@Steve_S, thanks for the reply!
I already have the lead-acid batteries (two actually... they were free, and not abused, still in great shape), so while I know Lithium is better, I'm looking to expand what I already have instead of invest in completely new batteries. I'd like to run the lead...
Hello DIY Solar folks, I'm a n00b looking for some better understanding.
I understand that it's a bad idea to mix old and new batteries, but I'm wondering what the reasons are, besides the basic idea that capacity is reduced over time, so mixing an old battery rated at 120Ah with a new one...
Thanks everyone for the discussion and all your insight!
For the record, this is for an on-the-cheap, off-the-grid solar ground install setup that feeds my RV parked at a creek camp on our property for weekend getaways and possibly a month or so stay if I get the urge to write the Great...
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...
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...
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:
Cross Section Area(cm) 19.4...
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...
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...
OK so to answer some of my own questions, cm in this case isn't centimeters, it's a unit known as "Circular Mils, Thousands," as I found on another sheet.
Thanks! I'm more worried about the amp draw of a particularly high item like the toaster oven making toast out of the batteries instead!
I bench tested the setup with the two batteries I have in parallel, and the voltage on the batteries drops to 11.3v while the toaster load is applied while...
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...
They are not in service yet in my system (but they are used - and not abused). I'm still cobbling together my hillbilly solar array, but have been keeping them charged regularly. What would the schedule normally entail besides checking the water level? I have an automotive electrolyte tester...
Actually, I also have a refractometer (calibrated in brix) and a glass floating hydrometer. Is one of those better, or is the bulb-squeeze automotive kind sufficient?