Re: Idiot's guide to a self build battery
Posted: Sun Feb 11, 2024 2:00 pm
Renewable energy and sustainability discussions
https://camelot-forum.co.uk/phpBB3/
https://camelot-forum.co.uk/phpBB3/viewtopic.php?f=14&t=1194
Ah. The two big fans are doing what you say already. They are shifting hot air from the ceiling to outside to be replaced by cool(relatively) air from the outside. The trouble is I still got the temp gradient. It was only when I mixed the air from top to bottom that I was able to get rid of the temp gradient.
My loading per cable at the moment will be about 66A when I've finished the upgrade. It would go to 115A if I put in another 32 panels. In reality maybe 25A less if I'm constantly exporting 5kW. I've been having a nightmare trying to determine the cable size. The websites all have such widely varying stats. Do you have a go to reliable table based on max continuous usage? I have been leaning back to 35mm but will take your advice and go 50mm. I had 50mm installed on the 100A mppt and they barely get warm. Thanks for pointing out my mistake.nowty wrote: ↑Sun Feb 11, 2024 1:56 pm 25mm is the same size as the standard pylontech cables, they get warm at 100A and hot at 120A. If your thinking of a continuous max over 100A I would be going to 35mm or even 50mm. I was shocked when you earlier mentioned “future proofing” at 25mm.
It’s not just the cables that generate heat, but the isolators, fuses, crimp connectors, etc.
I have 70mm cables to my main 8kW battery inverter and 50mm intermediates to each of my battery banks. I used to use 35mm for my intermediates but they got too warm for my liking if I was running only off a single bank at 150A so I upgraded to 50mm.
It's not quite the same. The cold air is being drawn in passively (albeit by expulsion of the two 6" fans). Thats not the same as forced cold air induction by a dedicated fan.Andy wrote: ↑Sun Feb 11, 2024 2:45 pmAh. The two big fans are doing what you say already. They are shifting hot air from the ceiling to outside to be replaced by cool(relatively) air from the outside. The trouble is I still got the temp gradient. It was only when I mixed the air from top to bottom that I was able to get rid of the temp gradient.
Ok, I'll try having reconfiguring the fans to an IN and an OUT and check out the difference. Will have to wait for a month or so as it's quite busy right now. Will keep you updated.
Think about setting up a positive crossflow. It does make a difference.Andy wrote: ↑Sun Feb 11, 2024 3:19 pmOk, I'll try having reconfiguring the fans to an IN and an OUT and check out the difference. Will have to wait for a month or so as it's quite busy right now. Will keep you updated.
I do need to get the thermal camera on the inside of the isolator to see what's up. That's the only bit I haven't checked yet.
I got an insulated torque wrench on the way from ebay so I'll go and give them a tweak when it arrives. I think I might have offered too much as the seller accepted on the first goJoeboy wrote: ↑Sun Feb 11, 2024 3:23 pmThink about setting up a positive crossflow. It does make a difference.Andy wrote: ↑Sun Feb 11, 2024 3:19 pmOk, I'll try having reconfiguring the fans to an IN and an OUT and check out the difference. Will have to wait for a month or so as it's quite busy right now. Will keep you updated.
I do need to get the thermal camera on the inside of the isolator to see what's up. That's the only bit I haven't checked yet.
Discharge cables much the same length? For heat generation its traditionally a slack connection somewhere. .
A VDE torque wrench is very swish!Andy wrote: ↑Sun Feb 11, 2024 3:29 pmI got an insulated torque wrench on the way from ebay so I'll go and give them a tweak when it arrives. I think I might have offered too much as the seller accepted on the first goJoeboy wrote: ↑Sun Feb 11, 2024 3:23 pmThink about setting up a positive crossflow. It does make a difference.Andy wrote: ↑Sun Feb 11, 2024 3:19 pm
Ok, I'll try having reconfiguring the fans to an IN and an OUT and check out the difference. Will have to wait for a month or so as it's quite busy right now. Will keep you updated.
I do need to get the thermal camera on the inside of the isolator to see what's up. That's the only bit I haven't checked yet.
Discharge cables much the same length? For heat generation its traditionally a slack connection somewhere. .![]()
Yes, it properly focusses the mind. I'll be isolating everything and even then wearing goggles in case I screw up. As someone said at work its worth working to a checklist.