engine and drivetrain Battery Not Keeping Charge Last Hope before mechanic!

[Guest Anonymous]

Hello everybody!

I posted about this issue roughly 10 days ago when I had much less knowledge about what was going on, basically, my 1974 2002 (sahara tan) is new to me since about a month and a half. As the weather has been getting colder, the 'L' light has been coming on when starting the car and occasionally when going in reverse it would stall out right after starting. Around 10 days ago, the car failed to turn over at all with the telltale engine clicking often associated with a dead battery. The responses posted here led to me to learn a lot more about how basic electronics work on cars and were really helpful, but did not lead me to a solution.

I took the car to Advance Auto Parts and they did the free battery check and said that the battery was testing fine, and so was the alternator, they said they couldn't test the regulator with their equipment and suggested finding a local alternator shop that rebuilds the things. The shop tested the regulator as providing a really low charge to the battery with no boost with acceleration. After swapping for a new regulator and getting better (but not ideal) voltage back to the battery, he wanted to check the old one one more time, which, all of a sudden tested okay (13.4). I thought the problem might have resolved itself but alas the 2002 is still having trouble turning over after a couple of starts and leaves me having to recharge the battery constantly.

SO- I wanted to reach out here as a last option of DIY hope before shelling out $$$ at the local mechanic. I am attaching a link to a couple pictures I took that might help with some dianosis.

http://picasaweb.google.com/adrianolsen85/BMW2002#

Thank you

-Alexandra

[RayC911]

Possible drain somewhere? aftermarket radio, alarm, bad switch for dome light or trunk light?

[cj]

Always start with basics.

I would start with cleaning the battery terminals. Get rid of the temporary terminal ends and get proper battery cables. The main lead for power to the harness looks like it's just crammed in with the positive battery cable. That should be a clean connections with a dedicated lead to the battery. Your positive terminal looks like it can get awfully close to the nose panel. I'd put a cover over it if you use "parts house" terminals.

Clean the ground cables at the block and chassis.

Now test the battery, check the charging system and check the draw of the starting system.

If the problem still persists, start looking for a draw with a mulitimeter.

[JerryC]

I suggest you go after all the ground connections associated with the charging system.

Install new battery cables. I've had problems with those clamp style wire connections on the after market battery clamps that you're using. I replaced them with cast-in-place (one-piece, no bolts) battery clamp style cables and all the issues went away.

Sometimes the wires inside the cable insulation will corrode and you have no way of knowing it. My dad's Honda Gold Wing had charging issues for years until the positive cable disintegrated and he replaced it. That solved it.

I've also had grounding problems with the voltage regulator mounting screw. To solve this, I changed the regulator mounting sheetmetal screw to a machine screw and nut with star washers on both sides of the sheet metal. I cleaned the metal around the mounting hole (which will need to be drilled out) so the washers will make good contact, then dabbed some paint over the bare metal to keep it from rusting after everything was bolted up. This solved an intermittent blinker and bouncy gauges problem, also (yes, I already had the gauge terminals grounded).

These suggestions are just from my own experience, you may have other problems. Good luck!

[ifayeoh]

all are good checks, also make sure alternator belt is sufficiently tight.

[jmr_1602]

+ 1 on checking to see if the alt belt is tight. That was my issue last week.

[c.d.iesel]

...so lets back up to your tale.

did you replace the voltage regulator?

or keep the old 'working sometimes' regulator ?

as mentioned above - new to your car means

the owner sold it because of the charging issues

that they didn'nt have the knowledge or money to

repair. So spend the time now cleaning every

electrical connecton under the hood.

Your alternator diodes could be bad but the

tester telling you it's 'charging'. Bad diodes will

account for a constant draw draining the battery

when switched off.

Disconnect the battery before cleaning any wire

connector ends!

[CharlieG]

New battery is about 40 bucks at Walmart. Rebuilt Alternator is ~75 off of Ebay. I'd do both to eliminate the simple stuff.

-Charlie

[Paul7002]

good time to switch to an e21 alternator too. The easy process is detailed on here under FAQ. A bit more juice that stock 2002 alternator plus it is internally regulated so no more separate regulator to worry about. A new/rebuilt Bosch e21 unit will probably run you $100-125.