Using 4 cell 18650 li-ion with 4 100W solar panel

[Sunking]

Karrak you are great and funny guy sir. Been my pleasure chatting with you. You should have been a politician in the USA. Good Lord knows you would get lot of votes and elected. Great material for late nigh comedy too, and the public could really use you a man like you in office like Biliary. You have a great day and a wonderful life. God Bless you sir.

[karrak]

Just how Stupid do you think the MODS and OWNER are Simon Mathews? Up until right now the link has been in your signature since you joined 5-9-2015 to attack me You only now modified your signature after I pointed it out yesterday you forked tongue lying SOB.

It took me al of 5 seconds to figure out your game on 5/9/2015. You came here to attack me and SPAM the site like you are doing right now.

Since when is a link to an Open Source project where someone can get free design information and software and participate in the project been considered as SPAM, have you actually followed the link to see what is there?

Maybe you think that Open Source software is all a Communist plot?

FWIW I am fairly sure that a large part of the Internet infrastructure runs on Open Source software.

Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

---

[Sunking]

Please do post the links?

BMS - Homemade Battery logger github.com/simat/BatteryMonitor

Just how Stupid do you think the MODS and OWNER are Simon Mathews? Up until right now the link has been in your signature since you joined 5-9-2015 to attack me You only now modified your signature after I pointed it out yesterday you forked tongue lying SOB.

It took me al of 5 seconds to figure out your game on 5/9/2015. You came here to attack me and SPAM the site like you are doing right now.

[karrak]

Simon Mathews I am not wrong. Shall I expose the real Simon Mathews and how many Large Format cells you have destroyed with you Simat Battery Monitor? You know the poorly designed resistor divider network with and insanely low resistance values. You have drained a lot of Cells to death with your monitor. Lots of websites talk about it and warm users to stay far away from it. Crystal Clear why you are so adamant thou shall use a BMS.

Last chance to leave now and never come back. Or shall I mail the mods the links and have you banned permanently with the SPAM in you signature trying to sell it here? I see you did not deny the reason you are here.

Merry Christmas, been waiting all year to give you that XMAS present

Gotcha!

Please do post the links, I am always interested in preferably constructive feedback and information on any mistakes I have made. The only discussion I know of about my BMS is here diyelectriccar.com/forums/showthread.php?t=167410 This thread points out a mistake I had made in the circuit diagram which I have since fixed.

As for destroying any cells you are wrong again.

At 24 volts "the poorly designed resistor divider network with and insanely low resistance values" draws 0.0033A. Drawing this much current from my 360Ah battery would take around 12.5 years to discharge it.

Here are other technical reasons for choosing the resistor values that I did, this is copied from the reply I posted at the other forum.

The main dividers values were chosen to give good noise immunity, while still giving a reasonable current consumption of ~3.3mA which is less than 5% of the total battery monitor consumption. The values I chose were ones I could get at a good price. If you want to use other values you can, just keep the ratios the same. As the monitor can be calibrated you could probably get by with 1% resistors but if you want high accuracy make sure they have low temperature and age drift. I don't see any point in varying the divider gain for different cells in the battery as the resolution is limited by the cell at the positive end of the battery. By keeping all the divider resistors the same values and hopefully from the same manufactured batch you should end up with better overall accuracy.

This project was designed to monitor a battery in off-grid Solar Powered applications where the batteries are going to get charged every day and will probably be > 100Ah is size.

Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

[karrak]

http://www.all-battery.com/32v24ahli...ery-30245.aspx


The price seems to be pretty similar to the soshine 26650s as far as $ per Ah but would require many many less cells and wouldn't require a spot welder and nickel tabs.. I suppose it might be worth the 40$ to get one and test it's true capacity.. The soshines were 70-80% of their rated capacity at low amperage draw.. Also I'm imagining the pouches are a lot less weight.

If it helps pinpoint some cells, I am going for about 75-100Ah.. give or take 1kwh. Would be nice to get 8 amps of power all night.

The price of those batteries is $1.50 per Ah, you might be better going for these Voltronix/Winston
batteries, voltronixusa.com/products/ the price on these works out at $1.36 per Ah.

If you are looking at 8 amps for the whole night in the middle of winter I would think you will need at the least 112 Ah (8A x 14 hours). If you were charging wholly from solar you will need at least a 200Ah battery to give you some reserve for when your solar panels will not provide enough energy to recharge the battery. The amount of reserve will depend on whether you have a back up generator or some other way of charging the battery and whether you are prepared to limit your power use on days when there is not enough sunshine.

Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

[PNjunction]

Also I'm imagining the pouches are a lot less weight...

Now what are your plans for providing the proper compression to those cells? You don't want to operate these with no compression. And unfortunately, that means most hacks just use duct-tape. BAD. Without the proper compression, you run the risk of developing hot-spots, and lesser known to benchtop hacks is the possibility of losing plate alignment - aka overhang - which is vital to avoid dendrites.

Suddenly your project takes on much more mechanical elements to do it right.

Not only that, but pouches are ripe for counterfeit, misrepresentation, used (missing zipper fuses, cut tabs and so forth). These cells are meant for manufacturers with their own casings, not the usual diy duct-tape and kapton tape crowd.

On a lighter note: Want a cell that only does 350 cycles? Use an agm down to 50% DOD. Want 1000 cycles? Use an agm down to about 25% DOD. Want 2000 cycles like LFP when run 10-90 DOD? Use an agm down to only 10% DOD per cycle. So yeah, a 10ah 4S bank of Headways is cool, but the cost and cycle life is about the same as a 60-75 ah agm taken down to only 10% DOD or so. AND that doesn't even have to be a so-called deep discharge agm. Your basic agm SLI battery will accomplish that when only taken down to 10%.

I know it doesn't fit your boating type application, but something for lurkers to think about if they are ok with the space and weight of lead. Counterfeits of Pb are not as common, can usually be gotten 10 minutes away, recycled 10 minutes away, and support standard off the shelf solar / charging hardware. AND when taken down to only 10-12% DOD, you have built-in autonomy, and perhaps lesser solar panel requirements to keep it charged properly.

I love LFP. BUT, unless you *really* need the space and weight and high-C performance, (like yours does) LFP even from a benchtop hack fun project, is a ripoff or at best a break-even (with a low-current application) if you know how to take care of lead and run shallow discharges.

At any rate, just a warning since it is soooo tempting to go down the slippery slope of buying into LFP trash. It can be done properly, but you gotta' do the homework while keeping your wallet closed! If you don't, you just become another diy financial disaster (or dumpster diver) statistic.

[Sunking]

Just in case you've run out of Christmas cheer, check out this guy who builds a controller electrodacus Just put a com after it.

Be careful there, you just lost your credibility with all the Mods and long time members here using the name Electrocudus. He showed up here a couple of years ago and got banned real quick from many reasons. Mainly because he was full of crap, dangerous, and a Spammer like Karrak. He has also been banded on every EV Forum there is for the exact same reasons. He showed up on Mike Holt Forum I moderate and lasted 6 minutes. I was two minutes too late to ban him myself before one of the other 16 moderators nuked him. In that 4 minutes of fame and glory generated 37 Red Flag Warnings from th emembership. Mike Holt Forum is for pros only with some 120,000 members in the USA. All pros know who he is.


Bad move dude associating your name with that idiot.

[PNPmacnab]

Just in case you've run out of Christmas cheer, check out this guy who builds a controller electrodacus Just put a com after it.

[drpatso]

Pretty dramatic forum here! Back on topic.

I have found these

http://www.all-battery.com/32v24ahli...ery-30245.aspx


The price seems to be pretty similar to the soshine 26650s as far as $ per Ah but would require many many less cells and wouldn't require a spot welder and nickel tabs.. I suppose it might be worth the 40$ to get one and test it's true capacity.. The soshines were 70-80% of their rated capacity at low amperage draw.. Also I'm imagining the pouches are a lot less weight.

If it helps pinpoint some cells, I am going for about 75-100Ah.. give or take 1kwh. Would be nice to get 8 amps of power all night.

[Sunking]

Wrong again, these are being 3-D printed by the person who designed then. As far as I can tell he is resident in the USA. See this website for more info batteryblocs.com

Simon Mathews I am not wrong. Shall I expose the real Simon Mathews and how many Large Format cells you have destroyed with you Simat Battery Monitor? You know the poorly designed resistor divider network with and insanely low resistance values. You have drained a lot of Cells to death with your monitor. Lots of websites talk about it and warm users to stay far away from it. Crystal Clear why you are so adamant thou shall use a BMS.

Last chance to leave now and never come back. Or shall I mail the mods the links and have you banned permanently with the SPAM in you signature trying to sell it here? I see you did not deny the reason you are here.

Merry Christmas, been waiting all year to give you that XMAS present

Gotcha!

[karrak]

OK here it goes. I have two arrays a 800 watt 24v array going to a pwm 40 amp CC. I have another 1200 watt array going to a midnight classic 90 amp CC (planning to expand in spring to fully utilize CC) both arrays are going to a 5 year old bank of rolls surrette batteries at 24v and 350 AH. I want to double my storage and replace these batteries with LFP (lifepo4) batteries. Do we have any recommendations for battery packages with or without BMS? I have followed the posts here on using the existing CC to prevent overcharge by keeping the charging voltage at 28.8 v and by setting the LVD near 10% SOC.. would like t start t look at available drop in options to replace my surrettes and Im thininking about 350-400 AH LFP. any suggestions for battery packages with or without BMS?
Thanks guys for any suggestions for my first foray into an alternate battery chemistry

Your current panel wattage and proposed 350-400 Ah LFP battery is pretty close to my system's 1200W solar and 360Ah battery @24V.

Most of the LFP batteries with inbuilt BMS of this size are usually 48 volts.

If you wanted to make a battery and add a BMS you could use CALB or Winston (sold as Voltronix in the USA) cells and a http://123smartbms.com/. I am not sure if there is an agent for the BMS in the USA. If not, you can get them from here http://www.ev-power.eu/Battery-Manag...-4-0.html#tab3.

May I ask what model the Midnight Classic controller is? Would I be correct in assuming you are using a 24V DC to 110V AC inverter, if so what is the make and model? Do you have any 24V loads?

Some figures on your daily consumption would also be useful.

Unless you want to charge the battery very fast at charge rates > C/2 (200A on a 400Ah battery) a charging voltage of 28.8 volts is unnecessarily high. A charge/bulk/absorb voltage of 27.6V (3.45V/cell) with a float voltage of 26.8V (3.35V/cell) will suffice and be kinder on the battery.

Simon

Off grid 24V system, 6x190W Solar Panels, 32x90ah Winston LiFeYPO4 batteries installed April 2013
BMS - Homemade Battery logger github.com/simat/BatteryMonitor
Latronics 4kW Inverter, homemade MPPT controller

[karrak]

Again Karrak is recommending cheap Chi-Com junk he peddles which carry no UL or any recognised 3rd part testing certifications or listings. More bad unsafe advice. Not surprised.

Wrong again, these are being 3-D printed by the person who designed then. As far as I can tell he is resident in the USA. See this website for more info batteryblocs.com

[Sunking]

end current: 4%
end voltage 3.65V per cell ( I know 3.6v is the safest but I had to for science)
charge current: 2.5A
charge time: 1hr 25min
capacity: 2742mAh,

voltage sagged back down to ~3.43V per cell and 13.734V total. Seems like a pretty minimal gain for lowering the end current and upping hte voltage.. 2661mAh vs 2742mAh


I'd say I can expect to safely draw 2400mAh from these cells, although I will lose a tiny bit of capacity charging to 14.2 with a solar charge controller vs 14.4

I think next I will try to cycle the battery without any balancing and see how well the cells keep balanced.

You are discovering what I have been saying all along. When you do the cycling use the Fast Charge Mode which only means you do not use the Balance Plug. As long as there no parasitic loads on the individual cells like Cell Monitors or Vampire Boards, the cells will not go out of Balance.

PN hit a subject I do not know if he realized what he said when he stated something to the affect of: Any other battery type other than LFP is crap with respect to cycle life is pretty much true. Even LFP doe snot match other chemistries. Bu tto PN's point no commercial EV manufacture uses LFP. So how do they offer such long service life. Real simple they would never allow the customer to ever come close to fully charging or discharging the EV batteries. It is a rare event a commercial EV to even Balance the cells. Just do not make the mistake into thinking a EV like a Telsa or Leaf allows you to fully charge the battery. What they call Full and you call Full is two completely different things. When they say "Full", is what they define as Full is not fully charged. If they allowed full charge, they would go bankrupt with warranty battery replacement. Follow their lead as best you can.

Just remember you cannot do what EV manufacture do by using matched cells within 1% capacity and closely matched internal resistance. This makes no difference where you try to Balance at the Bottom, Middle, or Top, and they do not allow Top Balance.

[Sunking]

Problems. Maybe best to leave this non-solar ebike app to those guys. Assuming PERFECT flat contact between the magnet and the anode/cathode surfaces with no oxide degradation, what is the voltage drop of the magnet under load / no load / and heat conditions?

Again Karrak is recommending cheap Chi-Com junk he peddles which carry no UL or any recognised 3rd part testing certifications or listings. More bad unsafe advice. Not surprised.

[totfcboatski]

OK here it goes. I have two arrays a 800 watt 24v array going to a pwm 40 amp CC. I have another 1200 watt array going to a midnight classic 90 amp CC (planning to expand in spring to fully utilize CC) both arrays are going to a 5 year old bank of rolls surrette batteries at 24v and 350 AH. I want to double my storage and replace these batteries with LFP (lifepo4) batteries. Do we have any recommendations for battery packages with or without BMS? I have followed the posts here on using the existing CC to prevent overcharge by keeping the charging voltage at 28.8 v and by setting the LVD near 10% SOC.. would like t start t look at available drop in options to replace my surrettes and Im thininking about 350-400 AH LFP. any suggestions for battery packages with or without BMS?
Thanks guys for any suggestions for my first foray into an alternate battery chemistry