Merged LiFeYPO4 1000Ah Winston prismatic cells and all electric galley...

[CatNewBee]

Originally Posted by goboatingnow

What’s wrong with FET power switches

Voltage spike sensitive, often one way only, not easy to fix. A relay / solenoid can be sourced everywhere usually.

[hzcruiser]

Originally Posted by goboatingnow

[...]

Today it’s simple get a proper Li capable alternator regulator that can be remotely controlled and or add in a alternator protector to boot.

If you are going to the lengths to install LI , do it right

I certainly agree with you on the alt reg! Moving to LFPs though _can_ be
done in baby steps.

[hzcruiser]

Originally Posted by CatNewBee

I am happy with the REC so far, it works and it is completely configurable. Well the balancer is on the weak side with 1.5A.
[...]

I personally like the small form factor and the well protected design, no screws that can loose on wires, a nice waterprotected harness. There are other BMS around, but most are a no-go for me.

I would dismiss

- any BMS with cell modules
- any BMS with built in FET transistors that switch the power
- any BMS with preset values that cannot be programmed.

1.5A balancing current should be way more than ever required.

By the looks of it, RECBMS is likely to use FETs. Or what do you think?

[CaptainRivet]

Originally Posted by Catapault

As above, this is the way I'm leaning. (Though I have 2 engines, Catamaran)

This depends how many hours your engines and therefor the alternators have and if they are 20years+.
Means if they technically outdated or soon to be replaced or overhauled it just makes sense to put 2x proper heavy duty alt with regulator in and this way also avoid a genny.
I have 150h on both engines and the modern 115A Mitsubishi alts, delivering 60A in real life permanently. So here DC to DC charger makes the most sense and starter are hybrid and oversized to act also as emergency house

[CaptainRivet]

Originally Posted by hzcruiser

Sorry, repeating it doesn't make it any more correct or wrong, it just annoys people that would come across it "1000 times".



So how do you then make use of those "other" batts, if they're separate? A complete second power bus maybe?

A simple 500A high current switch that is 1) Lithium or 2) starter/emergency house.
I have a strict load and charge bus separation and the 2 big inverters are connected straight to the LFP. So I only switch over to the starter the load bus without the 2 inverters and my starter can deal with this load for 6h without running the engine. That switch is easy reachable and on purpose manual, get 2 warnings before disconnect and enough time to flip the switch to have no interrupt.
A next step when reorganizing my switch panel is separate the load bus in must have load and rest loads (have already rooted 2 main battery cables to the switch board/Nav station, also helps regarding voltage drop) which then enables me to just switch the must have which enlarges the time till starter is depleted to around 24h without engine or any other charge.

[CaptainRivet]

Originally Posted by Catapault

As above, this is the way I'm leaning. (Though I have 2 engines, Catamaran)

This depends how many hours your engines and therefor the alternators have and if they are 20years+.
Means if they technically outdated or soon to be replaced or overhauled it just makes sense to put 2x proper heavy duty alt with regulator in and this way also avoid a genny.
I have 150h on both engines and the modern 115A Mitsubishi alts, delivering 60A in real life permanently. So here DC to DC charger makes the most sense as this creates backup+ in emergency i can directly charge the LFP as the Mitsubishi are semi controlled and limit the current they can deliver. The LFA starter are hybrid LFA (cheap heavy duty cooling truck 140AH FLA which can be refilled, they can withstand the most abuse/mistreat without or minor damage and are cheap) and oversized to act also as emergency house

[goboatingnow]

Originally Posted by CatNewBee

Voltage spike sensitive, often one way only, not easy to fix. A relay / solenoid can be sourced everywhere usually.

So a 400A , 2KA surge , 300V capable mosfet switch isn’t your thing

[Catapault]

Originally Posted by CaptainRivet

This depends how many hours your engines and therefor the alternators have and if they are 20years+.
Means if they technically outdated or soon to be replaced or overhauled it just makes sense to put 2x proper heavy duty alt with regulator in and this way also avoid a genny.
I have 150h on both engines and the modern 115A Mitsubishi alts, delivering 60A in real life permanently. So here DC to DC charger makes the most sense as this creates backup+ in emergency i can directly charge the LFP as the Mitsubishi are semi controlled and limit the current they can deliver. The LFA starter are hybrid LFA (cheap heavy duty cooling truck 140AH FLA which can be refilled, they can withstand the most abuse/mistreat without or minor damage and are cheap) and oversized to act also as emergency house

1050h on each engine here, 10yrs old, Yanmars. Very good condition overall.

I already have an 11kva Onan Generator, and a Victron Quattro, so really, Diesel -> DC Power is fairly well taken care of. (And main charge comes from a LOT of Solar)

I suspect I WILL do something with the Alternators to make them compatible with the new Lithium system, but, baby-steps, version 1 I think will disconnect them, and put in a switch for emergencies.

[Catapault]

Originally Posted by CatNewBee

Voltage spike sensitive, often one way only, not easy to fix. A relay / solenoid can be sourced everywhere usually.

If I recall right, they have a tendancy to fail-short as well, which can be less than ideal.

[Catapault]

Originally Posted by aybabtme

If you're in Europe, these are 2320€ for 406Ah, including BMS and everything. You could start with that, and use the rest of your budget to upgrade your alternators or install battery-to-battery chargers. Then later add a few of these when your budget allows.

https://www.europe.sokbattery.com/pr...th-built-in-he

The custom DIY raw cell stuff is fun but a bit janky, and not really cheaper once you factor in the BMS, wiring, switch, breaker/fuse, etc... versus a drop in pack like above. I've build a large raw cell pack before and I'm going to be upfitting a new-to-me boat in the coming weeks... I'm going with the SOK 12V I'm sharing. Life's too short and it's a wash as to which one is cheaper (DIY vs Buy).

I'm a nerd at heart, and have the electrical backgroud, so fine with DIY, it's fun and interesting !, so I'm planning the DIY route. Just timing of the LA failures was annoying.

[Catapault]

Originally Posted by fxykty

Buy Winston cells direct from the factory via Julia Yu sales@skypowerintl.com and I’m sure you can get 4x 1000Ah cells for USD4,000 + shipping. Doing it piecemeal doesn’t really make sense, unless you truly can’t afford it.

Will contact her, thanks !. Though VAT / Import duties often bring things to similar levels.

[Catapault]

Originally Posted by CatNewBee

I am happy with the REC so far, it works and it is completely configurable. Well the balancer is on the weak side with 1.5A.

ABYC is of no concern for me, we are a EU flagged boat, so CE certification would be an issue if any - but it is unlikely.

The REC can raise alarms before turning off, as it has 4 interfaces that are programmanle plus 2 data interfaces (RS485 and CAN), so depending on jour system design you could switch whatever you like whenever you like, including a fog horn.

I personally like the small form factor and the well protected design, no screws that can loose on wires, a nice waterprotected harness. There are other BMS around, but most are a no-go for me.

I would dismiss

- any BMS with cell modules
- any BMS with built in FET transistors that switch the power
- any BMS with preset values that cannot be programmed.

There are not many left after this.

I am not in the market for a new BMS, so maybe there are some good new ones around.

Thanks Cat, appreciated. Done some research in the last week, and assuming I can get one (Supply issues !), I'll go with the REC Active BMS. It seems the best all round, especially for DIY / complex setups.

[goboatingnow]

Originally Posted by Catapault

I'm a nerd at heart, and have the electrical backgroud, so fine with DIY, it's fun and interesting !, so I'm planning the DIY route. Just timing of the LA failures was annoying.

I’m doing diy too

[goboatingnow]

Originally Posted by Catapault

If I recall right, they have a tendancy to fail-short as well, which can be less than ideal.

Hit them with a big enough spike and they open and spectacularly so !

[s/v Jedi]

Originally Posted by goboatingnow

So a 400A , 2KA surge , 300V capable mosfet switch isn’t your thing

I agree with CNB that a latching solenoid is much more robust and reliable. The RBS series from Blue Sea Systems is excellent. They have models that are driven by a pulse which is perfect for use with a microcontroller, or they have models that use a on/off constant level signal which is good to drive with a relay from any BMS. These are 500A rated.

If you can program, I recommend using an Arduino to build your own BMS. You can buy little cheap modules that measure cell voltages so it’s just coding the alarms and high and low voltage disconnect; temperature very easy as well.