malewithatail
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Post by malewithatail on Aug 30, 2022 20:12:28 GMT 10
Having now bought 2 large format 24 volt, 400 amp hour lithium battery's and they have been in use for nearly 2 weeks, others may like to hear of my experiences with the technology.
Performance is awesome. They can take the solar charge at 100 amps plus without issue, and do it in one big gulp. The Victron regulators have been fine tuned to charge the lithium chemistry at its optimum, but as the battery paks have inbuilt battery management systems (BMS), so can accept the default parameters used with a lead acid battery pak without damage. That said, optimum performance will require the set points be altered to suit.
The battery's have a guaranteed performance of 3,000 cycles to 100% discharge, nearly 10 years, and 8,000 cycles to 20 %, over 21 years. They also came with a 3 year unconditional warranty.
Issues.
1) The data logging on the Victron 150/100 regulator is a bit clumsy, and so I installed an Plasmatronics PL-40 regulator, just to do the data logging as its much easier to read. But...the voltage from the Lithium pak doesn't usually fall below 26.5 volts, even under load and at night, and the Plasmatronics cant be programmed for a return voltage above 26 volts, so the point of putting it in the system to find out what time the system goes into float (fully charged), is lost. There is another way to do it, by programming the voltage limits, and that's the next step.
2) The Lithium pak is a large box, and is quite a bit wider than a average battery cell, so the battery rack will need modifications to fit it in, and they shouldn't be mounted on their side as that would block the safety vent. If the old system was installed in a cabinet, the door might not close. (Experience speaking here !)
3) As the pak comes completely assembled in a stainless steel box with a positive and negative terminal at one end, its heavy, 100 kg heavy, so will need 2 people to move it into place, or as I did, the crane on the tractor. Even though it comes fully assembled, its still good practice to sit it on a wooden frame off the ground, just as you would a lead acid pak.
4) The fully discharged voltage is around 20 volts (for a 24 volt pak), whilst the fully charged voltage is around 29 volts, so most inverters, and possibly regulators, will have difficulty in coping with such a large voltage range, especially the lower limit of 20 volts. They will trip off below about 22 or 23 volts dc, so that could be a nuisance. Conversely, the upper voltage limit of 29 odd, is above the normal boost voltage of a lead acid battery and the inverter may again trip off, this time on over voltage. This can be somewhat overcome by reprogramming the regulator for a slightly lower float voltage, say 28.5 volts, and just letting the under voltage cut out happen, as its wont do any damage and by the time it happens, the battery is 80 % discharged anyway. Alternately, the inverter may be able to be programmed to accept these limits.
5) Lithium battery's can hold a lot of energy, for their size, so be careful. Don't short out the terminals accidentally, even though the BMS system will probably stop catastrophic failure, don't open them up etc.
6) The battery's came with a specific warning that they were not suitable for vehicle use, only stationary duty. So if you intend to use a lithium battery in a motor vehicle, get the right kind.
7) Also, a note came with them that they wont reach full capacity until they have had 6 or so full cycles to 100% discharge. That will probably happen during bad weather naturally anyway.
8) The "days of autonomy" of a lead acid battery, inherently comes out to over a week in a properly designed system, as you shouldn't discharge a lead acid battery more than 10% a cycle, so if your daily load is 100 amp hours, the battery size should be around 1,000 amp hours. Giving theoretically, 10 days of power storage. (You should never go that low, but its there). However, lithium battery's in large format are expensive, and as they can be discharged safely to 100%, the pak can be smaller. This results in less storage for bad weather. With the costs of solar panels coming down all the time, I just add extra panels to make sure of adequate charge in overcast weather, except in really bad weather, then you may need to run the generator for a few hours occasionally. Be careful though that the regulator can handle the extra solar power in good weather. The Victron range seems to be reliable, and if the maximum output is going to be exceeded, it simply current limits to a safe value.
As the batteries get more hours on them, more information as to the performance will become available, and I will share it with the group.
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frostbite
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Post by frostbite on Aug 30, 2022 20:33:25 GMT 10
I didn't understand any of that, but I recently bought one of these:
DCS 12V 200Ah Slim Line Lithium Battery
Haven't connected it at the retreat yet, but my biomedical engineer mate who recommended this battery reckons it will be a major improvement over the existing, old lead acid batteries I currently use.
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malewithatail
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Post by malewithatail on Aug 30, 2022 20:45:39 GMT 10
About a 10 X improvement on old lead acid technology. More efficient, can be deep cycled without damage, lighter, but a few issues as above.
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tactile
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Post by tactile on Aug 30, 2022 20:48:15 GMT 10
Post some photos if you can MWT...I'd be interested to see the packaging of those batteries. It still seems a bit of the wild west in regards to packaging standards with lithiums...is there a standard?
I quite like the look and utility of the Fortress units that Engineer 775 has been playing around with.
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Beno
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Post by Beno on Aug 30, 2022 21:16:59 GMT 10
Where do you buy your gear from MWT?
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malewithatail
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Post by malewithatail on Aug 31, 2022 9:08:17 GMT 10
Solar panels, regulators, inverters are from Rainbow Power Company. Not the cheapest, but the after sales service is great, and I have dealt with them for over 35 years.
Miscellaneous electric gear, circuit breakers, wire etc, from the local Electrical Hardware supplier.
Battery's, from Big Wei battery's in Slacks Creek, Qld. The pack is configured to 24 volts, 400 amp hours, but you can get it as a 12 volt 800 amp hour, or 48 volt 200 amp hour pack. It comes in a stainless steel box, with terminals at one end. Nice and simple.
Cost was around $5,500 for each pack. They come with an inbuilt Battery Management System.
Trying to post a photo.
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Beno
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Post by Beno on Aug 31, 2022 9:23:53 GMT 10
Cool RPC was who i was going to use too. I still have not got my chest freezer yet so i’m waiting for that and then building something to keep it going once the power goes out.
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malewithatail
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Post by malewithatail on Aug 31, 2022 11:09:46 GMT 10
RPC has always looked after us, even when things are not supplied correctly, a quick phone call and its on its way. Luckily, they are only 1 1/2 hrs drive away, so easy access, and its fun to wander around Nimbin and look at the diverse range of people that are there.
I had a faulty Victron 150/100 regulator that wouldn't go into program mode. Took it up there, they connected it up and.....let all the smoke out ! Obviously faulty, so no quibbles and supplied a new one.
Just a heads up people. With the shut down in China, expect delays in solar gear. I ordered 2 Victron 150/100 regulators, got one, which was all I needed for now, the other is back ordered and for the radio room/spare. They seemed to have a good stock of solar panels in the shop, but that situation wont last when people realize the supply issues that have been created.
One of my daughters wanted to run a refrigerator in her room, but it would have pushed things to run off the main system. So I installed a second hand, 12 volt 1,000 amp lead acid battery bank, a 2kw Jaycar inverter, 9 off 175 watt solar panels and a Victron 150/100 regulator and display. A 20 amp 12 volt Repco battery charger is there just in case, but even in overcast weather, the system is full at 10 am and hasn't needed the battery charger in the 6 months its been going. If all you need to do in run a fridge, that may be the simplest way to go. It has enough capacity for lights and computer when I get time to swap over her room power to her own solar.
I don't get out of bed for less than $10,000 a day.
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malewithatail
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Post by malewithatail on Nov 10, 2022 15:26:45 GMT 10
Update on the performance of our new lithium battery packs. Since they were installed on 2 of the 7 power systems here in August, Ive been monitoring the performance of them pretty closely. www.bigweibattery.com.au/wp-content/uploads/2021/02/SS48200cover.pngwww.bigweibattery.com.au/product/bwb-48v-200ah-24v-400ah-12v-800ah-10240wh-lifepo4-deep-cycle-battery-stainless-steel-box-marine-off-grid/The standby generator hasn't been used in those 3 months, even with a week of rain. It helps that there is 3.6 kw solar connected to each system, and a MPPT regulator, but the battery voltage hasn't been below 25.2 volts at any time. Ive seen the battery taking 97 amps charge after an overcast day and full sun hits the panels. The inverters are 2.5 kw and 3 kw and apart from some whoopsies with overloaded inverters due to user errors, the battery's haven't put a foot wrong. I will probably never buy another large format lead acid battery again, that's how good I think they are. Rules that guys wish girls knew. 16) All men see only 16 colors, like Windows default setting. Peach is a fruit, not a color. |
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Tim Horton
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Post by Tim Horton on Dec 6, 2022 7:50:01 GMT 10
I am so not electrical literate...
Trivia....
So with all the talk of large format batteries.. I remember an electric indoor fork lift that was 6-8000 lb capacity that had a battery about a meter long, a meter high and about 3/4 meter wide... It got plugged into the charger after every day shift.. There was also a spare battery for it that seemed they were swapped out about once a year..
I have no idea what level of battery technology this would have been, or if it would be useful today....
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malewithatail
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Post by malewithatail on Dec 6, 2022 14:19:46 GMT 10
Probably lead acid traction battery. Yes, usable for off grid, but not particularly efficient, and it didn't need to be as it was charged from the grid every day. Efficiency is the key off grid, not wasting charge power in losses, like heat.
The lithium's have now been in for almost 4 months, and during that time I have not needed to use the generator once. It does help having 3.6 kw of solar on the systems, but still the lithium battery's are performing perfectly, better than I expected anyway.
The limitation is not the battery's or solar, but the 2.5 kw inverter/charger, which will trip if someone uses the kettle at the same time as the microwave. I class that sort of fault as user error !
Our main system is 5 kw, 48 volts with 2,500 amp lead acid battery's, so doesn't trip off, unless I have the hot water booster on , both water pumps going, and someone uses the microwave in one house at the same time as the kettle. Still, after a minute it comes back on.
Thats what I do, I fix stuff and know things.
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malewithatail
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Post by malewithatail on Aug 25, 2023 14:57:46 GMT 10
Update.
Now have 3 of the 24 v, 400 amp lithium paks. One had a trip off, and Big WEI said it was due to over temp as the pack was in full sun. Ive now installed some Styrofoam around the box and had no further issues.
The paks haven't fallen below 25.2 volts, even on bad days, but can go as low as 21 volts, but the inverters will trip off well before that level is reached.
This guy seems to know what lithium battery's are all about and has some good info re cell balance modules.
Still impressed by these battery's and if the main 2,500 amp 48 volt pak fails, I wont hesitate in getting a couple of lithium paks.
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