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Post by kris on Aug 24, 2022 17:10:11 GMT
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. Yes I can’t quite get my head around other people haven’t done this. I suppose all it’s doing is turning some of the electric current into heat.
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Post by kris on Aug 24, 2022 17:18:03 GMT
This seems an incredibly elegant solution especially when one considers the complicated lengths to which some have gone. Except for the dirty great length of cable required to limit the current, it certainly seems like a possibility. All hail Nick. The trouble seems to be that there is a mixture of people trying to adopt the technology, before mass take up has driven the price down,if it ever does. All the 'clever' people who made their own control systems, the people who have bastardised hybrid systems, not so clever as the clever people, but still pretty damn smart, and then there is everyone else, such as myself, who is trying to stumble through it. Thankfully for us, there are many people out there willing to help out with information. It I quite a minefield and easy to spend money without solving the issue.
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Post by Telemachus on Aug 24, 2022 17:24:36 GMT
This seems an incredibly elegant solution especially when one considers the complicated lengths to which some have gone. Yes I can’t quite get my head around other people haven’t done this. I suppose all it’s doing is turning some of the electric current into heat. The advantage of this method is that it limits the charge voltage to what should be a very safe voltage that won't take the cells "up the knee". Of course the disadvantage as you say, is some energy is wasted by heating up the diodes. But what is actually needed is 2-fold: yes preventing excessive voltage, but also preventing the alternator from having a very short life due to being at max output for a long period. Even at 13.7v a Li battery will take the full alternator output until it is well charged. So a means of limiting current such as the "long length of wire" thing is still needed. Bear in mind that the long wire on its own doesn't limit voltage because the voltage drop in the wire is proportional to the current, so eventually the current will fall off and the battery voltage will be the same as the alternator voltage (14.4v or whatever)
Other people have taken a different route eg having an LA battery in parallel with the alternator and using a long length of wire to drop voltage under the heavy alternator load a partially charged Li battery presents (tackles alternator overheating), and then disconnecting the Li once a certain SoC is reached, leaving only the LA to absorb any alternator transient voltage spikes (protects the Li battery from over-charging). People have used a BMV712 and some sort of electric or electronic isolation switch (operated by the BMV712) to disconnect in the event of high voltage or SoC.
All of which is a bit messy, and as you know not the way I went, but it does work (apparently).
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Post by Deleted on Aug 24, 2022 17:24:42 GMT
This seems an incredibly elegant solution especially when one considers the complicated lengths to which some have gone. Except for the dirty great length of cable required to limit the current, it certainly seems like a possibility. All hail Nick. The trouble seems to be that there is a mixture of people trying to adopt the technology, before mass take up has driven the price down,if it ever does. All the 'clever' people who made their own control systems, the people who have bastardised hybrid systems, not so clever as the clever people, but still pretty damn smart, and then there is everyone else, such as myself, who is trying to stumble through it. Thankfully for us, there are many people out there willing to help out with information. Also just had a funny thought that if the thing really is just a pair of diodes then it wouldn't be too diffic to make your own gadge for a lot less. Shirley.
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Post by Telemachus on Aug 24, 2022 17:27:45 GMT
If you do decide to do it properly and go with a fancy alternator regulator, speak to Ed Shiers (four counties marine services, fourcountiesmarineservices.com/lithium-batteries/) who is specialising in this area. As I have often said on these forums, he is a top bloke.
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Post by Deleted on Aug 24, 2022 17:31:32 GMT
Also just had a funny thought that if the thing really is just a pair of diodes then it wouldn't be too diffic to make your own gadge for a lot less. Shirley. Possibly not. People make their own galvanic isolators. But you would, of course, require diodes large enough to manage the alternator output, and a way to fix them to a dirty great heatsink, and a method to connect it. Maybenot worth the hassle for 40-50 quid. Yebbut what does a clown know about it anyway?
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Post by Telemachus on Aug 24, 2022 17:32:05 GMT
Except for the dirty great length of cable required to limit the current, it certainly seems like a possibility. All hail Nick. The trouble seems to be that there is a mixture of people trying to adopt the technology, before mass take up has driven the price down,if it ever does. All the 'clever' people who made their own control systems, the people who have bastardised hybrid systems, not so clever as the clever people, but still pretty damn smart, and then there is everyone else, such as myself, who is trying to stumble through it. Thankfully for us, there are many people out there willing to help out with information. Also just had a funny thought that if the thing really is just a pair of diodes then it wouldn't be too diffic to make your own gadge for a lot less. Shirley. By the time you have bought diodes rated for enough current, added suitable connections, adequately heat-sinked them, I doubt it would be much cheaper than the Sterling offering.
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Post by kris on Aug 24, 2022 17:44:19 GMT
If you do decide to do it properly and go with a fancy alternator regulator, speak to Ed Shiers (four counties marine services, fourcountiesmarineservices.com/lithium-batteries/) who is specialising in this area. As I have often said on these forums, he is a top bloke. Yes he fitted a lithium set up for a friend of mine. But that is all victron with a lead acid in circuit.
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Post by Deleted on Aug 24, 2022 17:54:00 GMT
Also just had a funny thought that if the thing really is just a pair of diodes then it wouldn't be too diffic to make your own gadge for a lot less. Shirley. By the time you have bought diodes rated for enough current, added suitable connections, adequately heat-sinked them, I doubt it would be much cheaper than the Sterling offering. Just a thought, if the aforementioned long bit of cable is offending, could an old-fashioned ignition coil do the same job?
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Post by kris on Aug 24, 2022 17:58:44 GMT
This is an interesting site, obviously they are trying to sell stuff. octopusasia.com/charging-lfp-or-adding-a-alternator/It seams most of these fancy regulators need to talk to the batteries bms. This isn’t going to be possible on my valences. It looks like it might be the voltage drop diodes and long length of cable. It’s all a bit confusing. I need to use the equipment I already have eg valence batteries and 120amp lucas a127 clones.
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Post by kris on Aug 24, 2022 17:59:33 GMT
Just a thought, if the aforementioned long bit of cable is offending, could an old-fashioned ignition coil do the same job? Oi. He hasn't answered my question yet. There is a queue here you know. Get to the back young (ish) man Can we save the bickering for the other threads ☺️
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Post by Deleted on Aug 24, 2022 18:01:44 GMT
American joke:
Why do Brits drink warm beer? Because Lucas make fridges as well.
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Post by kris on Aug 24, 2022 18:06:23 GMT
American joke: Why do Brits drink warm beer? Because Lucas make fridges as well. I think Kris just kicked us out of his thread. I've been kicked out of better threads than this before. I haven’t kicked you out, that’s impossible it’s thunderboat. It’s just this issue is confusing enough. Without the usual background noise.
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Post by Telemachus on Aug 24, 2022 19:51:18 GMT
Yes I can’t quite get my head around other people haven’t done this. I suppose all it’s doing is turning some of the electric current into heat. Its more to do with the inherent voltage drop that a diode possesses. I seem to recall a germanium diode has a 0.3 V drop, and a silicone diode is 0.7V. Silicone is in polishes etc. Silicon is the element. Yes geranium diodes drop about .3v but you don’t get them any more, probably because the petals all fell off.
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Post by Telemachus on Aug 24, 2022 19:52:01 GMT
By the time you have bought diodes rated for enough current, added suitable connections, adequately heat-sinked them, I doubt it would be much cheaper than the Sterling offering. Just a thought, if the aforementioned long bit of cable is offending, could an old-fashioned ignition coil do the same job? No.
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