Start your engine with 4 eve lifepo4 cells, lead makes no sense for this task!!

[Goodxcharly]

Lead acid will start anything plus won’t drain your bank account and catch on fire.
The latter is why I stay away from them.
I always here weight reduction too as a big plus which would be 150# on my 16000# boat.

4 100 amp 6 volt golf cart batteries, $400.

FWIW

[billyehh]

I tend to agree with Goodxcharly. However my 6 AGM 6 volt golf cart size batteries are at the end of their life. My research into LiFePo4 battery's are prompting me go in that direction form my house system. The BMS would be in excess of 200 amps so it would be OK for my windlass, which I usually use with the engine running. Every expert I have read said do not use for a starting battery. A cheap regular sealed lead acid battery works fine and lasts 5 to 6 years. With no or a bypassed BMS you are literally playing with fire.

[Fortytwo]

https://lithiumhub.com/product/12v-4...arter-battery/

[Fortytwo]

https://lithiumhub.com/product/12-volt-125ah-battery/

[CaptainRivet]

Just because its called Lithium you cannot use any lithium for starting or windlass application.

Its the same as for lead, you have starter and deep cycle and lithium that can both (which have the expensive cells like Winston and and an expensive BMS that can handle surges and reverse current.

Starter battery type:
You have starter batteries optimised for short high current cranking applications. Their BMS is capable of handling the high current surge and also reverse current. If its lifepo4 they mostly have a supercapacitor inside that delivers short high current and is recharged by lifepo4 or its a derivate of Lifepo4 like the Winstons which has higher enrgy density and deliver higher current. These are not made as house banks but compared to lead will not be damaged but AH for money is bad.
AH capacity is measured mostly like lead with C5 or C20 but will be much smaller then comparable storage bat.

Deep cycle:
Then you have deep cycle Lifepo4 (or called storage, offgrid or solar batteries) with cells like Lishen,EVE, most Calbs...these are optimised for high capacity but low C-rate start and discharge.
Prices here are close to AGM with same usable capacity. If drop ins mostly their BMS are FET based and not capable of starting an engine as FETs cannot handle the high surge and especially reverse current will fry them.
BUT if you combine enough of them together the C-rate is low enough to each BMS of the individual battery that you can start engine/run windlass of them, a so called hybrid bank. If you have a 2kw starter you minimum need a 600AH bank so cells or BMS is not getting damaged.
This CANNOT be done with BMS where the manual says you cannot parallel the BMSs. The reason is that multiple FETs in them are used to interrupt the current that switch simulataniously but one FET is always last and that FET gets the full current of the load and will litteraly explode and drop in is dead. Or if not because the architecture is different then next start next FET is killed till numbers of FETs are too small to handle load and BMS+battery is toast. This is the case for most chinese FET BMS as their FETs are not prescisely calibrated and matched. These cells like EVE, Lidhen,Hivium...will derate much faster if used above 1/3 of their continious C-rating means 1C is 0.3C and 2C is 0.6C. If starting current is equal to peak rating expect max 300-500 cycles doesn't matter how many cycles manufacturer states. I fried many of them already 10 years ago when i used them for competition and car hifi and starting applications. At this time no documentation was avaliable and it was trail and error

[CaptainRivet]

Originally Posted by billyehh

I tend to agree with Goodxcharly. However my 6 AGM 6 volt golf cart size batteries are at the end of their life. My research into LiFePo4 battery's are prompting me go in that direction form my house system. The BMS would be in excess of 200 amps so it would be OK for my windlass, which I usually use with the engine running. Every expert I have read said do not use for a starting battery. A cheap regular sealed lead acid battery works fine and lasts 5 to 6 years. With no or a bypassed BMS you are literally playing with fire.

Let the alternator regulator break and you don't realize it and then your AGM will get a thermal runaway...with these amount of AGM you first have a swimming acid gas chamber and if that didn't make you leave the ship to life raft then the AGM will set the boat on fire.
On my old ketch the bowtruster got seized and massivly overloaded the AGM and both got a thermal runaway. Was tossing them overboard in the habour wearing a protection mask from 3M with the highest grad filter they have which i use for epoxy work and my BBQ gloves...never AGM on any of my boats...
Much more dangerous then Lithium.

Cheap refillable FLA i agree are a simple,safe and cheap way to start your engine. If regulator breaks here they get dry, refill and they have little damage and lost some capacity but will still work.

[CaptainRivet]

My advice on this topic is the following:
Cat: hybrid starter/house in one hull, 80% of lfp house banks are big enough to start your engine even the manufacturer states not to use for starter. That concerns one batter but not 4 or 6 in parallel. Put LCV at 3.0V and your bank will always start the engine, starting is max 2-4AH so even at 3.0V a 600AH bank has min 30AH left till 2.5V...many starts. My advice if you DIY your system then breaker and wire starter directly to hybrid house and cutoff at 3.0V. This is not AbYC complaint but much safer as you know your system, stting in the dark as LCV at 3.0V but you have still multiple starts on LFP and enough time to switch to backup in other hull. The high current relays i experienced over 20 years are unreliable and will keep close or not engaging in the wrong moment and harm more then they protect and are freaking expensive. Use that money and add more capacity to your bank, so more reserve from 3 to 2.5V. The starter doesn't use any energy if not used and usage is always under your supervision so no need for system cutoff, your rest switched off so you know you are below 3.0V and if time and situation allows you have enough time to manually switch to backup bat. The breaker protects from overload when eg starter seizes or engine gets block by a net when starting.
Other hull FLA or LTO if you already have a regulated alt in both hulls.

Mono: costal and small have one hybrid bank and as much as possible capacity, as above 3.0V LCV but starter wired directly with a breaker.
Bigger: have a starter and house bank, if your solar is big enough and 1st charge source i would use FLA as starter and use DC2DC charger. That isolates circuits and makes install easier. Or have 2 alternators, standard charge starter and 2nd regulated charges LFP house.

If you use hybrid bank stay away from FET based BMS. Cheap is Electrodacus, otherwise i would use CAN based like REC and the canbus cuts field wire or steers regulator like wakespeed and therfor charge.
During stress testing your DIY system you get so much experience how your system reacts and how much room you have that this is safer then a unreliable high current relay as you have full control.

Disclaimer: if you don't DIY your system and let it install you must implement a cutoff solution for starter or windlass on a hybrid bank as you don't know what your system is doing. i would install an automatic transfer switch from LFP house to starter instead of a cut of relay.

[billyehh]

According to both the windlass and battery manufacturers, the fuse would blow before a problem with the battery. Each of my starting batteries are sealed lead acid batteries charged by a 40 amp internal regulator, exactly like an automotive system. They are about to start year 6.

As forty-two website, I could not find what the BMS was rated at and other fairly insufficient information. I also thought the prices were incredible high, almost as much as a Battle-Born.

[Marc13]

Winston's 12v LiFeYPO4 batteries can directly replace 12v batteries in thermal vehicles, without any modification to the electrical circuit. The 12V Winston can be charged between 14.5 and 15.5V continuously without any problem.



For over 12 years, my boat has been running a single set of 12v Winston batteries in parallel with no BMS. I prefer to have waterproof, robust and safe LiFeYPO4s between -40°C and 85°C rather than less safe and more fragile batteries that absolutely need electronics to avoid battery damage and fire. Before equipping my boat, I had been able to do a lot of testing of these batteries in the laboratory to use them in a professional application.



When you know that a starter of a large motor requires 600A, much less than 1Ah, I find it ridiculous to put large lead batteries. At worst, supercapacitors charged with LiFePO4 batteries or even a small backup battery with some electronics are safer.



My 12 year old LiFeYPO4 batteries never had a problem starting the engine easily.



The much higher voltage of my Winston when starting however led me to add bidirectional 20V TVS diodes everywhere on the electrical circuits of the boat and in particular in parallel with all the coils (starter relay, stop solenoid motor, windlass and winch relays).These diodes also have the advantage of increasing the service life of these coils by clipping self-induced overvoltages when the power is cut. They also help to protect the electronics against indirect effects lightning.

[Statistical]

Originally Posted by Marc13

Winston's 12v LiFeYPO4 batteries can directly replace 12v batteries in thermal vehicles, without any modification to the electrical circuit. The 12V Winston can be charged between 14.5 and 15.5V continuously without any problem.

For over 12 years, my boat has been running a single set of 12v Winston batteries in parallel with no BMS. I prefer to have waterproof, robust and safe LiFeYPO4s between -40°C and 85°C rather than less safe and more fragile batteries that absolutely need electronics to avoid battery damage and fire. Before equipping my boat, I had been able to do a lot of testing of these batteries in the laboratory to use them in a professional application.

When you know that a starter of a large motor requires 600A, much less than 1Ah, I find it ridiculous to put large lead batteries. At worst, supercapacitors charged with LiFePO4 batteries or even a small backup battery with some electronics are safer.

My 12 year old LiFeYPO4 batteries never had a problem starting the engine easily.

That is a special chemistry designed for 10C intermittent output. So properly sized the battery should have no problem starting just about any diesel engine out there. Your usage is both smart and safe.

The thread began regarding using cells not designed for high C output which is a quite different situation. You sure the Winston battery has no internal BMS?

Ultracapacitors might be a starter option and in fact teardowns of LFP "starter" or "dual purpose" batteries have found ultracaps in parallel with the cells. The largest drawback is simply cost. The almost two century old lead acid battery lives on because it is cheap and ubiquitous.

[s/v Jedi]

Originally Posted by Statistical

That is a special chemistry designed for 10C intermittent output. So properly sized the battery should have no problem starting just about any diesel engine out there. Your usage is both smart and safe.

The thread began regarding using cells not designed for high C output which is a quite different situation. You sure the Winston battery has no internal BMS?

Ultracapacitors might be a starter option and in fact teardowns of LFP "starter" or "dual purpose" batteries have found ultracaps in parallel with the cells. The largest drawback is simply cost. The almost two century old lead acid battery lives on because it is cheap and ubiquitous.

The problem for Winston cells isn’t amperage but the high SOC that the cells are in constantly.

[Statistical]

Originally Posted by s/v Jedi

The problem for Winston cells isn’t amperage but the high SOC that the cells are in constantly.

I think he is just using a single battery for starting and house so I presume it SoC is varying throughout the day.

[s/v Jedi]

Originally Posted by Statistical

I think he is just using a single battery for starting and house so I presume it SoC is varying throughout the day.

Then he is fine. Winston can do 10C for 30 seconds or so without impact on lifespan.

[Fuss]

Originally Posted by Marc13

Winston's 12v LiFeYPO4 batteries can directly replace 12v batteries in thermal vehicles, without any modification to the electrical circuit. The 12V Winston can be charged between 14.5 and 15.5V continuously without any problem.



For over 12 years, my boat has been running a single set of 12v Winston batteries in parallel with no BMS. .

We are really starting to make progress here… here we have proof that starting your engine with lithium works with no BMS.

When I originally mentioned the Winston 12v start batteries, I was shot down.

All those comments stating that bypassing the BMS is such a huge problem……:.

Ok, so now the only thing outstanding is that I am experimenting with Lifepo4 280ah Eve cells that are not designed on any way, shape or form as engine start batteries.

Or do you all still want to go on about how dangerous it is to bypass the BMS.

Time will tell…

[s/v Jedi]

Originally Posted by Fuss

We are really starting to make progress here… here we have proof that starting your engine with lithium works with no BMS.

When I originally mentioned the Winston 12v start batteries, I was shot down.

All those comments stating that bypassing the BMS is such a huge problem……:.

Ok, so now the only thing outstanding is that I am experimenting with Lifepo4 280ah Eve cells that are not designed on any way, shape or form as engine start batteries.

Or do you all still want to go on about how dangerous it is to bypass the BMS.

Time will tell…

You forget that your “start battery” sits at 100% SOC all the time while this system starts from a mixed LA/LFP house bank.