[C320-list] Batteries & Fridge

[Andrew Santangelo]

FYI - I do not leave the refrig on to protect the batteries. I leave  
it on to protect the food. :-)

However the shore power system is plugged in when at the dock. No  
problems, no issues. It just works.

Best
Andrew

C320 "Dawn Treader"
#333


Sent from my iPhone

On Oct 30, 2009, at 7:15 PM, Jeff Hare <catalina at thehares.com> wrote:

> Hi fellow 320 folks.
>
> The argument in favor of leaving the refer on to protect the  
> batteries, while leaving the charger on for extended periods doesn't  
> make sense from an electrical engineering point of view.   
> Particularly with multistage chargers that serve up *constant- 
> voltage* float mode.
>
> No charger with a high a float voltage should be left on  
> indefinitely. Period.
>
> Measure your charger's float voltage at the battery terminals with a  
> good volt meter and decide based on YOUR OWN charger whether long  
> term float charging is safe for your batteries.
>
> 13.3v max (13.8v Gel batts) or under is fine.
>
> If your float voltage is any higher than the above limits, or your  
> batts require a lower float, Don't leave the charger on for extended  
> periods. Just don't.
>
> Having a fridge or even a simple light bulb on WON'T affect the  
> float voltage, since the charger's JOB is to hold that voltage  
> constant in float mode regardless of the loads attached (within  
> reason).
>
> So if the charger wants the voltage at 13.8v, the fridge's measley  
> 4amp draw ain't going to affect that.  Turn on your fridge and prove  
> to yourself that the voltage at your battery terminals remains the  
> same.
>
> Some people claim *annecdotal* evidence that their batteries died  
> once when left on shore power while the fridge was off at the time,  
> and conclude that the fridge would have prevented this overcharging.
>
> That isn't proof that the batteries wouldn't have fried even if the  
> fridge was on.
>
> Some people (myself included) have had their ProMariner die and  
> either provide either too high or too low a voltage to the batteries.
>
> In either case the batteries won't survive an extended spell like  
> this. The fridge being on won't help with over-voltage and will  
> ensure fast battery discharge in the low-voltage case.
>
> So, leave the fridge on if you want cold beer and take comfort  
> knowing that it doesn't detract or contribute anything to the  
> charging equation...  At least in our physical universe.   :)
>
> If you don't  believe me,  believe Georg Ohm.  ;)
>
> Cheers!
> -Jeff