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Post by kris on Jan 22, 2020 14:53:06 GMT
Everybody reads here. Do not ask me how I know that lets just say it's written. okay Andrew.
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Post by lollygagger on Jan 22, 2020 14:56:06 GMT
You're probably better off out of it, I don't think this committee has any sway and CRT attentively listening to the committee's views while nodding their heads before doing what they want anyway could get a tad frustrating.
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Deleted
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Post by Deleted on Jan 22, 2020 14:56:53 GMT
Everybody reads here. Do not ask me how I know that lets just say it's written. okay Andrew. Oh, a gender theft?
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Post by kris on Jan 22, 2020 15:06:02 GMT
You're probably better off out of it, I don't think this committee has any sway and CRT attentively listening to the committee's views while nodding their heads before doing what they want anyway could get a tad frustrating. but at least I could tell them they are a bunch of cnut’s (edited for some members sensitivity) to their faces.But yes I know what you mean and have stated from the beginning I think this committee is a tick box exercise.
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Post by peterboat on Jan 22, 2020 15:17:05 GMT
Though I have voted for Kriss, and Thunderboater votes I hope will provide him a good base to start from, I doubt votes from here would make much difference to the outcome. Who knows? Well if my vote ever turns up I will vote for him but at the moment they have supposedly sent it out twice!!
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Post by Telemachus on Jan 22, 2020 17:46:04 GMT
thank you they look like they would do it. Now using your superior intellect and knowledge, what value resistor would I need? The suggestion for a normal regulator is 200 ohms. It is designed to be a thermistor (resistor whose resistance varies with temperature), so that when the batteries get hot, the voltage is reduced. Most thermistors have a negative temperature coefficient (resistance decreases as temperature increases) so the thought would be perhaps 150 ohms. Just a guess. Maybe you should get a wire wound potentiometer which you could vary to see the effect on the voltage. Or just a selection of resistors around 200 ohms to try. I have drawers full of resistors so i can post you a selection if you PM me a mailing address.
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Post by kris on Jan 23, 2020 10:45:52 GMT
thank you they look like they would do it. Now using your superior intellect and knowledge, what value resistor would I need? The suggestion for a normal regulator is 200 ohms. It is designed to be a thermistor (resistor whose resistance varies with temperature), so that when the batteries get hot, the voltage is reduced. Most thermistors have a negative temperature coefficient (resistance decreases as temperature increases) so the thought would be perhaps 150 ohms. Just a guess. Maybe you should get a wire wound potentiometer which you could vary to see the effect on the voltage. Or just a selection of resistors around 200 ohms to try. I have drawers full of resistors so i can post you a selection if you PM me a mailing address. thank you I’ll get one of the regulators ready to play with.
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Post by bodger on Jan 23, 2020 11:29:49 GMT
I have drawers full of resistors so i can post you a selection if you PM me a mailing address. hmmmm ........ not quite sure if we need to know what your drawers are full of, Nick
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Post by Telemachus on Jan 23, 2020 11:36:52 GMT
Just bear in mind that the orange lead is effectively the voltage sensing lead and so need to be connected to the battery under charge (via a switch). If you have a separate LA engine starter battery charged from a different alternator, don’t connect the orange lead resistor to it as is shown in the ebay diagram.
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Post by Clinton Cool on Jan 23, 2020 14:39:21 GMT
I like the idea of these batteries. Thinking out loud: I only use around 20AH/ day so 50 or so AH of lithium might make things affordable? I'd more than likely disconnect the new lithiums from the alternator charging system (don't cruise much anyway) and rely on solar for 8 months of the year, and genny at other times. Question is, can my Tracer solar charge controller safely control things?
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Post by peterboat on Jan 23, 2020 17:11:28 GMT
I like the idea of these batteries. Thinking out loud: I only use around 20AH/ day so 50 or so AH of lithium might make things affordable? I'd more than likely disconnect the new lithiums from the alternator charging system (don't cruise much anyway) and rely on solar for 8 months of the year, and genny at other times. Question is, can my Tracer solar charge controller safely control things? I use a Midnite controller which works well, I can set every phase of the charging cycle and over the last couple of years its worked well, I never like my tracers what I had before and wouldnt trust them for my 2 large expensive banks
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jimmy
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Post by jimmy on Mar 4, 2020 5:49:49 GMT
Hi I was toying with the idea of LIFEP04s myself and i was thinking of the same problem of charging from the alternators can you not just use a Dc>Dc / battery to battery charger connected from the starter battery to the LIFEP04s and let the charger do the regulating i think some of the chargers can accommodate LIFEP04s as they charge at 14.4 Volts
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Post by JohnV on Mar 4, 2020 6:43:41 GMT
I would say that 14.4 is too high !!!
LiFePO4's are weird in their charging compared to Pb ...... the magic number seems to be around 3.4 volts per cell.
Below 3.3 volts they don't do nuffin at 3.4, 3.5 volts per cell they will charge happily to about 80%.
over 4.2 volts per cell shortens their life.
they are greedy buggers and will suck in any power you offer them, you don't have to force feed them like Pbs
I charge mine at 14 volts as I want them to outlast me.
Remember as well that you can discharge them to 20%, much deeper than Pb's without harm.
Peterboat reckons you scratch for that last 10 or 20% on a car when that extra 50 or 60 miles range is important
Telemachus has gone into the technical side much more than I have, (I couldn't be arsed, I just wanted fit and forget)
I believe he has been building his own safety charge discharge limiter (mine never got beyond half built)
I just use a solar charger programmed for 14 volts to charge, and the low voltage dropout on the inverter for the discharge.
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Post by Telemachus on Mar 4, 2020 10:06:11 GMT
Hi I was toying with the idea of LIFEP04s myself and i was thinking of the same problem of charging from the alternators can you not just use a Dc>Dc / battery to battery charger connected from the starter battery to the LIFEP04s and let the charger do the regulating i think some of the chargers can accommodate LIFEP04s as they charge at 14.4 Volts 14.4v is of course 3.6v per cell. Which is ok. However you can not necessarily divide 14.4 by 4 and assume each cell will get to 3.6v. Unlike Lead Acid which passes any “spare” charge on to the next cell without issue, Li just stop absorbing charge when full and blocks current flow. This blocking takes the form of increasing its cell voltage to dangerous/damaging levels. So if you charge at 14.4 with the intention to fully charge the battery, and if one cell is eg at a slightly higher starting SoC or has slightly less capacity than the others, it will top out at fully charged before the others and it’s cell voltage will then rise into “bad” territory, with the 14.4v being made up of say 3.5, 3.5, 3.5 and 3.9. The last being too high. Or worse, 3.4, 3.4, 3.4, 4.2. The transition from everything fine and dandy, to one cell’s voltage rocketing up, happens very quickly. Hence the reference to the “knee”. At the very least you need to monitor individual cell voltages (The BG-8S is a cheapo way of doing this) and make sure you are in a position to stop charging as soon as the highest cell starts to climb up the “knee”. And keep the cells in exact top balance, preferably automatically.
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Deleted
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Post by Deleted on Mar 4, 2020 10:35:32 GMT
The discussion on these batteries always sounds very complicated and technical.
Can I ask a simple question ?
I use wet lead acid batteries, which are charged by the engine ... I cruise and I have power until I cruise again.
I have no guages or means of measuring state of charge, and no solar.
This works for me (fifteen years in) but if I wished to change to lithium type batteries, which I see would allow me to charge from solar and for much of the year do away with the need to charge by the engine, would I have to have all the knowledge, guages and technical know how as well ?
Rog
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