Why are people afraid of High Voltage Batteries?
- Thread starter jpwhit
- Start date
I'm not aware of any hv bms with inverter comms. Do you mind sharing?
Ampster
Renewable Energy Hobbyist
I am not either. I know the Orion JR2 can communicate using Victron settings but it is only 16S. The larger options can do larger number of cells and CAN communications with EV motor controllers and chargers but I don't know if those messages can be converted to something useful for a hybrid inverter.
Maybe that's why people aren't doing high voltage systems???
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
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REC allows multiple 16s cascaded up to 128s.
I think Batrium or whatever has per cell electronics can do it too.
But what I don't know is what protocol each HV inverter uses.
For instance Sunny Boy Storage or Sunny Boy Smart Energy.
I think firmware supports specific listed batteries. For instance, my SBS with LG RESU-10H, earlier firmware is last revision which supports. Dropped in later updates.
zanydroid
Solar Wizard
There’s obviously too much friction, as this thread has made eminently clear again. Now, the other implied question in this thread is, how close are we to an inflection point (and what are those changes that cross the threshold) where the rules of the game change and people start tinkering with them a lot.
FWIW comms have been decoded for a lot of HV traction batteries, and I’ve even seen a GitHub to do protocol conversion from the traction batteries to an inverter. But based on the above average writing eloquence and technical content, the participants there are an esoteric layer of battery DIYer, several expertise and experience strata above the average red neck DIY battery “engineer”.
green mountain boys
Solar Enthusiast
A short video of a Sandi high voltage inverter and a brief look at a high voltage diy battery bank.
Hi. They can now thanks to the work being done over on Dala's EV discord channel. So far they have quite a few working brands and models listed on their wiki page where they connect car EV battery packs with great success. The cost is very low for the kWh provided by these large battery packs.
His battery emulator software can emulate a bunch of HV battery brands now. So it's growing in capabilities quite fast. Definitely worth a look.
What's nice is you can just buy a Nissan Leaf pack, or Tesla pack, etc., and not have to rebuild it. You can just connect it via a can bridge device and load his software.
I think more and more inverter companies are going to be releasing inverters that handle higher than 48v as standard from now on. So up to 400v or even 800v support is likely to become the norm.
I joined his discord several months ago he he helped me upgrade my Leaf from a 24kWh pack to a 30kWh pack without much trouble at all. It's been great. But now I have this 24kWh pack just sitting around so am researching a solar DIY build to be able to use it as a storage battery. It's fun learning and applying new knowledge to great benefit. I hope to be getting 'free gasoline' so to speak soon from my own solar build. And have like 4 days of power for long power outages. Things are getting good finally with solar options these days.
Alkaline
Solar Wizard
"Why are people afraid of High voltage batteries?"
Because of
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Because of
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What are everyone's thoughts on what might be likely ideal or standard voltages might be?
240VAC has a peak voltage of ~340 (non rms value).
My "solar" well pump is a standard 3 phase motor, running off of a Solar ABB VFD, which receives power in the same terminals as single phase VAC. Other than having some additional software entries manage MPPT voltages, it runs just as a normal VFD on VAC one does. I suspect many more VFDs, could receive DC power from batteries without the MPPT software and run, but only at the single phase rating. It could be interesting for additional loads, such as Air Conditioning.
What would an ideal HV battery look like? Could it be one that could feed VFD's?
Efficiency could be higher, but is it? At what voltage would efficiency be highest?
Throwing out some numbers.
Assuming cheaper Lion cell. 3.35 low volt and 4.1 high volt.
If Batrium watchmon ($253.90) plus K-9 ($175.73) per 16 cells which appears cheapest already made.
A 80s 268v-328v (5x16) (bms =$1132.7)
A 96s 321.6-393v (6x16) (bms =$1308.46)
Might need higher rated wire for above 600v. Maybe solar wire at 1000v.
Request of those working with EV batteries, is there a common voltage?
What are safety rules?
240VAC has a peak voltage of ~340 (non rms value).
My "solar" well pump is a standard 3 phase motor, running off of a Solar ABB VFD, which receives power in the same terminals as single phase VAC. Other than having some additional software entries manage MPPT voltages, it runs just as a normal VFD on VAC one does. I suspect many more VFDs, could receive DC power from batteries without the MPPT software and run, but only at the single phase rating. It could be interesting for additional loads, such as Air Conditioning.
What would an ideal HV battery look like? Could it be one that could feed VFD's?
Efficiency could be higher, but is it? At what voltage would efficiency be highest?
Throwing out some numbers.
Assuming cheaper Lion cell. 3.35 low volt and 4.1 high volt.
If Batrium watchmon ($253.90) plus K-9 ($175.73) per 16 cells which appears cheapest already made.
A 80s 268v-328v (5x16) (bms =$1132.7)
A 96s 321.6-393v (6x16) (bms =$1308.46)
Might need higher rated wire for above 600v. Maybe solar wire at 1000v.
Request of those working with EV batteries, is there a common voltage?
What are safety rules?
zanydroid
Solar Wizard
Boosting and bucking from 48V costs like 5% and requires an extra conversion stage.
With a high enough voltage the inverter will not need to have a preceding boost stage, and I believe the PWM and filter will do all necessary “bucking” with an appropriately chosen input voltage rail
So you can save some transistors and use smaller transistors because less current has to pass through them.
There are two voltage classes, 400v and 800v, but often they are built from smaller voltage modules in series. Maybe like 24V each? So you don’t have to use the full pack voltage. You can check salvage EV battery sales websites for the specs
Dunno, this is why I don’t want to bother until it becomes easier for me to learn.
You can also use EV batteries as LV if you want
green mountain boys
Solar Enthusiast
Why are people afraid of HV batteries?
I can say why I kind of am.
After messing with 120mm2 (awg4/0?) cables, getting it through walls etc. for few days as I did I'd love to be able to use 16mm2 and get far higher power with a HV battery.
But on the other hand if you think about fault current HV batteries get well too far into "ridiculous danger" land in my book. Also, it is not possible to "switch off" a chciał battery. You can only isolate. You can always throw a rug over a solar panel.
Id feel very uncomfortable working on live AC as well.
But then there is the risk of DC shock vs AC.
I've got few pretty serious shocks with 420V AC (interphase 240AC) in my younger years.
I'm very familiar with the feeling one gets during the 50Hz AC shock and I have enough trust in my reflexes to know (unless it is serious enough to interfere with neuronal activity) to know the "right thing" will happen immediately. Without thinking.
I am much more careful around HV DC mainly because I never had a HV DC shock and I have no clue how I would react. What if the muscles would contract in a way that pulls me more into it? What if I notice it, but don't recognise what is happening and I don't pull myself off it fast enough? Etc. It may well be" less fear of something known vs unknown" but still. I'd rather keep it unknown for as long as possible.
I can say why I kind of am.
After messing with 120mm2 (awg4/0?) cables, getting it through walls etc. for few days as I did I'd love to be able to use 16mm2 and get far higher power with a HV battery.
But on the other hand if you think about fault current HV batteries get well too far into "ridiculous danger" land in my book. Also, it is not possible to "switch off" a chciał battery. You can only isolate. You can always throw a rug over a solar panel.
Id feel very uncomfortable working on live AC as well.
But then there is the risk of DC shock vs AC.
I've got few pretty serious shocks with 420V AC (interphase 240AC) in my younger years.
I'm very familiar with the feeling one gets during the 50Hz AC shock and I have enough trust in my reflexes to know (unless it is serious enough to interfere with neuronal activity) to know the "right thing" will happen immediately. Without thinking.
I am much more careful around HV DC mainly because I never had a HV DC shock and I have no clue how I would react. What if the muscles would contract in a way that pulls me more into it? What if I notice it, but don't recognise what is happening and I don't pull myself off it fast enough? Etc. It may well be" less fear of something known vs unknown" but still. I'd rather keep it unknown for as long as possible.
I'm building a 400V pack for a data center. It takes a lot more cells to build a high voltage battery, and considering cost-wise the sweet spot are the 280Ah cells, it takes a bit of space as well (but you do end up with quite some capacity). So it's not that people are afraid (although, if you build something like this, you need some proper PPE and understanding), it's just impractical for most DIY set-ups at this time.
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