diy solar

diy solar

18000lbs yacht elec inboard system

Indefatiguable

New Member
Joined
Nov 18, 2021
Messages
32
Hey folks,

I'm in the process of refitting and repowering a liveaboard sailboat.

I'm going to be using an electric inboard as auxiliary propulsion. I've purchased a motor kit (controller, gearing, thrust bearing, shaft coupler, throttle, harnesses, belts etc etc oh and ofc a 48v brushless dc motor) from thunderstruck ev (awesome folks 287000 stars) which I plan to power with 8x renogy 100w monocrystalline (4s2p I think is correct, 2 groups of 4 panels is how I think of it) and as yet undetermined vertical axis wind turbines.

Last summer I had my panels up hooked to a "demo" bank of 4 12v 100ah fla deep cycles. They suck. I'm used to AGM. Most importantly they do not meet my discharge requirements. I need to be able to discharge 60a continuous and 180a for 1 minute. No margin in those discharge rates either btw.

So I need opinions on battery brands. Planning to spend on lithium. Let's call it a $3k budget. 48v, >100ah (ofc more is better).

Was planning on expertpowers new 48v100ah metal box of coolness but it has very few reviews and is not rated for water resistance.

So any thoughts on who makes quality stuff for cheap? You'd think 3 grand would be enough but it's def restrictive
 
Sounds like an ambitious project, what model boat is it?

You could get 32 raw 100ah lifep04 cells for apx. $1500. Then 2 overkill 48v bms's would set you back $300. That leaves you with $1200 for the boxes, tools, wires, etc with a 3k budget. And you'd have 200ah capacity at 48 volts. The two bms's in parralel would let you pull 200 amps continuous or 400 amps intermittently, which is more than you need.

For a bit more you could get 200ah cells and double your run time.
 
Sounds like an ambitious project, what model boat is it?

You could get 32 raw 100ah lifep04 cells for apx. $1500. Then 2 overkill 48v bms's would set you back $300. That leaves you with $1200 for the boxes, tools, wires, etc with a 3k budget. And you'd have 200ah capacity at 48 volts. The two bms's in parralel would let you pull 200 amps continuous or 400 amps intermittently, which is more than you need.

For a bit more you could get 200ah cells and double your run time.
Its a Formosa 36, big and fat and pretty xD.

I toyed with the idea of getting cells instead of a premade battery, is there a preferred make/brand? Im pretty confidant i can fit a bank out of cells together with only moderate youtubeducation.
 
Check on ali express for raw cells. I just ordered 16 280ah cells from LiitokalaVariCoreFlagship with good success. Paid $1762 and it took about 3 months to arrive with port congestion.

That would make a 48v battery but since the overkill solar bms only pulls 100 amps continous you may want to double the cells so you cam have two bms. You can find 32 100ah cells for the $1500 range easily.

Check out Wills recommendations for good vendors on aliexpress:

 
For propulsion, you definitely want to build a battery from cells, not use premade drop ins. You also should look at a BMS system like the REC-BMS instead of a simple FET based BMS. You *could* meet the requirements with FET based systems, but for propulsion I just wouldn't do it.

Have you worked out an energy budget? Do you know how many kW of storage you need to run the engine for the distance you need to travel, and how much solar and wind power you need to produce that? You should not buy any solar or any batteries until you know those numbers, and have checked them and shared them with the engine supplier for confirmation.

No, $3000 does not go very far.
 
Hey, sorry for delayed reply. Connectivity is spotty on a good day for me.

I've located a vendor and specific cells I need, actually was referred by a different thread on this forum. Going with


Holy crap that's a long link, sry... 16s.

As per knowing motor power requirements yes the folks at thunderstruck-ev.com, where I ordered the kit from, were excellent folks and we had several lengthy discussions regarding specific application needs like amp hour requirements, gear ratios, effective system mounting regarding weight distribution etc etc. For brevity (and my data connections sanity) let it suffice to say 48v300ah is adequate. Btw thunderstruck as a company gets 287/10 stars from me. Awesome folks, awesome products, better prices.

I will be ordering 16 cells from the above link post Xmas, and have now turned my attention to finding the proper BMS.

I've watched several YouTube videos (am now highly qualified expert xD) on the subject, but have yet to hear of any BMS specifically made for salt marine environments.

I need a discharge capability of 60 amp continuous and 180a intermittently (more is better, controller can handle 800+ amps for a minute - 60 amps is "eco cruise" speed) which is i believe quality temperature sensors and shutoff (both hot and cold), an inherent display (wired OK, Bluetooth meh) and most importantly something engineered to withstand the problematic salt air and the probable repetitive pounding of beating to windward.

For the landlocked, think of putting bms in a strong secure box, then securing that box in a boat, then dropping the (again 18000lb) boat 15 feet to a hard tooth rattling landing once every 30 seconds for a week - 5 weeks a year - for a decade. Hopefully I never have to sail as such but build quality is absolute king here as that is a reasonable standard of adverse forces as exaggerated as it may seem.

Any recommendations?
 
Last edited:
I will be ordering 16 cells from the above link post Xmas, and have now turned my attention to finding the proper BMS.


Any recommendations?
As mentioned in another thread, I would seriously consider going with the REC BMS, namely their Q Series BMS (since you're doing 16s). It's more flexible than your typical FET based BMS, and the current limit is really that of your batteries and the Contactors that you use for actually controlling the current. Plus the developers of the unit (Based in Slovenia) are pretty responsive to questions/feature requests/bug reports. I've seen more than a few threads on here where an issue in a specific corner case is reported to them, and an updated firmware is released. It also does (passive) cell balancing, so while not perfect, it's better than nothing.

Since my pack will just be a 4s pack, we'll be using their Active BMS which is limited to 12V packs.
 
After the 1st post above mentioning rec bms I very briefly looked into them, outside of the lack of restrictions to amperage flow what advantages do they offer? Is there a decent write up or review on here or elsewhere that'd be relevant?

Thanks
 
Have you seen these? I am looking at these for a camp being rebuilt after hurricane Ida. Trying to go solar instead of diesel generator.

 
For Rec-bms the YouTube channel “beginning from this morning” installed the Rec-bms into their bus using repurposed Car batteries. There was a series of about 5 videos - but only one or two on the bms. I was considering using Rec-bms on my MotorHome and contacted them to see how they like it and they gave it a favorable review after using it for a while.

I ended up going with Batrium for my MotorHome and I really like it. I like it cause the software makes sense to me. I would highly recommend Batrium. One drawback in your situation is the bms is not sealed in a container. You would have to figure that piece out.

I really like the contactor based bms. Another one to look at would be Orion.

Good Luck!
 
After the 1st post above mentioning rec bms I very briefly looked into them, outside of the lack of restrictions to amperage flow what advantages do they offer? Is there a decent write up or review on here or elsewhere that'd be relevant?

Thanks
I'm going with their Active BMS (limited to 4s systems) mostly because of how it integrates relatively easily with the rest of my onboard systems. The rest of the system is going to include a Wakespeed regulator running the Boat's alternator, and a Victron inverter/charger for shorepower. All of it communicates over CANbus/NMEA2000. I will probably wire up some backup cutoffs and the like, but for me the big piece is that the integration work has already been done.
 
Back
Top