ACR and Pronautica 12-40p

[Q Xopa]

Originally Posted by Singularity

Kidding aside, what is more likely to happen:

1) some random catastrophic failure in a solo house bank rendering it completely unable to have a same-voltage (albeit smaller capacity) battery to be cobbled together

2) some error in switching coupled battery depletion rendering the boat incapable of starting/charging

I suspect that #2 is more likely. An analogy that I think is instructive:

In the 1950s small twin-engined planes entered the consumer market, sold as offering redundancy/increased safety over single-engined planes. Long story short, time has proven that, all things considered, the twin is just as likely to kill you as the single-engine plane is. The "redundancy" of a reserve engine is basically useless, but is very costly to buy and more complicated to operate.

From my amateur perspective, for pleasure craft operated by normal humans, the dual/reserve system with switches is analagous to a twin-engined plane. In theory it offers redundancy, in practice operator error is just as likely to result in a catastrophic failure as an 'all eggs in one main house bank' approach. If not for electrical enthusiast who enjoy promoting switches and circular logic, or salesman of switches, I'm thinking that the dual-house bank would go the way of the twin-engined plane....only useful for very select purposes to be used by people with truly exceptional operational practices.

The alternative is one large house bank, preferable of multiple cells that can be cobbled together for same voltage at decreased capacity if a cell fails, with the start battery fed off an echo charger off the house bus. Or just keep all the switches, ACR, and nuclear reactor needed to power all the weekly internet discussions on dual bank/switch/ACR systems.

I agree.

2) is more likely.

But for the cost of an extra switch its easy to eliminate possibility 1).

As you say this can usually be cobbled together with the remaining good batteries in the bank.

2) is the same possibility for both. This is more a training/ awareness/ placarding issue.

I also agree with your twin engine aeroplane analogy. It never really signicantly improved saftey. There is still only one fuel system and other factors. So running out of fuel a spare engine still wont save you.

Your view for one large bank rather than 2 smaller banks is fine. Its common and mostly works. And if thats what you are comfortable with fine.

I was simply offering an alternative. I wasnt saying it was better or worse in reply someone like you saying one big bank is far superior.

They both have pros and cons.

Its just different, like Cat or Mono discussions it simply comes down to personal preference mostly from familiarity.

[john61ct]

Another idea - two identical strings comprising a single bank

Pretty sure a big-enough fuse between them won't do the trick on its own.

But replace with a big contactor (maybe with CP built in?), put a BMV-712 on each side, monitoring that string's midpoint differential, from either side a gross imbalance (adjustable) triggering the separation of the two halves.

Just spitballing, call it a "good enough for lead BMS", feedback welcome.

[Q Xopa]

Originally Posted by john61ct

Another idea - two identical strings comprising a single bank

Pretty sure a big-enough fuse between them won't do the trick on its own.

But replace with a big contactor (maybe with CP built in?), put a BMV-712 on each side, monitoring that string's midpoint differential, from either side a gross imbalance (adjustable) triggering the separation of the two halves.

Just spitballing, call it a "good enough for lead BMS", feedback welcome.

Hmm, not sure what or why you're trying to achieve with this?

You posted a few posts back that one big bank, rather than a number of smaller ones, is a superior way to go.

I replied I didnt agree depending of how the system was designed and operated.

Now you are proposing a multi bank system? With some interesting sounding complexity.

I cant keep up.

[john61ct]

No, it is a single bank, as stated in the text you quoted.

Constant live monitoring to early-detect any uneven declining of performance,

Redundancy as well, the units would be available to put together a "reserve" bank, same-voltage half-capacity, in the event one unit fails

combined with the triggered isolation,

so that an unexpected sudden catastrophic failure of one unit cannot take out the others.

Of course if you care for and periodically monitor your bank properly, IMO that would not happen in a thousand lifetimes anyway.

But for those looking to be super cautious, arctic expeditions or whatever.

Not recommending to OP, just putting it out for feedback from others.

[Singularity]

Originally Posted by Q Xopa

...Actually depending on how you wanted to use your battery banks and system generally I would disagree and say that 2 seperate banks can be a very good way to operate a system. Without getting bogged down in details. Redundancy is an obvious reason.

Originally Posted by Q Xopa

...Also while your educating me if you can tell me what I am overlooking re redundancy. I thought with 2 x200AH setup if one went bad you could turn it off and you'd still have half left. How is you other ways to have redundancy with a single 400AH bank? ...

Originally Posted by Q Xopa

...Talking about circular, I did state in my post that it depended on how a system was used...
However with your 400AH single bank, if for example one of cells/ leads/ terminals goes out then the redundancy factor is nada.

Originally Posted by Q Xopa

...I also agree with your twin engine aeroplane analogy. It never really signicantly improved safety...

...Your view for one large bank rather than 2 smaller banks is fine. Its common and mostly works. And if thats what you are comfortable with fine.

I was simply offering an alternative. I wasnt saying it was better or worse in reply someone like you saying one big bank is far superior.

They both have pros and cons.

Its just different, like Cat or Mono discussions it simply comes down to personal preference mostly from familiarity.

Originally Posted by Q Xopa

...You posted a few posts back that one big bank, rather than a number of smaller ones, is a superior way to go.

I replied I didnt agree depending of how the system was designed and operated.

I will not say that one large bank is superior than multiple banks, but other subject matter experts have intimated as such, see:
https://forums.sailboatowners.com/in...light=windlass

Your emphasis on a second bank for redundancy to me is like a twin-engine pilot's love of his second engine. I respect that, and respect that you're able to utilize your system. But, with respect, I think you must recognize that the 'cons' of the dual-bank system is what bites people. That redundancy is as much a liability as it is an asset in hands of a typical user.

I'm not advocating that one system is less likely to leave you stranded than the other (referring to the only metric that counts). I AM saying that one system is ordinarily more complicated and potentially finicky to operate, such that when someone walks in the door asking about which system should be used...it makes more sense to advocate for the simple system....whereas you advocated for the more complex system.

[Q Xopa]

Originally Posted by Singularity

I will not say that one large bank is superior than multiple banks, but other subject matter experts have intimated as such, see:
https://forums.sailboatowners.com/in...light=windlass

Your emphasis on a second bank for redundancy to me is like a twin-engine pilot's love of his second engine. I respect that, and respect that you're able to utilize your system. But, with respect, I think you must recognize that the 'cons' of the dual-bank system is what bites people. That redundancy is as much a liability as it is an asset in hands of a typical user.

I'm not advocating that one system is less likely to leave you stranded than the other (referring to the only metric that counts). I AM saying that one system is ordinarily more complicated and potentially finicky to operate, such that when someone walks in the door asking about which system should be used...it makes more sense to advocate for the simple system....whereas you advocated for the more complex system.

Agreed.

As I said a few posts ago both have pros and cons. Depending how familiar you are and like to operate and which system attributes are important to you.

Yes I agreed with another posters opinion of the twin engine safety reality. However in that analogy you missed my point that statistically most aircraft engine failures are caused by 'air contamination' in the fuel tanks. That factor doesnt matter how many engines you have because there is only one fuel system. So your use of that analogy doesnt follow.

Batteries are our energy storage resorvior. So in my opinion is more comparable again to our fuel system. But more often in boats the issue is stirred up sediment in our fuel as opposed to running out.

So although we only have one fuel system we can get dual parallel filters.

So it sounds like you are now agreeing with what I am saying. Try not to make it a habit.

[Singularity]

Originally Posted by Q Xopa

Agreed.

As I said a few posts ago both have pros and cons. Depending how familiar you are and like to operate and which system attributes are important to you.

Yes I agreed with another posters opinion of the twin engine safety reality. However in that analogy you missed my point that statistically most aircraft engine failures are caused by 'air contamination' in the fuel tanks. That factor doesnt matter how many engines you have because there is only one fuel system. So your use of that analogy doesnt follow.

Batteries are our energy storage resorvior. So in my opinion is more comparable again to our fuel system. But more often in boats the issue is stirred up sediment in our fuel as opposed to running out.

So although we only have one fuel system we can get dual parallel filters.

So it sounds like you are now agreeing with what I am saying. Try not to make it a habit.

The problem with your assertion, and why the airplane analogy apparently isn't working, is that it's not correct to say that the increased death rate in twins is accounted for by an increased incidence of fuel starvation. Rather, the extra engine "redundant for safety" basically doubles the risk of an engine failure due to mechanical reasons, and when such failures occur, the pilot may not have the ability to salvage the situation (either because of environmental factors or piloting skills). It is these un-salvageable failures that provides the fatality increase in twins to make the twin just as likely to kill you as the single.

Over the decades in the aviation world most pilots have come on-board with the "single engine is just as safe" position, while the twin advocates still exist. I think it fair to say that the former group tends to appreciate all the metrics better, while the latter group are either pros who know the deal, or, are more likely to be a statistic in the making.

I recognize that it's pointless to try to convert anyone, but I'm just typing this out to provide an opinion for others who are considering the merits of one approach vs the other...that redundancy should not out of hand be expected to increase safety/survivability. Sometimes it's more complicated than that.

[Q Xopa]

Originally Posted by Singularity

The problem with your assertion, and why the airplane analogy apparently isn't working, is that it's not correct to say that the increased death rate in twins is accounted for by an increased incidence of fuel starvation. Rather, the extra engine "redundant for safety" basically doubles the risk of an engine failure due to mechanical reasons, and when such failures occur, the pilot may not have the ability to salvage the situation (either because of environmental factors or piloting skills). It is these un-salvageable failures that provides the fatality increase in twins to make the twin just as likely to kill you as the single.

Over the decades in the aviation world most pilots have come on-board with the "single engine is just as safe" position, while the twin advocates still exist. I think it fair to say that the former group tends to appreciate all the metrics better, while the latter group are either pros who know the deal, or, are more likely to be a statistic in the making.

I recognize that it's pointless to try to convert anyone, but I'm just typing this out to provide an opinion for others who are considering the merits of one approach vs the other...that redundancy should not out of hand be expected to increase safety/survivability. Sometimes it's more complicated than that.

Ok I didnt bring up the twin engine analogy.

But Im sure youre right. I will assume you are correct.

[Q Xopa]

Originally Posted by Q Xopa

Ok I didnt bring up the twin engine analogy.

But Im sure youre right. I will assume you are correct.

Actually reading your post a bit closer. Except for say that I said 'an increased rate of fuel starvation'. That was not what I was saying. What was saying is that fuel starvation is more common than engine failures.

I agree with what you are saying and I didnt say anything in opposition. You have thrown in a few more points to back up your position, but it sounds to me we are on the same page.

Im happy to not continue arguing for the same side.

Or shall I just say youre right and I agree.

[Singularity]

All told, I basically agree with you. My beef is that, from my perspective, the auxillary/ACR system is more complicated to install, perhaps more expensive, perhaps more prone to operator error than the alternative, all with ultimately no net reduction in catastrophic failure of the battery power system vs the one bank/echo charger to start battery alternative.

The evidence to support my claim about the increased relative complexity of the auxillary/ACR approach is the many, many threads started by people popping up asking how to wire it....vs like no one asking how to wire the one bank/echo charger system.

The evidence to support my claim that ultimately the failure rate between the two systems is the same is...weak. From the auxillary/ACR camp you read lots of stories of people frying this/that, inadvertently draining both banks, whatever. You rarely hear of people with a one-bank/echo charger telling such stories. For sure there must be a selection bias...where auxillary/ACR-type boats are more prevalent, you'd expect to hear of more problems with those boats. But when you stand back and review the whole situation in 2019...from my perspective...unless someone is going to Patagonia or visit Santa or something...the average cruiser is just as well served by the big-bank/echo charger system. This is particularly true, I think, when the cruiser has solar/generators to provide limp capability to replace the one-bank system (should it fail for whatever reason).

[Q Xopa]

Originally Posted by Singularity

All told, I basically agree with you. My beef is that, from my perspective, the auxillary/ACR system is more complicated to install, perhaps more expensive, perhaps more prone to operator error than the alternative, all with ultimately no net reduction in catastrophic failure of the battery power system vs the one bank/echo charger to start battery alternative.

The evidence to support my claim about the increased relative complexity of the auxillary/ACR approach is the many, many threads started by people popping up asking how to wire it....vs like no one asking how to wire the one bank/echo charger system.

The evidence to support my claim that ultimately the failure rate between the two systems is the same is...weak. From the auxillary/ACR camp you read lots of stories of people frying this/that, inadvertently draining both banks, whatever. You rarely hear of people with a one-bank/echo charger telling such stories. For sure there must be a selection bias...where auxillary/ACR-type boats are more prevalent, you'd expect to hear of more problems with those boats. But when you stand back and review the whole situation in 2019...from my perspective...unless someone is going to Patagonia or visit Santa or something...the average cruiser is just as well served by the big-bank/echo charger system. This is particularly true, I think, when the cruiser has solar/generators to provide limp capability to replace the one-bank system (should it fail for whatever reason).

No arguement from me.
Sounds like you got it all sorted.

[Q Xopa]

Originally Posted by Singularity

All told, I basically agree with you. My beef is that, from my perspective, the auxillary/ACR system is more complicated to install, perhaps more expensive, perhaps more prone to operator error than the alternative, all with ultimately no net reduction in catastrophic failure of the battery power system vs the one bank/echo charger to start battery alternative.

The evidence to support my claim about the increased relative complexity of the auxillary/ACR approach is the many, many threads started by people popping up asking how to wire it....vs like no one asking how to wire the one bank/echo charger system.

The evidence to support my claim that ultimately the failure rate between the two systems is the same is...weak. From the auxillary/ACR camp you read lots of stories of people frying this/that, inadvertently draining both banks, whatever. You rarely hear of people with a one-bank/echo charger telling such stories. For sure there must be a selection bias...where auxillary/ACR-type boats are more prevalent, you'd expect to hear of more problems with those boats. But when you stand back and review the whole situation in 2019...from my perspective...unless someone is going to Patagonia or visit Santa or something...the average cruiser is just as well served by the big-bank/echo charger system. This is particularly true, I think, when the cruiser has solar/generators to provide limp capability to replace the one-bank system (should it fail for whatever reason).

PS I cant see where u at or wot boat u got?