new battery, regulator, or alternator?

[orly_andico]

i'm having great difficulties starting my mazda 626. i noticed that after a night in the garage, my battery voltage is very low, 10.6 volts. this is the voltage of a fully-discharged battery, according to things i've read.

once the car has started, voltage across the posts is about 13.8 volts. i am concerned that this is a bit too low -- things i've read say it should be 14 volts. also, when idling, full aircon, full headlights, and stereo, the stereo drops out periodically (namamatay-matay). and the voltage across the posts drops to 12.5 volts or thereabouts.

i left the battery disconnected for a night, and its voltage went down from 12.65 volts to 10.6 volts, so it seems the battery cannot hold a charge anymore. however, i don't want to replace it right away because i think the alternator is not charging it fully, and a new battery might just get damaged after a month or two (the fact my stereo drops out means not enough juice is getting to it).

is there a way to adjust the regulator? maybe it is not providing enough field voltage to the alternator, so the alternator can't keep the voltage up at 14 volts. or could it be, the battery is so weak that the alternator's output is affected?

p.s. i have verified that the battery is not discharging overnight through some short or something (i put an ammeter in series with the battery), so it's not some dumb thing like the trunk light or dome light being stuck on..

[OTEP]

May free check up naman ng alternator in most battery centers (i.e. along Quezon Ave.). That way they can isolate if you have a battery or charging system problem.

In most old school cars, taking the battery off with the engine running was a way to check the charging system. Kapag hindi namatay agad, then the alternator is supplying enough juice.

[orly_andico]

ahh ok. motolite told me if i availed of their "home service" they would check the battery out but still charge me 300 if the battery turned out not to be the problem.

re: old school: i thought of doing that, but this isn't THAT old school, EFI na po siya. :P the battery daw helps regulate the output of the alternator, so removing the battery while the engine is running is a Bad Idea (TM). i don't wanna fry my ECU.

thanks though, i will call motolite again.

[antoy]

I think the battery is at fault. Have it checked to be sure

[kinyo]

a good battery will not drop to 10.6 volts overnight ... 13.8 volts is the normal voltage during charging (14 volts isn't that bad either) ... its a bad battery and alternator is ok ... how old is your battery, orly?

the regulator is an integrated circuit and there are no adjustments for it

[orly_andico]

re: battery age: i have no idea. :P i bought the car used with no service records not long ago (which is why i'm discovering soooo many things wrong with it, thankfully, none of them significantly impair the car's function).

i guess i better call the motolite hotline now. maybe the battery is less than 15 months old and they'll warranty it..

[OTEP]

If you don't have the warranty card, then you can't do a warranty claim for it.

[x-wind]

try mo na lang pumunta kung saan masmalapit na motolite shop dun libre ang service .........yun sa akin dun ko dinala sa tramo pagbaba ng flyover from edsa. naka off un engine then may equipment sila to chech kung how many volts and amp. ang down nya pag may load..............yun bossing dun advise sa akin na refil lang yun water free din sa kanila. dun ko rin nalaman na kahit free maintenance yun batery pwede refil ng water.

[x-wind]

try mo na lang pumunta kung saan masmalapit na motolite shop dun libre ang service .........yun sa akin dun ko dinala sa tramo pagbaba ng flyover from edsa. naka off un engine then may equipment sila to chech kung how many volts and amp. ang down nya pag may load..............yun bossing dun advise sa akin na refil lang yun water free din sa kanila. dun ko rin nalaman na kahit free maintenance yun batery pwede refil ng water............... hehehe muntik na ko nagpalit kasi nasa min. level na yun water yun pala pwede refil...............

[rodcarolino]

pwede tangalin ang battery habang umaandar ang efi engine as long na naka-idle lang and the positive terminal must not touch any ground/part of the body. kung sakaling na-rev mo na tangal ang battery siguradong dead ang computer box mo...