42Vdc battery system

[SolarMusher]

Hi all,
Does it matter for the Classic to be set for a 48V system with 42V battery settings?
One of my batteries goes dead today and I would like trying it in two strings x7 batteries for a 42Vdc system.
Bank was 2x 415Ah before and right now I'm using one string only and might be short on capacity, the time for a new bank to come.
Thanks for any input,
Erik

[mike90045]

as long as you set the voltages (Float, abs, Eq) to what you want, it should be fine - EXCEPT the temp comp will be a bit high thinking that there are 3  extra cells

[dRdoS7]

Hi,

Hi all,
Does it matter for the Classic to be set for a 48V system with 42V battery settings?
One of my batteries goes dead today and I would like trying it in two strings x7 batteries for a 42Vdc system.
Bank was 2x 415Ah before and right now I'm using one string only and might be short on capacity, the time for a new bank to come.
Thanks for any input,
Erik

Is there another device that will be charging the batteries? Can it charge to 42V?

What runs off the batteries? An inverter? Will 42v be OK?

dRdoS7

[SolarMusher]

My old Magnum 4448AE should be ok, voltage range is 36V to 67V. Outback is another story, Outback's manual is only talking about 42 to 68V for the vfx3648. The Magnum is my main inverter but I need the vfx to supply septic pumps and wire heater. I only use the Magnum for charging because of the gen that is 30A/240Vac, a bit low to power both chargers and loads.
Mike,  I believe temp comp could be set for 21 cells in the classic, right?
Main problem seems to be the Outback with its 42Vdc limit. Anyway, if another batterie goes dead suddenly on one string, I would still have spare batteries to keep the lights on.
Erik

[mike90045]

...Mike,  I believe temp comp could be set for 21 cells in the classic, right?...

It's set by the battery voltage setting, which assumes 2V per cell, 12V gives you 6 cells.  And the temp comp is in 5mV increments, so you can only get close, not right on

[Vic]

...Mike,  I believe temp comp could be set for 21 cells in the classic, right?...

It's set by the battery voltage setting, which assumes 2V per cell, 12V gives you 6 cells.  And the temp comp is in 5mV increments, so you can only get close, not right on

The Classics here have Temp Comp that can be set in 0.5 mV increments  --  500 microvolt steps up or down.

And,  YES,  the Classic knows the number of cells by the nominal battery voltage setting.

FWIW,   Vic

[SolarMusher]

Ok, but if it was set for 0.45mV with 21 cells, compensation should be "about" the same than for a real 0.5 mV x 24 cells.
Anyway, I'm afraid of a low disconnect voltage that would be too high for the Outback Vfx maximum lower 42V voltage limit when under loads. I would need to set the LBCO at 42.5V and that would be pretty high for a 42Vdc system, something around 75% SOC (+/- 200 amps at 42Vdc for a 830Ah bank capacity), not sure that it would worth it versus a single 415Ah/48Vdc string with a 40/50% DOD.
Erik

[boB]

I was going to say to set the Classic for 36V or 48V system and adjust the temp-comp -0.5 mV per degree C per cell appropriately but looks like Vic beat me to it !

boB