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paulz
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# Posted: 25 Nov 2021 05:29pm
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Here's the video of the guy that made his busbars out of copper pipe.
https://www.youtube.com/watch?v=jP1vVb-z0yc&ab_channel=RichardLloyd
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gcrank1
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# Posted: 25 Nov 2021 06:21pm
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Imo, its a judgement call....the old Good, Better, Best.
If a mashed copper pipe is better than the cabling you have to make equal heavy gauge cons then its an 'improved' system; right?
As invested as you are in this system work toward Best as you go 
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paulz
Member
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# Posted: 26 Nov 2021 10:59am - Edited by: paulz
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Not mashed, pressed flat in my 12 ton press. I'm going to scrounge around for something better. The bats are inside the cabin, haven't had any corrosion problems. 4 bats in parallel would take two of these bars.
So yesterday I had Bat 4 on the charger and went out to work on a car. One thing led to another and 3 hours later I came in. It was charging at less than 1 amp. A couple hours later it was at 13.7, higher than the other 3 which were at 13.4. So I put them on the charger last night and ran them down to 1 amp charge.
This morning the lowest is showing 13.7 and the highest 13.9. They all show 100% SOC according to the software. I expect they will drop but want to make sure that's close enough to hook up in parallel.
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gcrank1
Member
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# Posted: 26 Nov 2021 12:36pm
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One man's mashed is another man's smashed...
or flat, lol 
Does the pipe as buss bar really need to be flat? Is that so you have enough wall to drill/tap?
How about just drilling a hole straight thru and using a bolt/nut? Cant get enough lasting torque?
Or, in all your stash dont you have some better than copper pipe?
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ICC
Member
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# Posted: 26 Nov 2021 01:20pm
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I believe that copper pipe is a different alloy than what is used for wiring and that can make the copper pipe less conductive than copper sold as wire. But copper pipe is still better than steel I suppose.
Yes, it should be flat otherwise a bolt through the tube diameter is not going to be really as tight as it should be.
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paulz
Member
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# Posted: 26 Nov 2021 01:57pm
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Aluminum seems to be the other option. Got plenty o' that. About 20-25% less conductive they say, just need more of it I guess.
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ICC
Member
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# Posted: 26 Nov 2021 03:06pm - Edited by: ICC
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First problem is surface oxidation. It is rapid. Aluminum oxide is hard. Copper also oxidizes but copper oxide is soft and easily scraped away by tightening a fastener to it. Aluminum oxidation is one reason it is more difficult to weld. Aluminum oxide is not a good electrical conductor.
Aluminum is used for some commercial buss bars but they are tin plated, sometimes silver plated. All those shiny silver colored buss bars you see in electrical service panels are plated. You can't tell easily just by looking.
Surface aluminum oxide is why pv panels are supposed to be grounded using special clips that have S/S pads that dig into the aluminum when the mounting bolt is tightened.
If you or anyone else wants a good alternative power system I strongly suggest to stop messing around with second rate make-do parts.
It's somewhat like using regular grade gasoline in an engine designed for a premium grade or using canned green peas instead of fresh (or at least frozen).
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paulz
Member
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# Posted: 29 Nov 2021 09:56am - Edited by: paulz
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Been busy but not with bus bars. I bought an old Dell min-laptop running Windows 7 for $50. Actually surfs the Internet pretty well but it also runs the Valence software, so I'm dedicating it at the cabin for just that.
Got all my freshly charged batteries back in service at the cabin, using the previous 8" auto battery cables. With the bats at 100% I was able to program the Aili meter for SOC. The four batteries total 560 advertised AH, I programmed for 500. Day 3 at the cabin this morning and it's showing 406 left with 81% SOC. Battery voltage 13.29. I am a little skeptical about the accuracy but good to know there's till plenty of juice left. Did get a few hours of 2-3 amp solar charging yesterday, just enough to balance the draw.
Also still moving panels, this time up to the guest room above the cabin, slightly less tree blockage. About a hundred foot run, according to the online calculator it shouldn't lose much with 6awg cables.
Honestly with the ability to recharge the LFP batteries so quickly off a generator, and enough capacity to last several days, the solar may become secondary until I get more sun in the spring. Something to consider for anyone debating solar.
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gcrank1
Member
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# Posted: 29 Nov 2021 02:00pm - Edited by: gcrank1
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For our small off-grid 'recreational' cabin Im inclined to agree Paul. If our place had not come with 6 x 112w panels and a marginally working solar system I dont think I would have put it in. Our exposure is not that great, not what would have encouraged me to say 'let's go solar' right off anyway.
Ime, FLA bats are so slow charging if taken to 50% of usable a/hrs (thus my target is 25-30% dod) that it gets to be too many hours of gen running a charger. My work-around for that when I had the solar torn apart was to charge the bats whenever the gen ran for tools, etc and only use the power off the bat-bank for after dark and early morning; ie, mostly leds for good light, usb ports, all light draw stuff.
But LFP really seems to be a game-changer with a heavy duty charger that can slam the a/hrs back in.
If I would have had to 'buy some kind of system' Im thinking 200ah of LFP and a 30-40a charger to run on the gen would have been more cost effective than building a solar set up. And it would provide for running more demanding elec loads than 400ah/200 usable of fla can.
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travellerw
Member
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# Posted: 29 Nov 2021 02:42pm
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Quoting: gcrank1 If I would have had to 'buy some kind of system' Im thinking 200ah of LFP and a 30-40a charger to run on the gen would have been more cost effective than building a solar set up. And it would provide for running more demanding elec loads than 400ah/200 usable of fla can.
We replaced our 400ah/200 FLA bank with a 400Ah LiFePO4 bank. Sigh, I was shocked at how quickly we "grew" into the extra capacity. After a month or so, we wondered how we ever lived without it. LOL..
It was really a shift in mindset from FLA. No more did I worry about getting back to %100 every day. Instead I worried about not getting back (as sitting at float meant I was throwing power away). Those were good days when the solar was super strong and I could turn on the hot water heater to use that extra power
On cloudy rainy runs, it was pretty cool to run the Honda and one of our main motors. The Iota would dump 70A and the alternator would dump another 40A in. 2.5 hours and 300Ah was back in! LOL, I spent more on alternator belts than fuel though!
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gcrank1
Member
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# Posted: 29 Nov 2021 03:09pm - Edited by: gcrank1
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The recharge trick for lfp seems to be to run as much charger as your gen can power limited only by the c-rate the battery can take.
Short a gen a dc-to-dc charger off one's vehicle may be an alternative or 'spare'?
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travellerw
Member
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# Posted: 29 Nov 2021 03:43pm
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Quoting: gcrank1 Short a gen a dc-to-dc charger off one's vehicle may be an alternative or 'spare'?
You need to be SUPER careful charging LFP with an alternator. LFPs have fried more alternators than I care to count. I saw a nice Balmar alternator that got so hot it began melting the belt off the input pulley. It basically runs the alternator at FULL BORE for the entire duration. Alternators are not designed for that as they are made for charging FLA (where the charge current tapers after a period). By the time you get an alternator setup that will handle the load, you could buy one Iota charger and 2 Honda 2000s.
On our boat, the v-belt was actually the limiting point. I couldn't tighten a v-belt tight enough that it wouldn't slip. So the alternator never ran at full load since the belt was slipping. I would replace the belt about every 2 charging cycles. The belt dust in the engine bay was crazy!
Of course the best is a nice strong solar setup. As long as the sun is shining, its pouring electrons in at the max the panels could put out. Free electrons run stuff better than bought electrons 
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Steve_S
Member
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# Posted: 29 Nov 2021 03:49pm
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I'm glad you got that $50 lappie and everything hooked up & running as it should. LFP being 99% efficient is really nice. If in the 15-20% SOC Range and 8 hours @ 100A Charge fills & floats out "tops" off the main bank giving me 10 Days of LFP stored.
Your batteries @ 140AH should be able to take a max of 70A charge each. You can safely push that at your parallel set without worry BUT at roughly 90% of Gross capacity, CV is needed to finish off or the BMS will start to cut off as the cells cross 3.525Vpc (14.1V)
Enjoy your new found freedom !
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paulz
Member
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# Posted: 29 Nov 2021 04:26pm
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Thanks Steve, and again for all the help. Yes Valence says 70A per. I'm using my smallest 900w generator, it's the only inverter gennny and I know it's safe to run the Meanwell power supply. But when I hook it up it goes from a nice idle to really working to crank out 40A. I ordered one of those $50 oscilloscopes, hoping I can learn to figure out sine waves on other generators (tried the fan trick, couldn't be sure). I have an Onan LP RV 7kw genny, runs at half RPM (1,800 I think) that could really pump out the power. It also has remote electric start, meaning I could have it in a shack someplace and just fire it up and charge without even going outside.
As I mentioned I get a pretty good spark if I connect the Meanwell to the batteries before plugging it into AC. So I'm hesitant to hard wire it to the batteries without a big switch. Maybe just a capacitor but maybe not good to leave it on. I emailed Meanwell this morning, no reply as yet.
Not throwing in the towel on solar though. It's just a combination of spending more time out here this winter, the recent fridge addition and less recovery days when we're not here. Prior to the days getting shorter I was getting a 10A charge for a few hours a day, enough to break even on usage.
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travellerw
Member
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# Posted: 29 Nov 2021 04:32pm - Edited by: travellerw
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Quoting: paulz As I mentioned I get a pretty good spark if I connect the Meanwell to the batteries before plugging it into AC. So I'm hesitant to hard wire it to the batteries without a big switch. Maybe just a capacitor but maybe not good to leave it on. I emailed Meanwell this morning, no reply as yet.
You are getting a big spark because the Meanwell has smoothing caps on the output rail. When you connect to the batteries, there is a big inrush current as it tries to charge those caps.
If you want to hard wire it to the batts with a switch, its best to put a nice resistor in parallel with the switch. It keeps the caps charged up so no big inrush when you throw the switch (which will wear the switch out pretty quick).
You can just leave it permanently connected without a switch as once those caps are charged, they stay that way (although draw an itty bitty teeny weeny amount of power due to leakage). Personally I would make sure to have a fuse between them. However, you will shorten the life of the Meanwell as those caps will be "in use" 24x7. This is the disadvantage of using a "Power Supply" as a charger. Its meant to provide smooth power for instruments (thus big smoothing caps). Battery chargers usually don't have smoothing caps like that on the output rail!
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paulz
Member
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# Posted: 29 Nov 2021 07:12pm
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OK thanks traveller. So putting a resister in will also keep the caps charged, and shorten life. I think I'll try t a switch first and see how long it lasts.
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gcrank1
Member
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# Posted: 29 Nov 2021 07:17pm
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I suppose one could energize the caps by touching to a 'less critical' battery than the lfp, say a spare fla you keep around for test purposes, etc.? That way when you con up to the lfp there should be no arc.
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paulz
Member
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# Posted: 29 Nov 2021 07:29pm
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If I plug it into AC first there is no spark, neither at the AC plug or the battery, at least that I've noticed.
The dream wish would be to leave it plugged in at both ends and just fire up the genny to charge and turn it off to stop. Pretty lazy I know..
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Steve_S
Member
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# Posted: 29 Nov 2021 07:50pm
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Precharge
A design guide to DC precharge circuits.
Also a goldmine of knowledge
http://liionbms.com/php/precharge.php
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travellerw
Member
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# Posted: 29 Nov 2021 08:20pm - Edited by: travellerw
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Quoting: paulz OK thanks traveller. So putting a resister in will also keep the caps charged, and shorten life. I think I'll try t a switch first and see how long it lasts.
Yes. it will shorten the life..
However, you could put in 2 switches. One switches on the resistor first, wait 5 seconds, switch on the other one to fully connect the batts.
Another option is just one switch. Fire up the generator (which precharges the caps), then throw the switch to connect the batts.
Or just accept the shortened life as it would still be pretty long. It would also not be hard to recap it when it dies.
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gcrank1
Member
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# Posted: 29 Nov 2021 09:18pm - Edited by: gcrank1
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Arent there Lots of things that have their caps perm powered that live long?
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paulz
Member
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# Posted: 30 Nov 2021 09:06am
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Quoting: travellerw Another option is just one switch. Fire up the generator (which precharges the caps), then throw the switch to connect the batts.
Sounds good. With the genny and switch off, the caps are uncharged. Fire it up, caps charge, then flip the switch on the DC side. Basically what I've been doing except for a wing nut on the battery stud instead of a switch.
Simple really, I would have figured it out, sooner or later..
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paulz
Member
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# Posted: 3 Dec 2021 11:29am
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Yesterday I charged the bank at the cabin, with the 1000w genny and Meanwell, with the Valence software connected. Input was 7-8 amps per battery max.
I have another Meanwell, thinking about using two. Would be close to max capability of the genny, it has a circuit breaker though. Just wondering if it's OK for the power supplies. The Meanwell doc says something about 'built in parallel operation function', whatever that means. Just don't want to back feed from one into the other.
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paulz
Member
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# Posted: 6 Dec 2021 02:13pm
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Today's installment of As the Batteries Charge:
This morning my cells were at 3.290. I cobbled up a test using a second Meanwell, with it's own ammeter, full tank of gas in the little genny, hoping to pump in 80 amps. Didn't happen. One charged in the high 30s, the other around 5 I think. I unplugged the 30 one and the other shot up to 40 or so. Plugged both back in, same thing. I had large cables everywhere. Had the DC+ coming off one, - off the other. So:
Maybe 40 is all they would take at that level (3290)?
Maybe the 1,000w genny wouldn't put out enough AC current? The Meanwells seemed to be running fine, both fans going.
Maybe two power supplies won't work in parallel.
I ran a whole tank of gas, over two hours, using one charger, and got them to 3.360, still about 30 amps coming in, was hoping for more.
Harumph.
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travellerw
Member
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# Posted: 6 Dec 2021 03:12pm
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Quoting: paulz Maybe two power supplies won't work in parallel.
That should work. You should get double the current. Strange.. I can only think the battery BMS is limited!
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paulz
Member
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# Posted: 6 Dec 2021 06:28pm - Edited by: paulz
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I hauled the plot down to my shop and hooked it to the FLA bank, no BMS. Same deal.
A workaround might be to put a switch splitting my bank in half, and charge 2 with one Meanwell and 2 with the other. But I'd rather this worked..
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gcrank1
Member
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# Posted: 6 Dec 2021 07:03pm
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Have the meters been shown to be at least somewhat calibrated together?
Did you swap meters on the Meanwell's?
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paulz
Member
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# Posted: 6 Dec 2021 07:13pm
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Either one will jump to 30-40 if the other is unplugged.
The Meanwell spec says 'built in parallel operation function', whatever that entails.
Maybe the voltage adjustments have to be exactly the same? They are at 14.1 give or take.
https://www.mouser.com/datasheet/2/260/scn-600-spec-1180098.pdf
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gcrank1
Member
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# Posted: 6 Dec 2021 07:24pm
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Looks like you are running one MW into the other with only one pair of cables to the bat-bank; I assume to opposite bat corners too.
How about cabling each MW to opposite corners of the bats so each is feeding the bank from the 'other side'.
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paulz
Member
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# Posted: 6 Dec 2021 08:01pm
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I am feeding each battery cable from separate units.
But, found this further down in the specs! Looks like I have to connect some terminals on the MWs.
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