Hi, I'm new to solar and new to this forum and just need to check a few things. I have 2 ea. 320w panels, 4 ea. 100ah Renogy lithium iron phosphate batteries, a 100 amp Epever charge controller and a 3000w renogy inverter. With a freezer, small fridge and a few small devices my system will drop approx. 100 amps overnight and fully charge by 1p.m. the next day (if sunny). When we had 3 days of clouds the system dropped 250amps and it took approx 2 days to charge full. Does this seem OK to you guys? It works great so far, batteries don't get warm and everything runs fine but not sure if I'm charging the batteries too quickly or if there is some other problem I'm not aware of. Any advise would be greatly appreciated. Thanks
Is my system too big
- Thread starter rcmach1
- Start date
12VoltInstalls
life passes by too quickly to not live in freedom
To my way of thinking I’d want another panel pair and work towards another battery
But what you report seems ok, I’d just want more panels for quicker recovery
But what you report seems ok, I’d just want more panels for quicker recovery
Wondering if your system is too big is the good kind of problem to have. Sounds to me like you haven't identified any issues or shortcomings, but are just looking for confirmation that everything is okay?
I dont see any reason for concern. Seems like your system meets your needs. You are not charging your batteries too quickly, lithium batteries are tolerant of high charge/discharge rates. A typical maximum is 0-100% in 1 hour, with more conservative reccomendations being 0-100% in about 5 hrs. If I understand you correctly you are well below even the conservative recommendation so no cause for concern there.
Nope, you should be all good, for official confirmation you can look at the datasheet for the Renogy batteries you bought, it will state the charge and discharge limits.
The only other thing to maybe mention is that the max charge rate is reduced at lower temps. Many people/brands simplify this to the easy to consume "don't charge below freezing" so you can use that rule of thumb, but technically speaking its more of a gradient, its best not to charge at high rates when its close to freezing, and best not to charge at all below freezing. But if your batteries are in a living space, its probably not an issue.
iamrich
Solar Addict
I think you are under paneled, but if it is working then you are good. You could run the panels in parallel and face each one in a slightly different direction to extend your solar day to lower the charge rate, but assuming you running this configuration at 12v, my fuzzy math says 640w/12v=53a, so that is your max charge rate divided into 400ah of battery gets you .13C which is pretty gentle...
Some of the YouTube videos warn of charging these batteries all the way but not sure how how important that is or how to set it up to "stop short" of a full charge. Is that something to worry about or does it matter?
I'm just north of San Diego, CA so it rarely gets below 30degs. I'll have to check but did see a minimal temperature settings.
Thanks!!! for all the help.
I'm just north of San Diego, CA so it rarely gets below 30degs. I'll have to check but did see a minimal temperature settings.
Thanks!!! for all the help.
iamrich
Solar Addict
My batteries are used and like to sit at 26.7v most of the time. I charge them to 27.7v when there is sun, but don't go any higher than that. I don't think there is much above 13.4v (26.8v, 53.6v) worth charging for unless you are trying to get every last watt hour out of your batteries. On the other end I rarely go below 26v, and my cut off is 24v.
You can meaningfully increase the life of the battery by using more conservative upper and lower limits. Cutting the charge short of a 100% charge means tweaking the settings in your solar charge controller (or other charger) settings.
This beginners resource by Filter Guy and myself gives a semi indepth overview. This post by Will gives a much shorter and not super conservative recommendation, and this short article by Rob Becker at Solacity gives a great overall beginners intro to how to take care of lifepo4
Thanks! My battery settings are pretty close to Will's list.
I'm probably over-thinking this. It seems to run fine, nothing gets hot and has more than enough power to do what I need. My wife ran our washer and dryer the other night for hours and my system dropped to about 50% (it was a cloudy day). Next day partial sun and then full sun the following. The system was back to full charge within a day and a half.
I'm probably over-thinking this. It seems to run fine, nothing gets hot and has more than enough power to do what I need. My wife ran our washer and dryer the other night for hours and my system dropped to about 50% (it was a cloudy day). Next day partial sun and then full sun the following. The system was back to full charge within a day and a half.
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