Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Planning a Starter Project
#1
I'm in the process of planning a starter DIY powerwall project. I would like to build a ~1 kWh powerwall with 18560 cells and a couple of solar panels. I plan on using this to charge phones, laptops, power tools and an electric lawn mower. I know that I"ll need roughly 175 cells with 3.6v and 1800 mAh in a seven cell group which will come to around 1.1 kWh and 25 v. I was looking into using Jehu's kit to build this project.

Questions:
  1. Having 25 7 cell groups, would I need to break these groups up into smaller groups?
  2. If they are broken into smaller groups how would I connect them together?
  3. What type of inverter should I use to be able to charge the system with a couple of solar panels?
  4. I'm guessing a 1000 watt inverter will be fine since the larger thing I want to charge is a 550 watt lawn mower batter charger?
Thank you
Reply
#2
(07-02-2019, 12:55 PM)jtso8 Wrote: I'm in the process of planning a starter DIY powerwall project. I would like to build a ~1 kWh powerwall with 18560 cells and a couple of solar panels. I plan on using this to charge phones, laptops, power tools and an electric lawn mower. I know that I"ll need roughly 175 cells with 3.6v and 1800 mAh in a seven cell group which will come to around 1.1 kWh and 25 v. I was looking into using Jehu's kit to build this project.

Questions:
  1. Having 25 7 cell groups, would I need to break these groups up into smaller groups?
  2. If they are broken into smaller groups how would I connect them together?
  3. What type of inverter should I use to be able to charge the system with a couple of solar panels?
  4. I'm guessing a 1000 watt inverter will be fine since the larger thing I want to charge is a 550 watt lawn mower batter charger?
Thank you

This is a great forum, welcome.   Here's a few cents - I'm sure others will chime in as well!

>1. Having 25 7 cell groups, would I need to break these groups up into smaller groups?
If you do 7s25p with average 1800mah per cell - you will have a nice 24v (nominal) battery at ~1Kwh as you suggest.   

>2. If they are broken into smaller groups how would I connect them together?
7 packs of 25cells each is perfectly reasonable - not very heavy etc.  There's no point large numbers of small packs unless you have some kind of physical constraint or special consideration.  

>3. What type of inverter should I use to be able to charge the system with a couple of solar panels?
Typically you use a charge controller (not an inverter) to charge batteries.   You can find combination charge controller (charge battery) / inverter (120v output) but its not as common (cheap) as seperate units.       
The charge controller needs to be able to to take in the max wattage your PV panels produce AND be within specs of the max charge your battery can take.
Charge controllers are typically listed as 'amps' they can produce - but they also have max PV voltage input and DC output parameters as well - they all need to line up.
For example:
If you have 5 x 100watt panels - then you need a charge controller that can accept 500watts and output 24v (for your 7s battery).  500w/24v = 20.8amps.  So you'd need a 21amp (e.g. 30amp) charge controller in this example.   Going a step further, the 21amp output -> battery would mean that each cell of your 25p pack needs to accept nearly 1000ah of charge...  which fine.   Your cells will have a max charge specification.

 >4. I'm guessing a 1000 watt inverter will be fine since the larger thing I want to charge is a 550 watt lawn mower batter charger?
This sounds reasonable.
Reply


Who read this thread?
30 User(s) read this thread:
daromer, Sean, Korishan, PAF, Mazlem, Geek, djuro, spinningmagnets, Issac, Oliman, CBlack, Beholder, Wolf, Generic, ajw22, kevinjaye, oloyeadeniran, OffGridInTheCity, JBonesaw, ben teker, Saiya, krobertson, stok, jtso8, leangheng, Ed Gordon, Smolder, cx530559, heiko, kpeters000

Forum Jump:


Users browsing this thread: 2 Guest(s)