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Post by Deleted on Jan 11, 2021 12:11:17 GMT
That's why they put BMS systems on batteries.
It's to stop arguments.
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Post by JohnV on Jan 11, 2021 12:38:51 GMT
You are worrying about how to get the maximum charge into the LI's ...... Why ? It's not an automotive problem where you have to be able to get the maximum charge otherwise you end up stranded on the M4 ..... It's a boat, getting to full charge is not something to bother with, if you buy the same Ah as you had in LA's and only charge them to 80% you will have more usable power than you would with fully charged LA's ..... not getting to maximum charge doesn't worry LI's and it certainly won't be noticed by the average boater, they will be getting more than they are used to without the cost and complexity you are introducing.
You are falling into one of the most common pitfalls for someone developing a new system .... is it actually needed? I was involved very slightly in the demise of the Step electronic guitar. It was an incredible bit of design but it suffered from creeping featurism ..... One very clever designer added a new sound when it was almost ready for production and was incensed when he was told he couldn't .. "but this makes it sound exactly like an acoustic classical guitar" and didn't get it when he was asked who is going to pay over a thousand quid for a ultra modern state of the art electronic guitar is going to care if it can also sound like a £50 plywood one.
I already gave you the cheap discharge limitation ...... the inverter .... and if that voltage is too low then simply use another one of those £7 modules to switch the inverter off via its remote switching facility ...... I was taught that an engineer is someone who can build something for £10 that any damned fool can build for a £100
You insist on looking for complicated technical answers to simple problems, a practical system uses simple answers and that gives good reliability. make something complicated and you just make more things that can go bang.
It's like the overheating alternators .... stick a high wattage low ohmage resistance in series, that will limit the current ..... job done for coppers.
Well I did say that perhaps the failing to be able to get to full charge might not be an issue, but you have chosen to focus on that one. An inverter is just one of many thing that drain boat batteries, so switching it off at low voltage is only a partial solution. And a partial solution is not a solution. You are doing an armchair scattergun thing. Propose an actual system with specific components and a wiring diagram, costed, and then we’ll be able to see if it has any merit. You should be quite capable of doing your own wiring diagram for the bits I've mentioned. You are wriggling.
You said the devices were not available, in 10 minutes of looking I found one. I have no need to hunt further because I don't need to, my method suits me for now. If I need a better system I will design one. I do not have an ego that insists that I show how clever I am and design one for everyone to admire.
You are trying to produce a RollsRoyce to replace a Tuk Tuk. It's incredible overkill and totally unnecessary.
The extra power drains on a battery system excluding the inverter are minimal. Anyone who continues to use power in quantity after they get a warning (if you want put a sounder on it as well) and doesn't either stop use or re-charges. deserves to suffer. (remember with an aditional module controlling the inverter you can set the drop out voltage to whatever you like)
You can protect fools but not damned fools.
A system for a boat should be basic and easily understood, it should be capable of repair by any moderately competent handyman and idealy use basic off the shelf parts that don't cost the earth.
We are not discussing something for a hire boat where people might not have a clue. This is a forum whose members have reasonable knowledge of boat systems and are used to dealing with the much greater intricacies of trying to get the maximum out of LA's ... compared to that LI's are simple, Ignore the maximums just run them in the middle bit and they will last for ages and you will have more power to play with.
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Post by Telemachus on Jan 11, 2021 12:57:26 GMT
Well I did say that perhaps the failing to be able to get to full charge might not be an issue, but you have chosen to focus on that one. An inverter is just one of many thing that drain boat batteries, so switching it off at low voltage is only a partial solution. And a partial solution is not a solution. You are doing an armchair scattergun thing. Propose an actual system with specific components and a wiring diagram, costed, and then we’ll be able to see if it has any merit. You should be quite capable of doing your own wiring diagram for the bits I've mentioned. You are wriggling.
You said the devices were not available, in 10 minutes of looking I found one. I have no need to hunt further because I don't need to, my method suits me for now. If I need a better system I will design one. I do not have an ego that insists that I show how clever I am and design one for everyone to admire.
You are trying to produce a RollsRoyce to replace a Tuk Tuk. It's incredible overkill and totally unnecessary.
The extra power drains on a battery system excluding the inverter are minimal. Anyone who continues to use power in quantity after they get a warning (if you want put a sounder on it as well) and doesn't either stop use or re-charges. deserves to suffer. (remember with an aditional module controlling the inverter you can set the drop out voltage to whatever you like)
You can protect fools but not damned fools.
A system for a boat should be basic and easily understood, it should be capable of repair by any moderately competent handyman and idealy use basic off the shelf parts that don't cost the earth.
We are not discussing something for a hire boat where people might not have a clue. This is a forum whose members have reasonable knowledge of boat systems and are used to dealing with the much greater intricacies of trying to get the maximum out of LA's ... compared to that LI's are simple, Ignore the maximums just run them in the middle bit and they will last for ages and you will have more power to play with. No it is you who is wriggling! Lots of people don’t even have an inverter on all the time, and they do have 12v fridges which present an inexorable drain on batteries. If you want to aim an “over complicated” shot at my system, that is fine and a lot of people would agree with you. Do you really need a custom smart alternator regulator with a display and a CANBUS interface to the rest of the boat’s systems? A custom BMS also with CANBUS and Ve.direct interfaces? And bespoke software that could only be altered by one person? No of course not. It is just my flight of fancy, and my hobby that has kept me out of trouble for the past year. It will be bloody good though! In the case of Tony, we are discussing adding a B2B to control charging. This deals with the problems of over charging and overheating the alternator in an efficient and complete way. I am pushing him towards a battery monitor so that he has a rough idea of how much juice is in his batteries, the sort of thing many other people have. And I have in the back of my mind that this device also has the capability to operate a device to disconnect the battery via a suitable disconnection device if, in the future, he decides he wants high and low voltage protection. This doesn’t seem particularly onerous or at odds with the sort of equipment that many people already have on their boats. But you don’t seem to like it, presumably because it isn’t what you have.
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Post by JohnV on Jan 11, 2021 13:08:25 GMT
You should be quite capable of doing your own wiring diagram for the bits I've mentioned. You are wriggling.
You said the devices were not available, in 10 minutes of looking I found one. I have no need to hunt further because I don't need to, my method suits me for now. If I need a better system I will design one. I do not have an ego that insists that I show how clever I am and design one for everyone to admire.
You are trying to produce a RollsRoyce to replace a Tuk Tuk. It's incredible overkill and totally unnecessary.
The extra power drains on a battery system excluding the inverter are minimal. Anyone who continues to use power in quantity after they get a warning (if you want put a sounder on it as well) and doesn't either stop use or re-charges. deserves to suffer. (remember with an aditional module controlling the inverter you can set the drop out voltage to whatever you like)
You can protect fools but not damned fools.
A system for a boat should be basic and easily understood, it should be capable of repair by any moderately competent handyman and idealy use basic off the shelf parts that don't cost the earth.
We are not discussing something for a hire boat where people might not have a clue. This is a forum whose members have reasonable knowledge of boat systems and are used to dealing with the much greater intricacies of trying to get the maximum out of LA's ... compared to that LI's are simple, Ignore the maximums just run them in the middle bit and they will last for ages and you will have more power to play with. No it is you who is wriggling! Lots of people don’t even have an inverter on all the time, and they do have 12v fridges which present an inexorable drain on batteries. You earlier mentioned a simple latch out device for that kind of problem uk.rs-online.com/web/p/latching-relays/5111032/
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Post by Telemachus on Jan 11, 2021 13:24:37 GMT
No it is you who is wriggling! Lots of people don’t even have an inverter on all the time, and they do have 12v fridges which present an inexorable drain on batteries. You earlier mentioned a simple latch out device for that kind of problem uk.rs-online.com/web/p/latching-relays/5111032/That relay is a pulse off pulse on. It isn’t suitable because it could get out of sync and anyway you need a pulsed source to operate it. The Tyco relay I mentioned earlier has 2 coils, one for off and one for on, but again it needs to be pulse-driven. Which is why my BMS has a small section devoted to driving one of them. Unfortunately you can’t drive a pulsed relay from a level switch eg a BMV battery monitor.
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Post by JohnV on Jan 11, 2021 13:29:27 GMT
an c/o contact, centre to positive each arm a tant. cap and Mohm drain resistor and series diode was the way we used to use them
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Post by Deleted on Jan 11, 2021 13:41:14 GMT
...
We are not discussing something for a hire boat where people might not have a clue...
This is an interesting point. I'm going to be taking a few holidays next year or the year after, depending on virus restrictions, and I've rashly promised a few family members that they can borrow my boat for a few weeks' holiday- and a couple of them seem interested. So at the back of my mind is the thought that whatever automatic safeguards, manual checks or other measures I build into the electrical system might need to be explainable to a novice in half an hour. The tutorial will start with this motivational speech: "Right, in here are the batteries. If these get broken, it will cost you about £2000 to buy new ones. If you follow these instructions, you'll avoid breaking them...." Letting complete novices borrow your boat for a fortnight is not a very common situation, but it might be one I have to deal with, if I follow through on my offer.
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Post by JohnV on Jan 11, 2021 13:51:01 GMT
a brave man letting novices loose on your pride and joy ..... a very brave man
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Post by Telemachus on Jan 11, 2021 13:52:13 GMT
...
We are not discussing something for a hire boat where people might not have a clue...
This is an interesting point. I'm going to be taking a few holidays next year or the year after, depending on virus restrictions, and I've rashly promised a few family members that they can borrow my boat for a few weeks' holiday- and a couple of them seem interested. So at the back of my mind is the thought that whatever automatic safeguards, manual checks or other measures I build into the electrical system might need to be explainable to a novice in half an hour. The tutorial will start with this motivational speech: "Right, in here are the batteries. If these get broken, it will cost you about £2000 to buy new ones. If you follow these instructions, you'll avoid breaking them...." Letting complete novices borrow your boat for a fortnight is not a very common situation, but it might be one I have to deal with, if I follow through on my offer. You are brave! When Jeff and I bought Telemachus one of the first things we discussed was that we would under no circumstances ever lend the boat to anyone else, with the exception of my mate Chris, who had lent us his boat for 2 weeks a year for about 15 years ( we couldn’t really say no to that!). I can’t imagine that Wilson will be impressed!
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Post by Telemachus on Jan 11, 2021 14:10:57 GMT
an c/o contact, centre to positive each arm a tant. cap and Mohm drain resistor and series diode was the way we used to use them You can do that but in the case of the flip flop relay you posted, it could get out of sync. In the case of the Tyco relay it needs 3A for 50-100mS so that is one pretty huge capacitor, and of course the waveform would be asymptotic not square. And you have the holding current of the relay used to drive the bistable relay to consider when it is in one of its states. A brute force way of doing it as would be designed by a ... (you get the picture). Whereas in my case I have a microprocessor driving one small MOSFET for switching on, and one for switching off, giving a waveform exactly as the relay manufacturer intended. All very small, neat, elegant and cheap.
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Post by kris on Jan 11, 2021 14:35:43 GMT
It's like the overheating alternators .... stick a high wattage low ohmage resistance in series, that will limit the current ..... job done for coppers.
This. Is the solution I favour for the alternators although I’ve read some where 13.9 might be to high for constant charging and maybe 13.7-13.8 might be better. But best get them set up first then sort that out.
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Post by JohnV on Jan 11, 2021 14:37:05 GMT
an c/o contact, centre to positive each arm a tant. cap and Mohm drain resistor and series diode was the way we used to use them You can do that but in the case of the flip flop relay you posted, it could get out of sync. In the case of the Tyco relay it needs 3A for 50-100mS so that is one pretty huge capacitor, and of course the waveform would be asymptotic not square. And you have the holding current of the relay used to drive the bistable relay to consider when it is in one of its states. A brute force way of doing it as would be designed by a ... (you get the picture). Whereas in my case I have a microprocessor driving one small MOSFET for switching on, and one for switching off, giving a waveform exactly as the relay manufacturer intended. All very small, neat, elegant and cheap. When I said it was the method we used, I mean a method that was used on several custom built units, I do not recall any complaints as regards things getting out of sync on any of them. It worked and worked well, the relays concerned were actually GE DIN rail relays very simillar to the one in the RS catalogue.
A relay is not particularly critical about the waveform that you feed it .... it either is good enough or not .... that method was good enough. To be honest if it ever did get out of sync, it would be fairly obvious and could be reset by simply turning off and back on again the control driving it. as regards your method of drive certainly it's fine but you do realise that your one small MOSFET would just as happily drive the relay I described
just to add .... the reason I was using a c/o relay contact as the drive was because that is what the module from ebay uses as one of it's outputs
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Post by Deleted on Jan 11, 2021 14:40:41 GMT
I'd like to have a manual option so my little red isolator switch with an actuator which itself is wired via the isolator switch is ideal. Use the BMV output to drive the actuator until it has turned the switch off. Then the actuator will stop. Manual reset and manual override option. Simple really. The idea is that you don't let this situation occur anyway so it would just be an in case backup rather than something one would expect to work. Worth also having an on/off/on electric windows type switch to reset the actuator and do testing. Provided you have a supply available based on a high voltage trigger, which I think the BMV does, then it would probably only be about £20/£30. A 750N actuator would be a bit over the top but also quite nice. £22 for the actuator less than a tenner for the isolator switch. www.ebay.co.uk/itm/750N-Linear-Actuator-12V-DC-4-Stroke-Motor-Heavy-Duty-Electric-Window-Opener-UK-/333795236248 Build a framework out of Meccano and Bob is your non gender specific aunt.
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Post by JohnV on Jan 11, 2021 14:51:38 GMT
I like simple engineering
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Post by Deleted on Jan 11, 2021 14:55:43 GMT
I like linear actuators.
Excellent toys.
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