DC to DC charger - not needed for boats with proper alternators.

[newhaul]

Originally Posted by CaptainRivet

No not mainly your setup. Yours has already several charge and load sources and its not kiss.
You definitely need a Victron BMV as last resort with midpoint on your cells as jedi suggests as daly is not really the reliablest BMS and missing a last resort in case Mosfets fry close. Also 250AH bank with 2500W inverter plus rest load means you stress the cells quite high with 1C.
This is exactly the prime example where a hybrid bank with 2 batteries each 250AH 0cells that has then 400-500AH the whole system would profit, instead 1 service with 250 and one lead starter.
Another buddy boat a moody 33 decksalon has very close setup to yours but Victron MPPT and multi 2000VA, also daly 300A BMS.
3 month ago i helped him to replace daly with electrodacus BMS that now shuts all Victrons off via remote and made one hybrid bank of 8x 200AH calbs due to space constrains. No mosfets that can fry, the cells now are max loaded 0.4C instead 1C and mitsubishi 115A alt without any mods is steered via Nordkyn VSR200 regulator directly via BMS. One set of parameters that steers and controlls all, thats real kiss.
Now its kiss. Supereasy to test and troubleshoot, simply switch the EXTIo that switch load and charge on/off and you can see on optocoupler glowing red or stay dark if that works or not.

Did you switch off your tracer MPPT under full load on battery side? Victron survives that but other don't or only over a periode?
DC2Dc i suggest 40A as 60A is too high for a 75A alternator even at perfect cooling. Assume you wanna take renogy one, i think their 60A you can also switch down to 30A Limit, check it as that would be worth trying then.

Well not to nitpick but the reason I have the trace 2512 inverter charger is the 120 amp charge capability. I have never needed any more than 1500 watts . Running my drip coffee pot ( it died ) also got it for 40 bucks. The pass thru doesn't work. ( yet) . Under 99% of cases I draw less that 25 amps at any one time . That's when my rice cooker is running and my watermaker is running . So I really doubt I'm stressing my bank any.
5 years now and still tests out at 264 ah .

[CaptainRivet]

Originally Posted by newhaul

Well not to nitpick but the reason I have the trace 2512 inverter charger is the 120 amp charge capability. I have never needed any more than 1500 watts . Running my drip coffee pot ( it died ) also got it for 40 bucks. The pass thru doesn't work. ( yet) . Under 99% of cases I draw less that 25 amps at any one time . That's when my rice cooker is running and my watermaker is running . So I really doubt I'm stressing my bank any.
5 years now and still tests out at 264 ah .

Then bank size fits well, most use their inverter size they have.
I would highly recommend to add the BMV as last resort as the reason we changed BMS on my buddy boat was that 2 Mosfets of Daly BMS already died. Yes i know you use max 1500W so 120-140A of 300A but well the mosfets in daly are not very well calibrated, so its lottery if you get good or bad one, you get what you pay for

[newhaul]

Originally Posted by CaptainRivet

Then bank size fits well, most use their inverter size they have.
I would highly recommend to add the BMV as last resort as the reason we changed BMS on my buddy boat was that 2 Mosfets of Daly BMS already died. Yes i know you use max 1500W so 120-140A of 300A but well the mosfets in daly are not very well calibrated, so its lottery if you get good or bad one, you get what you pay for

I have a tr16 bcm with 500 amp shunt iirc could be the 350 amp shunt. ( minimal cost difference )
Does the same job as the bmv 712. But without the victron price.

[CaptainRivet]

Originally Posted by newhaul

I have a tr16 bcm with 500 amp shunt iirc could be the 350 amp shunt. ( minimal cost difference )
Does the same job as the bmv 712. But without the victron price.

Better then nothing.
Well not really, thats good for lead and i have 1 as well for my starter battery in BB hull but victron is much more precise, especially the SOC and it delivers everyting to cerbo GX so it works as a smart shunt too.
And thats worth the price difference.

[newhaul]

Originally Posted by CaptainRivet

Better then nothing.
Well not really, thats good for lead and i have 1 as well for my starter battery in BB hull but victron is much more precise, especially the SOC and it delivers everyting to cerbo GX so it works as a smart shunt too.
And thats worth the price difference.

The tr16 Has worked very well for me for the last 5 years . It doesnt care about the chemestry of the battety
As to the cerbo gx I don't have one and don't want/ need one. Remember I'm a 29 ft columbia defender with minimal electronics. Not some micro managed benahuntalina.

The cost difference bought 3 years worth of diesel for me at the time. ( now it would only be a years worth. )

[s/v Jedi]

Originally Posted by wholybee

There are clearly two opposing trains of though on the purpose of the BMS, and what level of control it should have.

I have seen zero evidence that having the BMS control everything offers any advantage. If the BMS and balancer are keeping the cells in balance, then any good charger that only has access to the pack voltage will work exactly as well as a device that has access to the cell voltages. If the cells go out of balance, then something is wrong, and the BMS will notify you of that.

Having the BMS control everything does not increase the cycle life of the cells. It does not allow for faster charging, or more capacity, or offer any advantage that anyone has shown. It is more complicated. It is more expensive. One of the amazingly great things about LFP is that I don't have to worry about my batteries anymore. Keeping the system simple is a virtue.

That doesn't mean the BMS should not connect to an alternator regulator. For the purpose of shutting down charging before a disconnect, not to tell the regulator how to do its job. A few drop-ins now do this, as well as many external BMS's. That is a great feature, but if you choose to use a DCDC charger that isn't even necessary.

I know there are a few very outspoken users that insist a BMS should control everything, but honestly, why?

Exactly, you got that exactly right. There is no added value at all; it’s all in the mind of the buyer to pour money into some gadgets that would keep them safe with scary technology, while in fact they create a huge single point of failure that can’t be fixed.

At the very best, which is a 0.1% scenario of actually happening, such a BMS could maybe prolong usage of the battery for another couple of minutes, hours when something is really wrong with the cells.

A second battery as in creating redundancy would 100% deal with that without relying on a single algorithm laced with who knows how many bugs.

[CaptainRivet]

Originally Posted by s/v Jedi

Exactly, you got that exactly right. There is no added value at all; it’s all in the mind of the buyer to pour money into some gadgets that would keep them safe with scary technology, while in fact they create a huge single point of failure that can’t be fixed.

At the very best, which is a 0.1% scenario of actually happening, such a BMS could maybe prolong usage of the battery for another couple of minutes, hours when something is really wrong with the cells.

A second battery as in creating redundancy would 100% deal with that without relying on a single algorithm laced with who knows how many bugs.

Well 180 Euro for a BMS that can do all this which has no current limitation (measurement of shunt goes till 1000A if needed) that can be used in hybrid syarter/house on any engine found in recreational boating....so i didn't pour any money into something not usefull and a have a BMV that adds security and data integration plus have 3 other layer of security.
Already one heavy duty relay costs more...

Often couple of minutes are deciding if a boat burns or not...so happy to have them extra too for 0 extra costs.

[CaptainRivet]

Originally Posted by newhaul

The tr16 Has worked very well for me for the last 5 years . It doesnt care about the chemestry of the battety
As to the cerbo gx I don't have one and don't want/ need one. Remember I'm a 29 ft columbia defender with minimal electronics. Not some micro managed benahuntalina.

The cost difference bought 3 years worth of diesel for me at the time. ( now it would only be a years worth. )

Thats a big system for a 29ft

[newhaul]

Originally Posted by CaptainRivet

Thats a big system for a 29ft

?? 250ah is big? It replaces what was previously installed ( via info from origional owner of the boat Dan Williamson) was 2 gc2 making 220ah fla.

[CaptainRivet]

Originally Posted by newhaul

?? 250ah is big? It replaces what was previously installed ( via info from origional owner of the boat Dan Williamson) was 2 gc2 making 220ah fla.

From installation...inverter/charger 2500W, MPPT,DC2DC.....250AH lithium is 400AH lead yes thats definitely on the big side for a 29ft.
All relativ, a lot people on 35 till 40ft would be happy to have what you have installed on 29ft.

[newhaul]

Originally Posted by CaptainRivet

From installation...inverter/charger 2500W, MPPT,DC2DC.....250AH lithium is 400AH lead yes thats definitely on the big side for a 29ft.
All relativ, a lot people on 35 till 40ft would be happy to have what you have installed on 29ft.

Bet they would love the price as well .
Built my own bank ( cost difference from 150ah and 250ah cells was 100 bucks / 25 each.)
Have less than a big boat buck. The 200 watts solar came off my old boat I donated.
All in

[Fuss]

dear oh dear… do we understand anything from this…

[Pete7]

Originally Posted by Fuss

dear oh dear… do we understand anything from this…

Yes, there is no one ideal system design.

If individuals are happy with some limitations or single points of failure then that's' fine (like a single mast on a yacht )

Folk are free to build what ever they like in most free countries.

Pete

[CaptainRivet]

Originally Posted by s/v Jedi

Exactly, you got that exactly right. There is no added value at all; it’s all in the mind of the buyer to pour money into some gadgets that would keep them safe with scary technology, while in fact they create a huge single point of failure that can’t be fixed.

At the very best, which is a 0.1% scenario of actually happening, such a BMS could maybe prolong usage of the battery for another couple of minutes, hours when something is really wrong with the cells.

A second battery as in creating redundancy would 100% deal with that without relying on a single algorithm laced with who knows how many bugs.

What's here the single point of failure, please explain?

My system design regarding operations and lines of defense is priorized from the most precise to least precise battery bank information based on that the prio level takes action
Means
prio 1 is BMS as its the only that has cell,SOC and total voltage via balance leads AND 2 shunts (total and charge) what goes out of bank and in. Shunts Sit on positive pole of bank, will be connected to cerbo, in development.
Prio 2 is BMV with shunt on negative pole of bank and connected to cerbo. Has total voltage, SOC and devation cell pack 1+2 and 3+4
Prio 3 is cerbo (gets data from 1+2+devices) has total voltage and SOC from various sources
Prio 4 is devices (MPPT/charger/multi...), total battery voltage but has error through cables/fuses/connections but gets battery data via BMV/cerbo but works without in case BMV and cerbo is down.
So i have 4 levels of security and i am level 5 as liveaboard who designed and installed it completely myself, so know it inside out. An ipad 1 permanently displays BMS Electrodacus Dashboard at the nav station in the salon.

Regarding bank design there is always a single point of failure if you have more then 1p bank setup.
1 bank and BMS of multiple cells, the single point of failure is you don't see the individual cell in a pack.
1 bank consits of multiple battery each with a BMS. The single point of failure is that no master BMS that steers and synch the individual BMS in parallel.
1 bank consits of 1p4/8... cells, means 1 large cell (eg 4x1000AH Winstons.
Single point of failure when 1 cell is dead your bank is dead.

[CaptainRivet]

Originally Posted by Pete7

Yes, there is no one ideal system design.

If individuals are happy with some limitations or single points of failure then that's' fine (like a single mast on a yacht )

Folk are free to build what ever they like in most free countries.

Pete

True as they are so many variations possible and whats ideal depends in a big part on your individual boat and also usage pattern plus security requirements
(By eg insurance and yourself).

But you have to be aware what limitations your system has and if you find a single point of failure eliminate it if possible. If not possible implement very conservative automated threshold of action and implement close regular checks and an action plan if thats happen.