Capacity test of our battery. How many Ah can I get out? (+🐸) 

Thanks for that, Ian!

Thank you, Peter.

It was a hot day 😜

Thanks Chris. I need to change the music at some stage. I hear this all the time 😂

Yes! Thank you! The bus bars seem to work very good now and have solved the issue with bad connections. I'm stimm not sure why the others didn't work for me while they do for other people.

Thank you, John! Yeah, I've got a good base and fine tune the system now to see how things go from there. I will get more solar over Easter. This will change everything again, I guess.

What bars are you going to use?

@@OffGridGarageAustralia I will put originals back on. Need to switch out bolts to studs and polish with carbon paste. I will see if I need the Al bus bars.

Thank you!!

Nice 👍

Thanks for watching and hello to Austria from Australia 😉

The inverter is actually specifically designed to life in tight spaces of RVs, boats, cabinets. It says this in the specs and manual.

@@OffGridGarageAustralia In maintaining the air flow (CFM) provided by the inverter internal fan you will achieve the best efficiency and longevity. The BMS should dictate when the Charge/Load disconnects based on the first cell reaching Max/Min (3.50/3.00 set voltage limit. The combined cells voltage set limits at the inverter/charger is a secondary fail safe type disconnect.

I am sure that you are correct but mounting the inverter inside the cabinet must restrict airflow. I don't see the point of putting it in the cabinet especially if you need to leave the door open. At marginal temperature/power load combinations it might just make the difference as to whether the inverter trips off or not. Running fans whether internal or external subtracts a little from the efficiency. . The internal fan runs for even intermediate power loads so asking it to run more often just so you can put it in a cabinet doesn't make sense to me. Also regardless of specification it is good practice to stay away from the edges of the operating envelope to enhance durability. Your type of usage normally doesn't get close to the limits but I predict that if you wish to run the inverter in the cabinet with the door closed in summer you will need to ventilate the cabinet with extra fans.

Ok next time

@@OffGridGarageAustralia It is even better to remove that enclosure completely, especially in your climate, this is so bad for the lifespan of your equipment, but well you will come up probably with a solution I guess, but leaving it out is better. haven fun

Thanks for your comment. It's not that hot any more. These extrem temperatures hit us only in summer time for a few days a year. But it was good to make these tests.

For another time, or friends in the north hemisphere, where the summer will come soon. ;-) cheers.

Thank you, I'll look into this.

Yeah, it seems this had made a big difference.

Installing more solar very soon (from 1.3kWp to 3kWp), so this should make a nice difference again to the system. Yeah, I have to find the sweet spot for these settings and see how I go. At the end I probably will go lower with all the settings a bit. My absorption time is set to 0, so the cells do not absorb at high voltage. But can you overcharge a cell with a small current even its voltage does not rise at the same time? I think this is correlated.

@@OffGridGarageAustralia Only at voltages above 3.375V. So, for example, holding a Float voltage of 3.35V (the recommended Float for a Solar/LiFePO4 system) will not over-charge the battery. So lets take two cases: (1) Bulk Target and Absorption This is why you usually want to specify a bulk target of at least 3.45V. If you specify a bulk target that is too low, you wind up trickle-charging the battery and the state of charge at completion (when it hits that voltage) can be almost anything. It's just too easy to reach a cell voltage that low. If you set a bulk target of 3.45V or higher you will get to a more consistent SOC. At low C-rates, though, you need to use the lower voltages in the range to avoid over-charging. So, a 3.45V at a low C-rate might get you 70-80% charged, where as a 3.55V target at a low C-rate might get you to 90-100%. If you set a low voltage target like 3.45V, you can then control the actual SOC at the finish line by setting a non-zero Absorption time, and playing with the absorption time to dial-in the state of charge that you desire. (2) Float voltage. The Float must be set at 3.350V to 3.375V. However, for a solar system it is usually a good idea to use the lower voltage of 3.350V. You can ask the question, what happens if I charge up a battery and then apply a Float of 3.35V 24x7 ? The answer is, the battery will continue to charge up to a point, but probably not go past 90% SOC. However, if it does continue to charge it will be an extremely low C-rate. We're talking 0.0001C to 0.01C.... so slowly that it might take a few days of continuous application of that float voltage to actually charge the battery up past 90% SOC. Eventually the current will go to zero at the Float voltage, somewhere around 90% charge. Probably not much higher than that. That's worst-case, say after a few days. Literally. But here's what is important... if you have any load on the battery at all that is in excess of the power supplied at Float by the charge controller, it won't matter. The battery will never get anywhere up to that kind of state of charge. In a Solar system, it just won't hurt the battery if the Float occasionally gets it up a bit higher than desired, as long as most of the time it doesn't. -- You need to distinguish between 'storing' the battery, as in not using it at all, and having an active system that does use the battery every so often. If you are 'storing' a battery, say for months or years, then you definitely do not want to apply any sort of voltage, Float or otherwise. Charge it up once every year or two and you are done. If you are actively using the system, though, then you just don't have to worry about a Float set at 3.35V. It will not add any significant cycle wear to the battery. -Matt

@@junkerzn7312 Great explanation, Matt. Thank you. I will try this out and test in a different setup and scenario 😉

You can stop earlier but it makes it harder for the BMS to balance because the curve is flatter. The higher you charge, the easier for the BMS to balance. And I don't absorb anymore, so I don't really charge the battery to a high SoC. Voltage falls back quickly. The heat from the outside wall is not a problem. There is plenty of space between that. The inverter already has spacers so does not sit flat on the cabinet wall.

I'm installing another 1.7kW of solar over Easter, so this should be fun then.

@@OffGridGarageAustralia Ya one can never have enough solar we just use too much power at least here in Canada

I have the multiplus inverter 12v 3kw mine has extra realize that you can use to trigger things like that

Or no float at all.

You can end absorption by two parameters. Either by setting a time or if the charging current goes under a set threshold (called tail current in the Victron). Whatever occurs first will switch the controller from absorption to float.

@@OffGridGarageAustralia Thanks mate, makes sense now.

Good job

Should have waited to the end of the video... Cooling system!

You have an aircon for your inverter powered by the inverter?

@@OffGridGarageAustralia yep!

The inverter is designed to be used in tight spaces in RVs, cabins, and boats of which none of them have large spaces usually. It also explicitly says it can be mounted inside an enclosure and has the additional relay output for external fans for this reason.

I would go up 10 mv on the float if the batteries will stay balanced.

The SoC will depend on the absorption time you give the cells. I only charge to 3.5V to trigger the BMS's balancing but I have no absorption time set at this point. I will test it and see how much more Ah it would take at this point until 100% full.

@@OffGridGarageAustralia I was also just cv no cc but my rebulk was only a volt lower. So it does mini cycles with a small load or no charging at all with no load . Keeps better balance on larger banks that the bms cant balance well. I posted a video how to set up lithium banks. Its in your comments.

@@frankz1125 Yes but get too close to the knee and they generally won't. What's the point for 1% capacity? Avoid the top/bottom 10%, cycle regularly and they'll stay within a few mv, for years, even without a bms....

@@mikeholt7881 I charge to 3.38v now without a bms because my batrium went down and I haven't had time to replace.

It's purely related to the cells not being matched. The curve over the majority of the discharge capacity is flat, so that's why the voltages match. Only at the knees of the curve this changes, and non-matched cells will not be in sync there. If you have matched cells (that is, capacity matched and internal resistance matched over the entire curve) you will have better results, but those cells are more expensive. It's easy enough to stay within the knees and don't care about it.

@@upnorthandpersonal Yeah, these iron cells have a really flat voltage profile which makes using voltage as some kind of indicator problematic. Except at the knees. I think Andy's cells are matched pretty well. I'm waiting to see how they look when he charges them up. :)

Eben, I tested all BMS voltages with the voltmeter and they are all matching.

@@OffGridGarageAustralia OK. Gotcha. I'm just very skeptical of Black Boxes. Stuff I don't have a schematic for. Looking forward to continuing updates. This is such a learning experience. :)

Yeah, I could do that. What an effort for these extrem days in the year though. I tested all this now to understand the limits of the system... more to come 😊

Finally, someone mentions it ☺

@@OffGridGarageAustralia The door is probly away at the shop to get racing louvers to exclude heat from the box. Please paint them dark blue on the bottom & red at top. Tks in advance. Haha cheers.

That's not correct. When the BMS app turns red on one cell, it shows the cells with the highest voltage. Many people get this wrong.

@@OffGridGarageAustralia Not the cells. The round Amp meter on top should be green unless it is completely discharge. Funtion setting then reset capacity when is fully charged or discharged.

@@OffGridGarageAustralia 14:39 Aparently the thick aluminum bars didn't help either because the problem is inside the cells. Cells 6, 7 and 8 is showing more than 300mv differences.

@@neliosamch3195 that's all good. We were at 2% SoC and the deviation increased at this point of time. They still delivered the full capacity.

@@OffGridGarageAustralia The Xiaoxiang bms is having a 19% discount in eight hours but I am undecided to buy two more because I found that these bms are very inaccurate. The cells that were in red with over charge were off by about 60mv with a fluke meter and another meter too. So I stil don't know if these bms should be recommended.

Was the same as now, just the contact area is no larger.

@@OffGridGarageAustralia I remember quite early in the build a discussion about how tight the bolts should be. I wasn't referring to surface area, however if two surfaces are not clamped tightly enough the connection will be suspect. Normally bad connections and inadequate conductor cross section get worse the higher the current flow.

Thanks, Jeremy. That is very interesting. What voltage (absorption/float) have you set your battery to?

@@OffGridGarageAustralia We discussed this a bit on one of your previous videos: I have my charge voltage set to 3.55v per cell, but I have shed loads that turn on once the cells reach 3.4v. This way I never lose any potential energy from the sun (IE: The MPPT keeps charging) but at 3.4v my shed loads come on and help prevent the battery from going above 3.4v. My shed loads include air conditioning, heating, and water heating. This way the excess energy that cannot be used by the battery gets used somewhere else useful.

@@JeremyAkersInAustin Oh, yes, sorry for asking this again. You had the Orion BMS which nicely talks back to your system and turns on this load so the SCC does continue to deliver energy. Such a great solution. Thanks again.

@@OffGridGarageAustralia No worries Andy! Always happy to answer questions.

See they drop really suddenly after about 3 volts per cell I don't like that I don't think you get very much power from then down so I just don't bother using it below 3 volts

Yeah, but erases all settings as well, not just the kWh...

@@OffGridGarageAustralia thanks for the reply!

The inverter is actually specifically designed to life in tight spaces of RVs, boats, cabinets. It says this in the specs and manual.

@@OffGridGarageAustralia Is there a spot in the manual thats says clearance allowance?

@@OffGridGarageAustralia I gotta tell you . You are the first guy I have ever seen over heat his inverter 10 times in a video. Just letting you know and not trying to be rude. I dont think that is good for it.

I would at least just lower the inverter in the cabinet so the air can escape better. Great videos anyhow

@@Mr.J345 I would put it on the floor. Safer lower as well.

Third

Yeah, I will get i contact with Victron about the inverter. It seems very sensitive and you're absolutely right, it should perform a bit better under heat. Especially reading the manual and spec, it seems to be designed for installations in trucks, RVs and boats, so, tight spaces...