question

tylera avatar image

Quattro without a battery?

I have a 48V Quattro, a 48V battery bank (2x24V), a 48V->24V charger (using a Victron MPPT for this), a 24V battery, a shore power connection, a second MPPT for solar.


Unfortunately, the 48V battery bank had to be replaced entirely. So I have two new 24V batteries from Victron to install.


I'm under the impression that prior to installing, I need to fully charge the 2x24V batteries individually before connecting them as the 48V battery.


My primary option at this point is to charge one from solar until it is full, then the second, then install them. Due to the size of my solar array, this could take some time.


Can the Quattro be run without a 48V battery? This would be taking 120V from the shore power, and converting it via the Quattro to 48V for the regular loads on the 48V circuit. This load would be the 48V->24V converter which I could use to more rapidly charge each 24V battery.


Shore Power (120V) -> Quattro 
                         |
                         |
                      48V Bus -> 48/24 Charger -> 24V Battery


(The regular schematic would be closer to:

Shore Power (120V) -> Quattro 
                         |
                         |
                      48V Bus -> 48/24 Charger -> 24V Battery
                         | 
                         |
                     48V Battery

)


MultiPlus Quattro Inverter Charger
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2 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @TylerA

Yes, this -could- work, it's not advised and can / will lead to all kind of low battery warnings. But you can try....

Please make sure to have the BMS connected and working while charging / balancing the batteries.

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Thanks for the reminder regarding connecting the BMS. I don't mind warnings, knowing this is merely a bootstrapping setup...

In this case, there would be no BMS connected to the 48V Quattro, correct? Because the Quattro would be expecting the BMS to be managing a 48V bank, and the BMS would instead be managing a 24V bank.

Hi @TylerA

yes of course the bms should be connected to the batteries, and controlling the device that charges the batteries.

But please be warned: you are on your own with this setup, as I stated, it -can / could- work, but it is in no way a supported setup.

owenfi avatar image
owenfi answered ·

Hi @TylerA Did you end up trying this? I'm in a similar-ish boat, wanting to warm up my Lithium prior to connecting my batteries and charging them.

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Negative. I was unable to have the Quattro without the 48V battery connected. I ended up using solar (I had no sails on the boat and it was ~April in New Jersey) to charge first one battery (I think 2.5 days), then the other battery (2.5 days), then I started over and charged the first then second again (just to make absolute certain) (very brief, just enough to get to float, basically), then was able to use the 2x24V as 1x48V.