Is it safe to operate XW6848+ with 67 volts DC input?

paulcheung

Hi guys,

Is it safe for the XW6848+ operate with 67 volts DC input? I Have a battery bank need to set the absorb voltage to 67 volts in order to get it properly charged. the XW6848+ manual said the maximum input voltage is 65 volt DC. I wonder if it is ok to push it to 66.6 volts and won't damage the inverter? Now I have the charge controllers set the absorb volts at 64.9 volts. I like to set it to 66.6volts if it is ok.

Thank you in advance.

Photowhit

paulcheung said:

 the XW6848+ manual said the maximum input voltage is 65 volt DC. I wonder if it is ok to push it to 66.6 volts and won't damage the inverter?  

These limits are set for the inverter to protect the circuitry. Very likely the inverter will shut down to protect it's self. It may give you some hints listing an 'alarm voltage' and a 'reconnect voltage'.

FWIW- I've yet to challenge my Magnum inverter, but my ProSine would shut down above 32 volts, it's upper limit. 

MichaelK

Could you go into a bit more detail about your battery, and why it needs 67V?  Is this all the time, or just an equilization charge?  Assuming you set your controller to max at 65V, then what would be this battery's state of charge at that point?

Keep in mind that your controller might also have temperature correction, and although you have it set at say 65.0V, on a cold morning it might bump up the voltage to 66.5V?

If the required 67V is a once a month equilization charge, I suppose you could just shut off the inverter at the main DC breaker for an hour or three till you complete the equilization?

Photowhit

MichaelK said:

Could you go into a bit more detail about your battery, and why it needs 67V?  Is this all the time, or just an equilization charge?  Assuming you set your controller to max at 65V, then what would be this battery's state of charge at that point?

Keep in mind that your controller might also have temperature correction, and although you have it set at say 65.0V, on a cold morning it might bump up the voltage to 66.5V?

If the required 67V is a once a month equilization charge, I suppose you could just shut off the inverter at the main DC breaker for an hour or three till you complete the equilization?

I would guess It's a Nickel Iron battery which is very inefficient. Nominal voltage is 1.2 volts per cell, but charge at 1.65-1.67 volts per cell.

A 48 volt bank would normally be 40 cells, which would charge at 66 volts. 40x1.65=66volts.

I came back to this thread to say that the XW6848+ might be adjustable in it's voltage range. Often sellers of these batteries suggest Magnum inverters which have a larger voltage top end, (at least in 24 volt models, I just looked up specs and 24 volt ranges to 34 volts but the specs on 48 only go to 64, perhaps it's adjustable?) 

If you want to use these with the Schneider inverter, if the inverter isn't adjustable, you might consider removing on battery. Keep it as a spare it has a long shelf life.

paulcheung

Because I am not sure if it is safe so I go back to 48 volts and stick with 65 volts maximum. it has cause some issues while at 67 and 64.9 volts at the charge controllers. it has tripped few times so it doesn't worth it. Thank you guys.

Dave Angelini

You actually answered your own question. Voltages above 65 V are not just inherently more dangerous but they run the risk of equipment damage,  fire, and explosion. People make mistakes and enter the wrong thing, or the more is better, and then the lawyers get in and Business Liability has to be paid.

For sometime Schneider was letting you get up to 70V and even higher with a signed release of liability. The equipment is very safe and protects itself with sensors on the Toroid and the heatsink assy. HALT testing and type A prototypes are run at 96vdc and sure enough, a guy on this forum who came to Bill and I hooked up (2) 48v strings in series.

Below are release notes and for you to go higher, you would need your firmware to be 2.01 or lower, before Schneider made the change.

paulcheung

Thank you Dave.

My Xw6848+ firmware is 2.03; the default high DC voltage cut off is 65 volts. but I can set it to higher to 68 volts. Does Schneider change the circuitry make it unfit to operate at 67 volts after they make the changes in the firmware? or the hardware is the same like before? Thanks again.

Dave Angelini

No hardware/circuitry was changed on XW+ during manufacturing !      XW+ was replaced with XWpro and did have circuitry changes.

paulcheung

Ok so it is better leave the maximum input at 65 volts. Thank you.

Dave Angelini

Better is subjective. It is better if it meets your needs and is safe for you. I have a client with a resort down in Nicaragua running XW DC at 72V and sending out warnings there. The firmware stopped all faults. As I said the circuitry can easily take this, and it does.  You are welcome.