Flat batteries

[barryhall]

Hi,
I have just visited the boat after a couple of weeks and found the batteries completely flat. This was due to an unfortunate combination of faults:
a) I stupidly left the fresh water pump on.
b) The water system developed a leak
c) The battery charger stopped working
d) Sunshine shortage (UK so not unexpected)

Good news is that after removing fuses to check them and replacing them (no faults) the battery charger started working - possible poor connection?

Can anyone quantify the effect on the battery capacity of a single instance of completely discharging them?

Barry

 

[NB Willawaw]

No it's hard to quantify it based on one complete discharge.
It also depends on how long they have been flat, whether they have sulphated up in the meantime and so on.

Hopefully they will be fine.

I have a GSM device on mine that tells me the voltage by text and sends me an alarm text when they go too low as sometimes the boatyard likes to disconnect my shoreline.

 

[duncan99210]

Only way to find out is to recharge them and see how they perform. They should be fine if this is the first time they've been deeply discharged.

 

[Topcat47]

A good modern "intelligent" charger can usually recover a battery from this state. They can ever overcome some sulphurisation, but if the battery has been repeatedly abused like this, I will die beyond the capabilities of even one of these.