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Diesel gen charging or solar panels?

L

linedog62

New Member
Joined
Jul 24, 2024
Messages
9
Location
Mexico
Hi guys.. I'm a sailboat cruiser interested in opinions on whether or not to buy a bunch of panels or stick with my generator and rebank with liFePo4.
Here is the current set up:
Start bank is 4 12v agms run series parallel to make 24v

House bank 8 200Ah 12v series parallel victron agms for 24v bank loads and also a 225 Ah Victron 12v 8d charged off a dc to dc 24v to 12v converter for the 12v loads

55 amp 24v alt external reg for start bank , 172amp external reg 24v alt for house bank ... Perkins 225 hp turbo diesel main

24v 24 amp alt external reg alt for start bank from a 20Kw 120/240 single phase Northern Lights generator for start bank

2 100 amp chargers 24v
1 120v 3000watt inverter
1 240v 3000 watt inverter --both stand alone.
Parallel switch between house and start bank.
Batts are 4 years old and in good shape. Very few cycles ...

(I burn 1.73 gph diesel with the gen and it takes about 6 to 8 hours to bring the Agms up to 100% from a 50% dod.)
Normal loads while cruising include a large hot water heater, two cold plate fridges and one freezer, water pumps , watermaker, starlink and various other loads such as TV, computers ,nav gear , dive compressor, radar and induction counter top cooking.

Large 70' sailboat 120/240 ac ,12/24v dc loads.
The question is... should I replace the AGM batts with lithium and charge dc-dc with the 20kw gen ? Or should I put a large solar array and keep the AGMs charged up with that and forego the lithium batts until the AGMs are shot.
I'm thinking that (with my limited knowledge) the large cap Alt, the rapidly of the lithium charging and the 80% depth of discharge ,I may be smarter to just buy and gen charge a new lithium bank and forget about the cost of panels and building a double set of arches to hold a bunch of 550watt bifacial panels. I have the room for at least 6 of these massive panels
What would be the opinions of knowledgeable people on the forum who can help me decide which way to go?
I lived on solar panels/agms with no issue and a 4kw gen on my smaller 45ft boat but that was before Ithe option of LiFePo4 batteries... so I'm really not sure how to play this.
 
Go to lifepo4 is always good.
You have dubbele Ah than your agm battery.
So you can do longer with battery power .
A lifepo4 battery charger faster than a agm
A agm cost energy to charge so you lose that .
On a lifepo4 not.

Oke now the problem
A lifepo4 you can not charge with a alternator.
You need a dc to dc charger
So you leave 1 agm battery for start the engine and set on that battery a dc to dc charger.

For you soler panels.
Look how many watts you can place .
And for that you gone calculate if that can be use.
Other thing how longer you can do solar means les diesel
 
It would be fantastic to do both.. but real world the cost is huge I am looking for an either/or scenario until the expensive victron batts give up.
 
linedog62 said:
It would be fantastic to do both.. but real world the cost is huge I am looking for an either/or scenario until the expensive victron batts give up.
Click to expand...
You can always use solar on your lead battery.
Still save diesel on a sunny day .
And than you have them till the day come for you to switch .

On my own boat i have set other panels this week.
So i do les power from the port (grid power)

I have 2x150Ah lifepo4 battery to use and for my self i can run the day with solar and the night easy on the battery .
But again its wat you use and i do not use a lot of power
Fridge and freezer are always on
Car radio
Tablet for tv
Wasmachine is 150watt only (camping machine)

Shower is on the port.
So i do not need hot water on the boat .
I use the port for that .
 
I also have a 24v boat. I use DC/DC chargers when engining but the vast majority of energy comes from solar. The genset can charge the lithium at high amps. Having both is perfect.
Maximising solar is always a good idea. Do that now and reduce your generator hours, come what may
 
I'm at anchor or travelling so don't have the luxury of a shore power source. My issue with the solar is creating large solar arches to accommodate panels. I need a rather large set up 11x 15 feet of 550 watt bifacials to keep up with the load. So in effect I'm looking at best 10 to 15k dollars. If I can swap over to using my 24v 172 (or larger)alt and lfa batts I may be much better off. A combo is fantastic I understand ..... but is it possible to run dc dc chargers to a 600ah lithium bank and not deal with the panels and arches? That huge array would be problematic when sailing as it acts as a wing.
 
linedog62 said:
I'm at anchor or travelling so don't have the luxury of a shore power source. My issue with the solar is creating large solar arches to accommodate panels. I need a rather large set up 11x 15 feet of 550 watt bifacials to keep up with the load. So in effect I'm looking at best 10 to 15k dollars. If I can swap over to using my 24v 172 (or larger)alt and lfa batts I may be much better off. A combo is fantastic I understand ..... but is it possible to run dc dc chargers to a 600ah lithium bank and not deal with the panels and arches? That huge array would be problematic when sailing as it acts as a wing.
Click to expand...
I have 1000w of solar that isn't on an arch on a 44ft sailboat. This contributes 3 to 4kwh per day when it's sunny.
 
Sometimes you have to look to see if you can use les power
Thinks old fridge replace to fridge with a compressor. (I have done that)

And try to use direct from the battery and not from the inverter.
Computer change to laptop that can charger from usb-c or nuc pc that run from usb-c
Tv that can use direct from the battery and not from the inverter self (12/24volt tv)

Inverter have energy lost almost 20% (20% extra power use)
And than the standby from the inverter.

My own inverter in standby use 1a .
Its still means it use on a day 24Ah just to be standby that i have to charger from the solar panels.
Than the rest that i use.

And yes the inverter have eco options but than my fans do not run .

A radar , marifoon, plotters do not use a lot
My own radar only use 5a.
My plotter 2a (navi)
My marifoon use about 4a.
Ais use about 2a.
Brand is Garmin.
I only use it if my engine is running .

What i see is that people on a boat or RV thinking its like a home.
Its not so you have always adjust to what is possible.

My airco only run on wallpower from the port.
Not from my inverters (it can) its just a lot of power.
And i can not replace it with solar panels easy .
 
Suijkerbuijk said:
Sometimes you have to look to see if you can use les power
Thinks old fridge replace to fridge with a compressor. (I have done that)

And try to use direct from the battery and not from the inverter.
Computer change to laptop that can charger from usb-c or nuc pc that run from usb-c
Tv that can use direct from the battery and not from the inverter self (12/24volt tv)

Inverter have energy lost almost 20% (20% extra power use)
And than the standby from the inverter.

My own inverter in standby use 1a .
Its still means it use on a day 24Ah just to be standby that i have to charger from the solar panels.
Than the rest that i use.

And yes the inverter have eco options but than my fans do not run .

A radar , marifoon, plotters do not use a lot
My own radar only use 5a.
My plotter 2a (navi)
My marifoon use about 4a.
Ais use about 2a.
Brand is Garmin.
I only use it if my engine is running .

What i see is that people on a boat or RV thinking its like a home.
Its not so you have always adjust to what is possible.

My airco only run on wallpower from the port.
Not from my inverters (it can) its just a lot of power.
And i can not replace it with solar panels easy .
Click to expand...
My boat has been my home for the last 3 years. With lithium batteries, we cook on an induction hob. Make water with our 240v watermaker, make hot water with the immersion heater, run two fridges. 1000w of solar is plenty for us. We don't have AC. We do have a mattress cooler that is fantastic and uses about 12w of power.
The diesel generator hardly gets used. We have only been into a marina once in 3 years. We love life at anchor. The boatmis set up to be independent of shore power
 
Just throwing out another idea. There are some chargers that kind of look like a torpedo that you tow.

They have an alternator in them and help to produce power when sailing. I cannot remember what they are called right now.
 
TimE said:
My boat has been my home for the last 3 years. With lithium batteries, we cook on an induction hob. Make water with our 240v watermaker, make hot water with the immersion heater, run two fridges. 1000w of solar is plenty for us. We don't have AC. We do have a mattress cooler that is fantastic and uses about 12w of power.
The diesel generator hardly gets used. We have only been into a marina once in 3 years. We love life at anchor. The boatmis set up to be independent of shore power
Click to expand...

O what brand model mattress cooler
Somting i gone look in to it.
Not for me but for my dog.
 
Looks like I can swap out the large agm victron bank for lfa batts.... probably go with swapping the 1000ah 24v agm bank for 3 200ah lfa in parallel. And one 200ah 12v on the dcdc converter coming off the 24v bank replacing the 8d. I have 220v wall chargers that will charge with the lifepo4 algorithm so I can use the 20kv to charge. How much faster do lithium batts charge up vs agms? Later I can add panels. I'm in mexico and the welder is at least 6 months behind before building an arch. The clock is ticking and I need a solution quickly as we are burning too much diesel for charging the agm bank.
 
Have you looked at atlantic towers? They do premade solar arches, I've seen a few in person and they seem quite well made, may be cheaper than custom if you can get it shipped to mex.
 
Suijkerbuijk said:

Mattress Cooler USA

Mattress Cooler USA
mattress-cooler.com

Click to expand...
mattress-cooler.com

Mattress Cooler Classic XL: Chilled Water Sleep Cooling System

Finally, an affordable and reliable Mattress Cooling System. The Mattress Cooler Classic XL comes with replaceable, longer-lasting parts and access to the extra large water tank for better cleaning. This Water Cooling System is now available at a great price! Say goodbye to night sweats and...
mattress-cooler.com
 
Yes I saw them and the other tower manufacturers. This is a pretty unique 70 ' Aluminum kiwi sloop named Maya by McMullen and Wing shipyards in Auckland. Evert thing is custom.
 
HarryN said:
Just throwing out another idea. There are some chargers that kind of look like a torpedo that you tow.

They have an alternator in them and help to produce power when sailing. I cannot remember what they are called right now
Click to expand...

Some examples

www.practical-sailor.com

Towed Water Generator - Practical Sailor

Since 1974, Practical Sailor’s independent testing has taken the guesswork out of boat and gear buying.
www.practical-sailor.com www.practical-sailor.com

Solutions overview

Complete solutions for cleaner & more enjoyable sailing
oceanvolt.com oceanvolt.com


 
Last edited:
linedog62 said:
Hi guys.. I'm a sailboat cruiser interested in opinions on whether or not to buy a bunch of panels or stick with my generator and rebank with liFePo4.
Here is the current set up:
Start bank is 4 12v agms run series parallel to make 24v

House bank 8 200Ah 12v series parallel victron agms for 24v bank loads and also a 225 Ah Victron 12v 8d charged off a dc to dc 24v to 12v converter for the 12v loads

55 amp 24v alt external reg for start bank , 172amp external reg 24v alt for house bank ... Perkins 225 hp turbo diesel main

24v 24 amp alt external reg alt for start bank from a 20Kw 120/240 single phase Northern Lights generator for start bank

2 100 amp chargers 24v
1 120v 3000watt inverter
1 240v 3000 watt inverter --both stand alone.
Parallel switch between house and start bank.
Batts are 4 years old and in good shape. Very few cycles ...

(I burn 1.73 gph diesel with the gen and it takes about 6 to 8 hours to bring the Agms up to 100% from a 50% dod.)
Normal loads while cruising include a large hot water heater, two cold plate fridges and one freezer, water pumps , watermaker, starlink and various other loads such as TV, computers ,nav gear , dive compressor, radar and induction counter top cooking.

Large 70' sailboat 120/240 ac ,12/24v dc loads.
The question is... should I replace the AGM batts with lithium and charge dc-dc with the 20kw gen ? Or should I put a large solar array and keep the AGMs charged up with that and forego the lithium batts until the AGMs are shot.
I'm thinking that (with my limited knowledge) the large cap Alt, the rapidly of the lithium charging and the 80% depth of discharge ,I may be smarter to just buy and gen charge a new lithium bank and forget about the cost of panels and building a double set of arches to hold a bunch of 550watt bifacial panels. I have the room for at least 6 of these massive panels
What would be the opinions of knowledgeable people on the forum who can help me decide which way to go?
I lived on solar panels/agms with no issue and a 4kw gen on my smaller 45ft boat but that was before Ithe option of LiFePo4 batteries... so I'm really not sure how to play this.
Click to expand...
I’m another cruiser with similar situation that previous owner did the solar first. The 3kw solar I have is ok in general, but often isn’t enough to charge my batteries as fast as I’m using them. My generator has to run 4-6 hours to charge my arm. I wish he would have done the lithium batteries first, as running a generator only a hour or so a day to charge up would be better by far as lithium charge multiple times faster than ago.
 
yabert said:
3kW is a lot for most sailboat.
How do you find place to put that much solar power?
Click to expand...
Its not a sailboat its kruiser .
Full steel boat .

I have one that is about 10m long and i have almost 1kW on the roof .
Soon i gone rebeult a extra part so i can place about 600watts more for the electrical engine hybride part to charge the battery.

If he have 15meter boat yes i see 3kw will fit.
Those boat are almost 5meter wide .
So more space to place them .
 
Last edited:
As a liveaboard trawler owner that has tried several different ways.

Install as much solar as you physically can. Remember you will have to be able to clean the panels often.

After getting all the solar installed that you can then upgrade the batteries.

Just my two cents
 
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