I think I had a senior moment... lol - Preping for traveling early SEP

GND is the left side... 100% positive 😁

 

Yes, you are correct! That means that I was checking the draw on the positive side. Would that mess up the results?

 

Nop, the current is exactly the same on either side with different polarity BUT when you disconnect the battery terminal, the car reboots (good deal ) and that wakes it up.

You want to use a DC-Amp-clamp to prevent disturbing the sleep you are trying to observe.

If you drive 8Hrs and the battery cranks slow after a 1Hr stop and the battery is tested ok... then you have a marginal starter brushset - One of the 4 starter brushes is worned out short forcing current into only 2 brushes circuit. We'll see...

 

The facts in your summary point squarely to.... STARTER!
(Batt + Alt are off the short list).


Buy an OEM starter brushset or a complete starter unit.


Do cross reference proper P/N


For reference what is your mileage?
​​​​​​

 

My mileage is a little over 140k, but the starter was replaced about 20k miles with one from a vehicle with 60k or so (if the yard was honest). Do you thinknthat the Bosh brush set would fix the possible issue with the starter?

 

Aside from an oxidized chassis GND strap, your used 80kMi starter fits the bill of slow crank regardless of battery charge.


> Free quick test:
Use your "jumper cables" to bypass chassis strap.

Here's how:
-- Connect black side to the chassis brass post (-)
-- the other end of black side cable to engine metal
(leave the Red side cable unused).
This setup is providing unquestionably good GND path for a normal starter to crank reasonably well.

Do you notice any speed difference with strap bypassef?

 

When I do parasitic test or I call it annual check on Deep Sleep power consumption, I have a special jumper wire and with simply a little extra work, the power never get disconnected at all.
Yes, loose power for a mere 2 seconds from ground or positive cable at battery post, the modules will power down and will wake up again, like a bad reset.

Anytime a battery is disconnected, often there will be DTC too, because some modules may wake up faster or sleep a bit slower as such when one of a known module is OFFLINE due to powerloss, the other modules
will think it is a fault condition. Later within seconds when the OFFLINE-ded module wakes up and all good, the DTC will then become STORED one, no more CURRENT one.

How I do it to not loose power is here : https://mbworld.org/forums/e-class-w...-your-car.html

 

So I just realized that my alternator charges my battery (between 13 and 14v is the norm) and runs properly during the winter months and I don't have to plug it in at all during the winter. As soon as the weather gets warmer, the voltage goes down to 12v or below and after a few days, I have a very slow crank, followed by requiring a jump. Is there something I can do to trick the computer to charge the same way it charges during the winter? Otherwise, I have to charge the battery at least once per week so I don't risk the embarrassment of jumping my car on the street.

 

Here are some suggestions that may bring you instant durable relief for free:

-- you can simply drive with headlights:ON

-- or you can research how to disconnect the ALT LIN

-- or you can try to fix factory painted GND posts


Do the above and keep monitoring your dashboard battery stats.
Let us know what's best.