Hi all,

In my livingroom at home, I’m running a small battery backup for the TV, wifi and occasional laptop or other small device.  The setup is:  Victron 375va standalone inverter, Victron 15A AC charger and a 105 ah, semi-deep cycle battery.

Does this setup need an ATS (Automatic Transfer Switch) or can I permanently leave the charger in the wall socket connected to the battery, the inverter connected to the battery and the wifi + TV connected to the inverter?

My reason for running this backup as “separates” instead of a convenient all-in-one UPS like a Mecer or something is that I believe those UPS devices use cheap/bad quality inverters and especially chargers inside which are real bad for battery longevity.  Will probably start a thread on that soon but for now, I need to know comments/opinions on the ATS requirement please.

Thanks

This may be of interest to you.

https://www.portablesolarexpert.com/can-you-charge-a-battery-while-using-an-inverter/

 

I'm not qualified to answer your question but the article basically says as long as your battery charger does not overheat by being constantly plugged in, AND, everything is sized correctly such that you charge faster than your load (i.e. the battery does not deplete even while being charged) it should be fine.

From my understanding those victron units are pretty high quality so I wouldn't personally worry about it.

Then again, adding the ATS isn't exactly difficult or super expensive so why not?

Victron also has integrated inverter-charger units which would handle this for you.

 

https://www.victronenergy.com/transfer-switches/filax-2

Edited January 13, 20232 yr by jeddles

8 minutes ago, jeddles said:

This may be of interest to you.

https://www.portablesolarexpert.com/can-you-charge-a-battery-while-using-an-inverter/

 

I'm not qualified to answer your question but the article basically says as long as your battery charger does not overheat by being constantly plugged in, AND, everything is sized correctly such that you charge faster than your load (i.e. the battery does not deplete even while being charged) it should be fine.

From my understanding those victron units are pretty high quality so I wouldn't personally worry about it.

Then again, adding the ATS isn't exactly difficult or super expensive so why not?

Victron also has integrated inverter-charger units which would handle this for you.

 

Thank you for this.

For now, I'll leave it as is and monitor the heat levels and battery state of charge.  I feel this system, even though small, is oversized for the use case - the load is really small.

It still is an interesting topic to me though; and it still confuses me quite a bit.  To my knowledge, from reading similar articles to the one provided, a battery CANNOT be charged and discharged at the same time.  That makes sense, because DC current can only flow one way, right?  

So, that means the load AND the battery will both draw power from the charger at the same time. If the charger is strong enough, it will power the load and charge the battery.  If the battery is full, the charger will power the load.  If the charger is switched off; or eskom drops, then the load immediately draws power from the battery via the inverter.

Now that's all good and I'm happy with that.   Here's my problem (or rather point of confusion):  most modern chargers are "smart chargers" right?  They have these special algorhythms with special charging stages, each stage with a very specific voltage and current - all designed to best manage the battery.   Now, how does the smart charger get these special charge parameters to the battery with an active load?  Does the load not interfere and basically void all these smart charge stages?

Anyway, thanks for the response.  For now I'll leave the setup as is and keep an eye out for a good standalone ATS.  The ones with a quick enough transfer time (to keep my network gear on during transfer), seem to go for about R1.5k to R2k.  I am also looking into a complete solar setup for the house which will render this little backup solution redundant.

Cheers

 

So far working OK...   The absorption charge seems to get stuck close to 3A though while a load is on.  I charged it full to "storage" stage once while I left the inverter off.  Maybe the time windows between loadshedding are not long enough to allow a proper full charge while under load.

Cheers