4 ms·

Battery prices are getting really low, if you're willing to do some DIY. Just received a 15kWh battery from China. A 'Humsienk'. Combined it with a GroWatt SPA3

by jstsch 9mo ago

Battery prices are getting really low, if you're willing to do some DIY. Just received a 15kWh battery from China. A 'Humsienk'. Combined it with a GroWatt SPA3000TL-BL inverter. Total price, 1600 euros. So close to the magical 100 euros per kWh. Driving it with some interesting combinations of Raspberry PI's and serial interfaces and custom written Go code, but it works... :)

j2kun 9mo ago
I do wish I could have a good, in-depth tutorial on how to set this up myself. Along with (pipe dream) an explanation of how it would interact with my local utility. I worry that due to some silly technicality, I won't be able to export to my local utility, or else I won't be able to run off-grid when there's an outage.
- jstsch 9mo ago
  I will do a write-up in a couple of days. It's all relatively simple, you just have to expect terrible documentation and do a bit of reverse engineering and serial sniffing. I expected the battery to be complicated, but it turned out that the inverter was. You'll encounter stuff like: manual says use RS485 port on Battery for GroWatt inverter → need to use CAN port on Battery. Meter Port (RS485 [serial] over RJ45) wiring on GroWatt is unknown (A: white orange / B: white blue, cross them over). Dinky RS485 serial → USB converter needs a 120ohm resistor between pins for line termination. Growatt meter port expects a SDM630 meter, not a DTSU666 (hardcoded), so vibe code another emulator. DIP switches for RS232 connection need to be both on the ON position (undocumented). CH340 USB→serial converter for RS232 does not work, but one with a Prolific chip does. Etc. etc. etc :) Oh, and the biggest one... I was expecting to be able to just send a command, 'charge at 500watts', now... 'discharge at 2000watts'. But no. You have to emulate a power meter and the inverter will try to bring the net power to 0. Fun! :)
  - rmcpherson 9mo ago
    I would appreciate this write up as well. Looking to do a DIY setup.
f1shy 9mo ago
> Battery prices are getting really low, if you're willing to do some DIY. Willing and allowed. In some countries it can only be done by certified electricians.
- pjc50 9mo ago
  UK considerations: must be at least signed off by an approved electrician ("Part P" regulations), and for any situations involving subsidy needs to be MCS approved as well. https://mcscertified.com/ https://mcscertified.com/
  - ozlikethewizard 9mo ago
    Surely it only needs to be signed off if you intend to sell the property with them or sell excess back to the grid. If youre just using the batteries how is anyone going to know?
    - pjc50 9mo ago
      shrug if you can rely on nobody noticing, or non-enforcement, sure, but it is actually a criminal offence not just an administrative requirement.
      - f1shy 9mo ago
        If is something does happen, and Li Batteries catching fire is not something unheard of, you will be in a world of suffering. Probably having no home, and having to pay damages to the neighbors. All to save what? 2k$... 5k$?
    - aniviacat 9mo ago
      I'd assume your fire insurance covers nothing if illegally installed batteries are found inside after a house fire.
    - baq 9mo ago
      If your house burns down for any reason, not necessarily the DYI batteries, the insurance company will know anyway.
Barbing 9mo ago
Awesome. Feel you have more unknowns on the safety front? vs. the expensive off-the-shelf. [in the USA, it’d also be “fewer names to sue” in that unlikely tragedy of combustion in home, but no euro/kWh targets there]
- tomashubelbauer 9mo ago
  LFP batteries are as likely to burn down your house as a stack of wood is. I'd be worried about the inverter or botched DIY wiring (especially not to spec torque on terminal connections and botched crimps leading to hot spots), but not about the batteries themselves. For a person who wants to save some money, but doesn't know how to work with electricity, the best move is probably to get cheap LFP cells from China, but have a professional install a BMS and the remainder of the solar system.
  - jstsch 9mo ago
    > especially not to spec torque on terminal connections and botched crimps leading to hot spots This was indeed my greatest concern. However the battery came with pre-crimped very solid DC wires, and nice push connectors for the battery itself. The battery also has an integrated DC breaker (great!). The system runs 3KW max, so I just added an additional breaker (with RCD integrated) in the conduit box. In NL this is something a DIY-home owner easily can do themselves :) (just use the right solid/flex stranded cabling for the connectors, etc...)
    - scarecrowbob 9mo ago
      And further, my position has been that learning the correct methods, paying a lot of attention to details, and not being cheap with tools is -still- cheaper and probably more reliable than paying contractors. I have only used my hydraulic crimper for a pair of cables, but it was the correct tool and did good work. I'm not interfacing with a grid, and there are already code issues with my places- I'd probably feel different if I could get insurance on my place. Cheap chinese tooling and youtube (plus pretty good general literacy) go a long way in this world. And FWIW, I live in the US west and am way more worried about fire coming from outside than from the batteries.
ViewTrick1002 9mo ago
We are finally starting to see Chinese prices externally. It’s been crazy seeing the western home storage market selling systems with the €/kWh being more expensive than buying a BEV. And that includes a car. https://www.docanpower.com/eu-stock/zz-48kwh-50kwh-51-2v-942ah-compelete-pack-eu-stock https://www.docanpower.com/eu-stock/zz-48kwh-50kwh-51-2v-942...
Dylan1312 9mo ago
Did the same, got a solar installer to fit panels on garage and a solis hybrid inverter. They fitted a CT clamp on my meter and a lora device on both sides for it to communicate with the inverter. Then bought a 16kwh battery for ~£1500, installation was plugging in a positive, negative and ethernet cable and configuring the inverter to use the battery. (if my home insnurer is reading this, I had an electrician friend double check while helping with some other work) Definitely recommended for anyone who likes tinkering, thousands cheaper than installer pricing.
microdrum 9mo ago
Yup, Growatt is the Chinese OEM that Base Power white labels to pretend it does US manufacturing. In fact this stuff is low quality. You need to be careful. There are gradations of quality at cell, pack, inverter, control levels. You will be crushed if you realize you AliExpressed your way to a home power "solution" only to have it fail young.
MisterTea 9mo ago
> Driving it with some interesting combinations of Raspberry PI's and serial interfaces and custom written Go code, but it works... :) What protocol is it speaking? I've seen some of the more mainstream models call out that they use Modbus but all the cheap import models either might use Modbus or some custom protocol you have to reverse engineer or hope someone else did.

by jstsch 9mo ago

j2kun 9mo ago

I do wish I could have a good, in-depth tutorial on how to set this up myself. Along with (pipe dream) an explanation of how it would interact with my local utility. I worry that due to some silly technicality, I won't be able to export to my local utility, or else I won't be able to run off-grid when there's an outage.

jstsch 9mo ago
I will do a write-up in a couple of days. It's all relatively simple, you just have to expect terrible documentation and do a bit of reverse engineering and serial sniffing. I expected the battery to be complicated, but it turned out that the inverter was. You'll encounter stuff like: manual says use RS485 port on Battery for GroWatt inverter → need to use CAN port on Battery. Meter Port (RS485 [serial] over RJ45) wiring on GroWatt is unknown (A: white orange / B: white blue, cross them over). Dinky RS485 serial → USB converter needs a 120ohm resistor between pins for line termination. Growatt meter port expects a SDM630 meter, not a DTSU666 (hardcoded), so vibe code another emulator. DIP switches for RS232 connection need to be both on the ON position (undocumented). CH340 USB→serial converter for RS232 does not work, but one with a Prolific chip does. Etc. etc. etc :) Oh, and the biggest one... I was expecting to be able to just send a command, 'charge at 500watts', now... 'discharge at 2000watts'. But no. You have to emulate a power meter and the inverter will try to bring the net power to 0. Fun! :)
- rmcpherson 9mo ago
  I would appreciate this write up as well. Looking to do a DIY setup.

f1shy 9mo ago

> Battery prices are getting really low, if you're willing to do some DIY. Willing and allowed. In some countries it can only be done by certified electricians.

pjc50 9mo ago
UK considerations: must be at least signed off by an approved electrician ("Part P" regulations), and for any situations involving subsidy needs to be MCS approved as well. https://mcscertified.com/ https://mcscertified.com/
- ozlikethewizard 9mo ago
  Surely it only needs to be signed off if you intend to sell the property with them or sell excess back to the grid. If youre just using the batteries how is anyone going to know?
  - pjc50 9mo ago
    shrug if you can rely on nobody noticing, or non-enforcement, sure, but it is actually a criminal offence not just an administrative requirement.
    - f1shy 9mo ago
      If is something does happen, and Li Batteries catching fire is not something unheard of, you will be in a world of suffering. Probably having no home, and having to pay damages to the neighbors. All to save what? 2k$... 5k$?
  - aniviacat 9mo ago
    I'd assume your fire insurance covers nothing if illegally installed batteries are found inside after a house fire.
  - baq 9mo ago
    If your house burns down for any reason, not necessarily the DYI batteries, the insurance company will know anyway.

Barbing 9mo ago

Awesome. Feel you have more unknowns on the safety front? vs. the expensive off-the-shelf. [in the USA, it’d also be “fewer names to sue” in that unlikely tragedy of combustion in home, but no euro/kWh targets there]

tomashubelbauer 9mo ago
LFP batteries are as likely to burn down your house as a stack of wood is. I'd be worried about the inverter or botched DIY wiring (especially not to spec torque on terminal connections and botched crimps leading to hot spots), but not about the batteries themselves. For a person who wants to save some money, but doesn't know how to work with electricity, the best move is probably to get cheap LFP cells from China, but have a professional install a BMS and the remainder of the solar system.
- jstsch 9mo ago
  > especially not to spec torque on terminal connections and botched crimps leading to hot spots This was indeed my greatest concern. However the battery came with pre-crimped very solid DC wires, and nice push connectors for the battery itself. The battery also has an integrated DC breaker (great!). The system runs 3KW max, so I just added an additional breaker (with RCD integrated) in the conduit box. In NL this is something a DIY-home owner easily can do themselves :) (just use the right solid/flex stranded cabling for the connectors, etc...)
  - scarecrowbob 9mo ago
    And further, my position has been that learning the correct methods, paying a lot of attention to details, and not being cheap with tools is -still- cheaper and probably more reliable than paying contractors. I have only used my hydraulic crimper for a pair of cables, but it was the correct tool and did good work. I'm not interfacing with a grid, and there are already code issues with my places- I'd probably feel different if I could get insurance on my place. Cheap chinese tooling and youtube (plus pretty good general literacy) go a long way in this world. And FWIW, I live in the US west and am way more worried about fire coming from outside than from the batteries.

ViewTrick1002 9mo ago

We are finally starting to see Chinese prices externally. It’s been crazy seeing the western home storage market selling systems with the €/kWh being more expensive than buying a BEV. And that includes a car. https://www.docanpower.com/eu-stock/zz-48kwh-50kwh-51-2v-942ah-compelete-pack-eu-stock https://www.docanpower.com/eu-stock/zz-48kwh-50kwh-51-2v-942...

Dylan1312 9mo ago

Did the same, got a solar installer to fit panels on garage and a solis hybrid inverter. They fitted a CT clamp on my meter and a lora device on both sides for it to communicate with the inverter. Then bought a 16kwh battery for ~£1500, installation was plugging in a positive, negative and ethernet cable and configuring the inverter to use the battery. (if my home insnurer is reading this, I had an electrician friend double check while helping with some other work) Definitely recommended for anyone who likes tinkering, thousands cheaper than installer pricing.

microdrum 9mo ago

Yup, Growatt is the Chinese OEM that Base Power white labels to pretend it does US manufacturing. In fact this stuff is low quality. You need to be careful. There are gradations of quality at cell, pack, inverter, control levels. You will be crushed if you realize you AliExpressed your way to a home power "solution" only to have it fail young.

MisterTea 9mo ago

> Driving it with some interesting combinations of Raspberry PI's and serial interfaces and custom written Go code, but it works... :) What protocol is it speaking? I've seen some of the more mainstream models call out that they use Modbus but all the cheap import models either might use Modbus or some custom protocol you have to reverse engineer or hope someone else did.