Planning My Lithium Power System - Looking for Feedback

[SVBLU]

Originally Posted by hlev00

Check out Rod's excellent articles on LFP if you have not already. Here is one : https://marinehowto.com/lifepo4-batteries-on-boats/

On the batteries you should verify with the manufacturer that they can be paralleled and if so how many can be. I suspect they will supply the maximum current required to support your inverter. If you think you will go to a higher capacity inverter then check that they would meet that.

Charging the house bank via a DC-DC charger is okay but it is slow and you lose efficiency. Though moving the alternator to charge directly takes protection of the alternator in case of all BMS disconnecting and also a sufficient alternator with external regulator being configured to handle the continuous charging the house bank could demand. If you are just using a stock automotive alternator then your current design is all you can do in that regard.

You don't show any fuses on the batteries. What are you planning for that?

Disconnect switches for the panels. I think likely fusing for the MPPT to Lynx distributor but check both manuals to be sure.

Thanks. Some good feedback. I reached out to the battery manufacturer.

Regarding the DC-DC charger, I'm aware it is slow, but after doing some research, it seems like a very safe way to charge the batteries from my balmar alternator. I've read a few articles stating that the lithium batteries will try and get as much energy as possible, risking burning out the alternator. So although it's slow, it's def safe. I do have an external portable generator as well incase I want to give the engine a break.

FUSES! This is the step I'm at and I'm not sure where the best place to start is. How would you recommend going about planning out fuses? I don't have an electrical background so it's hard to wrap my head around it.

Much appreciated.

[Nicholson58]

We have
24 VDC with Blue Heron LiFePo house and start batteries in parallel, total 710 Ah.
3 X Sanyo 220H panels parallel on a 45 amp MPPT
Panels have 3 circuits each with diodes
1 X 350 watt panel and separate MPPT (new this season)
Generator with 3.5 kW charger-inverter and piggyback large case alternator & Balmar ext regulator.
Main engine 60 amp alternator with Balmar ext regulator.
All lighting is LED PWM

Everything running we charge 80 amps @ 28 volts.

My alternators are not rated for continuous full load output. Balmar are pinched back to 50%. I previously burned up three alternators eventually homing in on 50%

Panels are highly susceptible to tiny shading, even shrouds. They pretty much must have diode isolation and multiple circuits.

I elected to do a lithium multi purpose for the start. Same chemistry and supplier. Works well in parallel with the house. No dc-dc and no lead battery losses. Easy install. Banks are still separately switched for possible isolation.

The parasitic drain of an inverter is usually 10-15% of full load even with no loads in use. Our 3.5 kW stays off unless we need microwave, tools, coffee.

We have a small 300 watt full sine inverter, high efficiency for special users like chargers etc. Small parasitic loss. It too is normally off.

We added a DC directly powered built in charging station, 5 ports. This is far more efficient than an inverter powering wall warts.

Our daily demand:
At Anchor- Fridge, freezer, water maker, lighting, stereo, VHF, AIS, WIND, DEPTH, 130 Ah/day @ 26 volts.

We live aboard in the eastern Caribbean. Solar in November to spring is insufficient. Longer days make a huge difference. Cloudy days are the kiss of death. This is why we are adding 350 solar watts this year. We had been generating 2 times per week for 1-2 hours.

When we installed the Frigaboat systems the 220 volt cold plates were kept. Running the generator knocks the freezer to 0 Fahrenheit so the DC load is eliminated for many hours.

I think if the OP critically looks at his users and takes advantage of potential power sucks he can cut the Amp hours.

BTW, the Blue Heron rep was extremely helpful and knowledgeable. He helped plan out the entire system and integration of my existing devices. Safety devices from Balmar to protect the alternators were included. Programming cables and software links too.

[Pete7]

Originally Posted by SVBLU

FUSES! This is the step I'm at and I'm not sure where the best place to start is. How would you recommend going about planning out fuses? I don't have an electrical background so it's hard to wrap my head around it. Much appreciated.

There is a risk as with any battery chemistry, that a short will release a huge amount of power, particularly from LFP batteries. There is also a risk that this may be big enough to jump a normal say ANL fuse even if its blown. That whilst very unlikely, could be very scary.

In the US, Class T fuses are popular and will prevent the surge jumping across even a blown fuse. In Europe they were for a while unobtainable and very expensive to import, so some of us have gone down the NH fuse route to achieve the same effect.

https://www.bimblesolar.com/DC-fuse-disconnect-1pole

There are also fuses which fit on a battery post which might be useful. I chose not to.

https://www.12voltplanet.co.uk/batte...s-50-300a.html

There may be occasions when you want to disconnect stuff. So I have put a Blue Seas circuit breaker in before the inverter. It actually bolts directly to the Victron Power In distribution box so a couple less connections needed.

The power In also makes a good fuse box for everything else all in one place with substantial bus bars in a neat solution, all be it at a price.

https://www.youtube.com/watch?v=LIVh...ife-DIYCampers

Do not be tempted to use cheaper thermal circuit breakers, particularly for any large load. I have replaced one and there is one more to do for the supply to the DC>DC charger.

You will be making a large number of heavy crimps. Buy a proper crimp tool. These do a good job for the money, just use one die set smaller to get a really tight crimp. There are better, but professional ones are hundreds of $$.

https://www.amazon.co.uk/ColdShine-H...5&sr=8-40&th=1

[Stu Jackson]

I, too, initially questioned the daily load. 22ah for lights? Man, what planet are you on? LEDs on the Titanic if all were left on wouldn't draw that much.


I think you seriously should look into your loads again.


Otherwise, good planning, but it sure sounds like you're reinventing the wheel here. Good luck.

[Stu Jackson]

Originally Posted by SVBLU

>>>>>>>>>>>
>>>>>>>>>>>


FUSES! This is the step I'm at and I'm not sure where the best place to start is. How would you recommend going about planning out fuses? I don't have an electrical background so it's hard to wrap my head around it.

Much appreciated.

Then you should spend some more time over at marinehowto.com. Rod has an excellent writeup on fusing for batteries. Really.


Short story: you size the wires based on the LOAD, circuit distance and voltage drop. Only then do you size the fuses based on the wire size. BlueSea has an excellent wire sizing chart:


Here's the link to the page, scroll down for the PDF download of the Protect Your Boat With The Correct Size Wire And Fuse - Wire Size Chart: https://www.bluesea.com/support/reference which links to this table:
https://d2pyqm2yd3fw2i.cloudfront.ne...ence/20010.pdf

[Nicholson58]

I have 300 amp fuses as pictured in 18 above. Shorted a spanner from the starter lug to the engine. Instantly blew the fuse. Nearly cut the spanner in two. It was welded to the engine.

[SVBLU]

Originally Posted by Stu Jackson

I, too, initially questioned the daily load. 22ah for lights? Man, what planet are you on? LEDs on the Titanic if all were left on wouldn't draw that much.

I think you seriously should look into your loads again.

Otherwise, good planning, but it sure sounds like you're reinventing the wheel here. Good luck.

Apologies for the confusion. I put my total daily amps. So I should have divided by 24 hours. So it's 0.91ah for lights, not 22ah!

[Peregrine1983]

Personally, I would:

- Add more solar given the size of this bank. Probably another 200w or so. I know I'd need it where I cruise in New England.

- Install a larger inverter - 2000w or more (make sure it's another pure sine - my Starlink does not like a modified sine).

- Also, 5 amps sounds like a lot of consumption for a modern inverter on standby.

Fun project! Good luck. (edited for clarity)

[JasonS]

The LiTime batteries are an “inexpensive” brand of battery whose BMS does not do all the functions you’d want in a house bank for a sailboat. Furthermore, you can’t use more than 4 in parallel, so you are limited to a 400ah battery bank.

We are installing Epoch 300ah batteries next week. We are putting in a 1200ah bank! We already have the batteries. Size wise, they are some of the most friendly for sailboat sized battery boxes. https://www.epochbatteries.com/produ...och-essentials

They sell for $1099.99, with a 10% discount available. They have a great Bluetooth app for the BMS (you can download a copy to your phone from the App Store and play with a demo). They also have a version for $100 more each that have CANBUS and will be able to communicate with your Victron. With the Bluetooth BMS, it’s certainly not a must and we chose to save $400+ cost of addl cabling. They are also a bit larger and heavier. Epoch is assembled in Atlanta GA and headquartered there. Note, if you need customer service, CALL! They are great on phone, but emails tend to go in a deep hole. They also respond on their FB pages quickly.

Watch some of the tear down videos on YouTube for all brands you consider. The cells may be similar, but BMSs, wiring size/type, quality of connections, and quality of build do.

We looked extensively.

Brands we would put on our boat (with reasons why we didn’t choose them)
Battleborn (size of 270ah too large and ~$2500)
Dakota (size of 270ah large and ~$2500 or 560ah $4700 and no way to see BMS function)
Epoch (small size for 300ah ~$1000. These are what we chose)
Kilovault (size too large 300ah ~$1600)
ReLion (size too large 300ah ~$3200)
Victron (330ah ~$3150 + separate BMS)

We looked at many “Amazon” Brands and determined most would not include all BMS functions needed and/or had poor build. We also looked at Big Battery Seal 228ah, but think their wiring is marginal/too small at the proprietary connectors and inside, and SOK Marine Plus 206ah, but would be limited to 824ah and cost per 206 is about the same as Epoch.

If you order from Epoch, please let them know Breathe Sail Dive LLC sent you. We are not currently an affiliate and do not benefit from your order, but would like to be. There’s a 10% coupon on their homepage currently.

[SV Confianza]

Originally Posted by JasonS

The LiTime batteries are an “inexpensive” brand of battery whose BMS does not do all the functions you’d want in a house bank for a sailboat. Furthermore, you can’t use more than 4 in parallel, so you are limited to a 400ah battery bank.

We are installing Epoch 300ah batteries next week. We are putting in a 1200ah bank! We already have the batteries. Size wise, they are some of the most friendly for sailboat sized battery boxes. https://www.epochbatteries.com/produ...och-essentials

They sell for $1099.99, with a 10% discount available. They have a great Bluetooth app for the BMS (you can download a copy to your phone from the App Store and play with a demo). They also have a version for $100 more each that have CANBUS and will be able to communicate with your Victron. With the Bluetooth BMS, it’s certainly not a must and we chose to save $400+ cost of addl cabling. They are also a bit larger and heavier. Epoch is assembled in Atlanta GA and headquartered there. Note, if you need customer service, CALL! They are great on phone, but emails tend to go in a deep hole. They also respond on their FB pages quickly.

Watch some of the tear down videos on YouTube for all brands you consider. The cells may be similar, but BMSs, wiring size/type, quality of connections, and quality of build do.

We looked extensively.

Brands we would put on our boat (with reasons why we didn’t choose them)
Battleborn (size of 270ah too large and ~$2500)
Dakota (size of 270ah large and ~$2500 or 560ah $4700 and no way to see BMS function)
Epoch (small size for 300ah ~$1000. These are what we chose)
Kilovault (size too large 300ah ~$1600)
ReLion (size too large 300ah ~$3200)
Victron (330ah ~$3150 + separate BMS)

We looked at many “Amazon” Brands and determined most would not include all BMS functions needed and/or had poor build. We also looked at Big Battery Seal 228ah, but think their wiring is marginal/too small at the proprietary connectors and inside, and SOK Marine Plus 206ah, but would be limited to 824ah and cost per 206 is about the same as Epoch.

If you order from Epoch, please let them know Breathe Sail Dive LLC sent you. We are not currently an affiliate and do not benefit from your order, but would like to be. There’s a 10% coupon on their homepage currently.

I don't know what BMS features you are missing on the cheaper batteries, but they have worked fine for us for years. We have a battle born bank and also have Redodo's and LiTime's mixed in. Going on almost 3 years of full time cruising with them.

The 4 battery parallel limit is not really a physical limit. It's a "keep us out of trouble" limit. If you want to put more in parallel, you'll need to properly fuse the batteries in case of a short in one, and you'll want to switch to a bus bar (with all equal length cables) instead of daisy chaining. This prevent charging unevenly to batteries (some never really getting charged, and some cycling a lot more).

I was a huge battle born fan years ago, but can't justify the high cost of the premium battery manufacturers anymore, so long as proper protection is in place.

[Kudos]

I have LiTime batteries, 700ah worth, I love them, they seem to be good batteries. Will Prowse youtuber did a teardown, said good components. I have 970 watts of solar, and just installed 2 115 bifacial Renogy panels on my lifelines, the rest are Renogy, they work great, no issues. I'm running those thru 3-30 amp Epever mppt controllers, with 8 gauge wire which is what Renogy recommends. Now in another test by Will, the Epever connectors did the best in handling 8 gauge wire. He said at that time, Victron terminals were a bit small. I also have a 600 watt wind generator, mainly because I've run out of real estate for more solar. Renogy 40 amp DC-DC charger, and a 75 amp charger to use with shore power or generator. So far summer time in the PNW 89% is the lowest the batteries have gotten overnight, and everything is charged back to 100% mid day.

[CarlF]

To cover a few issues.

1) Charging a big house bank from the alternator through a 30 amp DC-DC charger is just not enough amps to be worth the trouble. Better to just isolate the alternator to charging the start battery and charge the house bank with more solar or a genset. But, a conservative, properly designed LFP system with the alternator charging the house bank should never have a BMS disconnect. And if it somehow does, there are now easy, inexpensive ways to protect the alternator without using “communication”.

To make it worth the trouble the alternator should be big - something like the Balmar XT170. It should have a temperature sensor, alternator protection device, and avalanche diodes.

2) The alternator and inverter/charger should be set lower than the maximum voltage for the battery to leave “headroom” against a shutdown. I use 14.0v which charges to about 95%. Then I use the solar controller set to 14.2v to slowly charge the last little bit — with the alternator not charging..

3) Use a VictronDC-DC charger to charge the start battery from the house. This will safely route any BMS surges to the lead start battery.

4) If using more than 2 drop-in batteries, use equal length cables to a bus bar. Place a MBRF fuse on each battery positive terminal and then also a class T from the bus bar to the boat panel. Use large cables.

5) Have an ABYC electrician do part of the work.. Many insurance companies are suspicious of owner installed lithium batteries (you can’t blame them) and will ask for the installer’s name on an insurance application.

[mitiempo]

Originally Posted by Kudos

I'm running those thru 3-30 amp Epever mppt controllers, with 8 gauge wire which is what Renogy recommends. Now in another test by Will, the Epever connectors did the best in handling 8 gauge wire. He said at that time, Victron terminals were a bit small.

Victron 30 amp solar controllers (100/30) easily take 6 gauge wire which is what I use - with ferrules of course.

[krid2000]

Originally Posted by CarlF

3) Use a VictronDC-DC charger to charge the start battery from the house. This will safely route any BMS surges to the lead start battery.

Can you substantiate how a Victron DC-DC charger would mitigate any voltage spikes cause by a running alternator at a BMS cutoff?

Thanks!
Dirk

[sailingharry]

Originally Posted by krid2000

Can you substantiate how a Victron DC-DC charger would mitigate any voltage spikes cause by a running alternator at a BMS cutoff?



Thanks!

Dirk

I don't have any facts, but this is a question I have often pondered.
When an alternator is heavily loaded and receives a load dump, we get the voltage spike. This is well known.
But I wonder how much energy is in that spike. How many coulombs have to be siphoned off some place to mitigate the spike. I haven't thought about it in terms of a dc/dc, but I have often wondered about it with significant operating loads on the bus. Chart plotter, refrigeration, stuff like that. None of those things would like a 100 volt voltage spike, but I wonder what the voltage spike is if there is a 10 or 15 amp load sucking down some of those electrons. Of course, a 30 A dc/dc charger charging a start battery is a virtually non-existent load most of the time.