Battery drain

[DPJ]

MY SB 79 FI has gotten a new battery after the old one (10Y) died.
I never had enough drain from semi-modern (cassette) player and analog clock.
Nothing electrical has changed in the setup, but the new battery drains in about 3 days. After a week i just have 0.4 volt left. Battery seller tested and they claim it is not the battery.

By replacing the battery, they told me the alternator didn't function well, but I haven't driven it since it was installed.

can anyone list what other sources may cause this?


Thx,

[67rustavenger]

Well, if the alt is not working then your battery is not getting charged.
Also the distance that you drive the car may not be far enough to overcome the drain from starting the car. I mean if you crank the engine for 30 sec. to get it started and then drive three miles to work. Your not going to be able to make up the discharge.
I have a gen. car and have to charge the batt. every three weeks as my commute is 4 miles each direction.
Good Luck.
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[Cusser]

An alternator often can be source of your parasitic drain
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[67rustavenger]

[zoobyshoe]

[DPJ]

well, in my case i did not drive the car as they told me the alternator wasn't working properly.
I assume the alternator can not be the source of parasitic drain?

So, I didn't drive it, don't have a heavy load on the system and didn't change anything since it started draining...

[zoobyshoe]

[DPJ]

That is correct. just tested to see if battery works. Ran it for 30 seconds and drains afterwards. Tonight it was just dead, with 0.4V
All I have is the semi-old radio and the analog clock, which were not a problem before.

[ashman40]

Draining a new battery from 12.6v (fully charged) to 0.4v in a week is excessive. You have more than a small drain... or the first battery was bad. Did they replace the battery for you? Recharging a battery that had been drained to 0.4v would be difficult because the action of draining a battery that deeply will damage the plates.

Do you have a multi meter? Most multi meters have a setting to read amps. Most of the recent ones I have seen can handle up to 10A current flow THRU the meter. This normally requires the red probe wire be moved to a different jack. In the below pic the 10A test jack is the one to the very left. Most other testing (V, ohms) is done from the right most jack. The second from the left jack is the milli-amp jack and can test up to 400mA in the case of the meter pictured. Check your meter to see what it can do.

Testing amperage requires the meter be inserted in the current flow. To test how much current is being drawn from your battery while everything is OFF, disconnect the negative battery cable from the (-) battery post. Initially, set your meter to read up to 10A and plug the red test lead into the 10A jack. Touch the black COM lead to the negative (-) battery post. Touch the red lead to a clean chassis ground (wire brush it so you have good contact). Read the meter and see how many amps are flowing while everything is OFF. If you have a radio w/ a clock, it may draw up to 50mA (0.050A). If anything is drawing more than 50-100mA you have a big drain on your battery. If the drain is less than 0.4A you can switch to the mA connection and read the drain in mA. As long as your meter is fused you should have no issue, even if there is a surge in amps the fuse will blow to protect your meter.

Finding the drain can be a challenge. You want to remove all your fuses and see if the power draw is still there with all the fuses removed. If it is not, then start installing one fuse at a time until the drain comes back.

If the drain is still there even with all the fuses removed you will need to trace the wires to find the source. Start with those things that are connected and not fused at the fuse box. This includes the ignition coil, the FI computer and the headlight switch. In '79 there may have been other accessories that drew power, you will need to find and unplug these until you can pin down what is draining power. It could also be a short somewhere in the wiring. A break in the insulation that is allowing current to flow to ground.
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AshMan40
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[iowegian]

Maybe there is a hole in the bottom of the battery and all the electricity just runs out?

[67rustavenger]

[zoobyshoe]

[zoobyshoe]

[Cusser]

I have a 2004 Nissan Frontier with stereo that has clock, station memory, ECU, etc. I frequently let that sit for up to 2 months, and it starts right up, no significant drain.

So such electrical drain is excessive. I saw someone use the word "shorts"; if there actually is a "short" then excessive amperage would burn up the wires, or a fuse if such circuit was fused.

If you've done nothing recently on this, I would disconnect the alternator and see if the battery stays charged like a week. Because I'd bet (and you should try) taking off one battery terminal for a week to demonstrate that the battery can hold charge fine without parasitic drain.

I've read on other boards for different vehicles about alternators being a common source of parasitic drain, even though they charge fine with engine running.

Read up on Google about parasitic drains.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[DPJ]

Autozone charged the battery to 100% for me as my own charger didn't light up on the dead battery.

I will keep the battery out of the car and test it again in a few days to see if there's a difference.

I have a new Bosh alternator ready to be installed, but it will have to wait till I have moved and the car is shipped over there. Tools are packed also

[zoobyshoe]

[jhoefer]