S/V Ninaa Ootakii - next step/expansion/automation

[Stone]

I'd like to give my most heartfelt thanks to everyone who's helped me with this so far...
(This thread, lol : http://midniteftp.com/forum/index.php?topic=5071.0 )

This started as a 12v system design, and was bumped to 24v when I got to batteries, and now it's time for phase 2.

I'm on the fence, and looking for input.

Current system:
2120w flat mounted panels
Classic 150 + WBJ.
(4) L-16 6v lead acid. (435ah)
(1) 3000w samlex pure sine inverter that powers the ship.

The above is fully operational, and for the most part, works fine, although a 56% state of charge took 2 clear days to recharge to 100%. (acceptable)

I have 2, 24v Chinook wind turbines on the way to boost that bank, and I have a 60a 24v battery charger I can run off the generator if I need to (or the entire ship if necessary)

I have a second, 12v battery bank (4) 6v gc2's, that runs my peltier fridge (will be replaced eventually), an array of 6 bilge pumps, and various led lighting.

That bank is currently charged by a 30a battery charger that runs off my generator, or my inverter if my big bank is over 90%. (Manually controlled, need to change this)

So now on to the fun stuff.

I have space to mount 8 more panels, and I have a line on a bunch of 405 watt panels for reasonable.

I have a spare classic 150.
I have (3) Samlex sdc-30's.
(These are a 24v to 12v converter that can be modified, with a shottsky diode and a potentiometer adjustment, turning them into a 30a 24v to 12v battery charger)

Quick and reasonably efficient would be to load that second 150 up with new panels, set it up for 12v, and call it a day, but it doesn't quite do what I want, and pulling 12v for big runs makes me twitch.

... I don't use 110 power much except for cooking (instakettle, instapot, foreman grill, etc, and some areas have 110 fixtures with led bulbs)
Currently making ribs and pulling 65 amps for 28 minutes with the instapot, as an example.

I'm pretty technical, and I'm not afraid of complex systems.

Also, I feel like my battery bank isn't deep enough, and 8 more L-16's seem like a good idea, so that's coming down the pike.

Currently considering (sorry, lol):

I would like to break the 12v loads into zones. (Ninaa is 80', 65 tons, and about the size of a single wide)

2 gc2's will run 2 pumps at full throttle all night without dropping below 50%, so I don't feel like there is much risk here. (My tertiary pumps are all 24v and on the big bank already, they will just come on when the water is a lot deeper)

So I'm thinking, take a second set of panels, load up the second 150, set it for 24v and follow me, and use it on the big bank.

... Then take a 100a continuous duty relay, trigger it with the day/night aux control from the 150, or a voltage sensitive switch.
(What I want is to energize this relay when the sun is up and the 24v bank is over say 90%).

This will then power up the 24v run to the front of the ship (about 50' total) and will power up the 24v -12v chargers, for
bank 1, (aft pumps, lights, pilot house, fridge)
bank 2, (midship pumps and lights)
bank 3, forward pumps, lights, anchor windlass).

Currently building a custom 24v fridge / freezer, which will then shift the load to the main bank.

This makes sense to me because I don't immediately lose lights and pumps if I lose a voltage converter, and I'm not charging 12v batteries off the 24v bank all night.

I can also do some variant, like, since the 150 only supports 6 of the 405's, replace my current panels with them, add 8 more forward, giving me 2 fully loaded 150's on 24v, and take the 4 extras and put them on 12v, with another charge controller or 3.

Thoughts?

Thanks

[Vic]

Hi Stone,

Regarding your statement,   ...   "Also, I feel like my battery bank isn't deep enough, and 8 more L-16's seem like a good idea, so that's coming down the pike"   ...

Parallel battery strings  are generally avoided,  if this is at all  possible.  The more parallel,  the less good it generally is.  This primarily due to the difficulty in getting each string to charge well,   and handle the loads equally.  Also,  at some point,  it gets tedious to measure SGs and add water to each of the many,  many cells.  Sometimes this can lead to diminished battery monitoring and maintenance.

Also adding strings to batteries which have been in service for a while,  can result  in divergent compatibility  --  poorer balance in charge/discharge.   IIRC,  your existing L-16s probably date from December '20.   This age difference is not extreme,   but would recommend adding any batteries to the existing ones,  be done soon.

Also,  as your system grows,   would seem,  that a 48 V system would be the ideal.   Changing the inverter,  of course is expensive,   and you have done so once,  recently.

If you add those two additional strings of L-16s,  then simply switching to 48 V,  later would leave a spare string,  or  the need to add,  yet one more string of age-different batts,   and so on.

It can be difficult to "grow" systems,  without tossing out some parts which are still serviceable.

And,   forget if the topic of Flooded battery venting came up in the other Thread.   On shipboard,   this can be very important for safety.

Later,   Vic

[Stone]

Currently, everything is running off of the inverter.
(12 volt banks are on a 110v charger plugged into the inverter, along with the deep freezer)

Weather has been clear, and the bank is showing anywhere between 80 and 85% around dawn, and topped off around 2-3 pm.

It's really inefficient, but it's working.

Is that reasonable on the batteries?

'cause if it is, I'm overthinking it and I can just add my wind turbines (2, 24v chinooks) and start making things more efficient.

I'm thinking that some form of timer system may be the way, but I'm having analysis paralysis I think.

I'm not sure if I even need more L-16s.

Wouldn't I lose some charging capability if I went to 48v?

[Vic]

Hi Stone,

If your batteries are charged,  most days,  then the SOC readings from the Wb are likely to be fairly accurate.   It is also good to look at the Net Ah readings from the Wb pages.  This is a very accurate implied SOC,  if the batteries were actually fully-charged on the previous day.

The greater number of days between actual full charges,   the less accurate are the indications of SOC,  as,  each day that there is not a full battery charge,  inaccuracies in estimates used to calculate (due to factors that the battery monitoring devices like the Wb cannot know) the SOC compound.   This can result in SOC being fairly far amiss.   In the PNW,  there can be a number of successive dreary days.   In these situations,  as the Wb cannot recalibrate,  because the CC has not had a full Absorb-to Float transition.

But,  since you are using Flooded LA batteries,  you can actually measure true SOC.

You can choose at least on cell in each battery string to be a "Pilot Cell".   These are often chosen from cells that have the lowest measured SG.  These can allow you to fairly quickly see the nominal SG of the battery bank,   and therefore know the nominal SOC.

Be certain to thoroughly rinse your high quality Hydrometer (of Refractometer),  with Distilled Water several times after the SG measuring session.   This will help keep the Hydrometer accurate,  for years.

If your battery bank IS being discharged to 80 - 85% SOC on each cycle,   then this generally in a sweet-spot for good battery longevity.   It would seem that you also probably have sufficient recharge power from  the PVs,  if the batteries are generally in Float by mid-afternoon.   If you are in a windy area,   small wind turbines might be able to add a bit to the recharge abilities of your system.   You will probably have more sun available,  as this year progresses  ...

EDIT, to add:  You will Not loose any charging capability,  if you went to a 48 V battery,  vs your present 24 V battery bank.   You WILL GAIN charging power.   When the voltage is doubled,  the Classic will have the same output current capability (essentially),   but at twice your present battery voltage,   the Classic will be able to deliver TWICE the power into the battery.   You might need to revisit the PV string configuration if you went to 48 V.

Regarding efficiency that you referred to,  assume that was in reference to battery charge efficiency.   Flooded Lead Batteries (FLAs),   are not too efficient when receiving a full-charge.   But they are inexpensive,   rugged, forgiving,   AND you can actually,  easily measure their SOC with a Hydrometer.

They do need venting,   and care with working near acid,   are heavy compared to Lithium batteries,  and so on.   All in all  FLAs are generally a fine solution,   IMO

Just some opinions,  more later.    Vic

[Stone]

Thanks for the input

As I live with the system, I am faced with a few issues that have cropped up, primarily in the "I need to put my battery bank somewhere else" and the "do I need a deeper reserve" areas.

While parallel battery strings are to be avoided, it appears that it's not terrible if we're talking one more string, v.s. say, 3 or 4.

So if I were to add 4 more L-16s, would it be best to parallel
(2) 24v strings
[1]-[2]-[3]-[4]
[5]-[6]-[7]-[8]

Or make them into 12v groups first?

[1/5]-[2/6]-[3/7]-[4/8]

A new inverter at this time is a bit out of budget.

I can do another round of panels
( 400w) or 4 more L-16s, but I can't really do both.
(I also can't get more of the current panels I'm using, and the mounting place for the 400's is at the other end of the ship, so separate charge controller, but I have that)

I should have lots of sun for the next 5 - 6 months or so, but I suspect my loads are going to increase as I bring more equipment on line, which doesn't help me at night.

Thoughts?

[Vic]

Hi Stone,

Regarding adding one additional string of L-16s in parallel,  look at the recommendations and explanation,  here:
http://www.smartgauge.co.uk/batt_con.html

Would suggest that you not interconnect between batteries in the same position,  one string to the other,  as this will make it impossible to measure battery terminal voltages of each battery in each string.   Such measuring individual battery voltages is an important indication of string balance,  and of how well each battery is getting charged, and sharing loads.

As mentioned before,  if you plan to add batteries;  do so soon (to minimize age difference twix each string),   use identical batteries from the same manufacturer and same model number.

Good luck with your projects.   Seems like you have gotten on top of your system,  and how to care for it.

Also,  as noted before;  you need a good Hydrometer (or Refractometer),   and measure the SG of each cell of each battery,  every few months  --  particularly,  when the system is young.  Log these readings in your battery/system Logbook.   Record when the batteries are EQed,  duration,  settings,  and other observations.  Follow the EQ recommendations from the battery manufacturer. 

Be sure to watch the electrolyte levels of batteries,   add ONLY Distilled Water,   and do some Absorb after adding water,  to mix the water into the electrolyte,   this will help mix the water into the electrolyte.

And so on,   later   "here comes the Sun !!"   Vic