Using a voltage regulator or not

[spittet]

Hi,

I have a project that will use a MC050-110. This will be on a 12V machine. The ignition key (IGN and STA signals) will be sent into the CAN network. Then, the MC050 will use output pins to drive relays that will activate the engine ECU, fuel pump and the engine starter.

When the engine will crank, on a cold winter day, on a cold battery, I'm worried that the voltage might go below the rated 9V min value of the controller and the controller might stops. So, the engine won't continue to crank and won't start because the output won't be driven anymore.

I think it should be wise to use a DC-DC voltage regulator for the supply voltage pins of the MC050. Do you think I only need to regulate the voltage for pin C1P2 or also for pins C1p47 to C1p50? If so, do you have a suggestion for a big power DC-DC regulator built for automotive/heavy duty purpose? What power should I need?

Do any of you have ever done this type of setup? Please post some references if possible.

Have a good day!

Sam

[Mike AA]

How much of a power draw will you see for the daily use of the controller? If it is a small enough load you could possibly use a battery isolater and have a separate battery just for the controller and its outputs. We are looking to use a battery to run the controller, display and telematics that would kick on when key is turned on then during crank and normal use if main battery or key is turned off it would stay on for a predetermined time to allow things to save then the controller would disconnect the holding relay which would disconnect the controller display and telematics.
-Mike

[Remy]

To prevent using a big DC-DD converter, just plug it in parallel with the battery using diodes. This way you use the battery on regular usage and your DC-DC converter is used when your battery drops below 12V

[Remy]

We use these one, with good success so far

http://www.current-logic.com/dcdc/CLL.pdf

[pinias]

Spittet,

May be something was not included in the description of your concern. but according with you description I would say it does not make sense what you want to do.

if the voltaje drops below 9V you got a death battery, the ECU is also compromissed with low battery and it will not be able to keep the starting of the engine

if the voltage drops below 10 then the battery has no current (on my experience), I am thinking you have 2 batteries.

I would say the system needs to keep at least 9 volts so that everything Works, but as I said I may not have all the information about the system

I hope this helps

[jashom1]

Hi Sam,

Pinias is correct, if the battery voltage drops below 9 then you have other problems.  Normal load testing to determine the CCA rating of a battery is load tested to 9.6 volts. 
I wouldn't expect you would need to use a DC-DC converter.

Cheers,

John.

[Remy]

I've started multiple time engines in cold winter. Even if the battery is good, the current consumed by the starter is way enough to drop the battery under 9V. We recommend either shutting off controller with Starter key or if you need them to use a DC-DC (We have cases that we start the motor ourselves so we need the DC-DC)

[oiltronic]

After seeing too many drop-outs and damaged electronics due to cranking dips and inductive spikes, I use DC-DC converters when possible.   Especially when the electronics is required to crank the engine.  With proper engine and power distribution wiring, the Danfoss controllers shouldn't drop out, but your margin of error and robustness is improved with a quality converter.  Yes, the drop-out might actually be due to things like improper wiring, small cable gauge, corrosion, loose terminals, or weak batteries, but it doesn't take much to get a dropout.  Wire the raw battery voltage to a spare analog input to alert as necessary, but I find the customer is happiest if the %$&#!@ engine just starts.

[spittet]

Hi,

Thanks a lot for the answers.

My main concern is about pins C1p47 to C1p50 that are power pins on the MC050. Would you feed them through the DC-DC converter? Or only the C1p02.

I may need to find out how much amps go through C1p47 to C1p50 at worst (peak amps) to size the DC-DC converter accordingly.

Have a good day!

[Marbek_Elektronik]

c1p02, c1p47 to c1p50 is parallel and one pin only can max. 8 ampere.

What about SC-controller? The minimum voltage is 7 Volt !

In our project we use a mc-controller and it works below 9volts.
To be sure, machine would start at cold temperatures we have a second switch, the user can start the engine manually.

[Mike AA]

Hi guys,

Just adding another of my $0.02.

We purchased a 12aH lithium battery with a battery Management system and a 24volt to 12 volt charger for said battery. We are hooking the MC and Display and Telmatics behind a relay which will hold down to about 6 volts which connects to the battery. The charger keeps the battery topped off whenever the master is on. When the key is off the display is blank and all 3 items draw just over an amp so they should stay powered up for 3-4 hours without issue. When the machine is cranked we can easily see 3300amp of batteries drop off during the winter so we wanted to make sure the system stays powered up and it also allows remote access without the entire machine being powered up.

Mike