learning lessons or lessons learnt?
Ingenius idea.... may or may not be viable?
I was watching the cycle of the battery being charged by solar panels (in November!) and then discharging by being used. This was during the day and it was rather novel as shown below (the variance around midday was due to me fiddling around with the cabling)
As I was looking at this daily data, it got me to thinking.... that tailing off of power at the end of the day, that's not good, is it? I mean it's been great during the day, you see the batteries getting filled up, you see them being used / discharging, then up again and then down again...oh, then it got dark... and they carried on going down... and then they hit 12.3v and the ATS kicked in and switched the power over to 240v mains power. Ah, so the battery is currently at 12.3v, powering the inverter, so that will trickle down into the 12.1v range over a few hours... and then the battery starts to enter dangerously low territory. 12v and lower and we end up knackering the battery. But, there is all night left to go and if, a big if, there is nice daylight tomorrow morning, it'll start to charge everything back up, but that might not be until 09:00 or so.... hmmmm.....this is not ideal.
Okay, so I'm thinking that I need to increase CAPACITY - more batteries, more batteries = more storage and therefore should take longer to drain. However, it is night time, in November (7degrees C too!)
Then I had a thought... I use a C-TEK5 trickle-charge device to keep the car battery topped up in my Jag - as that doesn't like to be without regular power (or usage) and that has special cycles to keep it topped up etc... I wonder....
So, I connected the C-TEK charger up to the battery and the power plug into the extension cable from the mains - hmmmmm....(need to double check I connected to the right thing in a minute), the theory being when the ATS switches over to the mains power, it then powers the C-TEK charger, that then starts to re-charge the battery and then when the battery hits 13.1v, the ATS will switch from the mains power to the battery power and use the battery until it drains down to 12.3v and then the ATS will switch over to the mains again and repeat that cycle... therefore, whilst in the dark, the battery is being re-charged and then dis-charged - I'm sure there is probably a better way to do this and I'm sure I'll be doing it that way next week. However, for now....
And here's the charts after 10minutes of charging:
As you can see, it took about 10mins to charge the battery up and then that drop-off is when the ATS switched over and the battery started to dis-charge. My theory is that the C-TEK will be disconnected whilst the dis-charge occurs, if that is true then the battery will not be being charged whilst it is being used, so I should see a downward discharge of volts over time.
However, on this chart, it shows the battery actually going upwards slightly...
okay, I need to go check that the C-TEK is not continuing to charge whilst I'm using the battery - that would defeat the object of the task.......
In theory though, the logic is sound - let's see how it pans out.
The reality is though, I should have more capacity to store more power and then use that. I'll re-connect the extra battery tomorrow and we'll see how that works out.
I am still reluctant to switch over to the £300 Lithium battery yet! I will do at some point, but until I've got all this worked out, I'm not risking that battery.
Hmmmm...it was as I feared, the C-TEK charger was on "all" the time, not what I was planning for. I switched it off.. but I have an idea for tomorrow....
Well, tomorrow morning was a bit of a surprise!
...and that is with the battery being used to power the pond pumps too. wow, it kinda seems to be working. I saw this image and thought it looked a little too familiar:
I re-jigged the wiring as per the image from here:
Only thing I don't have in place is the RPi - I did connect the DC converter though ready to go. I will now need to find / make a housing unit for everything to go into. I will definitely need longer isolator to battery switch cables!
I did notice that the original battery I've been using was a little down on power stored, even though earlier it was showing well - I really do wonder if I've killed that leisure battery, so I've plugged it into charge for a bit - I did the re-jig between 3-5pm, which is why you see the drop off on the numbers here. I'll leave it on recondition charge overnight, as the pair of batteries are connected together, maybe it'll help give them both a little boost, we'll see.
Annoyingly, figuring this stuff out and getting it all to work, is a little "addictive"... I'll get there though.
So, I'm going to count my chickens before they've hatched and I'm going to say, I think I may have cracked it now!
From the image below (that was taken at Sunday 12:30 in the semi-darkness and some light rain!), you can see that at on Saturday at 16:00... the sunlight/daylight had gone, no solar power at all. The slow increase of the battery power as me plugging in the c-tek car charger, as you can see this was doing the job nicely until about 23:00-23:30 which was when I felt that maybe I should switch it off, don't want it to keep charging up & up and then explode the batteries (I know that is unrealistic, but I would rather not have a small fire waking me up on a Sunday morning). Then at 07:30 on Sunday morning, I switched the c-tek back on for a short-while, to give the battery little boost.. however, it didn't really need it so I switched it off.
This is where it now is interesting, I have 2 batteries, that should now be in good condition, I have the wiring setup properly and I started the day at 14.5v and it was using battery power and dropped down into the 13.5v range...then the solar boosted it a bit thanks to the sunlight/daylight, so the batteries have been fluctuating around the 13.5v region, which is perfect - the pond pumps ARE using the solar & battery power (and have done all night) and at around Sunday 11:00 the extra 2xpumps kicked in, so that's why you see a small drain there. In theory now, if we go into the evening (16:00+) with about 13.5v in battery reserve, then overnight with just a single pond pump running, I expect the voltage to now drop to 12.5v-ish, which is still within the safe-zone of the battery life (remember, I've split the load / capacity over 2 batteries now, so I have 200-220ah available) and then if the sun comes out the next morning, the solar panels should do their job and charge the batteries back up and repeat.
I do have the ATS setup now with a higher value to kick over to the 240v mains supply, so that we won't have drained batteries before it switches over to mains. Hopefully, the usage of the ATS will only be during the raining season/days, which, okay, in the UK is quite a lot! but you'll be surprised at just how much sunlight/daylight we do get, so fingers crossed.
Now all I have to do is fix up the components onto an MDF board, screw everything together to be all neat & tidy and then get a protective casing for it all and then leave it to just do it's thing.. until, I then decide to extend the power-supply cables into the house to power the odd laptop, the odd light, the odd TV etc...etc... and then I need to setup the RPi to store the data into that InfluxDB and setup Grafana to do the proper dashboard UI.... it'll keep me busy
UPDATE UPDATE:
A final image showing the solar and battery voltage / currents from 17:00 -> 17:00 (24 hour window), as you can see it was a bit of a grotty day today, it was sunny-ish this morning, but was raining and grey all afternoon, meaning the battery power was running low - however NOT that low, note it is 17:00 and the batteries are at 12.73v that puts them where they were at 23:00 last night, so they should in theory just trickle down slightly to 12.5v->12.3v (max) and then get charged up again tomorrow. We'll see.
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