[C320-list] Flooded acid battery and refrigeration questions

[Scott Thompson]

Jack, you can stop worrying about running the shore power charger and 
solar charger at the same time. See 
https://shop.pkys.com/multiple-charge-sources 
<https://shop.pkys.com/multiple-charge-sources> for a good discussion. 
There is no risk of overcharging from having two or more sources if they 
are all regulated and properly installed.

When you say your fridge "runs all of the time" I assume you mean it is 
on all of the time. The compressor should only run intermittently, and 
the power requirements are essentially zero when the compressor is not 
running.

Regarding the risk of overcharging because the fridge is pulling down 
the voltage I don't think that makes sense. Overcharging occurs only at 
voltages above the resting voltage of the fully charged battery, and 
only if the battery is fully charged. There could be a risk that a not 
too smart charger over-reacts to a temporary voltage drop by raising the 
voltage to bulk levels. But that would happen after the load is gone and 
the voltage is back up, not while the load is running.

On 11/16/2021 8:47 AM, Jack Brennan wrote:
> I have an unproven theory that boiling happens most often when I plug in and operate the battery charger while the solar panels are also working. It’s unclear to me how well the two forms of charging work as a team. I try only to plug in at night when we’re on a cruise and staying at a dock.
>
> My fridge runs all of the time. I also wonder whether the draw somehow makes it more difficult for the MPPT controller to figure out exactly how much to charge the batteries. I.E., the load pulls down the voltage, which makes the controller charge more.
>
> Jack Brennan
> Sonas, 1998 Catalina 320
> Tierra Verde, Fl.
>
>
>
> Sent from Mail for Windows
>
> From: Graeme Clark
> Sent: Tuesday, November 16, 2021 8:21 AM
> To: C320-List at catalina320.com
> Subject: Re: [C320-list] Flooded acid battery and refrigeration questions
>
> Interesting discussion. Since I installed solar I have had electrolyte level issues also. My boat spends two to three weeks between my visits, on a mooring and I guess the solar is boiling it off
>
> I have an MPPT controller which supposedly has a charge regime that eventually drops to a low maintenance charge
>
> Problem is I think that at night it resets itself so every day the charge regime begins again. Either that or it resets when a load is applied like the bilge pump?
>
> Anyway I’m thinking of deliberately applying a small load (LED light?) to the battery. The controller allows a load to be connected through it that cann be controlled to turn on for (say) 4 hours at a time
>
> I’m hoping this might prevent overcharging as the solar input will be charging the batteries rather than boiling off the electrolyte
>
> Could the OPs problem have a similar cause?
>
> But maybe I’m barking up the wrong tree!
>
> Graeme
> #366, 1996
>
> Sent from my phone. Excuse typos!
>
>> On 16 Nov 2021, at 11:13, Troy Dunn <troutwarrior at gmail.com> wrote:
>>
>> Scott
>>
>> As long as the water level never got down to the top of the plates you
>> could be fine.   I say could only because at certain heel angles for
>> certain types of battery installations what seems like an adequate level
>> could be partially exposing the plates while heeled.   Exposing the plates
>> is bad, and can result in rapid sulfation which at best will reduce your
>> capacity, but with sulfation the the probability of having a short in the
>> plates goes up.  This is what ultimately kills the battery.   Avoiding too
>> much heel is probably a good idea…especially since the C320 starts losing
>> performance once the windward deck goes past horizontal. (about 10°)
>>
>> Lot shoulds and maybes above.
>>
>> As to the curious case of 'rapidly' (two months feels rapid) boiling off a
>> significant amount of the electrolyte.  It's only while charging that you
>> typically boil off electrolytes, the higher the charge voltage and accepted
>> amps the more likely you are losing fluid.   Going for the highest charge
>> acceptance to charge quickly and the highest bulk and absorption voltages
>> reccomended by the manufacturer for longest battery life has a potentially
>> fatal flaw…as you have now discovered.  Those items ignore the ability of
>> the average sailor (yours truly included) to vigilantly monitor the fluids
>> in the batteries.    Expose the plates and suddenly that long life goal may
>> be blown.
>>
>> Let's face it.   The battery location is less than ideal.   Doing a check
>> on the batteries mid cruise is a pain in the butt which only further
>> enhances the likelihood of a screw up here.   I love my FLA set up and
>> would chose the GC2s over and over again.   Trojan and US Battery GC2 FLAs
>> are the best choice from a $/Watt-hr perspective.   No other battery type
>> can be expected to compete based on that metric.    LiFePO4 are the best
>> where weight and or form factor are a consideration and cost is a don’t
>> care.   AGMs are a loser on both counts.   Where AGMs shine is that they
>> are relatively maintenance free.   I guess the AGMs are good if you get
>> knocked down or I guess pitch poled (not possible in 95% of the
>> Chesapeake). But if that's your concern you are obviously putting your C320
>> in situations I hope to never encounter.   I am honestly considering
>> swapping out my Group 27 reserve for an AGM because it is such a pain to
>> get to for watering.
>>
>> As to the question of uneven boil off of the electrolyte.  Yup..that’s
>> definitely a thing.  A few variables there to consider.   On my setup I
>> have 4 6V GC2s in a 2p2s configuration to give me 462 AH at 12V and they
>> are essentially 2 per compartment where the 4Ds used to sit.
>> Theoretically the cells closest to the middle of these compartments would
>> get the hottest because the neighbor cells are also heating up.  That has
>> not been my experience.   My experience has been that the cell closest to
>> the positive terminal for each 2p config (12V) has the most boil off.   And
>> I too have pondered why this would be the case.  I haven’t gotten much past
>> the hmmmmmm that's odd phase of my pondering.
>>
>> FWIW
>>
>> Troy Dunn
>> Hull #514
>

-- 
Scott Thompson
Surprise, #653