Solar Watts : Daily AH Consumption

[john61ct]

If you have a dino juice charge source and it's not inconvenient to run it for an hour or two, do that to get the bank to say 85-90%

some mornings, not every day.

Even if you have lots of panels (relative to usage) and 7+ hours insolation, that routine helps in cloudy weather.

A small LFP pack can also be connected to your big lead bank with an Echo Charger, or better a B2B charger overnight and top them up.

Where there's a will. . .

Or buy Firefly.

Or just accept the situation for your setup.

[sailjumanji]

My last Deka AGMs lasted twelve years before being replaced with identical batteries. Blue Sky MPPT controller, 240 watts solar, 300 amp hrs total AGM bank. On sunny days the controller said we were on float by noon. In 2016 we were on a four month cruise with only a handful of marina days. I think if our batteries weren't getting to full charge each day, in four months of predominantly solar only, it would have been obvious. Especially with DC watermaker running every three days. I must be missing something?

[john61ct]

Yes, actually verifying Full against trailing amps as per the bank maker's specs.

Impossible to get there by noon solar only, 99% of controllers in use go to Float long before they should.

If you were shallow cycling or not cycling full-time,

and willing to push continued usage past the standard EoL at 20-30% loss of capacity

even mediocre quality batts can go over a decade.

I didn't know Deka's been making AGM that long.

Maybe you got a particularly good batch.

Note I'm a **major** fan of the company, plug their other lines at least 30 times a week across a dozen forums.

[CatNewBee]

Going to FLOAT on a LA (FLA, GEL, AGM...) at noon by solar is doable. It depends on your consumption (DOD) that needs to be compensated. If the vessels stays unattended in the marina, all loads switched off except bilge pumps 1 there is little discharge (self discharge, stand by loads like battery monitor, alarms...). So lets say 10Ah to be recharged.

Your solar will do this quickly, the voltage reaches fast ABSORPTION, tail current will be low, because the bank is full, FLOAT at noon or even earlier is very likely.

In opposite, liveaboard, even with LFP, heavy consumption, large array, in perfect conditions full at 2-3 p.m., on rainy days even not going to float / full. Probably no chance for a FLA to go to FLOAT without a little help in the morning by an alternator, generator or other sources (wind gen during the night can charge the battery, so solar needs just to topp up, do short absorption and then go to float ).

It really depends on the SOC when solar kicks in if there is a chance for a full charge or not. You not need necessarily to charge each cycle to full, it is sufficient to have it once a week or even once a month could be ok for most batteries. Most SMF, GEL or AGM die from overcharging (boiling) because of wrong settings or poor solar controller that do reconditioning or have no temp sensor to reduce voltage at hot conditions and not from not reaching 100% SOC.

[noelex 77]

Originally Posted by john61ct

Yes, actually verifying Full against trailing amps as per the bank maker's specs.

Impossible to get there by noon solar only

It depends very much on the location and solar set up, but it is not impossible even when actively cruising.

Currently in the morning we are producing useful solar power before 5 am and the panels can produce over 600w on good days before 9am (if they are not regulated by this stage). So meeting end amps by noon is achievable, and our panels are not tiltable, which would help early morning production.

Of course we are close to the summer solstice for the Northern hemisphere so conditions are close to as good as they going to get . This part of the world has long solar days, which helps, although the sun angle is not particularly high.

However, there is little advantage in filling up the batteries this early. The more important goal is to have enough solar power to manage when conditions are less favourable.

[john61ct]

I just wanted to emphasize that the goal is not "going to Float", at whatever time,

unless the owner has ensured the charge source is calibrated for her unique (and likely changing) usage patterns,

so that it does **not** go to Float until endAmps is reached.

Given normal deep cycling and lots of amps available for the early stages,

most banks still require **at least** 4 more hours to finish the long tail after they get to say 85-90%.

The **vast majority** of real-life setups are going to Float many hours too early, and fooling the owner with blinky lights, an LCD bar chart or even false numeric info, into thinking the bank is Full.

The **only** way to know whether or not that aspect is configured properly, is to periodically verify - with a known-accurate ammeter at the bank - that the controller is putting out Absorb voltage until endAmps is reached.

So without specifically stating that is the case, IMO the default response to "I'm usually done charging by noon" should be (a polite version of) "dog's bollocks you are".

[john61ct]

Originally Posted by CatNewBee

So lets say 10Ah to be recharged.

Boat sitting at the marina is not IMO a relevant use case for the topic.

Living, extended cruising off grid.

[CatNewBee]

Originally Posted by john61ct

Boat sitting at the marina is not IMO a relevant use case for the topic.

Living, extended cruising off grid.

Boats sit most of the time in the marinas, at a mooring bouy or on the hard, even circumnavigators sail maximum 10% of the time.

Any way, this is where FLA, GEL and AGM die hard. They are full and overcharged by dirt cheap solar regulators and small panels, because sailors do not understand what full means and want to do extra care for the battery by keeping her at absorption - to be really full - and enabling automatic frequent reconditioning as house keeping routine when not on board - to be really really full etc. It is not the cycling and sometimes not going to full, its the wrong care when not using the battery.

And manually extending Absorption is where the trouble begins.

[daletournier]

I'm not convinced that many batteries are dying from overcharging. In my experience I see very few house batteries being overcharged by cruisers. When I hop on other cruisers boats the conversation of batteries comes up regularly (mostly prompted by me out of curiosity). In my experience most cruisers are under charging their banks by a long shot. Few understand what's going in and what's going out.
In fact the majority of cruisers I meet have very little knowledge regarding their batteries and charging systems.
Over charging is the least of their problems.
The knowledge shown on this forum isn't representative of the majority out here.

Sent from my 9001D using Cruisers Sailing Forum mobile app

[john61ct]

The profile for maintaining no- or super shallow- cycling should be completely different from daily-life cruising.

The discussion here is the latter, where 99% of the time owners are completely unaware their system is going to Float way too early.

Originally Posted by CatNewBee

full and overcharged by dirt cheap solar regulators and small panels, because sailors do not understand what full means and want to do extra care for the battery by keeping her at absorption

Funny, most people transitioning to LFP carry old lead thinking along.

I reckon you're now going the other way.

Obviously quality infrastructure is required for proper care.

Fully adjustable may not be needed if the bank's and charge regulator profiles happen to match, but

since batts are consumables, I prefer to have the freedom to select whatever I like for the next replacement,

without having to also replace the chargers.

[john61ct]

Originally Posted by daletournier

Over charging is the least of their problems.

Absolutely, in fact hardly ever happens while away from mains.

[daletournier]

Regarding trailing amps, the number thrown around here is. 5%-1% of Ah capacity. How did this number come about? A quick Internet search comes up with a range anywhere between 1%-3%. 3% is alot different from .5%.

I can get my batteries to between 2-3% trailing amps using solar reasonably easily BUT can't get them to 1% let alone .5%. This is with absorption set at 14.8v and starting at approx 85%-90% SOC.
675Ah bank.

Although my T105's are less than two mths old I believe them to be a little down on capacity as there SOC, according to my voltmeter was about 50% when I purchased them, this was due to sitting around in storage.

My daily consumption is approximately 140Ah and solar array is 480w. Will be increasing to 800w in the future.



Sent from my 9001D using Cruisers Sailing Forum mobile app

[daletournier]

I should add that if I get bulk charge over early in the morning via generator or motoring I'm still lucky to get below 14a by the end of the day, not enough hours, 14a being just above 2% of 675Ah.
Not achieving a lower acceptance rate could be due some damage from sitting at PSOC in storage for to long?



Sent from my 9001D using Cruisers Sailing Forum mobile app

[john61ct]

Originally Posted by daletournier

Regarding trailing amps, the number thrown around here is. 5%-1% of Ah capacity. How did this number come about?

You should use the endAmps spec provided by the bank mfg.

You should not buy batts whose maker doesn't make such specs readily available.

But for those that do, I've seen .005C used as the highest level recommended for quality FLA.

But AGM I'd give .01C,

GEL .02C

Same with Firefly and LFP, but only for precise Full calibration, in daily use just hit V setpoint and stop, no Absorb at all.

Deka's is

Absorption End Point =*Current change over 1 hour period of less than 0.1A

______
> Although my T105's are less than two mths old I believe them to be a little down on capacity as there SOC, according to my voltmeter was about 50% when I purchased them, this was due to sitting around in storage.

Is that 2 months from mfg date, or since you bought them?

A set of rigorous commissioning cycles and/or 20-hour load benchmark should have at least partially brought their SoH back up.

I would not have paid full price for those.

[john61ct]

Originally Posted by daletournier

Not achieving a lower acceptance rate could be due some damage from sitting at PSOC in storage for to long?

Possibly, but

Solar conditions are "best attempt" but precise tools and a few cycles as above **on high amps via mains** will help, clarify.