Battery keeps dying / draining / discharging

[Gregs///M]

There are chips on the board with thousands and thousands of transistors. They actually consume a lot of power for no reason.
Do you replace them with modern chips that consume microamperes in the sleep mode?

The integrated transistors inside the chips do not consume an abnormal amount of power. The standalone NPN and PNP transistors are replaced, not the transistors integrated into the chips. The chips cannot be repaired or replaced. Transistors that drain abnormal amount of current is because they get stuck in an unwanted logic state from decades of use. This issue is also common in the DME, lock control module, check panel system and other vintage electrical modules.

[Vincenze]

in fact, if you replace the batteries on the SI board without replacing the 20+ transistors, it can permantely damage the SI board.

There are chips on the board with thousands and thousands of transistors. They actually consume a lot of power for no reason.
Do you replace them with modern chips that consume microamperes in the sleep mode?

[Gregs///M]

should i wait to warranty exchange the battery after i get the SI batteries replaced?

Coming from the guy that has rebuilt thousands of SI boards, I assure you, and you can check for yourself. Replacing the batteries on the SI board does not always repair the SI board, in fact, if you replace the batteries on the SI board without replacing the 20+ transistors, it can permantely damage the SI board.

I know this to be true because when we first started 10 years ago, I replaced only the batteries and many clients were having issues. Once I started replacing transistors, we have done thousands of SI boards with zero issues. Ever hear of smacking the dash to get the gauges to work again? That is stuck transistors. If your SI board has stuck transistors, which are 30+ years old now and most likely do, and you replace the batteries, you are essentially increasing the current load of a SHORT that is presented by one or more failed transistors, which will damage the microcontroller chips that trigger them. The chips are not repairable.

Unfortunately, there is a huge rumor going around that replacing the SI board batteries alone is the correct way to repair, which is completely untrue. You can also find many examples of people replacing the batteries and it does not repair it and they end up having to buy a refurbished SI board. I highly recommend not to replace the batteries but instead have the SI board professionally refurbished.

[reelizmpro]

so its been 24 hours since i took it off the charger and it went from 13.2v to 12.9 volts, is that normal loss?

Yes, a fully charged 12v car battery should be 12.7 volts. When you charge it, it will go higher though. If you charge it at a higher voltage too long you can degrade the battery that's why there are smart tenders and chargers these days.

[locar]

I just want to add that I had this issue and I replaced my SI battery board and the issue went away. I used the programma SI batteryless board which was a good cost compromise vs getting a reman board.

EDIT: I should follow that up to say that only certain models of the e30 can use the batteryless board. Make sure yours can if you want to go that route.

[JonsE30]

so its been 24 hours since i took it off the charger and it went from 13.2v to 12.9 volts, is that normal loss?

[JonsE30]

tomstin i took the bulbs out of the trunk and glove box light and all the dome lights.

reelizmpro the battery junction under the hood looks clean of corrosion ( i am assuming the block located on the passenger side where the batteries in euro cars come in?), i've never maintained an alternator, just usually replaced it. i will look into what's involved with testing the voltage regulator. i have a battery charger at home and i was able to recharge it over night. it now reads as 13.2v with no leads connected to it. this is a healthy reading right since its more than 12.3v?

i removed the gauge cluster and inspected the si board and it looks pretty straight forward from the youtube videos. i ordered a soldering kit and the SI batteries online.

[tomstin]

Are you sure its the cluster? Or something simple like the trunk or glove box light remaining on?

[Vincenze]

should i wait to warranty exchange the battery after i get the SI batteries replaced?

Pepboys won't exchange your battery because you think it's bad.

It will test and recharge it.

[JonsE30]

should i wait to warranty exchange the battery after i get the SI batteries replaced?

[reelizmpro]

These cars are 30-35 years old. In that time, things like alternator, power/ground cables, instrument cluster/SI board all have lost efficiency over the years due to breakage, corrosion, wear and tear, etc. I once tracked a low voltage problem to corrosion at the battery junction under the hood (battery in trunk). These are things you should look into. You have two problems, a draw and your charging system is weak. Anything under 13.5v while running is low. It should be between 13.5-14.4 to run your accessories and recharge the battery. Battery resting voltage should be >12.3. Any less than that and the battery is around 50% charge. If you're getting less than 12v then the battery isn't being adequately charged by the alternator. Wait too long and you can degrade the battery. First thing I would do is inspect or upgrade the wiring, clean up the junctions/grounds and inspect/replace the voltage regulator with a fresh higher voltage regulator. Find out what's causing your draw but even with the draw, you would be fine as long as you take care of the charging system.

[Vincenze]

You should have the battery warranty from Pepboys.
Try to bring it there, they will test and recharge it.

You should replace the SI batteries. There are 2 types.

You can remove the fuse 21 after a drive. Without it, the speedometer won't work, maybe something else.

These are the newer SI batteries.

Cluster removal.
It's a good idea to change the odometer gears too.

[JonsE30]

Vincenze i didn't just change it, but i was retensioning because i saw some slack in it.

i retested it again and with 21 fuse it was .06, without fuse it was .00-.01

SI batteries in the instrument cluster, meaning, i need to take out the cluster and solder new batteries in or replace it altogether? can the car be driven without fuse 21?

at this point, is the battery salvageable?

[Vincenze]

I think the charging voltage should be in the 13.5-13.9V range. Did you change and adjust the alternator belt?

0.05A shouldn't discharge your battery in a day.
Try to remove the fuse #21. Will the amperage drop significantly? If not, find the fuse that causes this drain.

If it's the fuse #21, the drain can be caused by the SI batteries in the instrument cluster.

[JonsE30]

0.05A is what i am reading between negative lead and negative battery post, What does this mean?

i jumped it again and while the engine is running, the voltage of the battery is hovering around 13.1volts.

if the alternator is bad, wouldnt the the battery light on the dash be light? because right now it is not lit.

is it supposed to stay at 12.5V at rest? is 13.1 volts while engine is running good?