Mech33

Couple questions if you don’t mind sharing:

- Did you do reflashing, or just coding?

- What was the state of the battery before you started? (Freshly charged? Sitting for a week not driven?)

- Did you measure the continuous current draw, or how did you determine the “90A required”?

Thanks!

FerdinandAG

Piwis will immediately give a warning that there is not enough power
I programmed

JB911

The 997 Service Manual from Porsche, 10 years ago said 40 AMP required. 12 years later, the newer cars require a lot more. Why not get a 100 Amp unit? I'm sure you can return what you bought-read the BMW forums and the insanity over the years, they were coding way before anyone else. Many used the computer power units with 100 amps, made their own cases for them, with digital volt meter, etc
If you do a search for "BMW coding clean power supply" , or BMW flashing, you can follow all the options. The BMW cars need a lot of current during coding and flashing.
A lot of people also get power supplies from CB radio dealers-
There are tales of bricked ECUs, don't take chances.

JB
Watching Daytona 24 race

Mech33

Well, for one, the PowerMax 100A unit I tried went out of regulation and nearly fried my battery and more. This was not a permanent failure and it went back to seemingly operating normally once I disconnected and reconnected it, so I would never trust it again. One needs to be very careful when hooking up such a stiff power supply to the car and monitor it closely because it is powerful enough to do real damage if it goes out of regulation. For example, you will likely damage your battery if you let it charge the battery itself at 100A. And your 100A supply will likely let you do just that if you don’t carefully set the voltage at a low enough level to limit charging current manually. I wouldn’t be surprised if those having problems with their batteries now after coding with these supplies for a while may have accidentally cooked their Lithium cells this way. Anyone hooking up these supplies without an active voltage *and* current monitor is a bit crazy, IMO.

So I started a search for a real high current supply that has the appropriate safeties in place to shut down if the output goes out of regulation or current levels are exceeded. The best I could I could find (outside the $2000 VAS5908 tool) was the Clore PL6100 100A unit, but I spoke to one of their engineers and they confirmed that there are no fail-safe limits on the output other the shutting off the supply if the voltage goes over 16.5V. That’s too high of a safety cutoff for Lithium. This isn’t surprising because the charging modes of that unit do not support Lithium.

So then I set off to investigate what the actual current requirements are because you can get many more higher quality supplies with well-controlled outputs at the lower amperage levels. So I measured the draw on my car to start, and was surprised at how low the draw actually is once the draw of battery charging is removed (by first charging the battery).

Again my theory is the general high amperage guidelines are so you can throw any battery with any state of charge on without worry of having an issue during programming, but I would love some actual data from folks on what their cars are consuming.

Its not difficult to measure. You can rig up the $20 meter I linked to, or one can use any DC current clamp meter available at hardware stores everywhere and put it around one of the leads leaving the battery towards the car (the positive cable If you’re using the separate charging ground lug off the battery for charging). This would separate the battery charging current from the vehicle electronics current draw.

If we can share this info from different activities then we can learn what the true needs actually are and can only put as stiff of a supply as needed on the car with the most protections.

JB911

Search the BMW forums-
And if your powermax had a failure, they have a warranty or return policy.
Many Powermax users, especially in the RV and CB radio groups-
JB

Mech33

For anyone interested in helping gather data on what the current consumption is of these cars during coding, you can get yourself a cheap DC current clamp meter like this $40 unit and put it around your positive battery cable (on the side between the battery and the rest of the car, not the charging cable side) and report back on what you see.

KAIWEETS Digital Clamp Meter T-RMS 6000 Counts, Multimeter Voltage Tester Auto-ranging, Measures Current Voltage Temperature Capacitance Resistance Diodes Continuity Duty-Cycle (AC/DC Current)


And throw it on the charging cable side if you want to see the sum of the car’s consumption plus the charging current going into the battery.

greymda

this is an option, not mine. at a service point:

siberian

Wow, near 2 grand...?

siberian

rainer

No need to search for it, I copied the manual from the BMW forum some while ago and am using this since about 1 year now.

Gives me around 70A with the unit I use, which so far worked nicely for my Macan.

25,- EUR investment.

FerdinandAG

Delta Electronics DPS-750EB - 90A

greymda

can’t seem to find less than 60-70. Europe.

rainer

That's the one I have and also the one pictured in above manual.

How did you derive the 90A? According to the sticker it delivers approx 70A..

FerdinandAG

rather 70-75, but great for working with panamera 971, does not write warnings (panamera requires 90)

sac02

Yeah, it seems like if you wait you can snipe them occasionally for cheaper, but they usually go for more on eBay if you just want to "buy it now".
IMO it's not realistic to claim anyone can get one for that price on a whim.
Looking through completed eBay listings, one person got lucky and snagged one for $30. All other sold listings are $55 and up. :shrug:

EDIT:

I wonder if people who bought them at low prices got them over 2 years ago, before crypto mining resurged.
Maybe all the crypto miners are also more subtly driving up prices on 12V power supplies, in addition to more obvious GPU price increases?

sac02

I'm not sure I believe when you say 90A.

The model name includes "750" because it is a 750W unit.
750W / 12V = 62.5A

If you modify the PS (to override the overvoltage protection) to allow output of 14.4V, 750W becomes only 52A.

With cheap Chinese PS, it is good to assume power output capacity is 10% less than rated power.
And on the other hand, a brand-name server PS may produce at or slightly above the rated power.
But I do not think a 750W PS can produce 1260W (14V*90A).