How many amps is to much for agm batteries wired in parallel. (2 Viewers)

[garysavannah]

Good evening all
Hope you can help!
I have 2 agm batts wired in parallel give a total of 190amps combined.
I’m fitting a 12/12/50 Victron xs which you know has a variable voltage setting.
I intend to get the full potential of this when I get my lithium.
Question is what could I set the max charge current to on the xs so the fitted agm’s get as much as they can but don’t cause the batteries damage.

 

[Lenny HB]

Should be fine on max as each battery will only get 25 amps.

 

[garysavannah]

Should be fine on max as each battery will only get 25 amps.

Cheers Lenny
Will definitely be an improvement on the Sargent that is in there at the moment

 

[garysavannah]

Should be fine on max as each battery will only get 25 amps.

I didn’t understand how the voltage would be distributed between the 2 and still don’t.

 

[bigtwin]

I didn’t understand how the voltage would be distributed between the 2 and still don’t.

It isn’t distributed between them; they are in parallel and will see the same voltage at whatever voltage the charge source is putting out.

Ian

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[autorouter]

I’m fitting a 12/12/50 Victron xs which you know has a variable voltage setting.

I didn’t understand how the voltage would be distributed between the 2 and still don’t.

It's not the voltage. Voltage is exactly the same for both batteries, which is what you are probably thinking of. The variable setting on the Victron XS is the current flow (amps). The current flow amps into each battery should be about equally divided between the two, assuming they are both the same size and type of battery. So as Lenny HB says, if there is 50A available then about 25A should go into each battery.

The recommended charging amps for a 190Ah of battery is C/5, where C is the Ah capacity. So that's 190/5 = 38A. To be ultra-cautious you could dial down the amps to 38A instead of 50A. But for AGM batteries you'll probably get away with 50A OK. Especially if they are 'Dual Purpose' starter/leisure batteries.

Before you do that, it's worth checking whether the fridge heater element power is coming from the XS output, or going via a different route. If it's coming from the XS then that's 10A to 14A less for the batteries anyway, so it works out about right.

 

[garysavannah]

It isn’t distributed between them; they are in parallel and will see the same voltage at whatever voltage the charge source is putting out.

Ian

Hi Ian are you saying they both will receive 50 volts then, have I read this incorrect.

 

[bigtwin]

Hi Ian are you saying they both will receive 50 volts then, have I read this incorrect.

No, the 50 refers to the current capability of the charger, not the voltage.

The charger will output between 14.5V and 13V depending on the charging phase it’s in.

Ian

 

[garysavannah]

It's not the voltage. Voltage is exactly the same for both batteries, which is what you are probably thinking of. The variable setting on the Victron XS is the current flow (amps). The current flow amps into each battery should be about equally divided between the two, assuming they are both the same size and type of battery. So as Lenny HB says, if there is 50A available then about 25A should go into each battery.

The recommended charging amps for a 190Ah of battery is C/5, where C is the Ah capacity. So that's 190/5 = 38A. To be ultra-cautious you could dial down the amps to 38A instead of 50A. But for AGM batteries you'll probably get away with 50A OK. Especially if they are 'Dual Purpose' starter/leisure batteries.

Before you do that, it's worth checking whether the fridge heater element power is coming from the XS output, or going via a different route. If it's coming from the XS then that's 10A to 14A less for the batteries anyway, so it works out about right.

These are the batteries I’ve fitted in parallel and yes I got confused so now understand it’s the amps that are distributed between the 2.
Thankyou for the reply

 

[garysavannah]

No, the 50 refers to the current capability of the charger, not the voltage.

The charger will output between 14.5V and 13V depending on the charging phase it’s in.

Ian

Got it thanks Ian

It's not the voltage. Voltage is exactly the same for both batteries, which is what you are probably thinking of. The variable setting on the Victron XS is the current flow (amps). The current flow amps into each battery should be about equally divided between the two, assuming they are both the same size and type of battery. So as Lenny HB says, if there is 50A available then about 25A should go into each battery.

The recommended charging amps for a 190Ah of battery is C/5, where C is the Ah capacity. So that's 190/5 = 38A. To be ultra-cautious you could dial down the amps to 38A instead of 50A. But for AGM batteries you'll probably get away with 50A OK. Especially if they are 'Dual Purpose' starter/leisure batteries.

Before you do that, it's worth checking whether the fridge heater element power is coming from the XS output, or going via a different route. If it's coming from the XS then that's 10A to 14A less for the batteries anyway, so it works out about right.

no element connected as I’m installing xs feed as instructions direct to starter battery positive so no additional existing wires are involved.