electricthot
New Member
- Joined
- Aug 17, 2022
- Messages
- 31
For all that's been said here no one has explained why the number of equal batteries in a bank should be limited to four. Is this manufacturer specific?
Battery Bank Size
- Thread starter electricthot
- Start date
Renogy like to play hard and fast with the rules at the best of times lol (not a fan)
I personally don't like to see more than a pair in parallel, and a single string is far preferable anyway (and quite frankly- considering the loss of service life for parallel strings- and the widespread availability of suitable batteries/cells in any size you are likely to see in most offgrid systems, it makes little sense to be doing it in the first place...
I personally don't like to see more than a pair in parallel, and a single string is far preferable anyway (and quite frankly- considering the loss of service life for parallel strings- and the widespread availability of suitable batteries/cells in any size you are likely to see in most offgrid systems, it makes little sense to be doing it in the first place...
Q-Dog
¯\_(ツ)_/¯
Adhesive lined heat shrink is water resistant. That is plenty good enough for most installs and doesn't need voodoo juice to keep them working.
Yes. If the manual says limit to 4 you should probably ask the manufacturer why.
Hard to explain something that may be lacking context. You would need to post where Renogy says this.
They are easy swapped in a diy battery and pretty cheap. About the cost of one cell
electricthot
New Member
- Joined
- Aug 17, 2022
- Messages
- 31
I like the sound of the lifepo4 advantages. Didn't know they were so light. Good news for old bones. And the DOD capacity is impressive. Would my Xantex C-60 charge controller still work with lithium?
Offgridiot
New Member
Page 22 of your user manual lays out how to adjust the voltage settings in charge control mode. Should work fine, depending on the charge requirements of whichever batteries you’re considering (usually 14.2-14.6 V for LiFePo4 12 volt batteries). Don’t forget about the sequence for disconnecting/reconnecting your panels/batteries when it comes time to switch things around, or you could find yourself in the market for a new controller to add to the expense (I fried a C40 because of incorrect sequence)
SilverbackMP
Solar Addict
- Joined
- Apr 4, 2022
- Messages
- 928
Marine grade or better grade heat shrink. Hell, even harbor freight sells marine grade (albeit not in 4/0). No way in hell am I pounding copper to make lugs or painting on solvents to keep oxidation at bay. I don’t like fire. That and all my shit is in trays or greenfield, not stapled to a plywood wall.
My 20kwh LYP bank came home in the back seat of a Mazda 3 (shared with a grumpy teenager who couldn't lie down like she did on the trip there lol) total weight is 216kg (476lbs)- the total weight for a 20kwh L/A bank that has a twenty year life expectancy- well that is literally close to ten TONNES of them in total... (2 complete sets of 4000Ah of L/A batteries... wow...)
For safety. A single battery with a shorted cell will become overcharged, heat up and may vent. Four will create three batteries discharging into one and moderate the safety risk. More in parallel creates more heat and possibly a spark to ignite the venting gasses or the case as it drys out. That is my take on it.
We did it that way for decades before we got the fancy smancy hydraulic crimpers- I still got my old set of 'crimp punches' for making cables from when I was an apprentice- made by Bosch...
Select the appropriate size (if you felt like it), grab the ballpein hammer and start crimping cables...
LOL
hwy17
Anti-Solar Enthusiast
Yes but if you don't notice when it fails it could cost you your whole pack.
Offgridiot
New Member
Please tell me more about this. Or link to a thread that spells it out. Would it be a relatively quick demise of the pack? Or a more gradual decline/shorter lifespan due to imbalance?
pollenface
Solar Addict
robbob2112
Doing more research, mosty harmless
Put as many as you like together -
However many you put together - Fuse each one at the bus bar end of the cable. Ideally you would fuse at both ends but if you fuse at the bus bar end of the cable only you are depending on the BMS shutting down current in the cable. You ask why not just fuse at the battery post?
With 4 batteries in parallel if the cable for one is shorted in th middle by a sharp shelf edge or dropped tool you have the current from all 4 going through the single cable and it will melt in fractions of a second. If you do the more likely scenario and drop a wrench across the posts of 1 battery and it welds in place the wire burns off the sheath in about 1 second and melts in about 2 minutes. In that same 2 minute the wrench is red hot and melting. That assumes the plasma arc from dropping it across in the first place doesn't just fling molten metal at you.
read this thread on battery cable placement -- The summary seems to be to group batteries in sets of 4 with the uplink cables in between post 1/2 and 3/4 for a total balance then to the inverter. If you have 8 batteries same grouping of 4 and then connect to a second set of bus bars and uplink to the inverter.
diysolarforum.com
Hammering flat pipe to use for a permenant setup seems cringe worthy to me. I assume you are just making lugs with that so only hammering 1 end and then drilling the proper size hole at the other? The problem with that method is the lugs created aren't to any sort of spec and may not hold up over time, or fit a crimper correctly to make the cold weld that is needed. Not to mention lugs even the good ones aren't that expensive and you get an exact fit on the wire that you don't get with coper pipe.
However many you put together - Fuse each one at the bus bar end of the cable. Ideally you would fuse at both ends but if you fuse at the bus bar end of the cable only you are depending on the BMS shutting down current in the cable. You ask why not just fuse at the battery post?
With 4 batteries in parallel if the cable for one is shorted in th middle by a sharp shelf edge or dropped tool you have the current from all 4 going through the single cable and it will melt in fractions of a second. If you do the more likely scenario and drop a wrench across the posts of 1 battery and it welds in place the wire burns off the sheath in about 1 second and melts in about 2 minutes. In that same 2 minute the wrench is red hot and melting. That assumes the plasma arc from dropping it across in the first place doesn't just fling molten metal at you.
read this thread on battery cable placement -- The summary seems to be to group batteries in sets of 4 with the uplink cables in between post 1/2 and 3/4 for a total balance then to the inverter. If you have 8 batteries same grouping of 4 and then connect to a second set of bus bars and uplink to the inverter.
Calculation of parallel string battery currents
Hi, everybody! I'm a retired EE. I didn't want my EE skills to fade away after retirment, so I exercise them when I can. Whenever I see a non-trivial circuit analysis problem on one of various forums I frequent, I challenge myself to solve it. Recently I watched Will's video about current...
diysolarforum.com
Hammering flat pipe to use for a permenant setup seems cringe worthy to me. I assume you are just making lugs with that so only hammering 1 end and then drilling the proper size hole at the other? The problem with that method is the lugs created aren't to any sort of spec and may not hold up over time, or fit a crimper correctly to make the cold weld that is needed. Not to mention lugs even the good ones aren't that expensive and you get an exact fit on the wire that you don't get with coper pipe.
Similar threads
