Good evening,
@mattie170 , and? How are things going, can you give us an update?
We are really interested in some graphs what can show your improvements.
How is starting heavy loads going in particular, this to see if super caps are needed.
Regards, Jeroen.
Good evening,
We have also some info for Lithium enthusiasts, about placing a super cap to boost starting heavy loads and prolonging their batteries.
For every 7500KWh of lithium at 48V, place about 20F of super caps at 54V as this will reduce your current taken from your battery drastically, and so more lifetime for your install.
That means, as can be seen way above that we would test that, placing 3 times 62F super caps in series first (thatâs 62/3=20.7F) and then in parallel over the battery terminals.
We have seen them âfiringâ during heavy starts now for some time and the amperage from the battery itself was of course way lower and so way way below the recommended maximum amperage from the manufacturer for the same time (we talk from milliseconds to only 1 second here).
The graph with a super cap with lithium showed us 16 years of use, with one charge/discharge a day instead of 10 years in the same condition, thatâs massive and worth the investment, the sooner the betterâŠ
Check our old topic as well, basically nothing is changed since we tested that as well, Supercapacitors vs. LiFePO4 - #35 by Jeroen2
What it tells there basically is the 2 lifetimes of 2 different things connected together prolonging the overall lifetime of the most expensive component, the battery!
Regards, Jeroen.
Morning Jeroen,
The simple answer is the system is totally stable with pretty much no ripple that is of any concern considering the loads and load changes. We have had a lot of sun recently so thatâs taken care of most loads. This morning it is over cast and the batteries are giving out 120-160kwâs (2200-3000amps) but still, as you will see below, only small peaks and if you zoom in it will only ever read a peak of 0.4vdc. If you use a multimeter, the peaks will be slightly higher as it sees it faster but the average is lower than the vrm shows, average over time via multimeter is about 0.1vdc. I have ordered the extra 12 batteries so they will be here in a couple of months, shipping and fuel shortage dependant, so that will take the total storage to 1408kw. We will see if that makes any difference, which I donât think it will.
Per your other post about temperature of batteries, I now keep the whole battery house between 15-18c at all times (humidity between 40-60%, its higher when the system isnât working very hard as it needs the heat from the inverters to dry the air), so I will see how this affects the batteries and inverters long term and I hope, per your findings, it keeps them in good health for a long time.
Regards
Matt
Good Morning Matt,
Outstanding ripple, you do not need any super caps, thatâs now proven.
Extra batteries never hurts a system, it will help you to overcome days without enough sun and save more on your energy bill.
Personally, I would keep your tech room around 18-25 degrees, this as Lithium on 15 degrees or below should be limited while charging or consuming, but, please read the advised temperature from the manufacturer.
Regards, Jeroen.
Hi Jeroen,
Ok good to know on the temps, I have adjusted it to be between 18 and 21, I donât want to go any higher as I want to keep the core temp down so when it does start charging or discharging at 3000amps the core temp is low to deal with the extra heat being produced. This is mainly during recharge as its sustained heat for hours on end which does start to over power the air con. I have also fitted 3 circulating fans to mix the air between top and bottom shelves of batteries so it keeps the min/max cell temp difference between 0-2c.
Regards
Matt
Edit: Got the temp specâs for my batteries Working Temperature: 0 - 40°C Charge. -20°C - 40°C Discharge.
Good afternoon Matt,
Ok, good, thatâs basically standard info for most Lithium batteries, be aware that below 15 degrees you can have already a 20-30% temporary degradation, but doing so many times then permanent damage will or can occur, and below zero they fail in an instand.
Therefore in a cold climate a battery heating system is build in EVs, well, the more expensive ones of course.
The best regards, Jeroen.
Hi Jeroen,
What I should of said is the room temp was between 15-18c but the cell temps are always 1-2c high than room temp as the batteries are pretty much always in use apart from when exporting solar but by that time they have warmed up a lot from the charging. From a big charge cell temps will be in early 20âs but room temp is 3-4 c less. Ac use to turn off at 15.9c and turn to dry mode at 17.5c, now I have just raised it by 2c so I will see how that goes.
Good evening Matt,
Itâs a bit off topic, but I found a way to keep it here, as temperature indeed can improve ripple, read on!
If you keep the temperature alone around 3 degrees (or way more) above the outside temperature of your tech room than the moist level is normally already within the limits, thatâs what we do, we close all ventilation, doors and âcable holesâ hermetically, this to have as less as possible forced ventilation and so to save energy.
Then, as you do, with a âdryerâ, that will save a massive amount off energy when not taking air from outside, but keep in mind heating is cheaper than drying.
For lead acid we do the same, ?, you think straight away about explosive gas right, no, we use catalyzers (gas regeneration to water again, so, no gass) on each cell and use an air pump to mix the acid from the bottom to the top on 2 diagonal corners of the cells.
For lead we mount on the outside of the entrance door a red light which goes on at 26.4V (for a 24V bat, about gassing start point), and only 2 fans switch on for the whole room (pending size of power and room itself of course), one supply at the bottom, and one extract in top from within the building (on a save place), so already dryer than directly from outside.
Well, what has that to do with Lithium, the same, only no gas, but yes the moist level for your tech room drops drastically keeping it 3 degrees (or way more) higher than outside, and you save lots of energy by not having to switch on your dryer, just let the whole system heat up the room, and donât worry to much about individual cells to much as only when the charge is getting to the point that the BMS is equalizing the cells, then 2-3 degrees above ambient is still nothing as they like to be warm when charging and so prolonging their lifetime.
An easy test for you to do, is, as you have the equipment to do it, let your tech room heat up to, say, 30 degrees, then charge, you will discover that your charge efficiency went up and so charging is shorter in time, also when you now use power you will notice that your system is way more âcalmâ, and you see that cells are closer to themselves and that you see also directly in the ripple heights, repeat that test at 15, 20 and 25 degrees and you clearly see the differences, not much but it does, then choose your most ideal/efficient temperature, but normally itâs about 30 degrees!
At one Lithium install (since a couple of months), now, outside 14 degrees, inside the batteries 29 degrees and the room 24 degrees, no ventilation (hermetically closed, stand alone besides the house) sun down, just radiation of the tech room itself, called Octagon house.
At one Lead install (our own test site, now 14 years) just 5km from the above install, now, outside 14 degrees, inside 22 degrees and the batteries as well, no ventilation (but has, not hermetically above gassing point), sun down, just radiation of the tech room itself, called quintacasadafonte.
Yes, both installs in the north of Portugal, many Victron there (also just a few Outba.., Mastervo.., etc) hahaha, I donât know why, but that is what we do with Lithium and Lead installs ashore.
You will notice it with your ripple, please try, temperature, ooh yes, big differences!
Iâm in Las Palmas now btw for a jobâŠsame time as yours, Greetz.
Best regards, Jeroen.
Hi Jeroen,
Ok thatâs interesting.
The other thing you must remember with the temperatures is the inverters start reducing output from 25c so I want to keep away from that temperature as I do use the full capacity of them. So I want a safety factor of over 5c in case an ac unit fails etc and if I keep everything cooler it also gives you time as there is about 25 ton of concrete, batteries, wire, steel work and inverters which will take time to warm up. So you have time to fix any problems.
Oh nice, enjoy.
Matt
I find this topic very interesting from a technical perspective. I am planning on buying a Victron system with lithium ion batteries and I am interested in the lifespan increasing comments. Is this something that applies to a smaller household system as well or just for the 100kWh+ setups ? (Of course, install and measure first)
Good afternoon Christian,
Every battery operated systems improves adding the above mentioned equipments, of course in proportion to the install, and if the ripple is ok from new, then no equipments need to be installed of course.
Please follow the guidelines how to connect things and add the correct amount of batteries to an inverter with the correct cables, that fishes out 95% of the issues with ripple!
You can always propose what you want to buy here, and we can help with the do-s and not do-s, but it is easier to ask your local Victron vendor/distributer/installer directly.
Regards, Jeroen.
Hi @Jeroen2
Thank you for answering. I will make sure to remember this. Since I want to try to go âoff grid as much as possibleâ (NL, normal house 3x25A) I feel I need to know the inns and outs of these type of setups to actually make sure that the seller is not being to positive and in case things do turn out to not function as they should I would need to be able diagnose, troubleshoot and fix it.
I did read the forum rules and would not want to be a bother discussing a potential future setup, but since you asked; I am thinking either 3x multiplus II 6k5 GX running 3 phase with a SmartSolar MPPT RS 450|200 or 3x Multi RS Solar 48/6000/100 running 3 phase, depending if I am comfortable with a max of 4.8kW per phase. With at least 3 dyness power brick plus to start with (https://cdn.shopify.com/s/files/1/0811/2327/9185/files/POWERBRICK-PLUS_DataSheet_compressed.pdf?v=1773321902) and I am unsure that 3 would be enough going by the general guidance.
Good afternoon Christian,
The most bog standard instal is the 3x6.5kw multi, with a Cerbo for better integration of the house and future add-on , a Fronius inverter on the output and pylontech bats, plug and play.
You can also take 3x10kw, as power is taken from the bats offgrid, as these deliver then also just above this 6.5kw at night, better.
But you really need that much power for a normal house?
Please make a topic for your install and kick me in, as this should be asked separately of this one of course.
Regards, Jeroen.
Good morning Christian,
Did you open another topic for yourself?
Here is the bog standard configuration as a base to start with, Victron with Fronius.
SE_SOLS_Microgrid_EN (4) (1).pdf (600.9 KB)
Regards, Jeroen.
