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If you're buying BMS controllers from China and are disappointed as to why claims of higher currents fall short this should help give you some perspective. The problem lies in thin wires supplied, you can't have an AWG 22 wire controlling high currents (over a few hundred mA). It's not that the...

That should work fine. Also make sure to have good connections to the battery and the inverter. AWG 6 (100 amps) or AWG 4 (135 amps) battery cable can be purchased with connectors on it if you can't do your own. They will cost a little more but you'll be sure of getting good terminals...

You can. Make sure you vent the batteries, especially if you plan to add a charger and PV. The inverter should have a low voltage cut off to keep the batteries from too low a state of charge. Usually golf cart batteries are 105 to 110 aH. That means you get about half of that with a...

LiFePo4's are the best if you're worried about fires. I'm running them in the house, in my basement. I've tested them with a short to dead. Not only do they not explode they can be charged to full again. I didn't believe it until I had a 36V DeWalt pack fail to charge. I had left it in it's...

That "thing" is exactly what I'm talking about and they still sell like hotcakes on eBay. I explained why they don't work. You seem to believe you can switch off a high current shunt and instantaneously measure battery voltage, you can't do that with any degree of accuracy and, again, you can't...

Modified sine is a misnomer, these are really modified square wave inverters for the most part. Certain electronics will have problems with them and anything with an inductive load such as AC motors run hotter because the load sees the square wave as DC at certain points in the wave. Without...

You make some very good points. My advice to people is to build an intertie system with back up. It may look glamorous but running on batteries constantly is a bad idea if you have grid available. An intertie with back up keeps your pack charged for when you need it and sells all your excess...

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This is why I think we have to classify battery applications. If you're just using batteries for backup when there are power failures in your area then Lithium's may not be the best choice. My last L/A batteries lasted 13 years, they cost me $1,600. and I got back $300 when I sold them for...

11Mwh a year = ~30Kwh per day 85Kwh / 24 = ~3.5 days you can run your house without any battery recharging. We usually consider about 4 to 5 hours a day of sunlight in the poorest areas of the US so I'll use this. At 11Kw of PV in one hour you will produce 11Kw of energy times 5 = 11Kwh...

I would say do it one piece of equipment at a time. The other thing to look for is adding heavy loads with sensitive electronics also hooked to the inverter. Trace engineering became Xantrex and it was the gold standard at the time, noted for being very robust and well made. My thinking is that...

I see the problem you're using a specific battery curve and applying it to all LiFePo4's. I'm working off my specific battery curve and doing the same thing. Also I suspect that the batteries coming from my manufacturer (Tenergy) are already condition because I took several out of the lot and...

No problem, glad to help.

For point of reference. My bank is a 16S by 36P. Max charging is 60 or 80 amps, I forget which off hand. What I did when I built it was to use #24 wire as fusing between each pos battery terminal to the continuous neg rail of the next parallel 3.6v leg. Each 4S battery in the 48v system is ~12v...

Check your inverter data and how long and large a surge it can take. I suspect it's at least double for several seconds. At 4kw you're drawing over 300 amps at 12v. The inverter also very likely doesn't double its power instantly, it's like a delay line. The 200A fuse will see the load before...

Not true, First you can't shut off a comparator to check cell voltage and some of these use comparators. If you want a balancer with 50 or 60mA balance current these are fine but some claim higher current capabilities. Shutting off charging to test cell voltage doesn't work well because...

Will, Good luck with the project. If I was building it I would excavate a trench around my property and bury cooling lines instead of air conditioning. I try to keep my usage foot print as low as possible. Rob

Will, I did some prelim tests on my LiFePo4's. What I found is that charging to 3.5 volts gives you 100% charge. Charging to 3.65 doesn't give you anymore than that. Once you hit ~ 3.55 to 3.6 volts the battery isn't as stable as it is at lower charging voltages so if you have batteries in a...

If you're on a budget you can use 1/2" copper pipe flattened out and drilled. You can even get creative with shrink tubing if you want. I did some prelim numbers and I think 1/2" 'L' ('L' is thick walled and carries more amps than 'M' pipe) pipe carries well over 100 amps with no problems. Rob

You can use battery cable the same AWG as your power cables. A simple solution is to get bare stranded ground cable at box stores like Home Depot.

Hi Everyone, I have a SolarEdge SE6000 system on my roof for ten years now with the SE6000 grid tie inverter. The system works fine but I have a couple of questions. I always assumed the inverter would supply the house needs first then sell excess to the grid, can anyone confirm this - thanks...

My bank is 36P @ 5.5A ~200A total. What I do is keep the single leg at 3.4 volts. I use very little if any capacity and I find keeping the battery under the high slope of the charge curve keeps any batteries from charge runaway at lower internal resistances. The balancers work very well, each...

Yes, right typo 3.42 V! For my bank I set my charge controller to ~54.4V (48V system 3.40 V per leg). This way the clamps aren't fighting the charge controller. This is important, you don't want the charger high total pack voltage to be above the low cut off voltage of each clamp comparator. A...

Thanks for all the comments everyone! Here's the circuit I designed to keep my batteries in balance on my 576 cell 48V pack 16S-36P. it works very well with my two charge controllers on my system which go up to ~60amps if I remember. I keep the max charge voltage to 54.4 or ~3.4V / cell. Because...

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I tried that balancer and found it didn't keep my pack in balance. I forgot what I tested the current at but it was not as advertised.

That's exactly right, if you look at the curves you can see where the voltage rise is almost exponential, that's because there's very little more charge they can take that will make any difference and the internal resistance drops causing balance problems because at the knee of the rise battery...

Good question sorry I didn't address it fully. OK, let's say you have an inverter that can run continuously at 1,000 watts with a 2,000 watt peak for 3 seconds. Ideally what you want is to fuse it for those 2,000 watt surges plus just a little more. Now let's say your inverter is 110 VAC out...

I tried this balancer, actually it's the one I tested that shows exactly what I'm talking about. Yes, if you're going to do small cells with minimum charge current they will work but don't expect more. It still has to follow the wires back to the controller to dump current to other batteries. It...

I think it's a good idea, you might get better prices on eBay or Speedy Metals.com. Expansion is greater but I've seen industrial applications using aluminum flat stock, just allow for the expansion. Also use some Noalox around the connections like electricians do in house wiring. What you have...