Battery Test - Voltage Dip Limiter

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ashtray1987
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Battery Test - Voltage Dip Limiter

Post by ashtray1987 » Fri Feb 07, 2020 8:39 am

Hi Guys,

This is probably aimed more towards the Pico Technical Staff;

Will voltage dip limiters affect the battery test measurement?

The voltage dip limiter is a switched series resistor, installed on the starter cable that temporarily (around 100ms) reduces the amount of current delivery by increasing the resistance to the starter motor.

Do you think this would affect the measurement of the battery internal resistance/ starter motor resistance measurement? I'm thinking yes...

Appreciate your feedback.

Thank you.
Ash

liviu2004
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Re: Battery Test - Voltage Dip Limiter

Post by liviu2004 » Fri Feb 07, 2020 10:29 am

Which vehicle / truck has that?

ashtray1987
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Re: Battery Test - Voltage Dip Limiter

Post by ashtray1987 » Sat Feb 08, 2020 2:30 pm

Mercedes-Benz, for the last couple of years.

Designed to prevent voltage fluctuations during cranking. Really simple method and replaces the need for an auxiliary battery.

Would assume therefore that VW Audi and BMW are probably using similar technology.

Cheers
Ash

ben.martins
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Re: Battery Test - Voltage Dip Limiter

Post by ben.martins » Fri Feb 14, 2020 6:25 pm

Hi Ash,

Thank you for bring this to our attention. The battery test will use the measured values to do the calculations which give you the battery results. If the current is being 'restricted' then we must assume that this will affect the results of the battery test.

What would be interesting is if you have a 4 channel scope, you can use channels C & D to perform a voltage drop test on the started cable. I'm wondering if the results here will show the user that the switched resistor is having an affect on the starting circuit.

Something for us to look into for certain though Ash, thanks once again.

Kind regards

Ben

ashtray1987
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Re: Battery Test - Voltage Dip Limiter

Post by ashtray1987 » Tue Feb 18, 2020 3:07 am

Hi Ben,

I've attached a current measurement of the voltage dip limiter in action.

Technically we could quite easily remove the control connection to this device.

I would assume there is no way around this through the measurement software, so perhaps it's just worth writing a note to advise people using to ensure the voltage dip limiter is deactivated before doing the test.

Cheers
Ash
Attachments
w213 voltage dip limiter.psdata
(219.16 KiB) Downloaded 10 times

ben.martins
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Re: Battery Test - Voltage Dip Limiter

Post by ben.martins » Tue Feb 18, 2020 11:43 am

Thanks again Ash,

I think you're right, being aware of this is probably more important than anything else. I will ask the tech pub team to look at adding a note mentioning this. Really appreciate you bringing it to our attention and for the capture.

Cheers

Ben

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