Bulk/abs chg with XW-MPPT60-150

Brent

I have a 840A/H, 48 volt battery bank and every morning the charge controller cycles through the Bulk [57V], Abs [59V] and Float [53V] charge profile [voltages recommended by mfg]. The batteries are not discharged frequently so stay pretty much fully charged.

My question is that the batteries gas quite a bit during the bulk and abs cycles. Is this ok for the long term health of the batteries and since the batteries gas is this a substitute for periodic equalization.

Thanks,

Brent


PV:6500W, [2] XW6048, [2] XW-MPPT60-150

mike95490

Re: Bulk/abs chg with XW-MPPT60-150

How long is the battery in each stage ?

Some gassing is needed to keep elelctrolyte stirred, and since you are not discharging much, you don't need much EQ, so this is likely good, if you've checked each cell for gassing.

Brent

Re: Bulk/abs chg with XW-MPPT60-150

The charge controller abs chg is set for 10 min. The bulk charge can't be set but typically stays in bulk for 20 - 60 min depending on solar output.

Brent

mike95490

Re: Bulk/abs chg with XW-MPPT60-150

What loads do you have on the system that pulls the battery down nightly?

Brent

Re: Bulk/abs chg with XW-MPPT60-150

When not in the sell to grid mode the system is in the AC feedthru mode so there are no loads on the batteries unless the grid goes down.

I guess my real question is, since the batteries are always charged and in float for most of the day, would it make sense to set the bulk and abs voltage to say 55 volts until the time comes when the batteries do get discharged then I can raise the charge voltages.

This would prevent unnecessary gassing which I understand is hard on the batteries over the long term.

Brent