question

adric avatar image

How to setup multiple chargers connecting simultaneously.

Hi,

I have purchased the following devices and I am starting to setup the system on my Boat, where I have a Starter Battery and a House Battery:

  • Blue Power Charger 12 30 3
  • Smart solar MPPT 100 30
  • Orion-TR Smart 12 12 - 30
  • Smart Battery Protect 12/24 100
  • BMV-712 Smart
  • 2 x Victron 12V 175W Mono Solar Panels

My question relates to situation in which these devices will all be working at the same time.

The AC/DC and DC/DC Charger, will rarely do that, as I will either be on Shore Power or on Engine Power, but there could be very rare instances of the engines being run while on the dock for a few minutes when also still connected on Shore power.

My main concern is the MPPT Solar Charger running at the same time as the DC/DC Charger when under way and in daylight. But technically, if I am in the situation described above at the dock, all three chargers could be working at the same time, for some short period of time.

Can this damage the devices or the Battery? At present the Battery is a AGM 100Ah Deep Cycle but I will soon be replacing it with a LiFePO4.

Can someone please recommend the best way to setup this system? Am I better off switching manually things on off based on the usage? Or can I setup the devices parameters in such a way that they will automatically stop working at the right time based on the voltage produced by other devices?

I would appreciate some guidance and help.

Thank you in advance,

Adri

MPPT - Solar Charge Controllerdc dc convertersshorepower
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2 Answers
Guy Stewart (Victron Community Manager) avatar image

Hi @adric,

Generally speaking, there is no big harm to connect multiple charge sources to the same DC bus.

Especially as you have described. There can be issues though.

If the DC bus voltage is artificially high because of one charger, another charger may think the batteries are very full, and then change it's charge state accordingly.

So you might have a less efficient charging of the battery from the MPPT because it goes into float early, thinking the battery is full.

That will happen automatically if things are programmed correctly, they will all be looking for an absorption voltage, and not really care how you get there.

There is also the possibility of overloading your DC wiring. If you have only wired and fused for 30A at a time, and you get 2 going at once, you might get 60A and blow a fuse.

30A into a 100Ah Lead Acid battery is too much anyway, so it is likely the battery voltage will shoot up and the chargers will back off and restrict their current anyway.

Battery charging is a balance between performance and longevity. The faster you charge a battery, the shorter its life will be, and the less efficient that charging will be.

I wouldn't bother with any fancy manual switching system. The best thing to do would be to get a GX device (like a Cerbo GX), connect the BMV and MPPT to it, set up DVCC, and set the maximum charge current (for the solar at least) to be dynamically controlled there.

But that isn't necessary either, just the best thing to do.


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adric avatar image

Thanks Guy for your feedback, it is greatly appreciated.

Would this be less of a problem if I switched to a LiFePO4 Battery?

I will also look at at those two links in detail tomorrow and try to understand better what you mean by getting a GX device and setting up the DVCC, This is all new to me and I have yet not fired up the system, for the time being I have just finished wiring it all onto a panel at home and I will be installing onto the boat in the following days.

Thanks again and I will get back to you soon regarding the GX + DVCC setup.

Regards,

Adri


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