WF-8955 PEC / AGM charge voltage

[JohnP-ESC]

Hello,

We have the WF-8955 PEC installed in our 2020 Escape travel trailer. I recently purchased a new AGM battery (MOTOMASTER NAUTILUS EXTREME AGM Group Size 27 Battery | Canadian Tire). The label on the battery states: "This battery requires a voltage limited charger set to: Float Charge 13.5-13.8V, Cycle Service 14.4-14.8V Maximum @ 25 Degrees C (77 Degrees F)."

The manual of the WF-8955 PEC states: "Absorption charge voltage: 13.6V; Bulk charge voltage: 14.4 V; Float (storage) charge voltage: 13.2V

My questions:

1. Is the 13.2V float charge voltage from the WF-8955 PEC acceptable for charging the Nautilus Extreme AGM battery (requires 13.5-13.8V as float charge)?
2. Are the 14.4V Bulk charge voltage and 13.6V Absorption charge voltage from the WF-8955 PEC acceptable for charging the Nautilus Extreme AGM battery (requires 14.4-14.8V Maximum for 'cycle service')?

Thanks for your help!

 

[vermilye]

Hello,

We have the WF-8955 PEC installed in our 2020 Escape travel trailer. I recently purchased a new AGM battery (MOTOMASTER NAUTILUS EXTREME AGM Group Size 27 Battery | Canadian Tire). The label on the battery states: "This battery requires a voltage limited charger set to: Float Charge 13.5-13.8V, Cycle Service 14.4-14.8V Maximum @ 25 Degrees C (77 Degrees F)."

The manual of the WF-8955 PEC states: "Absorption charge voltage: 13.6V; Bulk charge voltage: 14.4 V; Float (storage) charge voltage: 13.2V

My questions:

1. Is the 13.2V float charge voltage from the WF-8955 PEC acceptable for charging the Nautilus Extreme AGM battery (requires 13.5-13.8V as float charge)?
2. Are the 14.4V Bulk charge voltage and 13.6V Absorption charge voltage from the WF-8955 PEC acceptable for charging the Nautilus Extreme AGM battery (requires 14.4-14.8V Maximum for 'cycle service')?

Thanks for your help!

The float stage does not charge any battery. It is designed to supply voltage to the trailer (and battery) to maintain the charge rather than drain the battery. 13.2V is acceptable as a float voltage. While the battery will recharge faster if the bulk is at the highest acceptable voltage (14.8V), 14.4V will work, just take a bit longer before switching to absorption.

I hope your WF-8955 PEC does better at the bulk stage than earlier WFCO converters. The early ones rarely stayed in the bulk stage long enough to provide rapid charging, ie they spent most of their time in absorption slowly charging the battery or in float not charging at all.

The ideal charging cycle would be for the converter to stay in bulk until the battery reaches around 80% of capacity, then switch to absorption and slowly charge the battery to full, then switch to float until a large enough draw pulls it back into absorption.

If you have solar, be sure to switch off equalization (if the solar controller provides that stage). While a few AGM battery manufacturers recommend equalization, most don't.

 

[JohnP-ESC]

Thank you!
WFCO tech support also confirmed compatibility with this AGM battery. I've installed it and it charged no problem with the WF-8955 PEC.

 

[John in Santa Cruz]

yeah, those specs are fine. and indeed, the early (say, circa 2014) WFCO voltages were suitable for flooded lead acid but not really optimal for AGM. I'm using a PD4655L now with LFP batts, and it charges at a bulk rate of about 50 amps til its 95%+ charged then settles in at 14.5V or so and stays there. This charges my batts about as fast as it can, which is OK, but I do kinda wish it would drop to a lower 'float' voltage once they are 100% charged. I solved that by switching off the power converter unless I really need to fast charge my batts, my 360W Solar with a Victron 100/30 does just fine almost all the time.