[C320-list] Flooded acid battery and refrigeration questions

[Graeme Clark]

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