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Started by disco4wd, September 10, 2023, 05:24:58 AM
Quote from: boB on September 10, 2023, 03:32:05 PMAt 350W times 3 panels, you have 1,125 watts label rating available. If you take that power and calculate the amps possible current into the batteries, assuming 100% of the rating gets through, that would be 85 to 90 amps which is too much for a Kid... That would be into a 12V bank. The Kid will more than likely current limit.Then , the panels will heat up in the sun and put out somewhat less power. Usually it's about 80% for various reasons because of losses. I still use the label rating though because it does happen that you can get that 100% some times. The 1.25 kW power rating is based on STC or at 25 degrees C. That will be rare in the summer where the panels heat up and put out less power. The PV cells could be twice that temperature which makes a difference.Check to see if the Kid is limiting from partial shading too. That will make a huge difference just having a shadow line across the panel(s)At say, 40 amps output limit, that is 40/200 aH or 0.2C as they say (20% of the Amp-Hour rating) but should be enough to get them charged as long as they aren't drained by too much power draw.So, from what I am hearing, and I may be reading it wrong, a single Kid isn't large enough, current wise, to use all of that PV power. If you went to 24V (series batteries) you may still be slightly limited because that would be around 40+ amps.Do you ever see the Kid go into the Absorb stage or go to Float on its own ? If so, then the batteries should be getting a charge up to that set point voltage.Let me know if I have something wrong. I may very well have a senior moment here boBAppreciate the reply.The panels, even though they are labeled as 350W are nowhere near this figure and my estimate is around 80 - 100W max. (dodgy eBay seller)The max I can get out of each panel at @18V is 4.5A and this lines up with what my Fluke clamp meter, the Kid and Whiz Bang Jr are telling me. That's in near perfect conditions.All strings measure the same, the diodes have been checked along with all connections re-crimped and soldered.The 3 panels in series gives me around 55V @ 4.5A .. so about 250W .. which is what The Kid also tells me.I was hoping to be able to push out close to 30A from The Kid but I still can't get anywhere near this.Might try to get two fully functional 200W panels from a reputable supplier to swap over.