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Steve_S
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# Posted: 9 Feb 2022 13:30
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IF you set charger to 14.6 it will get there as the IR changes and amps taken reduces and the voltage matches up to the input current. BTDT many times. Learned an Expensive lesson that way and I got "lucky".
If 14.0V / 3.500 is your 100% CAP then don't go over it and as the IR changes Amps taken will reduce till everything is smooth at 14.0V.
Also remember LFP Settles no matter what. IF you charge to 14.0 and Amps taken drops and the battery is fully saturated to that voltage, it will still settle after charge input stops (load or no load) which is natural. On average I see 1.0V Settle after full saturation within One Hour of charge input stopping. BUT I have a Blend/Mix of battery cells which contributes a bit to that... IF all identical in every way then the settling will be less (tested with exactly identical packs and that bears out).
I dunno if I call my system Big or Small, I consider it small @ 5 Packs with 3x280AH & 2x175AH / 30.4kWh Bank. Fo my place it's plenty. So it's a matter of perspective.
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ICC
Member
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# Posted: 9 Feb 2022 14:50
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Quoting: Steve_S I dunno if I call my system Big or Small, I consider it small @ 5 Packs with 3x280AH & 2x175AH / 30.4kWh Bank. Fo my place it's plenty. So it's a matter of perspective.
FWIW, IMO 30 kWh is big for many cabins but small to moderate for a full-time residence. We have a little over 100 kWh in total storage. Large.
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paulz
Member
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# Posted: 9 Feb 2022 17:47
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The issue I've had with the Meanwell 16v 40a adjustable power supplies is the amperage only goes up as the voltage is increased. I know they are not actually battery chargers, maybe that's the problem. Steve at one time mentioned a 'kit' to make them into true Li chargers, I've poked around a bit and haven't seen anything. But in my experience to get anywhere near 40a output I have to have the voltage up in the high 14s.
Got to wondering about specific Li chargers, found that the Victron charger goes up to 14.7 in the absorption phase. Whether that's open voltage (as I set the Meanwell), or voltage at the battery I don't know.
https://www.victronenergy.com/upload/documents/Datasheet-Blue-Smart-IP22-Charger-230- VAC-EN.pdf
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ICC
Member
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# Posted: 9 Feb 2022 18:40 - Edited by: ICC
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Some power supplies are made to be able to provide either a constant current while the voltage remains adjustable OR a constant voltage while leaving the current adjustable. There are also kits, or front ends, that provide CC or CV, that can be used with a power supply such as the MW.
Any good charger that has adjustable set points should operate just like a good solar charge controller. The voltage that is set should be the voltage you want the battery to end up at.
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gcrank1
Member
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# Posted: 9 Feb 2022 18:59 - Edited by: gcrank1
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The fundamental that I focused on is that 3.5v/cell is a 'target' that will give some 95% (+?) and not stress those cells by going well into the 'knee' to 3.65 TOPs. A higher than 14.0 set-point will go there, stress the cells, maybe trip the BMS (needlessly) and not provide any Meaningful Increase In Amp Hours/Watts. And even if you go there the cells will 'settle out' to the 3.45-3.5ish. So, Why Go There at all unless to top balance the cells occasionally? Even the TB may not be needed unless dealing with paralleled batteries?
My MW set to open voltage 14.0 didnt change much at all when I hooked it to a slightly depleted battery. I need to check it again with a deeper discharge.
Hooked up and with my dvom I tweaked to 14.0 (its touchy to adj). My 'full charge' target (when needed) is to get a dvom read of 13.5v, the amps will have fallen off by then to basically a trickle, and I will shut down. If I miss seeing this happen and it runs a bit at virtually no amps it wont go past the 14.0v (3.5/cell) so all should be good.
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paulz
Member
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# Posted: 9 Feb 2022 19:09
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Oops, looking at the Victron spec again I see that charger is not just for Lithium, and the top voltage for them is 14.2. I searched for Li battery chargers and assumed that it was specific.
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Steve_S
Member
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# Posted: 10 Feb 2022 05:43
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There are a few companies making these Bench PowerSupply Kits to be used with Meanwell type that gives you finer controls. A few models even have Software for the PC for monitoring etc.
These are available from ALiExpress/Baba but also on EBay & Amazon and some have North American stock as well...
These are popular with a lot of people, there are many YT Videos and write up with people assembling and using them.
https://rdtech.aliexpress.com/store/group/RD-series/923042_516640842.html?spm=a2g0o.s tore_pc_home.pcShopHead_6131645.1_0_0
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paulz
Member
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# Posted: 10 Feb 2022 11:02
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Looks like the top of the line for those is 24A. I can imagine what a 80-100A one would cost, but I'll look around. Thanks.
I seem to have squeezed through the winter solstice, when my trees block the most sun, and have decent solar charging at the moment (although it has been sunny lately), partly because I moved some panels up the hill and cut some trees. I did do some generator charging the other night after 5 days at the cabin but my cells were still at 3.29, sure I could have made it. Haven't really gotten a feel for how fast things drop off when they start getting low. I need to play with the AH meters, one on the SCC and an Aili meter. Heading out to the cabin today, if the cells are at 3.5 I'll reset them. My batts being 10 years old they are probably no longer good for their rated capacity so I'll set it lower.
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gcrank1
Member
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# Posted: 10 Feb 2022 11:17 - Edited by: gcrank1
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Unless you do a high to low capacity test you wont know what each has. With a bunch of bats thats a lot of trouble; maybe just figure they are at 80%?
Just like with FLA the LFP has some sag under load so Ive been watching my onboard v-meter during use to get a feel for it. It looks like the sag isnt as bad as my old FLAs, and I wont have any new ones to compare, and the bounce-back is really quick. But if the sag isnt as bad then the rise isnt much either; think 'narrower window'.
That said, iirc I dont even need to start being careful until I see 12.8-12.9ish under load? With yours at 3.29/13.16 you are still in the 'almost flat-line' and that is pretty linear.
You may not know what your BMS LVD is, it would be nice if the inverter LVD cut it off before you hit the BMS limit. That way no real monitoring is needed, just wait for the lights to blink off and go swap bats.
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paulz
Member
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# Posted: 10 Feb 2022 11:53
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Quoting: gcrank1 That said, iirc I dont even need to start being careful until I see 12.8-12.9ish under load? With yours at 3.29/13.16 you are still in the 'almost flat-line' and that is pretty linear.
Agreed, just at night with the fridge, wifi router and various USB junk on chargers running all night I get nervous. I have the Victron cutoff set at 12.5, plus the Valence batts have their own internal BMS.
Yes, 80% of rated capacity on the AH meters sounds good.
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Steve_S
Member
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# Posted: 10 Feb 2022 12:15
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Tip: Put your wall wart chargers and such on a Switched Powerbar and eliminate the parasitic loss while not in use. You could even use an external timer to allow that powerbar only ON during the day or whenever you usually use it.
My Satelite Modem/Router are on an independent Switched Plug (off when not in use it's a pig), as is my Radiant Heating System for off season.
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Steve_S
Member
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# Posted: 10 Feb 2022 12:24
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On RD Tech... They sell kits with the Meanwell type PS and Without, of course cost reflects that but it's not as clear on the listings as they should be.
My own TeckPower TP1545e (not kit) has served very well was a affordable a couple of years ago, now hard to find and Crazy Prices too. All of these Bench PS units have gone cookoo in price.
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gcrank1
Member
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# Posted: 10 Feb 2022 14:04
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Fwiw, when I did my initial capacity trial I took it to 12.7, which must have been 'on the edge' because it came up to 12.8 after sitting.
With the MW at 14.0 my simple old automotive 'hold on the wire' ammeter read (eyeball) 26ish amps, I figure that is what the MW pumps when at set to 14.0. Someday, after a deeper discharge I'll know more....
So a more adjustable add-on, expensive unit that wont do more than 25ish amps wont do any better.
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ICC
Member
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# Posted: 10 Feb 2022 17:18
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Quoting: gcrank1 So a more adjustable add-on, expensive unit that wont do more than 25ish amps wont do any better.
If you were looking for an improvement in battery charging wouldn't it be better to look at an actual battery charger with the ability to have set limits or charge profiles to suit the battery type?
Power supplies such as what can be made with a front end like what RD sells are very useful for certain tasks. I have a couple. For regular everyday battery charging a unit designed to charge and stop charging batteries has many advantages.
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paulz
Member
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# Posted: 11 Feb 2022 10:35
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Well I got to the cabin yesterday and the cells were at 3.3. I didn't set the AH meters. I'm thinking today I will charge up to 3.5 with solar and generator, turn everything off for an hour and let them settle (probably back to 3.5 I'm guessing), then set the meters.
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gcrank1
Member
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# Posted: 11 Feb 2022 13:40
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My inclination would be to hit 3.5, charge a 'little bit longer' and stop, use that for your 'calculated' top charge for the devices.
My guess is it will either stay at 3.5 then or if it falls off to 3.4 you will know the bat(s) are showing their age (hope not below 3.4). I will find that result of interest as we dont see much about long term LFP use yet.
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paulz
Member
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# Posted: 11 Feb 2022 15:38 - Edited by: paulz
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OK got the 7kw Onan going, two MWs set at 14.2. Cells were at 3.275. 40A going in. Now at 3.360 after only a few minutes.
Solar still hooked up, 7A going in there. Cabin still powered up, fridge, wifi, radio.. about 4A going out.
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paulz
Member
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# Posted: 11 Feb 2022 17:13 - Edited by: paulz
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Not really sure what's going on, been over an hour and hovering at 3.365 per cell. 28A going in. Measuring at the MWs 14.1v, with a drop of a couple tenths at every connection along the way: ammeter, 4' of 4awg cables, circuit breaker, Aili meter, until 13.46 at the batts.
Goes back to the previous thought: Does 14.1 at the PS really mean 14.1 getting to the batts? I guess as long as amps are going in, it's charging.
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gcrank1
Member
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# Posted: 11 Feb 2022 17:17
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So, you are set at 2x MW @ 14.2 to get that 40a as fast as possible? Thats 20a each?
Your ammeter(s) are likely more accurate than mine but as said, at 14.0v I got 26a+.
Wonder what your ammeter would read if you tweek those MWs down to 14.0?
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Steve_S
Member
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# Posted: 11 Feb 2022 17:22 - Edited by: Steve_S
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removed.
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paulz
Member
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# Posted: 11 Feb 2022 18:42 - Edited by: paulz
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Up to 3.390 now, just taking it's time. Yes, 2 at 14.2, 20A each when I started. It depends how depleted the batts are how much they take. Right now I'm at 24A total. Goes down as the resistance goes up I think. I have a car ammeter gauge at the MW, 0-30-60, not accurate but tells me something. Then the Aili meter at the batts and the Valence software going on a laptop, both reading the same 24A.
Going to let it run, this Onan LP genny is so quiet (under the deck) I only know it's running because of the charge.
This is what an exciting Friday night is when you get old.
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gcrank1
Member
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# Posted: 11 Feb 2022 21:04
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That Internal Resistance increasing as the charge tops up making the amps fall off is my understanding too. Iirc, Steve said when the amps fall to about 5-8 the bat is pretty well as full as it can get?
Watch for that amps fall off and see what the voltage is for future reference.
My learning curve on this is taking place in home. I used my bat at the cabin on Wed when I burned the summer slash pile (wish I could save those btu's for heating the cabin!). I got the lp furnace running about 9am until 3:30, had the 120v low-end ceiling fan running off the 300w inverter that whole time on med speed to circulate the cabin air.
6.5 hrs hardly dented the charge, only .2 volts drop, just off the battery, no solar running.
Im not even topping it up here, unlike FLA it doesnt need to be. So Sweet.
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paulz
Member
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# Posted: 11 Feb 2022 21:54
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Well, the genny ran out of propane, that thing sucks it down. Batts were at 13.7. Dropped pretty quickly to 13.5 with the cabin load. I set the AH meters to 480 (advertised 560) and called it a night. We'll see how that goes.
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Steve_S
Member
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# Posted: 12 Feb 2022 05:40
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Total Saturation for 100AH Battery is attained @ (100AH X 0.05 = 5A) which BTW is EndAmps/Tail Current. at which time only Float should be applied.
If you charged to 3.5Vpc / 14.0V per pack and Amps dropped to below even 10% of AH Capacity (10A for 100AH batt) that can be considered full and should settle reasonably high relatively. Depends on state / condition of cells.
The Gotcha with more than One Battery in Parallel is that EndAmps/TailCurrent is the sum of the batteries in the collective and that is where the Trixy begins and that's the fine finesse we all have to figure out for the systems.
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paulz
Member
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# Posted: 12 Feb 2022 10:17 - Edited by: paulz
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Quoting: Steve_S Total Saturation for 100AH Battery is attained @ (100AH X 0.05 = 5A) which BTW is EndAmps/Tail Current. at which time only Float should be applied.
I was at somewhere near 5A per batt last night when the genny died, I wasn't paying close attention. The Valence software shows stats per batt.
Bank at 13.38 this morning, 2-4A (12v) draw at night depending when the fridge kicks on. I was anxious to see what the AH display said but, ARGH!!!, there is an anomaly with the Aili meter that I experienced again. It has a bright LED backlight that can be turned on and off by holding down two buttons for 3 seconds. The buttons are under the plastic face and hard to feel. One of the buttons is the AH percentage and it you don't do it just right it resets it! Long story short, I no longer have it on that meter.
I also set the AH on the Epever MT50 SCC meter but it only has a picture of a battery with bars, no way to display a numeric value that I can find. It, of course, still shows full. I guess that's worth something..
So basically I have to do it over again, and put that Aili meter where the light isn't bothersome, or better yet turn it off and just use a flashlight to read it.
Leaving for a couple of days, will let the solar charge, top it up again with the genny if needed and do it over.
Speaking of the Epever, the values I lowered after reading the DYI thread are now:
Over V disconnect 14.4
Charge Limit 14.2
Over V reconnect 14.1
Equalization Charge 14.1
Boost Charge 14.0
Float Charge 13.6
Boost Reconnect 13.3
Low V Reconnect 12.6
Under V Reconnect 12.2
Under V Warming 12.0
Low V Disconnect 11.1
Discharge Limit 10.6
Equalization time 0 minutes
Boost time 180 minutes
Lot of parameters, and some mist be lower than others, and some won't take zero as a value. All have been lowered around a half volt from previous settings.
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Steve_S
Member
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# Posted: 12 Feb 2022 11:10
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Quoting: paulz I was anxious to see what the AH display said but, ARGH!!!
Nice way to put Drunken Sailor Trash Blue Air eh... LOL, I sure as heck would have tainted the air.
To me it sounds like you have things nailed down pretty neat & tidy though. If had everything down to just taking 5A+/- they were good & saturated.
You can have a damp sponge, a wet sponge, or a soaked sponge, yours were soaked LOL.
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paulz
Member
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# Posted: 16 Feb 2022 18:29 - Edited by: paulz
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Thanks Steve. Well I reset the Aili meter a few days ago, today with my bank at 13.19V it said I still have 75% left. Seems a little optimistic looking at LFP SOC charts, just going to have to keep playing with ti.
Quoting: gcrank1 With the MW at 14.0 my simple old automotive 'hold on the wire' ammeter read (eyeball) 26ish amps, I figure that is what the MW pumps when at set to 14.0. Someday, after a deeper discharge I'll know more....
I wanted to run the new 1000i genny today so I hooked up the MW again. Most I can turn the voltage up without the genny shutting off is 13.85v. With the batts reading 3.300 per cell it charged at 23A, not bad. Just fyi.
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paulz
Member
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# Posted: 20 Feb 2022 13:55
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Got to the cabin yesterday, MT50 was showing 13.7 volts, yippie. Then I looked at the Aili meter, located at the other end of the output cables from the CC, 13.3. Hmm. Got out the DVM, same thing, 13.7 at the CC, 13.3 at the other end of the cables. Later that night when the batts drained some the both read closer to the same. So I swapped out the cables. Hadn't realized the ones I had were small, like 10g, but then I have only seen double digest amperage to the batts once or twice. I replaced with very heavy, 0 or 00g, could barely cram them in the CC sockets. So far today both reading are with a couple hundredths of a volt.
More oddity. Today is overcast, it's late morning and I've got double digit charging, twice what I've seen in the last week in pure blue sky! No changes on the panel side of things, just those battery cables.
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gcrank1
Member
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# Posted: 20 Feb 2022 14:43 - Edited by: gcrank1
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To avoid line-losses Ive been keeping all my dc wire runs as close as possible as well as decently fat for the amperage carried.
This next season I need to get my 2s/3p array out into the sun and oriented better so my 24v run from array to scc will be my long one. The panels come with 10ga. stranded, from combiner box I have need of about 30' carrying 24v/30-36ish amps max for only a few hours; I figure 8ga. might make it?
All the rest will be a max of maybe 4' then it will be 120vac from there on. Our demands have been fairly light though I do have an unused 1000/2000w peak psw inverter that could change things now with the LFP. Been thinking of giving it the old 2-slot toaster test.
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paulz
Member
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# Posted: 20 Feb 2022 15:10
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I think you mentioned early how surprising it is that the CCs come with smallish wire sockets. My batts are 3 feet from the CC, cables short. But I probably should rewire for 24v and get a transformer for all the 12v stuff I have going.
Still crazy here, 12A charge, no sun. I'm lucky to see half that on a sunny day. Can't believe changing the battery cables changes CC output. More likely having it powered off rebooted it and that changed its ways. Both ends of the new cables reading more closely, 13.41 at CC, 13.38 at the batts.
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