of the hydrogen gas created). Don't ever charge it using the alternator.
-start on the 10amp for 10-20 seconds to warm up the chemicals, unplug, and switch over to the 2 amp. A slow charge is better. Go by 15 or 30 minutes if not sure.
-If you fast charge it for too long unattended on the 10amp setting, it will boil over and burn a hole strait through the carpet of your rental appartment and you'll be recarpeting soon afterwards(ask me how I know).
-after you think the battery is fully charged, put a small load on it like a lightbulb to remove the false surface charge(a couple volts higher) and show the true charge state.
-Also, while it's in the car, check the reading while cranking the engine- it shouldn't fall below 9V. 10V+ is better.
When recharging:
- check the voltage first(12.6V is fully charged, 12.2V is 50% charged, below 11.8V'ish and you want to start shopping)and plan the length accordingly.
-check the water level if it has the removable cell caps. Refill to the correct level only with distilled water, but this is usually a bad sign of an overcharging alternator.
-do not smoke, or hook up backwards, or short the positive to chassis.
-disconnect the battery so the cpu/alarm/etc doesn't get spikes. Quick disconnects for the negative terminal are handy, but removing is better (because of the hydrogen gas created). Don't ever charge it using the alternator.
-start on the 10amp for 10-20 seconds to warm up the chemicals, unplug, and switch over to the 2 amp. A slow charge is better. Go by 15 or 30 minutes if not sure.
-If you fast charge it for too long unattended on the 10amp setting, it will boil over and burn a hole strait through the carpet of your rental appartment and you'll be recarpeting soon afterwards(ask me how I know).
-after you think the battery is fully charged, put a small load on it like a lightbulb to remove the false surface charge(a couple volts higher) and show the true charge state.
-Also, while it's in the car, check the reading while cranking the engine- it shouldn't fall below 9V. 10V+ is better.
