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paulz
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# Posted: 22 Oct 2022 15:00
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Mine are 140AH. As I mentioned, I'm only looking to charge to 14.0 or less, just that the amps go up when turning up the Meanwell from 14.2 to 14.6. The batteries, at either setting, still read in the 13s, with no plans to go any higher, just wasted gas and genny time to do so.
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gcrank1
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# Posted: 22 Oct 2022 15:26 - Edited by: gcrank1
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That would be like 7Amps endcurrent for yours. Just do keep that eye on and yer good.
Do you have a timer you can run the MW from? I think such could be a good 'safety' doing what you want to do.
Fwiw, Im still shaking off the old LA thinkin' but Im gettin' better 
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paulz
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# Posted: 24 Oct 2022 21:37
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Quoting: gcrank1 Do you have a timer you can run the MW from? I think such could be a good 'safety' doing what you want to do.
Sort of. The little generator I'm using doesn't even hold a gallon of gas..
I've been firing it up at 12.9 volts last few days. Out of curiosity I checked the specs on my LFPs. 'Nominal' voltage is 12.8. So what does that mean? Also charge voltage 14.6..
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gcrank1
Member
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# Posted: 25 Oct 2022 14:25
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Well, as we are used to in automotive and motorcycles, 12v is the 'nominal' voltage but we know that a typical 12v battery is closer to 13v and when down to 12v it is basically 'dead'. The 'nominal' thing is an archaic hold-over useful conversationally but not accurate at all.
Then we have the translation thing, both in understanding and in literal. Imo that 'rating' you quote would be better to me if it dropped the 'nominal' since they are spec'ing a specific voltage.
We know from (ref. Steve_S again) prev posts that LFP has its real flat 'power window' from pretty much 13.0 to 13.4. With LFP Im more inclined to be Specific, it is very important.
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paulz
Member
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# Posted: 25 Oct 2022 15:26
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I guess that 12.8 nominal was wishful thinking.  My bank has been down to 12.9 every morning lately, even after some generator charging. Seems to be dropping from 13.2 rather quickly, more than it used to. Soon as I get this cable reconfig done I'm going to give it a serious charge, get it up towards 14 and see what happens. Could be my old batteries are starting to go but on the other hand the solar charging is nowhere near what it was a month or two ago.
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gcrank1
Member
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# Posted: 25 Oct 2022 16:29
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What is your bat's LVD?
Since LFP doesnt need to be fully charged asap maybe it doesnt matter if your 'window of use' varies a bit in the level of charge profile as long as it isnt tripping the LVD?
I do agree that a solid 'top charge' may be of use, just sos ya knows, but the bat will still always settle where it wants to be. The question to me is it going to settle at the bottom, mid or top of 'a tenth'; ie, (example only), 13.31, 13.35, 13.95 which may translate into several hours of usage.
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paulz
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# Posted: 25 Oct 2022 17:14 - Edited by: paulz
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LVD is 10 volts for the internal BMS, as show in the pic above, but I have an external Victron set at 12 or 12.5, I'll have to check that, and write it down.
I'm in the city today getting glasses (to go with the hearing aids..) so it has all day to charge without any load, and it's a sunny day. Should be looking better tomorrow. I, on the other hand, will look like a nerd.
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gcrank1
Member
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# Posted: 25 Oct 2022 19:09
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According to Steve, iirc, what we want to find is the point that the LFP starts to 'fall off the cliff' and use that as our bottom end.
I dont have any of those programmable devices to set with the bat to get them to sorta accurately talk together, and that not being matched seems to be common in misreading of where the LFP is 'at'.
I have kept my eye on during a steady discharge use to find where the 'tenths' start ticking by faster, telling me that the slide is on. As long as I know where that is, even if my voltmeter isnt truly accurate, is fine functionally.
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Steve_S
Member
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# Posted: 26 Oct 2022 08:49
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With LFP the cliff falls to bottom really starts around 2.800-2.850 11.2V-11.4. When a heavier load hist at those voltages, the voltage sag is greater and may trigger LVD.
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paulz
Member
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# Posted: 27 Oct 2022 17:37
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Whew, big reconfig today.
Replaced the doubled up 6awg inverter cables I put in after you guys figured out that's why my inverter was shutting off, with 0awg.
Installed two Meanwell's in parallel, inside instead of outside, also with 0awg. These big cables are a pain. Newbies, go 24 or 48v, smaller cables.
Mounted the Victron LVD and main CB on the wall, previously unmounted. New main power cable, 2/0. Cleaned up some other wiring.
Got all done, everything works. Fired up the genny, at 13.1v I got a 50A charge, should be even higher with a lower bank.
Enough brain work, tomorrow I'm going to cut firewood.
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gcrank1
Member
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# Posted: 27 Oct 2022 22:55
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That sounds promising!
I eagerly await your over-time report
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paulz
Member
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# Posted: 28 Oct 2022 09:15 - Edited by: paulz
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Another thing occurred to me last night.. As you've probably noticed, the Meanwells spark when connecting to the battery, as they charge their internal capacitors. I think it was Traveler who mentioned it may shorten the life of the power supply to have them permanently connected, like I did yesterday. SCCs and inverters do this too though, and are of course permanently wire in.
I did a little reading on switched power supplies and as usual with electronics came away more confused. There is also something called Leakage Current, I think that's a drain on the batteries. The cure, as discussed on this DIY electric car forum, is a diode, or a switch, which cures the capacitors being on all the time issue.
https://www.diyelectriccar.com/threads/using-switching-power-supplies-as-charger-wiri ng-options.83420/
To make it even more confusing, apparently there are different styles of switched power supplies, some good for battery charging, some not, and I don't know where our Meanwells fall in. Here's the page on that.
https://forum.digikey.com/t/using-a-switching-power-supply-for-battery-charging/4281
Here's the data sheet on our MWs
https://www.meanwell.com/productPdf.aspx?i=469#1
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gcrank1
Member
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# Posted: 28 Oct 2022 11:01
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Iirc there is more than a little info over at diysolarforum.com on power supplies as chargers, the W in specific And 'pre-charging capacitors'.
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paulz
Member
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# Posted: 28 Oct 2022 12:06
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Yeah I read about pre-charging, I think it just avoids the spark when installing. Or maybe softens in the in rush current, if that is a problem.
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gcrank1
Member
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# Posted: 28 Oct 2022 14:22
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It depending upon the size of the spark you get with a particular device, big spark, more need to soften it.
You may have the 'right size' resister in your bins, otherwise they arent expensive online, but an incandescent Edison base light bulb in a socket with a couple 'gator clips to wired inline on either the + or - lead (NOT across + to - !) will do it.
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paulz
Member
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# Posted: 2 Nov 2022 11:09
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Last night, throwing caution to the wind and after a rainy low solar day, I decided to forgo any generator charging and went to sleep with the batts at 12.9. This morning down to 12.8, and even 12.7 after turning on lights and chargers. But no signs of trouble. Fired up the genny, 50A going in, same as when I charged from 13.1. So I guess that's all the charge I'm going to get out of this setup, which is OK. Long as I brew coffee off the genny and limit TV we should be OK for the winter.
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gcrank1
Member
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# Posted: 2 Nov 2022 12:27
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Ive been swapping out bats at about 13.0-13.1 all season but thinking now that is premature.
Just yesterday brought home the cabin lfp bat that we have had there for about the past month with No cabin charging, it is at 13.1.
Hooking up the MW set at 13.7 my amps are only at 10 (granted, my ammeter is crude, but I have seen it go much higher if I crank up the volts to 14.4).
Im suspecting Im not down far enough to have even brought it home.
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