Upgrading Sailboat Solar/ Battery System

[Bob Morane]

Hello everyone.

As I am making the leap from week-end sailing to living aboard for the next 5-10 years, I'm contemplating a full refit of the solar and batteries on my Beneteau First 38.

It currently has 220w of solar panels and these are 18 years old and producing nowhere near as they should anymore.
In the same fashion, the house battery bank is composed of 2 × 100 AH 12v AGM batteries, both from 2016 and starting to get very tired.
Starter battery is the usual L-A starter.

The boat has a fridge, a small fan per cabin (x3), an autopilot and a VHF. Cooking is gas, no icemaker or freezer.
I have a small 300w inverter that I very rarely use for laptops, hair clippers and small power appliances.
Plotting and nav will be done on tablet and phone, no radar, very little integrated electronics overall apart from the depth sounder.
I plan to change most lights to LED and install a small watermaker which draws as little as 4-6A on 12v for 2gal/hour.
I will also have a 12v diving compressor that I will charge during the day occasionally drawing 4A@12v during 4hours for full charge.

I have roughly budgeted that I would need 130-180ah per 24h underway and ~80-120ah per 24h on anchor.
I want to be able to live on anchor for extended periods without starting the engine or using a generator.
I can start the engine for a few hours to run the alternator if necessary when underway but I'd like to avoid if possible.

With rough calculations, I came up with requirements of a 400w solar system and a ~300ah LFP battery bank.

I've been trying to fit the whole system within a 2000$ price tag which seems to fit with the solar system blueprints available on the site.

From the top-down :

1) 4 × 100w solar panel (400$)
Haven't decided yet which as I need to take a few measurements on the boat first and check the weight ratings of my arch.

2) 40A MPPT controller / 50A DC-DC charger (300$)
I'd appreciate any suggestions here as I am a bit confused as it is supposed to be 2 different components or there are controllers that do both solar and DC-DC charging and what makes the most sense here.

3) 4 × 310ah 3.2v Varicore LFP cells (550$)
This is the best I could find for simplicity of setup and cost effectiveness.

4) Daly 4s 150A BMS with BT. (120$)
Would appreciate any suggestions here as well. I am looking for something I can monitor from my phone and good enough for my use.Or maybe add a battery monitor I'm not sure.
I will be sailing tropical and temperate climate in summer so no need for a low temp cut-off.

5) Casing for the battery. (100-150$)
Very important as this will be on a sailboat going offshore, lots of movement and vibrations.
I have only started looking at what would work here.

6) wires, connectors, fuses, breakers, clamps etc (300$)

7) Tools (150-200$)

Which brings me to a price tag of 1800-1900$.

Is there anything shocking in that system ?
Does that seem to fit the usage ?
Are 280-310ah cells usable in a marine environment ? The battery will be inside and dry but moving a lot.
Any suggestions for BMS/Panels/Casing or general upgrades you think are necessary ?

Cheers and have a good day !

 

[MisterSandals]

400w solar system and a ~300ah LFP battery bank.

400w / 12v = 33.3a at 100% efficiency

330ah / 33.3a = ~10 hours of full sun to charge (a couple days for full charge without using any power).
400w seems low, the rule of thumb is generally 5 hours full sun each day.

For panels, if you have room for bigger panels, look for big cheap ones on craigslist or ebay in your area. If you cannot find something nearby, just ask the group for ideas and resources.

 

[Bob Morane]

400w / 12v = 33.3a at 100% efficiency

330ah / 33.3a = ~10 hours of full sun to charge (a couple days for full charge without using any power).
400w seems low, the rule of thumb is generally 5 hours full sun each day.

For panels, if you have room for bigger panels, look for big cheap ones on craigslist or ebay in your area. If you cannot find something nearby, just ask the group for ideas and resources.

I was thinking about this the other way around.
I calculated that I would use on average 120-140ah and maximum 200ah in a 24 hour period.

So I settled on 400w solar to cover that.
I was thinking 400w at 60% average efficiency for 10 hours a day would give me ~200ah/day.

Is that way off ? Should I go for more ?

I will be sailing mostly in the tropics and using the alternator a bit if it's cloudy several days in a row, or maybe go for a wind generator.

Then I just wanted the bank to be a bit bigger to absorb more than the max 200ah and if possible not cycle to deep everyday.
310ah or 280ah cells are pretty cheap so that sounded perfect.

 

[MisterSandals]

I was thinking 400w at 60% average efficiency for 10 hours a day would give me ~200ah/day.

How many "solar hours" of sun do I get per day throughout the entire day at a city near me?

Is that way off ? Should I go for more ?

Seems reasonable to me. But I think having enough to not worry about it everyday is a must.

 

[5teve]

2) 40A MPPT controller / 50A DC-DC charger (300$)
I'd appreciate any suggestions here as I am a bit confused as it is supposed to be 2 different components or there are controllers that do both solar and DC-DC charging and what makes the most sense here.

Hi Bob

Where are you based? In Aus we have an option of an enerdrive DC2DC Charger with MPPT it will do 50A and 45v solar input.. the renogy also does 50A, but only 25/25a solar / alt when both are available i believe - solar is also capped at 25v... renogy is cheaper but the enerdrive is a quality bit of kit ( i have 2 on order as I'm paralleling them.. for 100a) Not sure if Enerdrive are available outside Aus though.. be surprised if not..

I like the all in ones as they simplify wiring (and therefore my life) dramatically.. downside is that if one component goes.. you are up for a whole new unit..

Steve

 

[Bob Morane]

How many "solar hours" of sun do I get per day throughout the entire day at a city near me?


Seems reasonable to me. But I think having enough to not worry about it everyday is a must.

Thats an excellent link.
So roughly 6 solar hours equivalent for most my destinations.
It should fit well with 400w solar and average consumption of 120-150ah per day.
If I end up needing more, I will add a windgen later I reckon.

Hi Bob

Where are you based? In Aus we have an option of an enerdrive DC2DC Charger with MPPT it will do 50A and 45v solar input.. the renogy also does 50A, but only 25/25a solar / alt when both are available i believe - solar is also capped at 25v... renogy is cheaper but the enerdrive is a quality bit of kit ( i have 2 on order as I'm paralleling them.. for 100a) Not sure if Enerdrive are available outside Aus though.. be surprised if not..

I like the all in ones as they simplify wiring (and therefore my life) dramatically.. downside is that if one component goes.. you are up for a whole new unit..

Steve

I've worked in Oz for the last 5 years but the boat is in the Mediterranean sadly.
So I plan to get all my stuff delivered in southern France and finish my boat refit over there.

I had a look at Will's recommendation and I was thinking about going for a Renogy 40a MPPT. Seems good value for 400w solar and I honestly can't tell the difference with Victron or others. I'll have a look at Enerdrive, see if they are available in Europe.

I ended up ordering 8 Lishen cells with individual BMSs to make two separate 200ah bank for redundancy.
This is taking shape ! I'm excited.

 

[5teve]

I've worked in Oz for the last 5 years but the boat is in the Mediterranean sadly.
So I plan to get all my stuff delivered in southern France and finish my boat refit over there.

I had a look at Will's recommendation and I was thinking about going for a Renogy 40a MPPT. Seems good value for 400w solar and I honestly can't tell the difference with Victron or others. I'll have a look at Enerdrive, see if they are available in Europe.

I ended up ordering 8 Lishen cells with individual BMSs to make two separate 200ah bank for redundancy.
This is taking shape ! I'm excited.

Bah.. not you too I have ordered a single 326AH lithium (CALB cells) with a 250a BMS and the first thing my wife said was .. what about if it goes wrong!.. now i'm thinking I've done it wrong oh well it keeps things simple.. I can always carry a spare BMS..

I looked at quite a few including stirling (dctodc only no mppt) but settled on the enerdrive, I would have gone renogy but all info i have seen says they cannot be paralleled.. which wont effect you at all.. the victrons i would have needed 4 of which was not cost effective, both in actual cost - wiring cost and complexity..

There are another couple mentioned on here Kisae is one https://www.kisaepower.com/products/battery-chargers/model-dmt-1250/ very similar to the enerdrive.. but lower PV input.

Steve