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Post by kris on Oct 9, 2020 16:16:22 GMT
Anybody got any ideas for a relay/low voltage cut out?
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Post by JohnV on Oct 9, 2020 17:31:00 GMT
Anybody got any ideas for a relay/low voltage cut out?
Looks klike it should do what you want but I must admit that the instructions look a bit confuscubating but it's cheap enough that if you do lose your rag trying to get it to do what you want then you can always throw it overboard
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Post by kris on Oct 9, 2020 19:12:33 GMT
Anybody got any ideas for a relay/low voltage cut out?
Looks klike it should do what you want but I must admit that the instructions look a bit confuscubating but it's cheap enough that if you do lose your rag trying to get it to do what you want then you can always throw it overboard
I think I’ll just throw it overboard when it arrives. It does look complicated to program. But thanks for the suggestion I’ll have a read through.
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Post by lollygagger on Oct 9, 2020 19:34:02 GMT
Looks klike it should do what you want but I must admit that the instructions look a bit confuscubating but it's cheap enough that if you do lose your rag trying to get it to do what you want then you can always throw it overboard
I think I’ll just throw it overboard when it arrives. It does look complicated to program. But thanks for the suggestion I’ll have a read through. I don't think I'd want to trust the health of expensive batteries to that either. Following with interest, we plan to go this route when more confident and you can't beat real life examples.
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Post by kris on Oct 9, 2020 19:46:32 GMT
I think I’ll just throw it overboard when it arrives. It does look complicated to program. But thanks for the suggestion I’ll have a read through. I don't think I'd want to trust the health of expensive batteries to that either. Following with interest, we plan to go this route when more confident and you can't beat real life examples. you can’t trust the low voltage cutout in inverters either. I’ve got two here now that don’t cut out when they should. To be fair ones been on pretty much constantly for 12 years. But the other one is a s/h victron I bought this year.I must check the settings in the victron before condemning it completely. I’m beginning to think what have I got myself into? Just when I think I’ve found a solution that works for me, it evaporates into thin air. Oh well such is life I suppose. I’ve got three grand in batteries just sat,I did want to get the most out of the lead acids before I got rid though.
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Post by Deleted on Oct 9, 2020 20:23:18 GMT
I know it wouldn't sort it completely but one possible option could be to wire a VSR so that it dials your phone in the event of batteries going a bit low.
If you were there you could monitor or disconnect manually.
For the cellphone part you could either take apart an older type phone and solder to the pads under the number after programming the speed dial or if you don't want to look like a terrorist you could buy a GSM dialler device.
There used to be some excellent toys on a site called pocketdiallers but they seem to have disappeared.
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Post by Telemachus on Oct 9, 2020 20:24:40 GMT
Well of course the Tyco BDS-A bistable relay is a pretty good solution, and one which I am using, however operating it is not straightforward since you can only apply the voltage to the relay coils for a few hundred milliseconds, or it will overheat the coil. If it was going to be operated from the BMV you would need some electronics between the BMV and the relay to make the permanent operation of the relay into a 250mS pulse to the Tyco.
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Post by kris on Oct 9, 2020 20:25:58 GMT
It’s the “some electronics,” bit I have problems with.
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Post by Deleted on Oct 9, 2020 20:34:56 GMT
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Post by kris on Oct 14, 2020 18:56:03 GMT
Sorry to keep troubling you nick but I’ve been thinking if the over voltage on the input side is taken care of by the mppt for solar and battery charger for top up. Would the 250 amp relay controlled by bmv but just for low voltage cut out be any good?
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Post by Telemachus on Oct 15, 2020 17:51:08 GMT
Sorry to keep troubling you nick but I’ve been thinking if the over voltage on the input side is taken care of by the mppt for solar and battery charger for top up. Would the 250 amp relay controlled by bmv but just for low voltage cut out be any good? There is no “right answer” to any of this - there are many ways to skin the cat! My opinion is that the purpose of these sorts of relay is to cater for an unexpected or fault condition. Which can feasibly be both undervoltage (put simply, using too much power compared to what is put back, due to leaving something on, solar or charger fault) or overvoltage (fault with charging device resulting in it giving too much charge). Neither are likely, but then again the consequences of either is severe. Hence the emergency disconnect relay! If you are going to have one, I can’t see why you wouldn’t want to use it to protect for both over and undervoltage. In this specific case that means connecting the BMV NO and COM terminals to the relay Remote and Minus terminals. You then simply programme the appropriate maximum and minimum allowed voltages into the BMV, and the BMV relay will operate if the battery voltage goes outside these limits, turning off the 250A relay. Of course if the relay operates when the solar is charging, there is a good chance that it might blow the solar controller, so you will have to decide which is the priority - protecting the battery or protecting the solar controller. All of this is not ideal because you are not monitoring individual cell voltages, therefore the max and min voltages need to have a significant safety margin to allow for cell imbalance.
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Post by Deleted on Oct 27, 2020 22:03:33 GMT
Reading this thread again, I'm also being bitten by the Lithium bug. In fact I'm getting tempted to buy this year, rather than wait till my LA batteries expire. The advantages sound very appealing, particularly for winter boating when there is not much solar. The big one for me is that even on my canaline 38 with its 50 amp alternator, I could probably put in a day's worth of charge within 90 mins, even in winter, instead of having to run the engine for 3 or more hours for that last float part of the charge. And its no bother if you only charge to say 60% or 80% most days. I was going to wait a couple of years till my current batteries start to tire, but given that lithiums will last for the full length of time I'll have the boat either way, and given how much engine running time they will save me over the next two years, I'm thinking there are real benefits in buying now, rather than wait. I have 3 x 100ah batteries, so about 150ah that is usable charge. I could replace that with a single 200ah lithium battery- something like this: www.amazon.co.uk/gp/product/B088RM4W48/ref=ox_sc_act_title_2?smid=A3NTIDJ3MRQUN3&psc=1
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Post by Deleted on Oct 28, 2020 7:36:55 GMT
Quite interesting googling "amperetime" which is the branding on the £1200 200ah LFP battery in the link.
It seems they have some lofty ambitions.
From the website:
"ABOUT US
23 Technological progress is the human civilization towards a higher civilization Hengda power, but also our unswerving faith and pursuit. We explore the biology of the depth of learning in the field of innovation and development, is committed to the future of science and technology can bring all the good, create a safe and intelligent ideal world. "
"Our Solution. It has survived not only five centuries, but also the leap scra"
Interesting !
"All rights reserved: Fashion Women Co., Ltd. 京 ICP 备: 00000000 号 Powered by XX network"
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Post by Deleted on Oct 28, 2020 7:52:49 GMT
It often strikes me as odd that having put so much effort and resource into producing electronic devices, a good number of the Chinese manufacturers are then content to allow some very expensive products to be advertised in an English-speaking market using very poor translations (the same happens in the US and elsewhere). There are risks involved, of course. Poorly translated advertising copy might mean you are less likely to get a positive outcome in the event of communicating the details of a faulty product, or when chasing replacement parts etc. But for me, those risks are often reflected in the price, and to has to be said that the cost of UK based distributors and other support can add hundreds to the price- so you pays your money and takes your gamble, I guess... But here is another example- a 200ah lithium battery with a built-in BMS (of some sort) for under £700: www.amazon.co.uk/gp/product/B07SQ7BJ5X/ref=ox_sc_saved_title_1?smid=A2G7VUT3A5U4WF&psc=1When you think that you'd need at least 300ah of lead acid or even lead carbon as an alternative, it starts to look very tempting indeed- at least to the uninitiated like me.
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Post by Deleted on Oct 28, 2020 8:02:50 GMT
That one looks interesting and certainly very cheap !
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