Solar and stability issues

[skyhawk]

I appreciate that your decision to go lithium is final...so that's that.

but I can't get past that 80°F operating limit. Is that across the board for all these lithium deep cycle house type batteries...or is it just the ones you are considering? That just seems like a non-starter!...I'm just not sure where in the world you'll be able to go without running the air conditioner!...and you'd better get a spare air conditioner too, in case your fails!

I'm not familiar with AGM chemistry and spec, but I understand it's basically the same as flooded lead-acid but without the spilling potential....I know that in the old school world of FLA the 50% discharge limit you state is an overblown rule of thumb that's simply not true...except maybe for starting type batteries. True enough they don't like extreme deep discharge..as in down to near zero (I've learned that lesson the expensive way)....but 50% isn't utilizing the battery that you paid for. I don't recall the exact spec number but I recall reading Trojan's manual that had a much lower number. My opinion...treat the 50% target as a "usual when able" sort of target but not an absolute floor. That way you can get a lot more utility out of your purchase.

 

[skyhawk]

curious minds...I had to go find the reference
page 23
https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf
don't discharge more the 80%
...meaning don't drop below 20% SOC

I understand that's not a target to routinely hit necessarily, but it's what the manufacturer states...and I'd bet there's a safety factor built into that number!

 

[diver dave]

-20 to +60 deg C for Relion operating range... Long ways from 100F.

 

[sunchaser]

The Lion Li batteries I've considered have an optimal operating range temperature of 15C to 35C. Temperatures above or below these numbers affect efficiency and charge rate but hardly enough to impact performance in the Med, FL or Alaska. Motor homes in Arizona have no problems with Li battery performance summer or winter according to those I know.

My curiosity remains the stability effects of adding +500 pounds more than 15' above the COG while removing about 500 pounds of batteries from below the COG.

As I mentioned earlier and reiterated by Flatswing, check in with the DeFever Cruisers group. There are many DF 49s cruising in warm FL waters with good insight on temperatures and potential battery locations.

 

[diver dave]

Seems like a stability equation is in order. At least in the roll axis. You MIGHT find that the CG moves very little.

 

[Mambo42]

Curious that your AGM battery bank is 200 Ah. I assume you have other start/ generator batteries? DeFever 49 configurations vary according to which yard they were built in but many have battery boxes for 2x 8D’s for each engine (total of 4). Over the years most owners add additional bank for inverter.
Switching the 4x8D’s to 8xGC 2’s gives 600Ah. If you have enough height for 8xL16’s (floor scrubber batteries), you can get 1480Ah in those boxes alone with cheaper FLA. Even if you make 1 large bank for start/ house/ inverter, you will have ample CCA,s for starting & separate gen battery for back up. Having all (connected) batteries the same chemistry & charging profile, makes system much simpler & cheaper even if you replace every 5-7 years.
We also have to run the gen set to cook. So we always load it fully with AC to cool boat, run Watermaker, chargers etc. 12v fans, only run AC at night if plugged in.
FWIW, The extra weight of the Li batts under the Pilothouse seat is like having an extra guest on the flybridge. If you are concerned, contact Wilson Lin @ POCTA yard (present builder of DeFevers), he has the old specs from Sen Koh yards also, I believe. Wilson.POCTA.yacht@gmail.com, 88693305868.
Definitely join the DeFevers Cruisers for more info.

Basically our current set up has been that the engines have their independent batteries and next to that we have the house battery bank for small stuff (lights, a laptop etc), plus the generator for all the heavy stuff, which meant the generator is running quite a lot.

Now that the house battery pack is finished I have to consider what to do. Remain with the AGM's or go flooded and continue as before or do a complete overhaul of my electrical system.

With the soaring fuel cost in Europe and having to listen to the generator all night long (plus most of the day), while being in a location where there is ample sun available (Greece and Croatia) during the summer months, and watching countless videos on Youtube from people who made the switch, I decided I will do the same.



With 3 Kwp solar I can charge the batteries quite fast during the daylight hours, making sure I have full batteries again by sunset. With AGM's or Flooded that is a lot more difficult, they cannot be charged that fast. Ultimately that would result in not having full batteries by nightfall and thus creating the need to run the generator again.



Perhaps I should explain our 'mode of operation' during the summer months. We fly to Europe around mid-april, prepare the boat and take her out to sea at the beginning of May. We only come back in our home port around mid- to end October, prepare the boat for winter and fly back to Curacao. During the summer months we basically only come in port for a couple of hours to empty the black water tank or to stock up the food and drink supply. The rest of the time we are on anchor outside a marina or in a quiet bay, moving every 3rd or 4th day to a different location. Basically we are island hopping, but spending as little time in a marina as possible. But since the temperatures in August can soar to 105 - 110 we do need air conditioning during those hot months.



I have read all the info on AGM's, Flooded and lithium, but the one test that sealed the deal for me was this video on Youtube.

This is an electrical engineer who decided to finally run the test the way they should be done, which means doing tests at higher Amp loads instead of the trickling drain like most manufacturers do.

The end result was clear to me. Lithium can supply us with the power we need on board and we can charge the batteries quickly during the daylight hours with the expanded solar set up. And that will make our life on board a little bit more comfortable, also extending our range, which means we can travel further away from our fuel supplier. There is a big difference in taking fuel for almost 2 euro's per liter and fuel for 0,6 euro per liter (tax free in Albania).

I calculated I will need about 700 Ah, but it is very well possible my calculations are off. I appreciate any corrections on this matter.



The electricians would like to reconfigure the boat this winter season, which I also prefer, so that we can actually take her out again in April / May. But it is a costly refit, probably around 25.000 to 30.000 USD in total, but with the fuel prices in Europe and the months that we spend on board we should be able to recover that in 4 to 5 years through fuel savings.



In the mean time I did find pictures of other Defevers with hard tops on the fly bridge and am wondering if that was an aftermarket install or whether it came off factory ? They would not have done it if the stability issue would have been a big problem, I guess. Or did they simply not think about it ?

 

[Mambo42]

I appreciate that your decision to go lithium is final...so that's that.

but I can't get past that 80°F operating limit. Is that across the board for all these lithium deep cycle house type batteries...or is it just the ones you are considering? That just seems like a non-starter!...I'm just not sure where in the world you'll be able to go without running the air conditioner!...and you'd better get a spare air conditioner too, in case your fails!

I'm not familiar with AGM chemistry and spec, but I understand it's basically the same as flooded lead-acid but without the spilling potential....I know that in the old school world of FLA the 50% discharge limit you state is an overblown rule of thumb that's simply not true...except maybe for starting type batteries. True enough they don't like extreme deep discharge..as in down to near zero (I've learned that lesson the expensive way)....but 50% isn't utilizing the battery that you paid for. I don't recall the exact spec number but I recall reading Trojan's manual that had a much lower number. My opinion...treat the 50% target as a "usual when able" sort of target but not an absolute floor. That way you can get a lot more utility out of your purchase.

I started 'investigating' lithium, deep cycle, agm etc after my electrician came up with the idea to change the whole electrical lay out of the boat after my house battery pack decided to call it quits. At first I thought 'you are just looking to make a lot of money out of me', but when I started reading articles, hearing experiences of others and most of all seeing the video (I placed the link below) I decided that lithium was indeed the best way to go.

The idea for expanding the solar I already had for a long time. We always have the bimini up and I could not help but thinking of the wasted empty space it was. It is an ideal location for a hard top with solar panels.



The 80 degrees fahrenheit came from both the electrician and from the test I saw. They can handle temps above 80 degrees, but you reduce the life cycles quickly and that is not the idea. The engine bay is therefore completely out of the question.

The lazarette is fully occupied, but I could swap things around now that there will be space where the house battery pack was. Then again, in high summer it could also become warm there, unless perhaps I add a ventilator as was suggested in an earlier post. We will basically be always on board when the ventilator needs to run, so I could install an alarm for when it fails.



The supplier I am looking at is GWL, they make the winston cells with which the battery producers make the final battery. But you can actually buy the cells yourself as well, it is going to cost me around 8000 euro for a 24 V 700 Ah battery set.

So the idea is that I will drive to the Czech republic, pick up the batteries and solar panels, take on some more items that need to be replaced and drive on the ferry to Corfu, where the boat is lying.

By that time all the wiring should be finished, the frame for the panels installed, so the only thing we will need to do is install the panels and winston cells, connect the whole system and test it plus adjust where necessary. I guess that will take about a week (maximum) which means we will still be able to leave port by the end of April (latest).

 

[Mambo42]

Seems like a stability equation is in order. At least in the roll axis. You MIGHT find that the CG moves very little.

Flatswing posted the e-mail of the current builders of Defever and I hope they will be able to make that calculation. I don't have the information which is required to be able to make it.

If they come back to me and tell me it can be done I am going to be a very happy person

 

[catalinajack]

Mambo

You've a right to be concerned about stability. A thought to keep in mind is 300 pounds added "up top" or 15' above the CG requires 4,500 lbs added 1' below the CG to maintain the same righting moment.



Art's stability calculations done in the 80s took into account a modest dinghy on the boat deck, a genset in the ER and heavy FLA batteries in the bilge. Assuming you're in Curaçao beam seas, the more weight down below the better and weight added up top worse.



With a nearly identical hull and a somewhat lower CG than your 49 I've been careful about weight added up top as we do some big seas cruising. When we consider lighter lithium batteries one concept is to add compensating lead weight down low.



You may want to join the DeFever Cruisers group and toss this question around, there are some very smart folks and fellow 49 owners on that site. You're thinking and questions are to be applauded on this issue.

Here is what I do not understand about this concern. Three hundred pounds is the weight of two lightweight human beings.

 

[catalinajack]

I appreciate that your decision to go lithium is final...so that's that.

but I can't get past that 80°F operating limit. Is that across the board for all these lithium deep cycle house type batteries...or is it just the ones you are considering? That just seems like a non-starter!...I'm just not sure where in the world you'll be able to go without running the air conditioner!...and you'd better get a spare air conditioner too, in case your fails!

I'm not familiar with AGM chemistry and spec, but I understand it's basically the same as flooded lead-acid but without the spilling potential....I know that in the old school world of FLA the 50% discharge limit you state is an overblown rule of thumb that's simply not true...except maybe for starting type batteries. True enough they don't like extreme deep discharge..as in down to near zero (I've learned that lesson the expensive way)....but 50% isn't utilizing the battery that you paid for. I don't recall the exact spec number but I recall reading Trojan's manual that had a much lower number. My opinion...treat the 50% target as a "usual when able" sort of target but not an absolute floor. That way you can get a lot more utility out of your purchase.

+1

 

[mvweebles]

...but I can't get past that 80°F operating limit. Is that across the board for all these lithium deep cycle house type batteries...or is it just the ones you are considering?

This is not correct, at least for the popular batteries in the market right now. Battle Born and Lion both show range of operating temperatues of -4 to 131° F. The SOK 206AH battery has high-quality internal components and is a good buy at $1029 - just a few bucks more than the 100AH BB and is also rated at about the same operating temperature range. Interestingly, Battle Born states no temperature compensation is required which is significant considering an engine room can easily reach 100F (a 0.8V compensation to a 12V FLA/AGM bank). Lithium Batteries are susceptible to freezing, so some sort of heater is required for extreme cold climates (BB makes a self-heating battery).

According to the Trojan T105 spec sheet, operating range is -4 to 113° F, so lower than lithium.

Peter

 

[Mambo42]

Here is what I do not understand about this concern. Three hundred pounds is the weight of two lightweight human beings.

Perhaps it is indeed not a problem, but I would like to be sure. Am taking roughly 600 lbs away in the engine room and adding 350 lbs in the pilothouse plus another 400 lbs at the highest point on the boat.



I hope it can be done safely, but I like to know I am safe in doing so.

 

[Comodave]

What is the total displacement of the boat? I doubt that you will see much change in stability. As said above it would be similar to adding a few people up on the flybridge.

 

[sunchaser]

Mambo
Regarding panels and batteries you may want to look up Reuben Trane. Some years ago he was on TF walking us through his solar powered vessel. He may well be a significant data point on your system redo.

 

[Mambo42]

Mambo
Regarding panels and batteries you may want to look up Reuben Trane. Some years ago he was on TF walking us through his solar powered vessel. He may well be a significant data point on your system redo.

Thanks for the tip, I will try to find the posts, would be great to read the experience of someone else.

 

[Hippocampus]

Would,at least think about fireflys. Lighter than AGm but heavier than Li. More expensive than Pb but less than Li. Much less risk if overcharged. Still get nearly the same acceptance rate and can bring down to 20% SOC so adequate for your energy budget. Don’t have to change your entire electrical system.
As to panels added weight up top will effect your roll period and make your boat more comfortable but will be detrimental to your AVS. You need to know your current AVS, metacenter throughout your displacement range , range of displacements and can then do the calculations to determine your new AVS knowing the distance from the metacenter, height and weight you’re going to add up top. For,sailboats a AVS of ~120-130 is usually considered adequate for open ocean passage making. Multihulls are nearly always limited to 90 so need to look at Gz curve and righting arm.
For motor I’ve yet to read a consensus but think it’s around 90-100. May wish to look at EU, Norse, Lloyds, ABYC to see if they supply a AVS required for force 8 work in small powercraft. With current weather routing abilities think it unlikely you’ll see more as long as you’re careful and not doing high lat. cruising.

 

[Mambo42]

Would,at least think about fireflys. Lighter than AGm but heavier than Li. More expensive than Pb but less than Li. Much less risk if overcharged. Still get nearly the same acceptance rate and can bring down to 20% SOC so adequate for your energy budget. Don’t have to change your entire electrical system.
As to panels added weight up top will effect your roll period and make your boat more comfortable but will be detrimental to your AVS. You need to know your current AVS, metacenter throughout your displacement range , range of displacements and can then do the calculations to determine your new AVS knowing the distance from the metacenter, height and weight you’re going to add up top. For,sailboats a AVS of ~120-130 is usually considered adequate for open ocean passage making. Multihulls are nearly always limited to 90 so need to look at Gz curve and righting arm.
For motor I’ve yet to read a consensus but think it’s around 90-100. May wish to look at EU, Norse, Lloyds, ABYC to see if they supply a AVS required for force 8 work in small powercraft. With current weather routing abilities think it unlikely you’ll see more as long as you’re careful and not doing high lat. cruising.

Problem is that, at this moment, I have no data available about the weight and balance of the boat. So much has been added and changed after it was built that none of the original data is still valid. I have seen pictures of the engine room and lazarette before and after, believe me it is a world of difference. Same goes for the salon, kitchen and even pilot house.



If I would have been the original owner I would have know what the status would be right now, but the way it is at this moment is that I have no clue at all. That is why I would like to know what the additional impact of the change (that I have in mind) can be.

 

[diver dave]

THat U Tube vid is a death sentence for LA for house storage and use. There just is no logical reason to go with AGM, or any other LA technology. Including life cycle cost. The chemistry is against them.

 

[Hippocampus]

DD might want to read MaineSails discussion about all the different chemistries of batteries. Maine Sail works on boats for a living and a extremely smart guy. At this point think choice of chemistry depends upon style of boat, type of use and desire of owner to be involved (and afford) changes.
If on a weight sensitive vessel totally agree Li is the viable choice.
For a small boat in protected waters flooded Pb may make economic sense.
For a SD boat fireflies where saving a bit of weight and expanding capacity without expanding required room maybe more cost effective than Li.
Personally don’t like flooded on anything and think you should always have multiple charging sources so AGM is just plain safer. Still, share your enthusiasm about Li. Think further advances in Li chemistry will occur and new chemistries will be brought to market as given the strong driver of electric land vehicles.

 

[Hippocampus]

Mambo know with sailboats in similar situations they’ll put the boat in a slip put lines high up and tilt the boat. With sensors can establish how much force is required to tilt the boat X degrees. Thereby getting the many of the data points of the Gz curve between 0 and 90 degrees. Alternatively if you can establish the weight of major components and their locale in all three axis the metacenter and righting arm could be calculated with reasonable accuracy. Of course this varies depending upon load of fuel, water and consumables.

 

[diver dave]

...
..
For a small boat in protected waters flooded Pb may make economic sense.
...

BUt only if you are going to sell the boat straightaway. Life cycle cost on Pb is inferior. And, that just the long term economic view. The other metrics are even more crucifying.

But yes, I do use Pb for engine starting (x2).

 

[sunchaser]

THat U Tube vid is a death sentence for LA for house storage and use. There just is no logical reason to go with AGM, or any other LA technology. Including life cycle cost. The chemistry is against them.

Today's Li batteries may well be cast aside by the rapid development of fast charging solid state designs. Today's hot electrical technologies in all areas are virtually disappearing overnight as new and more interesting products enter the market place.

For the designers and manufacturers though the current and forecast chip shortages are now real impediments with ongoing power storage centers caught clearly in the cross hairs.

 

[mvweebles]

Rick Etsell, NA and a fellow Willard Owner was hired some years ago by Nordic Tug to calculate Nordic Tug stability so they could market into Europe. Interesting article by the owner of NT:

http://www.glantoa.net/nordic_tugs_stability.pdf

David Gerr has decent articles on his website, including this one on measuring stability. Might be able to work-through the exercise on your boat.

https://www.gerrmarine.com/Articles/PowerboatStability.pdf

Finally, Michael Kasten is also quite generous with his writing - here's a decent article on stability, ballast, etc. He dispels a couple myths on ballast.

Beam vs Ballast for Stability

Peter

 

[Mambo42]

THat U Tube vid is a death sentence for LA for house storage and use. There just is no logical reason to go with AGM, or any other LA technology. Including life cycle cost. The chemistry is against them.

In another video someone explained it really simple. All three types of batteries have their purpose.

AGM primarily for delivering short bursts of high Amps, such as starting an engine.



Flooded and Fireflys as a back up in case of an electrical failure. You can draw a lot of Amps from them and discharge them below 50 %, but don't do it on a daily basis, it will ruin the total available cycles of the batteries.



Lithium if you want to live off grid, draw the batteries to their minimum every single day and use solar power to charge them again (lithium can handle prolonged high charging loads, the others cannot).


My idea is to switch from living primarily off the generator to living off the solar and batteries. I will be drawing the batteries to their minimum every single day for a period of 4 to 5 months a year. I want to load them again via my solar panels (3 Kwp) and the excess energy from the panels I can use to power systems on board (through the batteries). Only for the real heavy equipment I will be using the generator, thus reducing the total hours on the generator massively, thereby saving fuel, which in turn offers me more usuable fuel for the engines, which means a bigger range and thus sailing area for the boat.
Based on that I can only end up with Lithium batteries. Yes they are expensive, but they will do the job for me and seeing the reports of people who live onboard already for 10 years who still have the lithiums in good condition after draining them each and every single day (to 20 %), convinced me it is the right choice.



Now it is just a matter of finding out whether it can be done safely (with regard to stabilization).

 

[Mambo42]

Rick Etsell, NA and a fellow Willard Owner was hired some years ago by Nordic Tug to calculate Nordic Tug stability so they could market into Europe. Interesting article by the owner of NT:

http://www.glantoa.net/nordic_tugs_stability.pdf

David Gerr has decent articles on his website, including this one on measuring stability. Might be able to work-through the exercise on your boat.

https://www.gerrmarine.com/Articles/PowerboatStability.pdf

Finally, Michael Kasten is also quite generous with his writing - here's a decent article on stability, ballast, etc. He dispels a couple myths on ballast.

Beam vs Ballast for Stability

Peter

Thanks for the links, I will go over them.



Last week I got the e-mail address of Wilson Lin who is basically the producer of the current Defever models. Today I got a reply from him and it does not sound promising, this is what he wrote:

I will recommended do not put heavier staffs in flybridge normally. Especially in the pilot house model.

I have to provide him with some more information about the engine room set up and additional equipment that has been installed, but his first reaction sounds like a warning to me.

 

[Mambo42]

DD might want to read MaineSails discussion about all the different chemistries of batteries. Maine Sail works on boats for a living and a extremely smart guy. At this point think choice of chemistry depends upon style of boat, type of use and desire of owner to be involved (and afford) changes.
If on a weight sensitive vessel totally agree Li is the viable choice.
For a small boat in protected waters flooded Pb may make economic sense.
For a SD boat fireflies where saving a bit of weight and expanding capacity without expanding required room maybe more cost effective than Li.
Personally don’t like flooded on anything and think you should always have multiple charging sources so AGM is just plain safer. Still, share your enthusiasm about Li. Think further advances in Li chemistry will occur and new chemistries will be brought to market as given the strong driver of electric land vehicles.

It seems that sodium Ion would even be better, but unfortunately the development has come to a halt since lithium is the battery to go to at this moment. If there would be a sodium ion battery available I would go for it, but so far have not been able to find one in the Ah that I need.

 

[sbman]

According to my calculations I should be able to run at least one airco (inverter airco 220 V / 1200 W = 5.5 A) plus all fridges and freezers (total around 3 A at 220 V) at night on the 700 Ah lithium batteries.

This is very tight. 1870W continuous. You then have at least 5% losses in DC-AC conversion (optimistic) getting right up to about 2000W. For 24V batteries, that's 84 amps. If you are using the 20-100% capacity range of the batteries, your 700 Ah is 560 Ah, at 84 amps that's only 6.6 hours at this rate. You need more capacity or less draw, or a shorter night. Some of the loads may not be continous, but you've also got lights, pumps, chargers, entertainment, etc... to drive as well.

With 3 Kwp solar I can charge the batteries quite fast during the daylight hours, making sure I have full batteries again by sunset. With AGM's or Flooded that is a lot more difficult, they cannot be charged that fast. Ultimately that would result in not having full batteries by nightfall and thus creating the need to run the generator again.

This is not entirely true. Your bank will be so large that the acceptance rate of AGM or Flooded will be far more than your solar can put out. Yes the last 10% slows down on lead acid, but it still only takes 3-4 hours to fully charge a bank from 50% with a large enough charger. The big advantage lithiums do have here is a bit more efficient energy storage rate, you lose 5-10% of your charge in inefficiency with lead acid, and it's 1% or so with lithiums. Choosing lithiums is a cost/weight benefit more than anything else, as well as a convenience, they last longer and there's less concern about SOC causing damage.

Reason for changing to 24 V is also because it will give me much more Kwh via the batteries. 12 V 700 A will give me around 8.4 Kw, but at 24 V and 700 A I will get double the amount.
It is going to be twice the size, however if I wanted to have the 16 Kwh in 12 V I would also have to double the amount of batteries.

This is not correct. 12V at 700 Ah is half the batteries physically that 24V at 700Ah is. The 24 volt batteries are physically double, no way around it. The only thing that might make it seem like the 24V system is half the batteries is that they are twice as large and you have the same number of battery terminals to hook up. 24V makes a lot of sense for what you are doing, the currents at 12V to support an 8KVA inverter are just too large to deal with, that's why there is no 8KVA inverter available in 12V.

If it were me in your exact situation, I'd keep the 12V lead acid house bank, in fact I'd increase it's size if possible and go with basic flooded deep cycle batteries. Get an automatic watering system for it. I'd continue to power the house off of it and keep all the alternator chargers the same as well.

Then I'd buy the lithium's you are talking about and dedicate it to the giant inverter. I'd hook the solar up to it and let the Quattro charge it from the genny when needed. I'd put a large DC-DC charger (or two) from the lithiums to the old school 12V house bank so that extra energy can be diverted over there to refresh the house bank as needed.

This would solve some of your ballast/weight issues, the old school house bank would be put on 'light duty' mode, last a long time, and the lithiums and inverter/charger can do the job they are best at, the best of both worlds. You also eliminate having to rely on a 24-12V converter to power your 12V normal house loads, if something breaks down, you've got more options to get by until you effect repairs.

 

[Flatswing]

Just to put this stability concern in perspective: A DeFever 49 RPH has a 5’ draft, full keel & weighs 65000lbs+. Pilothouse proposed Li battery location is approx 10-12’ above waterline. Fuel tanks (at 0-3’ above ER lead battery locations) hold 1000+ gals.
We are talking the difference between a couple of guests on fly bridge vs full/1/2 empty fuel tanks.

 

[Mambo42]

This is very tight. 1870W continuous. You then have at least 5% losses in DC-AC conversion (optimistic) getting right up to about 2000W. For 24V batteries, that's 84 amps. If you are using the 20-100% capacity range of the batteries, your 700 Ah is 560 Ah, at 84 amps that's only 6.6 hours at this rate. You need more capacity or less draw, or a shorter night. Some of the loads may not be continous, but you've also got lights, pumps, chargers, entertainment, etc... to drive as well.

Good point, means I will have to increase the capacity to at least 1000 Ah (better is 1100 or 1200 Ah) in order to cover 10 hours nighttime. The airco is an inverter airco, the 1200 W is a maximum, my guess is it will run most likely at half of that capacity each night.

During the period we are on the boat there is about 6 hours between sunrise and sunset, we should be able to get a load on the panels 2 hours after sunrise until 2 hours prior to sunset (I hope). That would still leave me with 14 hours or sunlight, which should be enough to charge the batteries.

Unfortunately you cannot load AGM or flooded that fast, it will take much longer, but Lithium will be no problem to load at high amps and with 2 charger / inverters I should be able to accomplish the job.

This is not entirely true. Your bank will be so large that the acceptance rate of AGM or Flooded will be far more than your solar can put out. Yes the last 10% slows down on lead acid, but it still only takes 3-4 hours to fully charge a bank from 50% with a large enough charger. The big advantage lithiums do have here is a bit more efficient energy storage rate, you lose 5-10% of your charge in inefficiency with lead acid, and it's 1% or so with lithiums. Choosing lithiums is a cost/weight benefit more than anything else, as well as a convenience, they last longer and there's less concern about SOC causing damage.

If I would work with AGM's I would basically only have 50 % of the Ah available, which would mean I would need about 2000 Ah, that is a bit much. Also, AGM's are primarily for short, high, powerbursts, not really to use on a daily basis from 100 % to 20 % and back up again.

This is not correct. 12V at 700 Ah is half the batteries physically that 24V at 700Ah is. The 24 volt batteries are physically double, no way around it. The only thing that might make it seem like the 24V system is half the batteries is that they are twice as large and you have the same number of battery terminals to hook up. 24V makes a lot of sense for what you are doing, the currents at 12V to support an 8KVA inverter are just too large to deal with, that's why there is no 8KVA inverter available in 12V.

Thanks for the explanation !

If it were me in your exact situation, I'd keep the 12V lead acid house bank, in fact I'd increase it's size if possible and go with basic flooded deep cycle batteries. Get an automatic watering system for it. I'd continue to power the house off of it and keep all the alternator chargers the same as well.

Then I'd buy the lithium's you are talking about and dedicate it to the giant inverter. I'd hook the solar up to it and let the Quattro charge it from the genny when needed. I'd put a large DC-DC charger (or two) from the lithiums to the old school 12V house bank so that extra energy can be diverted over there to refresh the house bank as needed.


This would solve some of your ballast/weight issues, the old school house bank would be put on 'light duty' mode, last a long time, and the lithiums and inverter/charger can do the job they are best at, the best of both worlds. You also eliminate having to rely on a 24-12V converter to power your 12V normal house loads, if something breaks down, you've got more options to get by until you effect repairs.

Woudn't I run into the problem that the discharge load will be much higher than the maximum charge load of the lead acids ?

Problem at this moment is that the current batteries are finished, I cannot depend on them to help me during next season, they need to be replaced this year.

This basically leaves me then with the option to buy only Lithiums or buy both Lithiums and AGM'S or flooded.



Based on what I have seen in the battery test (link I placed in a different topic) the AGM's and the flooded are not really meant to be drawn to 20 % on a daily basis. But that is exactly what I have in mind, so am in a bit of a jam right now.

 

[Mambo42]

Just to put this stability concern in perspective: A DeFever 49 RPH has a 5’ draft, full keel & weighs 65000lbs+. Pilothouse proposed Li battery location is approx 10-12’ above waterline. Fuel tanks (at 0-3’ above ER lead battery locations) hold 1000+ gals.
We are talking the difference between a couple of guests on fly bridge vs full/1/2 empty fuel tanks.

My total dispacement is about 21 tons or 45000 lbs (according to Defever). And on top of that I just got an e-mail from the current producer of Defever and he warns me not to go on with my idea.

Now I am just a bit confused.