water pump power problems

ClayBanks

2021 TAB 320S.  Connected to shore power everything works. Disconnect from shore power and lights, refrigerator, tv and radio work UNTIL the water pump engages either by turning it on with inside or outside switch or opening any value. Reconnect to shore power and everything works, pump included.  No blown fuses, no tripped breakers and the batteries are at 100%.

Any comments or ideas as to what's happening?

Thanks

rfuss928

The water pump draws relatively high current.  If your battery is marginal it could easily pull the system voltage too low for the other loads to operate.  When connected to shore power the converter has no problem delivering higher current and maintaining proper system voltage.
Measure battery voltage while the pump is running with and without shore power to verify this guess...

jbajor

I completely concur with rfuss.  look at the voltage at the battery with pump on and with pump off (off of shore power..  I suspect it is dropping below 11v when it is on...  I had the same issue and it turned out my battery was toast.

ClayBanks

interesting. Except that the power completely shuts down when I turn the pump on,  But I'll check.