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Post by kris on Jan 15, 2020 11:16:44 GMT
Sterling do the AtoB (alternator to battery) as well as the B2B you mention above. The B2B would I think do the job, though I'm not a fan of Sterling stuff. But at quite a price if you want one that can pump a reasonable amount of current out. The A to Bs are cheaper but, while I can't be sure, I suspect that they only boost the voltage, they cant reduce it. So you would need a basic alternator regulator voltage down at say 13.6 and use the A2B to increase it. I am fairly sure an AtoB can't say reduce 14.4v output to 13.6v. All of which is of course why I am designing my own alternator controller - long term project though.
No I disagree that the same low disconnect argument applies to LA. LA batteries make it obvious they are getting flat - light go dim over a prolonged period. Whereas LiFePO4 hold up and are fine - right until the moment the voltage crashes. And anyway, fully discharging a LA battery, whilst bad for it, isnt catastrophic. Fully discharging a LiFePO4 battery is catastrophic. As borne out by the fact that drop in LiFePO4 replacements have low voltage cut off whereas I don't think any or many LA installations have it.
I’m not sure these bits of sterling kit do the job either, no where in their literature do they mention lithium batteries.
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Post by Deleted on Jan 15, 2020 11:20:15 GMT
On the force4 details page from JohnV link above. • 9 Pre-set battery chemistry options including AGM, LiFePO4, Gel, flooded & sealed lead acid Slightly intrigued what the other 4 are !!
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Post by Telemachus on Jan 15, 2020 11:32:28 GMT
Sterling do the AtoB (alternator to battery) as well as the B2B you mention above. The B2B would I think do the job, though I'm not a fan of Sterling stuff. But at quite a price if you want one that can pump a reasonable amount of current out. The A to Bs are cheaper but, while I can't be sure, I suspect that they only boost the voltage, they cant reduce it. So you would need a basic alternator regulator voltage down at say 13.6 and use the A2B to increase it. I am fairly sure an AtoB can't say reduce 14.4v output to 13.6v. All of which is of course why I am designing my own alternator controller - long term project though.
No I disagree that the same low disconnect argument applies to LA. LA batteries make it obvious they are getting flat - light go dim over a prolonged period. Whereas LiFePO4 hold up and are fine - right until the moment the voltage crashes. And anyway, fully discharging a LA battery, whilst bad for it, isnt catastrophic. Fully discharging a LiFePO4 battery is catastrophic. As borne out by the fact that drop in LiFePO4 replacements have low voltage cut off whereas I don't think any or many LA installations have it.
I’m not sure these bits of sterling kit do the job either, no where in their literature do they mention lithium batteries. They do have a LiFePO4 setting, although the voltages seem rather high. Not sure about the A2B but the B2B has a custom setting that you can set to what you like. So I think it would work, but the cost is very high if you want a reasonably high charge current. With that much cost, you might be better off buying the programmable regulator (ex-hobby design, now being sold commercially). www.wakespeed.com/products.htmlBut very expensive, which is why I’m designing my own.
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Post by kris on Jan 15, 2020 11:41:00 GMT
I’m not sure these bits of sterling kit do the job either, no where in their literature do they mention lithium batteries. They do have a LiFePO4 setting, although the voltages seem rather high. Not sure about the A2B but the B2B has a custom setting that you can set to what you like. So I think it would work, but the cost is very high if you want a reasonably high charge current. With that much cost, you might be better off buying the programmable regulator (ex-hobby design, now being sold commercially). www.wakespeed.com/products.htmlBut very expensive, which is why I’m designing my own. that’s no cheaper especially as I would need two. It’s very difficult to know what to do.
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Post by Deleted on Jan 15, 2020 11:46:36 GMT
I reckon sticking with Lead Acid is the way to go.
For low consumers anyway.
My superyot is going to be residential off grid and it will have one 110ah leisure charged by engines, a single 80w solar panel and a 300w wind turbine manually switched on and off.
That'll do. No fridge on there but there is a cool box for when engine(s) running.
It does come down to how much domestic comfort you are after. Personally I've always been into minimal use of power but no candles so a 12v system is needed. Actually most of the lighting is now running off USB as is phone charger. Water pumps are 12v though.
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Post by Telemachus on Jan 15, 2020 12:07:06 GMT
They do have a LiFePO4 setting, although the voltages seem rather high. Not sure about the A2B but the B2B has a custom setting that you can set to what you like. So I think it would work, but the cost is very high if you want a reasonably high charge current. With that much cost, you might be better off buying the programmable regulator (ex-hobby design, now being sold commercially). www.wakespeed.com/products.htmlBut very expensive, which is why I’m designing my own. that’s no cheaper especially as I would need two. It’s very difficult to know what to do. Do you have solar? Can’t remember. If plenty of solar that presumably does you for most of the year? Solar controllers are generally programmable for different battery types including LiFePO4 or a custom setting. Other folk have kept a LA battery in circuit with the alternator, they can then isolate the Li battery if it is getting overcharged when cruising. Something like a BG-8S is adequate for cell monitoring (dirt cheap). Because the Li battery discharges at a higher voltage, if the Li and LA batteries are in parallel, most of the discharge occurs from the Li and only towards the end does the LA start to discharge a bit.
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Post by kris on Jan 15, 2020 12:39:09 GMT
that’s no cheaper especially as I would need two. It’s very difficult to know what to do. Do you have solar? Can’t remember. If plenty of solar that presumably does you for most of the year? Solar controllers are generally programmable for different battery types including LiFePO4 or a custom setting. Other folk have kept a LA battery in circuit with the alternator, they can then isolate the Li battery if it is getting overcharged when cruising. Something like a BG-8S is adequate for cell monitoring (dirt cheap). Because the Li battery discharges at a higher voltage, if the Li and LA batteries are in parallel, most of the discharge occurs from the Li and only towards the end does the LA start to discharge a bit. yes I’ve got solar and my controller is programmable, so that is most of the year sorted. I have battery chargers with lifepo4 functions so generator charging is taken care of. But I’d like to bulk charge in winter from alternators, obviously get battery charging when cruising as well. I have two 75amp alternators not fitted yet and I bought a sterling split charge relay that’s not fitted yet. I do have a lead acid starter battery that I use for my diesel generator and main engine.
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Post by kris on Jan 15, 2020 12:41:15 GMT
I reckon sticking with Lead Acid is the way to go. For low consumers anyway. My superyot is going to be residential off grid and it will have one 110ah leisure charged by engines, a single 80w solar panel and a 300w wind turbine manually switched on and off. That'll do. No fridge on there but there is a cool box for when engine(s) running. It does come down to how much domestic comfort you are after. Personally I've always been into minimal use of power but no candles so a 12v system is needed. Actually most of the lighting is now running off USB as is phone charger. Water pumps are 12v though. unfortunately I have a workshop and music studio aboard, that I like to use now and again. But no I don’t have a fridge or washing machine and my daily domestic use is very low. I live as low an impact lifestyle as possible, without falling into aseteticism if I can help it. In fact I’d like a few more creature comforts at some stage.
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Post by Deleted on Jan 15, 2020 23:09:53 GMT
I need confirmation I'm right in my math. My 34w tv uses 66ah going through an inverter?
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Post by Deleted on Jan 15, 2020 23:21:16 GMT
I need confirmation I'm right in my math. My 34w tv uses 66ah going through an inverter? If it's a 34w TV then at 12v it is drawing about 3 amps per hour from your batteries. However as the inverter is stepping the voltage up to 240c and your TV is stepping it back down to something like 12v again there will be inefficiencies. So your TV is probably drawing 3-4 amps per hour from your batteries.
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Post by Telemachus on Jan 15, 2020 23:22:21 GMT
I need confirmation I'm right in my math. My 34w tv uses 66ah going through an inverter? 34w is presumably what it says on the label on the back? That’s likely to be the absolute maximum power with full brightness, full volume etc. Normal power consumption is likely to be less But let’s presume its correct. Taking into account inverter efficiency can be done by assuming the voltage is 10v and thus the current is 3.4A. So 3.4Ah for each hour it is on. If it is on 24 hrs a day that would be 81.6Ah. But presuming a more normal 4 hrs a day, that would be 13.6Ah a day.
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Post by Telemachus on Jan 15, 2020 23:25:17 GMT
I need confirmation I'm right in my math. My 34w tv uses 66ah going through an inverter? If it's a 34w TV then at 12v it is drawing about 3 amps per hour from your batteries. However as the inverter is stepping the voltage up to 240c and your TV is stepping it back down to something like 12v again there will be inefficiencies. So your TV is probably drawing 3-4 amps per hour from your batteries. “3 amps per hour” is a meaningless statement.
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Post by Deleted on Jan 15, 2020 23:28:03 GMT
I need confirmation I'm right in my math. My 34w tv uses 66ah going through an inverter? 34w is presumably what it says on the label on the back? That’s likely to be the absolute maximum power with full brightness, full volume etc. Normal power consumption is likely to be less But let’s presume its correct. Taking into account inverter efficiency can be done by assuming the voltage is 10v and thus the current is 3.4A. So 3.4Ah for each hour it is on. If it is on 24 hrs a day that would be 81.6Ah. But presuming a more normal 4 hrs a day, that would be 13.6Ah a day. Ok. So tonight I've had it on for 2 hrs, along with my fridge freezer. The bmv says I have used 17.6 amps, and my voltage reading from a separate meter says 12.52. The full charge finished at 8pm. I'm assuming my trojans are on the way out?
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Post by Deleted on Jan 15, 2020 23:31:40 GMT
Everything is switched off now, and the volt reading is 12.56.
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Post by Deleted on Jan 15, 2020 23:38:47 GMT
If it's a 34w TV then at 12v it is drawing about 3 amps per hour from your batteries. However as the inverter is stepping the voltage up to 240c and your TV is stepping it back down to something like 12v again there will be inefficiencies. So your TV is probably drawing 3-4 amps per hour from your batteries. “3 amps per hour” is a meaningless statement. Why? 1ah is equivalent to 1 amp of current flowing for 1 hour.
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