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Post by kris on Aug 15, 2022 17:12:07 GMT
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Post by Telemachus on Aug 15, 2022 17:12:11 GMT
What kind of switch would I need to be able to switch between the lithium’s and lead acid whilst the alternator is spinning? I’m going to set this up on my engine as I think it will be the most economical way to charge my batteries in winter. I was let down by the kipor and my diesel generator last year. Luckily I had the trusty Honda ex1000. I think an alternator on the main engine is probably more reliable. The alternators I have are 120amp. I didn’t have to run a generator much last year. My main drain was my inverter, so I’m going to organise a low power inverter this year and maybe some 12v lighting. It would be good not to run a generator at all, but that’s the dream. I suggest that it is best not to switch BETWEEN lithiums and LA when the engine is running. The normal practice is to have the LAs permanently connected to the alternator, and use the switch to parallel up the Li (or not). That way there is no possibility to open-circuit the alternator, which could blow it up and or damage any other stuff connected. If you REALLY want to switch between them, you need a "make before break" type of switch so that the alternator is not momentarily open circuited. I think most 1 2 both battery switches are make before break but you would need to check. Obviously the switch needs to be rated to at least the max alternator output.
Oh just seen the later posts. Yes that battery switch should be OK, just be certain it is make before break. And if I were you I would avoid switching it when the engine is running just in case there is a momentary poor connection which could cause a large voltage spike.
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Post by kris on Aug 16, 2022 7:07:26 GMT
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Post by Telemachus on Aug 16, 2022 7:33:32 GMT
Yes that is what I’m suggesting. It is not how I’ve done it - I have a pure lithium system - but it is how a number of other people have done it. Having the LA battery in parallel doesn’t significant affect charging the Li because most of the time the Li will be charging at around 13.4 to 13.6v which is a float voltage for LA so no significant current flows into or out of the LA. The advantage of doing it this way is that the LA acts as a transient soak if the LI should be disconnected with the engine running either accidentally or deliberately. An alternator rotor is a big electromagnet with a lot of inductance, ie it can store a lot of energy as magnetism. If the alternator is charging hard (as it will be with Li unless the Li is full) and the Li is disconnected, the regulator will stop supplying rotor current but the magnetism and associated rotor current will take a while to subside. A while as in a second or so, but in the mean time if there is nowhere for the charge current to go, the alternator voltage will momentarily shoot up to maybe 80-100 volts which will likely trash the alternator diodes and anything else connected to it. Having an LA permanently in parallel gives that transient surge of energy somewhere to go and everything is fine, voltage only momentarily rises to 14.8v or so and there isn’t a downside other than the space needed for an LA battery.
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Post by kris on Aug 16, 2022 7:42:04 GMT
Thanks I’ll sort it out.
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Post by kris on Aug 16, 2022 7:51:00 GMT
I’ll only be charging at 13.7v (tractor regulator.) when not charging I’ll be isolating the starter battery from the domestic lithium’s. I can use a battery charger to occasionally fully charge the lead acid starter battery.
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Post by kris on Aug 24, 2022 10:52:24 GMT
So I’ve got to have a re think. None of the three tractor regulators I bought are working. Bugger, I’ve had them sat for a while so no chance of returning and these are no longer available. So I have got to have a serious rethink. Any other ideas appreciated.
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Post by Telemachus on Aug 24, 2022 13:14:57 GMT
You could use an old fashioned type of split charge diode which drops about 0.7v, taking 14.4v down to 13.7v.
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Post by kris on Aug 24, 2022 13:20:55 GMT
Thanks I’ve emailed them. Although I bought three already and they don’t work so reluctant to buy another. Although it’s a different seller they look the same cheap rubbish.
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Post by kris on Aug 24, 2022 13:22:16 GMT
You could use an old fashioned type of split charge diode which drops about 0.7v, taking 14.4v down to 13.7v. would you have a link please. I’m thinking of biting the bullet and buying a specialist lithium regulator, but I’ll have to does some research.
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Post by Telemachus on Aug 24, 2022 14:05:09 GMT
You could use an old fashioned type of split charge diode which drops about 0.7v, taking 14.4v down to 13.7v. would you have a link please. I’m thinking of biting the bullet and buying a specialist lithium regulator, but I’ll have to does some research. This kind of thing. sterling-power.com/products/split-charge-diodes-70-200a-2-3-outputs?_pos=2&_psq=Diode&_ss=e&_v=1.0It has a common anode, and the design idea is to connect one of the cathodes to each battery (ie engine and domestic) but in your case you could connect both cathodes to the Li battery, that way you would get the 0.7v or so voltage drop and the load would be shared by both diodes. You would need to select the one that is equal to or greater than the max alternator output current. Of course it means no current could flow the other way (from the Li back to the alternator / LA battery (if you have one) but I don’t think that should be a problem unless you have a 6 diode alternator and no LA battery.
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Post by kris on Aug 24, 2022 16:18:59 GMT
would you have a link please. I’m thinking of biting the bullet and buying a specialist lithium regulator, but I’ll have to does some research. This kind of thing. sterling-power.com/products/split-charge-diodes-70-200a-2-3-outputs?_pos=2&_psq=Diode&_ss=e&_v=1.0It has a common anode, and the design idea is to connect one of the cathodes to each battery (ie engine and domestic) but in your case you could connect both cathodes to the Li battery, that way you would get the 0.7v or so voltage drop and the load would be shared by both diodes. You would need to select the one that is equal to or greater than the max alternator output current. Of course it means no current could flow the other way (from the Li back to the alternator / LA battery (if you have one) but I don’t think that should be a problem unless you have a 6 diode alternator and no LA battery. Now you’ve given me something else to think about. It’s so confusing I really don’t know what to do. But I could really do with getting an alternator up and running. Lots more reading.
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Post by kris on Aug 24, 2022 16:24:53 GMT
14.5 volts that one. They call it a tractor alternator because of a temp sensor connection on it.
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Aug 24, 2022 17:06:42 GMT
would you have a link please. I’m thinking of biting the bullet and buying a specialist lithium regulator, but I’ll have to does some research. This kind of thing. sterling-power.com/products/split-charge-diodes-70-200a-2-3-outputs?_pos=2&_psq=Diode&_ss=e&_v=1.0It has a common anode, and the design idea is to connect one of the cathodes to each battery (ie engine and domestic) but in your case you could connect both cathodes to the Li battery, that way you would get the 0.7v or so voltage drop and the load would be shared by both diodes. You would need to select the one that is equal to or greater than the max alternator output current. Of course it means no current could flow the other way (from the Li back to the alternator / LA battery (if you have one) but I don’t think that should be a problem unless you have a 6 diode alternator and no LA battery. This seems an incredibly elegant solution especially when one considers the complicated lengths to which some have gone.
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Post by kris on Aug 24, 2022 17:08:30 GMT
14.5 volts that one. They call it a tractor alternator because of a temp sensor connection on it. I must admit, this "Tractor regulator" thing is confusing me. Perhaps you or Nick could enlighten me. I thought the idea was that the temperature sensor could be connected to a resistor or potentiometer effectively giving you a variable regulator. If that is the case, could you advise how you connected your ones up to test them please? I have not quite reached this stage myself, but thought now would be a good opportunity to understand things a bit better. it’s my understanding that the tractor regs I bought where regulated to 13.7v so as not boil the battery when running all day. I might be wrong it’s over a year ago I bought them. I tested them by taking them to an auto electricians workshop. We fitted the first to my alternator and spun it up on his test bed. Then he then connected the other two regs to a piece of test equipment and they didn’t work. So that was that. I’m leaning towards buying one of the specialist lithium regs. But I need to find out which I’d the best.
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