Understanding Battery Aging
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Tomthumb62
Solar Wizard
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Sorry I don’t know much about maintaining flooded batteries. I know there are some experts on this forum, perhaps one of them will chime in.
Zwy
Emperor Of Solar
Refractometer is best.
As you are not well versed in flooded lead acid batteries, I suggest starting with videos Trojan put out. There are quite a few but this video is very important, look at their channel for more.
I can not stress enough you should consider 2 banks where one bank is being used and the other is charged thru absorption, then once absorption is done on that bank and the bank reaches 100% SOC, then the banks are reversed and the other bank is now charged. At least once a month, equalization should be performed to reverse sulfation and stratification. To perform EQ, you will need a capable charger and the refractometer.
Flooded lead acid can last a very long time or only a few short years. This is determined by how deep the batteries are discharged, full charge thru absorption and routine equalization.
There is more information on the https://diysolarforum.com/forums/lead-acid-batteries.20/ forum. I suggest you become a sponge and start reading absorbing the knowledge presented. Some very good information has been posted over the years.
OK great, thanks!
Another related question:
When I add the additional batteries, I'd like to directly connect them with busbars. When determining the cross sectional area needed for the busbars, am I calculating using the highest possible load the bank might see (in my case would be the 4KW peak my inverter is rated for) divided by the number of batteries? So here 4000W between four batteries would mean the busbar calc would be done with 1000W. Or do I plan it so every interconnect between every battery could handle the full load on their own, and therefore use 4KW as the operative for all connections?
I'm using this:
www.allumiax.com
Another related question:
When I add the additional batteries, I'd like to directly connect them with busbars. When determining the cross sectional area needed for the busbars, am I calculating using the highest possible load the bank might see (in my case would be the 4KW peak my inverter is rated for) divided by the number of batteries? So here 4000W between four batteries would mean the busbar calc would be done with 1000W. Or do I plan it so every interconnect between every battery could handle the full load on their own, and therefore use 4KW as the operative for all connections?
I'm using this:
Bus Bar Size Calculator
Current carrying capacity and budget as under size busbar can cause heating and damage in busbar while over size busbar can affect the cost of project. By using BUSBAR Size Calculator we can prevent these issues by predicting them in the first place.
www.allumiax.com
Tomthumb62
Solar Wizard
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- Sep 25, 2022
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Fuse and wire to rated power, not surge power. So if your inverter is rated for 2000W, 4000W surge, your fuses and wires should be rated for continuous power at 2000W. This includes your bus bars. And it’s never a bad idea to go a gauge or two bigger, if it’s not financially prohibitive and can physically fit in the space. Bigger gauge everything means less resistance, heat and voltage drop.
Thanks!
Re: fuses, I'm planning to use a terminal fuse as the main fuse so I can connect it right to the battery bank positive, and branch from there. Maybe a good way to do it would be to have the main terminal fuse be rated at 250A, and then have a 175A fuse after that goes to the inverter, and another branch with a 60A fuse that goes to the charge controller. So maybe like a double terminal fuse holder on top of a single terminal fuse directly on the battery terminal. Does that make sense?
Should I move my further questions to a new thread??
Re: fuses, I'm planning to use a terminal fuse as the main fuse so I can connect it right to the battery bank positive, and branch from there. Maybe a good way to do it would be to have the main terminal fuse be rated at 250A, and then have a 175A fuse after that goes to the inverter, and another branch with a 60A fuse that goes to the charge controller. So maybe like a double terminal fuse holder on top of a single terminal fuse directly on the battery terminal. Does that make sense?
Should I move my further questions to a new thread??
Last edited:
Tomthumb62
Solar Wizard
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- Sep 25, 2022
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I wouldn’t stack fuses like that. Get some custom length cables from BatteryCablesUSA.com. Good prices and high quality cables.
What size cables will you use for the main battery cables, inverter and charge controller? You want to fuse for the wire rated capacity not the device.
Also, consider bus bars. Tidier, can save $$ on expensive copper cables and much better than wiring everything directly to the battery. Terminal fuse on the battery, cables to bus bars. Then everything else has their own fuse and cables, wired to the bus bars. The 250A brass ones are cheaper and are fine if you keep your loads under about 175A.
What inverter and charge controller are you using?
This is a ghetto fabulous system on the cheap, so stacking the fuses is to keep the cost down, so thanks for the tips in that arena! The terminal fuse holder is a cheap-o from Amazon, but I might just make one with busbar material.
Here's how the battery fuses would look:
Doesn't seem too crazy, but it's still a work in progress.
Here's how the battery fuses would look:
Doesn't seem too crazy, but it's still a work in progress.
Also researching cheap-o busbar material. Getting some conflicting info between this chart and this calculator regarding the relationship between cross-sectional area (CSA) and ampacity.
Example: Chart shows this re: a 3/4" x 1/8" (19.05mm x 3.175mm) copper busbar:
Which should I rely on?
Example: Chart shows this re: a 3/4" x 1/8" (19.05mm x 3.175mm) copper busbar:
- Cross Section Area(cm) 19.4 (?)
- ampacity at 215A.
Which should I rely on?
I'm assuming the calculator is correct, although I don't understand how the chart could be so off... And for the record, I calculated the ampacity of copper pipe using data from this chart to make the following chart:
I used 1.2 Amp/mm² for the calculations. Is that correct or am I missing something?
I used 1.2 Amp/mm² for the calculations. Is that correct or am I missing something?
Zwy
Emperor Of Solar
Yes, temp rise.
Bare copper busbar doesn't have insulation like a wire. The calculator is basing ampacity based upon insulated wire cross section to a busbar.
Use the first chart, it agrees with other information out there.
Q-Dog
¯\_(ツ)_/¯
Have you actually looked at an MRBF type fuse holder? It isn't just a bus bar ... the stud on the fuse holder is insulated from the bar the fuse sits on. These are protection devices that will hopefully never be used. It would be foolish to try to rig up something when the real deal fuse holders are so cheap. buy these and sleep well at night https://shop.pkys.com/Blue-Sea-5191-Single-Terminal-Fuse-Block-30-300-Amp_p_7755.html
For fuses I want to know they are manufactured and tested to perform. Don't cheap out on fuses, especially when you want to experiment with mixing different capacity batteries.
Excellent advice, thank you! The diagram I drew does include an MBRF holder as the upper part. Maybe I just need two instead of going directly on the battery terminal on the main fuse...
I'm using a 60A MakeSkyBlue charge controller and an old Centech 2000W modified sine wave inverter.
