BMS advice needed for 7s8p or 7s16p solar storage


MASSIVE restock of EV Batteries at www.batteryhookup.com 5% coupon "POWERWALLS"

grossy34

New member
Joined
May 16, 2022
Messages
9
Hi im about to finish 7s8p or 7s16p for solar storage, still undecided if 8p or 16p as no idea what kind of bms is needed for smaller and bigger pack, cells used brand new 18650 eve-26v, would appreciate for any advice.
 

italianuser

Member
Joined
Feb 25, 2020
Messages
502
Possibly get yourself a BMS which can handle 1.5 / 2 times the nominal capacity of your battery. For a 40Ah battery a 60Ah BMS could be a good choice. You don't want the BMS to work at it's nominal limits all the time!
 

grossy34

New member
Joined
May 16, 2022
Messages
9
what about that one?
if not can you post or attach photo of suitable one?
 

Attachments

  • Screenshot_20220519_121109_com.amazon.mShop.android.shopping_edit_621304769557278.jpg
    Screenshot_20220519_121109_com.amazon.mShop.android.shopping_edit_621304769557278.jpg
    147.1 KB · Views: 19

italianuser

Member
Joined
Feb 25, 2020
Messages
502
Yes, that's it but you need the 60A version for a 40Ah battery.

The product's name is "7S 60A BMS", something like this:


Daly 7S 60A.jpg
 

grossy34

New member
Joined
May 16, 2022
Messages
9
regarding my progress, battery still not finished as my portable spot welder was too weak to weld 0.15 nickel strip so i ordered a stronger welder and expecting it within a days, my inverter arrived and im stuck somehow with a breaker/fuse box for panels, asked seller regarding those and for my ac input 32a breaker is recommended, for a battery 120a one and for a pv panels 20a and my question is which one should i but for pv strings as there are few types but not sure if it doesn't matter which one will get or need specific one so advice needed, attached pics of them no.4 or no.5? also attached pics of my inverter details, ac input breker and battery breaker so please advice
 

Attachments

  • Screenshot_20220614_234114.jpg
    Screenshot_20220614_234114.jpg
    246.7 KB · Views: 6
  • Screenshot_20220614_234233_com.android.chrome_edit_540477739608672.jpg
    Screenshot_20220614_234233_com.android.chrome_edit_540477739608672.jpg
    159.8 KB · Views: 6
  • Screenshot_20220614_234316_com.android.chrome_edit_540516601575853.jpg
    Screenshot_20220614_234316_com.android.chrome_edit_540516601575853.jpg
    238.3 KB · Views: 12
  • Screenshot_20220614_233554_com.android.chrome_edit_540084958366023.jpg
    Screenshot_20220614_233554_com.android.chrome_edit_540084958366023.jpg
    209.6 KB · Views: 8
  • Screenshot_20220614_233508_com.android.chrome_edit_540102721769146.jpg
    Screenshot_20220614_233508_com.android.chrome_edit_540102721769146.jpg
    172.6 KB · Views: 9

italianuser

Member
Joined
Feb 25, 2020
Messages
502
my question is which one should i but for pv strings as there are few types but not sure if it doesn't matter which one will get or need specific one so advice needed, attached pics of them no.4 or no.5? also attached pics of my inverter details, ac input breker and battery breaker so please advice
To be able to control each string individually you can use a DC MCB (photo 3 "TOMZN MCB 125A DC" and photo 4 "DC Circuit Breakers All Sizes") with an amperage of 1.5x/2.0x your string amperage. If a string is for e.g. 10A then a 20A DC MCB will be ok (I bought 20A DC MCBs for my each of my three 8.64A strings). You choose a slightly over-dimensioned MCB to avoid it working at it's nominal limits. It's a good practice to disconnect panels from the inverter when doing maintenance.

IMO It's a good idea to have an MCB for each string.

Some people just have a single MCB for all panels; if inverter supports two PV inputs then it would be two MCBs.

Photo n.5 is a fuse holder (looks like a model for 10x38 fuses, the numbers are millimeters), I use them in couples on both negative and positive. A good choice for the fuses is the ones with sand inside because they are more effective, when they blow, in extinguishing arcs which happen when interrupting an electrical line. I use fuses on the battery (between battery and inverter), with the amperage the closest as possible to the battery size. If your batteries are in parallel you could put a fuse holder on each individual battery; 10x38 are not the biggest fuses, for higher amps there's a bigger size (which requires it's correspondent holder, that means a 22x58 fuse holder and 22x58 fuses).
 

grossy34

New member
Joined
May 16, 2022
Messages
9
thx for info, bought them all, not arrived yet though, need some advice regarding daly bms
as is rated 60a but output wires are 10awg/30a?
is that ok or i should replace them with 6awg?
 

Attachments

  • Screenshot_20220617_222926_com.amazon.mShop.android.shopping_edit_680915959744534.jpg
    Screenshot_20220617_222926_com.amazon.mShop.android.shopping_edit_680915959744534.jpg
    198.9 KB · Views: 7

floydR

Member
Joined
Aug 23, 2017
Messages
1,466
Since the wire has 200c rated silicone insulation it should do 60A uou can up size the wires connected to the b- p- wires
later floyd
 

italianuser

Member
Joined
Feb 25, 2020
Messages
502
Top