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Post by Deleted on Oct 25, 2020 15:20:12 GMT
To Tony: An easy start. Buy a multimeter. There's plenty on the web about how to use it. Don’t buy a normal multimeter, buy a DC clamp meter (that also does voltage, of course). Can you use that device to test the efficacy of the alternator?
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Post by Deleted on Oct 25, 2020 15:22:18 GMT
I don't use fridges but for next summer I am going to have a small ice maker which will run as and when on excess solar power. It's handy to have something cold but a fridge on all the time is wrong approach on an off grid boat in my opinion. A fridge uses about 35Ah in 24 hrs, which doesn’t seem a lot to me. Once I get my lovely Lithiums installed, and with our power generation capability, that equates to about 15 mins engine running time per day, which I would say is well worth the ability to have ice and Magnums instantly available, chilled Cava, Peroni etc. I understand this and yes it is a sensible solution for some people. I have lithium batteries as well now and a kilowatt of solar but the latest boat, which will at some point be the only one, is not really big enough to have a fridge and I am anti fridges on boats in general. I also crave minimal space so will deliberately choose a small volume vessel over a larger one. I can see that efficiency-wise a fridge makes sense yes and if you like your luxuries. I partly live on a boat because I specifically do not want too many luxuries and feel the need to make it reasonably uncomfortable otherwise it all goes wrong. An ice maker does seem reasonable and not too much of a luxury to cause it to all go wrong. It's a caveman thing. The kilowatt of solar may sound cutting edge but most of that is going to go towards auxiliary electric propulsion rather than chocolate flavoured lollies. Beer is acquired daily via the Beer Acquisition Protocol. No alcohol stored on boat. Happy to eat worms and gruel so no need for a fridge there.
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Post by Deleted on Oct 25, 2020 15:27:00 GMT
But of course with lead acid batteries you can be limited by what the batteries will take. We have a 100A charger built into the Combi and a 175A alternator. But the LA batteries can’t take that sort of current. But the lithiums will be able to, so I should be able to charge at 275A at least for a while (before the alternator gets too hot) so to put in 35 Ah (1 fridge-day) should only take 8 minutes of engine running time. That will be interesting ! I'm sure you will but please keep us updated on this. I wonder how the belts will deal with it. Beta usually put a poly vee belt on the large alternator so it should be ok. I could see the alternator getting quite hot in this situation but I suppose if the engine room is well ventilated it should be ok. Interesting times with these lithiums which can take high C rate charge currents.
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Post by Telemachus on Oct 25, 2020 16:03:02 GMT
But of course with lead acid batteries you can be limited by what the batteries will take. We have a 100A charger built into the Combi and a 175A alternator. But the LA batteries can’t take that sort of current. But the lithiums will be able to, so I should be able to charge at 275A at least for a while (before the alternator gets too hot) so to put in 35 Ah (1 fridge-day) should only take 8 minutes of engine running time. That will be interesting ! I'm sure you will but please keep us updated on this. I wonder how the belts will deal with it. Beta usually put a poly vee belt on the large alternator so it should be ok. I could see the alternator getting quite hot in this situation but I suppose if the engine room is well ventilated it should be ok. Interesting times with these lithiums which can take high C rate charge currents. Yes there is a polyvee belt for each of the domestic alternator and the travelpower. 100A is only about 1.4kw which is well within the capabilities of the 3.5 kw travelpower even at idle. The Iskra alternator does prefer to be spinning at normal cruise rpm (1300 or so) when giving its full output. I have installed a temperature sensor which will reduce the alternator output if it gets too hot, so the exact maximum output into the Lithiums will depend on engine bay temperature, rpm, how long it has been running etc.
We routinely use the tumble drier (2kw) and electric kettle (2kw) and the domestic alternator typically charges at 150A or more when first started, and the polyvee belts have currently done around 2000 hours and barely ever need adjusting so I don't think they will be an issue.
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Post by ianali on Oct 25, 2020 16:22:51 GMT
On the subject of drive belts. The chap that sorted out our new alternator tensioned the belt, far tighter than i tension. I think I worry about over tightening, comes from years of owning lotus cars, and all the problems associated with over tight belts. I’ve always thought that if you don’t hear them slipping, then all is well. Anyway, new alternator is a marked improvement on the last one. I think that one had been struggling for some time.
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Post by Telemachus on Oct 25, 2020 16:24:27 GMT
Don’t buy a normal multimeter, buy a DC clamp meter (that also does voltage, of course). Can you use that device to test the efficacy of the alternator? Yes, you can use it to measure the output of the alternator. If the alternator is loaded up (flat batteries, or a heavy load from some cabin service), and if it is spinning fast enough, you would expect the alternator to make its badged output if it is working properly.
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Post by Telemachus on Oct 25, 2020 16:34:29 GMT
600 Ah at 12v. Well, with lithiums you get more like 13v. I think those power monitoring gadgets are reasonably accurate, after all you don’t really need great accuracy. Yes you can supplement battery charging with a Travelpower and charger. We have a Combi so any time the TravelPower is on, the Combi is in charger mode. But of course with lead acid batteries you can be limited by what the batteries will take. We have a 100A charger built into the Combi and a 175A alternator. But the LA batteries can’t take that sort of current. But the lithiums will be able to, so I should be able to charge at 275A at least for a while (before the alternator gets too hot) so to put in 35 Ah (1 fridge-day) should only take 8 minutes of engine running time. Thank you. To be clear, we will be swapping to lithium. It's expensive initially but the convenience of quick charging alone makes it the obvious choice. Is it sensible in reality to hit them with 275A? You must have hefty wiring or you're pulling my leg. Lithiums are generally rated to be charged and discharged at 1C, which in my case would be 600A. So 275A is less than half that. We have shortish 75mm cable between the Combi and the batteries, and between the Alternator and the batteries, so yes there is no reason why I can't stuff in 275A. I currently see 175A going into the LA batteries for the first minute or two in the morning with my new alternator controller set to fast charge mode.
All that said, there is no point in stuffing 275A in if one is going to be cruising all day, hence the system will have slow and fast charge modes. Battery life is prolonged by avoiding fast charges and discharges - although battery life is so long that I'm not sure it matters too much! And when the engine is having to stuff in 275A it won't like doing so at idle eg when passing the endless lines of badly-moored boats!
So since we normally cruise for 6-8 hours most days, it will generally be left on slow charge, maybe 85A from the alternator plus 50A from the Combi if the travelpower is switched on. But if we are moored for several days, as sometimes happens, we will be able to flick the switch to fast charge and put a day's worth of charge (around 100 Ah in summer to 200Ah in winter) back, in less than an hour.
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Post by Clinton Cool on Oct 25, 2020 17:22:20 GMT
If I was going to carry on living on a boat I'd acquire the knowledge and fit lithiums. While it all seems a bit complicated (I read all the threads) I felt the same about lead acid battery behaviours and charging regimes when I moved aboard, it's fairly easy for me now, so I think gaining the knowledge is possible. I think these battery systems are fantastic, definitely the way to go if only to reduce the amount of droning diesel engines, hour after hour, just to produce a few amps of electricity.
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