Some fun facts: Maintainer conducted noise as applied to vehicle power when impressed on the CAN bus should be mostly common mode noise, and CAN being differential should reject this noise at probably a minimum of 40 dB. The battery noise filtering effect on Maintainer output noise is dependent on the Impedance of the network (the battery, vehicle loads and all the cabling). If you increase the impedance by using jump start posts under hood (because the battery is in the trunk) the noise magnitude will increase at a given supply current because of the increase in network impedance. The high frequency noise as applied to the vehicle power network will be filtered to some extent by way of VBAT filtering on board the module. However, this critical filtering is many times under-designed on-board the modules. Fundamentally a battery charger should not be used as a maintainer. This is because one of the first modes of the charger will be Bulk Charging mode which is a current regulated mode and not a voltage regulated mode, it will however set a maximum average voltage level depending on if the battery type is flooded or AGM. A System Maintainer should be a voltage regulated supply, that is, it regulates output voltage given a changing load current (also with a changing line voltage). The Schumacher INC70 is not amazingly quiet. A good industry performance target for vehicle 12V power rail maintainer supply peak-to-peak ripple should be 50mV at 50 Amps (this is the old GM standard), with this worse case being when connected to jump start posts under hood with the battery in the trunk. That means at the battery the noise measured would be less than 50mV, this is a very challenging specification to meet given the switching power supply techniques most often used. Another important power supply requirement is the dynamic response when during reprogramming and system test a load is actuated like a cooling fan. The supply should momentary exhibit a voltage drop with a step change in current which should not be more than 250mV before recovering. This is also a very hard requirement to meet. Let's do some basic math when we talk about a maintainer that can supply 100A at 13.5VDC. The 100A at 13.5VDC is a very common maximum requirement from the OEMs for reprogramming which includes system load actuator tests, but I have yet seen the need for anything over 60A at 13.5VDC with USA domestic passenger vehicles and light duty trucks. At 100A @ 13.5VDC the output power is 1350 Watts, and at a supply efficiency of 80% with perfect power factor correction on the input the minimum apparent input power (VA) needed is 1687.5 Watts, at 120VAC the branch circuit current needed is 14 Amps, which is getting close to a nominal common branch circuit limit of 15 Amps in the USA especially so if you include any voltage drop in the cabling. So for the 100A @ 13.5VDC you would really like to see the requirement for a 20A branch circuit which would have a different plug style especially if the maintainer does not have PF correction. I think a much more realistic maintainer output would be a maximum of 60A at 15VDC giving an input requirement of around 10A at 120VAC, which is reasonable for a 15A branch circuit. Another problem not usually addressed properly is maintainer output voltage drop across the cabling (heavy duty cable clamps) which should be the set voltage at the vehicle and not the maintainer. Some newer design have a procedure to null out the cable resistance, but you rarely see a separate remote sense like you would see on an electronics lab test bench when supplying currents over 10A. Many automotive load testers in the past used 4-wire connections to account for voltage drop across the cables.

Outstanding explanation!

Hello, new subscriber here... I've watched a few of your videos and I must say, you do a great job at presenting a case or product. I'm researching information on the Autel MS906BT and I watched your 906TS videos (Cobolt and Cadillac). I picked some up some good tips for my review and future use of that tool. Now I see your using a MP408 scope, something I was not aware existed. With all the rage being the PICOscope, this looks like a good option. Nice job.

There's lots of filters and switching regulators that lower the voltage down to 3.3Volts in cars Mirco controllers, Feedin direct voltage to the ECU will separate battery voltage from ECU voltage but it needs a good knowledge of pins schematics. Plus, a modified PSU can deliver up to 120A and cheaper, further details and protection needed as well.

How much of a load did you put on that battery?

Totally makes sense as to why the stable battery power supply is needed to flash ecu's and that the typical battery chargers/maintainers just can't do the job as you've demonstrated. My question is, if I only have those basic battery chargers/maintainers, and I don't own a stable power supply, would I just be safer flashing the ecu without anything attached, and just flash using the car's battery as long as i've driven around for awhile and made sure it is fully charged? In the video, you didn't show the "flashing" load on the battery just by itself. On a fully charged battery, would the load from flashing cause the voltage to drop below the "minimum" in the 20ish minutes it could potentially take to flash and ecu?

Great video. Thank you

Excellent. Thank you. How did you load the battery? 70a seems really high for programming.

i like your scope . i have the same on . and many others

How many volts - 13.5v - do Mercedes and BMW programming need? What are some more affordable power suppliers out there?

Hi there, I am using ista-d and inpa programs what power supply do I need? Thanks for the very informative video, I am subscriber. Thanks, Joe.

Not agreeing with your conclusions. The fact that you can see a microsecond dip to 9V, because of fancy autel nowadays, does not mean that you brick a module. Second, been there done that, when I did not had a supply, had a battery die on me during flashing. But that ecu was good designed and I could start again flashing how many times I wanted. That is proper ecu design.

What tablet are you using? I didn’t know the maxiscope could work on a tablet. You should do a video showing the maxiscope functionality.

I have a 10A 12V charger and I'm just trying to flash my ECU back to stock. It has a 12v 10A "supply mode" would that be better than just letting it charge while flashing?

do the inc700 / inc100 need to be plugged in the standard socket while in operation? or do they have a built in battery?

Great video. I wonder about a fourth option? What if someone was to attach two batteries together with a tiny charger to keep those maintained and use that as a supplemental battery to attach to the car to maintain good voltage and more importantly clean voltage? Do you think this would be an economical alternative? What do you think the negatives would be in that situation?

Hi, i'm using two server power supply connected in parallel. What you think about it?

Very well done video I have a question about the Autel scope that you have in your video I have the same scope and I don’t have much experience with oscilloscope but it seems like you have the hang of it I was reading the manual on the scope and my main question is how many reference wave form can it store for future reference in the manual it says only 4 is this true and I don’t even know how to do it it would be nice if you could do a how to on the Autel scope there is no good video on U tube on this tool only lots on the pico scope .

👍👍

Hello, can I use a 12v battery jumper/booster pack?

700mV of ripple is enough to screw up a programming. Below 50mV is ideal

What if you take another car and use jumper cables? Will that brick the computer while flashing? Thank you. GREAT VIDEO!!! :D

I can't afford to spend that much 😅. Can i use a server PSU 1000w as a stable battery supply ?

Hi i have a question, i just recently downloaded bmw software and bought a schumacher battery charger/maintainer its rated at 200/40 amp with 6/12v, was wondering if that will be enough to maintain voltage on the battery? or if i should return it and buy a battery supply. i dont want to be the next magician that bricks his modules lol

Can U use another car with jumper cables!??

So I'm the first view!! "saludos desde Puerto Rico"

Alway program wired to the vehicle

Charger works 95% of the time

A video criticising people for not having the right tools. 'I'm gonna test every tool for voltage, AC ripple and amperage', except he couldn't because he didn't have the right tools to do so!