ABYC and ISO Li reference diagram

[goboatingnow]

Originally Posted by zurk

correct - a lot of people dont understand flow thru system design for lifepo4 or modern systems for boats which have power to spare. a design for 100Ah is completely different than one for 2000Ah and burning 10-20Ah on a 2000Ah setup is nothing as ive tried to point out to people.

Indeed , this is the case. Also even where consumption and capacity are tighter there may be acceptable trade offs which result in a standing consumption or others may decide that’s not a suitable trade off. It’s horses for courses.

[newhaul]

Originally Posted by zurk

correct - a lot of people dont understand flow thru system design for lifepo4 or modern systems for boats which have power to spare. a design for 100Ah is completely different than one for 2000Ah and burning 10-20Ah on a 2000Ah setup is nothing as ive tried to point out to people.

I beg to differ 10 to 20ah extra may just be the breaking point for the solar or wind charging system whatever that may be . Requiring use of the engine for charging . And that in my opinion is the worst use for the iron wind
Remember the battery just stores power it doesn't make it . What goes out must go back in

[wholybee]

Originally Posted by goboatingnow

The original RGleason proposal was two switches.

The thinking developed that if the bms contactor reengaged while the SLA was switched in this was bad. Hence the desire to interlock the SLA with the contactor.

Of course this could be done via two switches but you still needed a relay interlock of some sort or a custom battery switch.

So if you use your 1-off-2 you still run the risk that the bms could reengage whilst the SLA is in circuit.

The elegance of the interlock prevents this by inverting the AFD logic

You really needed to participate in the long thought processes on diysolarforum to see how the thinking evolved , there were many iterations of that diagram.

Yes, I was over there and follow that as well. I even posted a drawing of what I propose. Oddly, I think the bizarre (IMHO) interlocked solution grew out of my suggesting to use a 3 position 1-off-2 switch, but you took it a different way. And frankly, I'm confused of your dismissing of it. As I drew it, if the BMS re-engages, there is zero consequence. It just seems so simple and obvious. You have (after the relay not parallel with it) a switch to switch between LFP and SLA. If that switch is on SLA, the LFP battery is disconnected. If the relay closes, the LFP still disconnected. And if it is off, then both batteries are disconnected. Just as is done with conventional dual battery switches, just without the "both" position.

[goboatingnow]

Originally Posted by newhaul

I beg to differ 10 to 20ah extra may just be the breaking point for the solar or wind charging system whatever that may be . Requiring use of the engine for charging . And that in my opinion is the worst use for the iron wind
Remember the battery just stores power it doesn't make it . What goes out must go back in

I would opine if you’d Solar is pitched on such a knife edge you need more solar.

[goboatingnow]

Originally Posted by wholybee

Yes, I was over there and follow that as well. I even posted a drawing of what I propose. Oddly, I think the bizarre (IMHO) interlocked solution grew out of my suggesting to use a 3 position 1-off-2 switch, but you took it a different way. And frankly, I'm confused of your dismissing of it. As I drew it, if the BMS re-engages, there is zero consequence. It just seems so simple and obvious. You have (after the relay not parallel with it) a switch to switch between LFP and SLA. If that switch is on SLA, the LFP battery is disconnected. If the relay closes, the LFP still disconnected. And if it is off, then both batteries are disconnected. Just as is done with conventional dual battery switches, just without the "both" position.

The issue was the decision to combine the bms bypass and SLA into one 1-off -2 then an additional switch is needed which was there in a previous version.

Once you bypass the BMS you then have to interlock the contractor so that the bms relay doesn’t re parallel the SLA.

I agree if you go back to two switches you can side step the interlocking this was discussed at the time.

But more switches mean more “ sequences “ to remember hence I think the final compromise is quite elegant as it combines two functions and interlocks them.

[newhaul]

Originally Posted by goboatingnow

I would opine if you’d Solar is pitched on such a knife edge you need more solar.

Wrong 20ah would almost double my boats power usage .
Remember what is right for your boat is not right for everyone's vessel.
I currently use just under 30ah per day and harvest about 40ah off my solar I run my water heater and of refrigerator more after bank is full . Now add your 10 to 20ah extra and I'm losing . But on your solar farm it's not an issue .
Every boat and installation is different. It's what I did for a living.

[zurk]

Originally Posted by newhaul

Wrong 20ah would almost double my boats power usage .
Remember what is right for your boat is not right for everyone's vessel.
I currently use just under 30ah per day and harvest about 40ah off my solar I run my water heater and of refrigerator more after bank is full . Now add your 10 to 20ah extra and I'm losing . But on your solar farm it's not an issue .
Every boat and installation is different. It's what I did for a living.

youre probably not running a giant LFP bank. i use close to 200Ah per day between all my systems. and i could do that for 10 days without any real issues from a fully charged bank. dont forget in those 10 days youre likely to run the engines at least for 8 hrs of motoring (at 200Ah gained every hour at normal cruise speed, potentially 1600Ah per day), get 1000Ah from solar (100Ah per day x 10 days), run the duogen 3 at sailing or at anchor ( at 128Ah gained every day or 1280Ah every 10 days ) .

yes what goes out must come in - but think about how long and how fast it must come in. over 10 full days is a lot of potential going in vs what is coming out. youre burning slow with a big LFP bank and putting it in fast.


it does require a change in thinking style to think about things as flow through systems with storage vs the old model of storage only, use as little as possible. once you make the leap, you will never go back. in a flow through system time is your battery bank not your actual LFP battery. think about 10 days and what you can store in them and take out. dont think about Amp hours. think about days.

[newhaul]

Originally Posted by zurk

youre probably not running a giant LFP bank. i use close to 200Ah per day between all my systems. and i could do that for 10 days without any real issues from a fully charged bank. dont forget in those 10 days youre likely to run the engines at least for 8 hrs of motoring (at 200Ah gained every hour at normal cruise speed, potentially 1600Ah per day), get 1000Ah from solar (100Ah per day x 10 days), run the duogen 3 at sailing or at anchor ( at 128Ah gained every day or 1280Ah every 10 days ) .

yes what goes out must come in - but think about how long and how fast it must come in. over 10 full days is a lot of potential going in vs what is coming out. youre burning slow with a big LFP bank and putting it in fast.


it does require a change in thinking style to think about things as flow through systems with storage vs the old model of storage only, use as little as possible. once you make the leap, you will never go back. in a flow through system time is your battery bank not your actual LFP battery. think about 10 days and what you can store in them and take out. dont think about Amp hours. think about days.

I do think about days with everything running except watermarked I use 30ah to 35ah daily and I have a 250ah bank. I'm also on a narrow 29ft Columbia defender. More than 250 makes no sense for my boat. Now I ran a 500ah bank on my Spencer with 409 watts solar but a 42 ft boat has a lot more room and a lot different power usage scheme than a 29.
Like I said on my boat . (stress the MY in that last ) yours is a different critter .

[goboatingnow]

Originally Posted by newhaul

Wrong 20ah would almost double my boats power usage .

Remember what is right for your boat is not right for everyone's vessel.

I currently use just under 30ah per day and harvest about 40ah off my solar I run my water heater and of refrigerator more after bank is full . Now add your 10 to 20ah extra and I'm losing . But on your solar farm it's not an issue .

Every boat and installation is different. It's what I did for a living.

Yes not we’re talking about 3Ah in the context of a diagram with big Li batteries , decent solar , and Li connected alternator.

I fully accept there may be small systems. But in the context of the diagram presented and the engineering arguments behind it 3AH is nothing.

[goboatingnow]

Originally Posted by newhaul

Wrong 20ah would almost double my boats power usage .

Remember what is right for your boat is not right for everyone's vessel.

I currently use just under 30ah per day and harvest about 40ah off my solar I run my water heater and of refrigerator more after bank is full . Now add your 10 to 20ah extra and I'm losing . But on your solar farm it's not an issue .

Every boat and installation is different. It's what I did for a living.

I have a small system 240 AH VRSLA , 240kwp solar. I use about 45 Ah a day. My solar will return the bank to full by 11am.

In that context 3Ah is of zero concern. I simply wouldn’t notice it.

Others night be more on a knife edge. I said many times the use of various components in the presented diagram is in the context of that diagram. It’s not universally applicable nor was that ever claimed.

[newhaul]

Originally Posted by goboatingnow

I have a small system 240 AH VRSLA , 240kwp solar. I use about 45 Ah a day. My solar will return the bank to full by 11am.

In that context 3Ah is of zero concern. I simply wouldn’t notice it.

Others night be more on a knife edge. I said many times the use of various components in the presented diagram is in the context of that diagram. It’s not universally applicable nor was that ever claimed.

I would first doubt you are actually fully charged due to the charging profile of all lead based batteries wrt the final 10% . But with 240 kilowatt peak solar I wouldn't doubt you are at 85% by 11 am solar time
Question is how did you fit that much solar on a sailboat ?

[s/v Jedi]

Originally Posted by goboatingnow

I have a small system 240 AH VRSLA , 240kwp solar. I use about 45 Ah a day. My solar will return the bank to full by 11am.

In that context 3Ah is of zero concern. I simply wouldn’t notice it.

Others night be more on a knife edge. I said many times the use of various components in the presented diagram is in the context of that diagram. It’s not universally applicable nor was that ever claimed.

The solenoid is almost 10% of your daily total consumption added to that. It is of great concern to observe how wasted power (literally wasted on a f’in relay) is laughed off

[hjohnson]

Originally Posted by s/v Jedi

The solenoid is almost 10% of your daily total consumption added to that. It is of great concern to observe how wasted power (literally wasted on a f’in relay) is laughed off

I, like you am using an ML-RBS as my charge-side contactor. My static loads are 21W (I leave my instrumentation, AIS, and LTE router on all the time). The 7mA hold current on the 7713 was very attractive.

But I am now quite curious about its internal design, and an what the failure modes of it are. But I’m not about to cut mine apart to see how it works. I just have to trust that Blue Sea knows what they’re doing.

[s/v Jedi]

Originally Posted by hjohnson

I, like you am using an ML-RBS as my charge-side contactor. My static loads are 21W (I leave my instrumentation, AIS, and LTE router on all the time). The 7mA hold current on the 7713 was very attractive.

But I am now quite curious about its internal design, and an what the failure modes of it are. But I’m not about to cut mine apart to see how it works. I just have to trust that Blue Sea knows what they’re doing.

Short of cutting it open, I am pretty sure it works like this: it starts with a standard solenoid with Normally Open contact, closed by an electro-magnet and opened by a strong spring that is compressed while closing it.

Now there’s a small mechanical device called a sear that catches the solenoid when it is closed and keeps it closed even when the electromagnet is switched off. Think of the hammer of a gun that is hold back when cocked. Now you only need to release the sear, after which the tensioned spring will open the contact.

This is where opinions differ: I think the sear is holding the contact closed by the small “hold” current that is consumed. When that control signal is removed, the sear triggers and the contact opens.
Others say that the sear will only release after receiving a signal, rather than removal of a signal. This would mean that it will not open when you remove power from it. I do not agree with that, because this wouldn’t be auto releasing and also it would not consume anything during hold. Like the pulsed 7700 version, which consumes nothing in either state, only during changing state.

[goboatingnow]

Originally Posted by newhaul

I would first doubt you are actually fully charged due to the charging profile of all lead based batteries wrt the final 10% . But with 240 kilowatt peak solar I wouldn't doubt you are at 85% by 11 am solar time
Question is how did you fit that much solar on a sailboat ?

Sorry typo 240 Wp not Kwp

And yes I’m at 100 percent Soc as I have full tail current monitoring.