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Simon Glet avatar image
Simon Glet asked

Orion XS Engine Start Detection and Multiplus II Starter Battery charging

Hi,

We have a motorhome on a Ford F53 chassis and currently upgrading our electrical system. We went full Victron on the Inverter, Solar Chargers, etc.

The Multiplus II (MPII) is set to trickle charge the starter battery and I was wondering if it would interfere with the Orion XS Engine Start Detection feature.

The MPII states the max Starter Battery amperage is 4 amps but nothing about the voltage.

The graph below is today's Starter Battery voltage (engine stopped) plotted on our VRM:

starterbatteryvoltage.png

The Orion XS manual states the default voltage to start charging is 14 Volts but I wonder if it will detect the engine has started.

So, do the MPII and the Orion XS play well together?

Thanks

Simon

Multiplus-IIstarter batteryorion xs
starterbatteryvoltage.png (24.4 KiB)
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2 Answers
pwfarnell avatar image
pwfarnell answered ·

The trickle charger is a basic system which is a current limiter and diode, the diode stops current flowing from the starter battery to the house battery if the house battery is low. The diode means that the starter battery will typically be about 0.3V lower than the house battery if the engine is not running. This means that if you have another charger that can take the house battery above 14.3V then you may get the starter battery to 14.0V. Create a custom widget in VRM with your house and starter battery voltages on the same scale and they will follow each other when the engine is not running.

Here are mine on a boat, twin alternator one for starter and one house. They start at about 10pm, starter battery is still full from days cruising and the domestic are declining under load so no trickle charging. 07:00 solar charging starts but not very well, by 09:00 when the house battery rises to 13.4V the starter battery increases to 13.1V, 0.3V behind. 13:00 to 16:00 we cruise, the two alternators dominate. after mooring up we have solar on the house battery and the trickle charger keeps the starter at 13.2V until solar is lost.

screenshot-20240706-221703-kindlephoto-1082531217.png

hope this helps you.understand how this works.

ps, the bog dips in starter battery voltage is the bow thruster being used.



screenshot-20240706-221703-kindlephoto-1082531217.png (40.9 KiB)
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Simon Glet avatar image Simon Glet commented ·
Are the chemistries of your starter and house batteries the same? Or it doesn't matter?
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pwfarnell avatar image pwfarnell Simon Glet commented ·

Mine are both lead acid. If you have lithium house and lead acid starter then the trickle charge is not ideal because the higher lithium voltage will keep the starter battery permanently on charge with a permanent drain on the house battery. Depending upon your lithium battery BMS and load shut down, the trickle charger may not get isolated on a low battery voltage as it is not a controlled load, it is connected to the main DC power on the Multiplus.It is not recommended to use the trickle charge with lithium house batteries.

It works properly with lead acid on both because it only trickle charges when the house battery is being charged. It would probably be OK with lead acid house and lithium starter.

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Simon Glet avatar image Simon Glet pwfarnell commented ·

You got me a little worried there ... I looked for Victron documentation but cannot find anything you mentioned. Could you point out in which manual I could find that information? Thanks

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pwfarnell avatar image pwfarnell Simon Glet commented ·

1. The documentation on the trickle charger is not comprehensive and the concerns about lithium house to lead acid are not listed. Victron is aware and the documentation will probably be updated.

2. You do not need the documentation to understand this effect, it is basic electrical knowhow.

  • If the resting voltage of a full lithium battery is 13.5-13.6V and the trickle charger allows current to flow if the starter battery is 0.3V lower than the house battery then as a full lead acid battery is 12.8V you will always get a load on your lithium batteries until they are down to about 13.1V. If the starter battery has a drain on it then as it depletes it can draw the lithium down further. Some people are happy to accept this as the starter battery will be maintained at about 13.2V, which is a storage voltage that will not harm the starter battery AS LONG AS you appreciate the permanent drain on the house battery. For lead acid to lead acid, the house battery has to be above the full voltage for the trickle charger to start working, i.e. be on charge.
  • As the trickle charger takes its supply from the DC input it is always working when the DC power to the Multiplus is on, even if the charger or inverter functions are turned off. If you have drop in batteries with a built in BMS that has isolation built in then this will shut off the trickle charger if the BMS shuts down discharge because the whole Multiplus is isolated. If you have a Victron Lynx BMS then the same applies as the contactor isolates everything. If you have a Victron VE Bus BMS then this does not shut down the DC feed to the Mutliplus, it shuts the Multiplus down by DVCC software controls, so in tis case the trickle charge could remain as a parasitic load which is not good if the batteries are very low. This could be avoided by putting the trickle charger output through a Victron SolidSwitch that is controlled by the ATD output on the VE Bus BMS.
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kevgermany avatar image
kevgermany answered ·

@Simon Glet

From your graph it looks as if you have an intelligent/smart alternator. And starter battery voltage isn't going to trigger the engine detection properly. @pwfarnell graphs confirm this.

Might be easier to use the LH pin method to control the Orion on/off. There should be an unused switched connection in the wiring of the truck. Or use the switched radio positive, tapping into that.

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