earl0101 avatar image

AC shore power availability for Multiplus output

I've searched extensively and am still confused. In this link @markus suggests "switch to charger only and now the AC shore supply will still be on and the inverter will be off, leaving ...AC shore supply available for DC charging and AC power...".

Another post from @JohannesBoonstra to this blog states "[for] ... Multi and Quattro the inverter always works (and the ACout is powered) when the unit is charging"

However, currently the experience I'm having with my multi (purchased Sep 2021) is that the ACout is only available if the unit is in the full on mode. The 'charger only' mode eliminates ACout to the receptacles. The problem with the full on mode is that if the shore power is unknowingly disconnected, the batteries drain very quickly due to the standby current draw. I did try the AES function but the modified sine wave didn't help much and the AES surge mode caused issues with the microwave.

What I want is to configure my multi so the following happens:

* When shore power is connected/ON (120V up to 15A)

Ability to use ACout to power receptacles

Inverter is off (eliminating standby current draw)

Battery is kept full or charging

* When shore power is disconnected/OFF

Battery is prevented from discharging

Inverter is off (eliminating standby current draw)

(which also means no power available at ACout power receptacles)

To do this what is the configuration I need? @markus references an article suggesting setting the multi to 'charger only' and the current to zero. Can someone clearly confirm this and whether I need to actually purchase a Digital-Multi-Control to achieve the above behavior? Are there other alternatives?

One would think the default behavior with a 'charger only' configuration would be to allow any ACinput to pass through (if present). In the 'charger only' configuration it does not make sense to me that the current limiting function should have any bearing on pass-through ... a value of zero seems to imply there is no current available/allowed for charging (i.e. the multi is equivalent to fully off). Any explanation as to why this is not the case is greatly appreciated.

thank you.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

2 Answers
Alexandra avatar image
Alexandra answered ·


The simplest way is to have a bypass switch in.

We have ours able to charge and the loads can draw direct from shore/grid on one way. Or the other way the loads and power draw through the multiplus so it can power assist if needed.

Then we dont have to worry about draining the battery if we randomly disconnect and we will know when it happens.

And on the Multiplus when we have on charge only there is power to the output, it does pass through. And obviously if the shore disconnects there is nothing.

2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

earl0101 avatar image
earl0101 answered ·

Thanks @Alexandra. I ordered the Baomain Universal Rotary Changeover Cam Switch SZW26-63 (version with case) that will allow me to do as you suggest with the added capability to easily bypass the Multi if it were to fail.

BTW, I learned something new regarding setting the Multiplus to the 'charge only' state. In my initial tests when flipped to the 'charge only' state the power to my outlets/microwave was indeed cut. This caused me to immediately switch back to full on (hence the post above). However, I tried again yesterday and went to get a cup of coffee ... when I returned much to my surprise I noticed the power to the microwave/outlets was present. Apparently one needs to wait for the multi to pass the ACin directly to the ACout!

I tested again and confirmed this. The Multiplus does not act like a switch as expected. When it is switched to the 'charge only' state it does not immediately put power on the ACout line; one has to wait a moment or two to get that. A fact that now makes the @markus comment in the link above all the more confusing to me.

1 comment
2 |3000

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.


Maybe the older units couldnt oass through or some models could. I dont know there.

That changover is a beast, we have MCB based COS available to us as well as the rotary type. But anywyay Glad you have your solution. We are all learning new stuff with our systems all the time. Part of the fun of generating your own power.