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Car Forum / Porsche / Porshe 944 / August 2008Charging system probs
Need a good electrical guy to help me out. I have a 1984 944 na. Bought a new battery last year and noticed it wouldnt hold its charge after a few months. Returned it and got a new one. Problem solved. Car started and ran great. Few weeks later (after not even driving the car) i noticed car was turning over very sluggish. Checked battery and sure enough it had drained off to approx 12 V. Recharged it over and over but it still keeps discharging. Checked parasitic load. 20 ma`s. Alternator putting back about 14.6 volts. My charger cant seem to put back more than 12.3 volts back into it. Anyone have any advice. Battery is a generic brand from auto mega store. thanks Mark I also own an 84 944. You should not have any "parasitic load" on the battery. I don't and my battery holds its charge. > I also own an 84 944. You should not have any "parasitic load" on the > battery. I don't and my battery holds its charge. I have a 5/85 944 and the clock draws 6mA with 10mA pulses every second. So there is a small load (it is not parasitic it is there by design). If you have 20mA load then in about 50 hours (~2days) you will drain the battery 1 A. So a 40 amp hour batter will be flat in about 80 days if it is not periodically recharged (this is neglecting self dicharge of the battery). When charging a battery it is a good idea to monitor the charge current. The 12.3v may be due to the charger supplying its max current. If this is the case its output voltage will then drop, which is to be expected. If the charger has 12.3v without being attached to a load then it is most likely faulty. Hans I have not measured my 944 but it holds it's charge for at least 2 months of no use. 20ma is not unusual for the parasitic load remember you probably have the clock and the radio and the security alarm. The alternator should put in about 14 volts with the engine running at about 1500 to 2000 revs and the headlights on. More than 14.5 is suspect(overcharging) and less than 13.5 also( undercharging). Any charger from the mains worth it's salt should show 13.5 to 14 or higher after a few hours. More than 15 will overheat the battery and "boil" off the electrolyte if left on too long. Alec > Need a good electrical guy to help me out. I have a 1984 944 na. > Bought a new battery last year and noticed it wouldnt hold its charge [quoted text clipped - 9 lines] > > Mark others have made measurements and given you some advise If you have a security system, disconnect it - I've seen several 1980s vintage systems fail (including on my 85.5 944) where they start drawing excessive current and kill the battery. the factory system doesn't seem to do this, but the after market ones do. > Need a good electrical guy to help me out. I have a 1984 944 na. > Bought a new battery last year and noticed it wouldnt hold its charge [quoted text clipped - 9 lines] > > Mark ** Posted from http://www.teranews.com ** |
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