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mvader (Victron Energy) avatar image

Is a switch necessary on a battery charger? Why?

Hello Victron Community,


Some of our existing larger battery chargers have an on/off button while other do not.


For some new larger battery chargers we are wondering if such a button is really necessary.


Why shouldn't they just charge when connected to AC; and otherwise stay off?


We would like to hear from you what the use cases are for such a button. Have you done installations where the on/off button is essential and why?


The product designers are listening....

chargers
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6 Answers
Boekel avatar image
Boekel answered ·

Yes, especially bigger chargers that are generally hardwired in the system. The corresponding breaker might not be in reach / have other devices on the same breaker.

The switch doesn't have to be at the front panel, can be at the bottom like Mplus II

Smaller chargers usually have a plug you can pull.

(hoping there will be more 48V chargers coming..small and big)

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Ok. But why would you want to switch a charger off? Whats the use case?

(And thanks for the quick reply ofcourse!)

WKirby avatar image WKirby ♦♦ mvader (Victron Energy) ♦♦ ·

If quiescent standby current is low enough, then it's probably not necessary.
Some people are paranoid and like to be sure that appliances are completely off, no standby LED's on at all.
A large charger will surely have an isolator switch installed close by, so customers can use that if they want to.

Yes; that I understand. The idea is to work towards super simple: power from ac only. No ac = No leds = no canbus communication and so forth.

As soon as you want to keep it powered from the battery when AC is off; to do some comms orso; then the complexity comes in; wrt low standby current and-so-forth.


So then the only draw on the battery would be a few divider resistors for the voltage measurement.


Update: but that does add complexity in monitoring side -> Venus OS m; with the chargers coming and going.

Markus avatar image Markus ♦♦ mvader (Victron Energy) ♦♦ ·

I think WKirby is very right. A big reason, some people want to have a switch is, being afraid of backdraw or standby consumption.

Maybe it's an idea to market a "missing" switch as a product feature of the charger. It is just so good, that it doesn't need a switch. ;o)

Boekel avatar image Boekel ♦ mvader (Victron Energy) ♦♦ ·

Why swith off?


Besides maintenance reasons (and installing / changing)

I have a 48 volt system in my boat, and a 24 volt battery used for the hydraulic crane, if I leave the 24V charger on it will always trickle charge the battery. I know, not an every day use-case.

Would I miss a switch? maybe, I'd change the system around it if I need it easily switchable. Most chargers I use now are CANbus controlled anyway.

Markus avatar image
Markus answered ·

Maybe to use e.g. solar energy to charge the batteries instead of the grid in a hardwired system.

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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

If the product is designed to operate without a switch, I think that is fine to remove it.

If a switch is still 'in demand', a very simple one could be just an AC switch on the active AC input wire before it reaches the charger circuits. This should be very low cost and reliable. The unit is designed to always operate when AC input is there (as it would without the switch). But there is a convenience.

Bottom mounted, and hiding it next to the AC input connection in a similar fashion to the MP-II switch would be fine. Ideally IP43+ rated too.

Other reasons for switch:

You may not wish to have the load on the AC. If the generator or charger is large, it is likely to be hardwired, so you cannot just unplug it. You might want to wait a time for the generator to warm up before switching on the load, or quickly turn it off if there is an issue (overcharging, overloading generator).

Though this could easily be addressed at point of installation by adding an external switch that is appropriate to the conditions (eg water proofed, locked out, etc).

Personally I prefer the design without it, I don't think it would affect the purchasing decision much either way.


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Stefanie avatar image
Stefanie answered ·

I prefer the On/Off switch for cost reasons when hooked up to shore power AC in the harbour where each KW can cost a fortune. Ideally I switch the AC charger off and let the solar array or wind gen charge the batteries. The switch does not have to be physically at the charger, a remote works perfect.

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Mark avatar image
Mark answered ·

No switch on the charger would suffice and be a better option.it would be nice to possibly switch the charger on/off via the Bluetooth App,this coupled with a password would restrict unwanted interference!

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Gary Pacey avatar image
Gary Pacey answered ·

I can not see a practical use case where it is an advantage.

  • Smaller units plug into an AC Outlet so use the switch on the AC outlet
  • Larger hardwired units should have a dedicated circuit breaker on the AC switchboard. They should also (by Australian Standards) have a local isolation switch external to the charger for maintenance purposes.

In my mind, a switch on the unit is another potential point of failure that we can do without.

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