[C320-list] Batteries & Fridge

[Chris Burti]

I leave it on to protect the fridge...the low voltage disconnect on the
fridge protects the batteries in a power out situation...but then I use
truck batteries at half the price and 20% more amp hours than
marine...so....

On Fri, Oct 30, 2009 at 9:21 PM, Andrew Santangelo <
andrew_santangelo at mac.com> wrote:

> 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
>>
>


-- 
Chris Burti Farmville, NC