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New Solar on Conversion Van Questions
Hi All. New to the groups here. This is fascinating stuff and I can’t get enough of it. Thank you to everyone who posts and those who reply. It’s really helpful!! I recently installed a new system in my conversion van (2004 Chevy Express Quigly 4x$). I installed 2 x 100 watt 12v Renogy flexible solar panels on the roof with one VMAX AGM 12v 155ah battery. I have an Epever 4210 MPPT solar controller as well and all of this is wired with 6-8 Gauge wire (6 gauge to/from battery and 8 gauge to panels).
Here’s my issue, when I connect the battery to the controller first and then the panels, the controller shows that the panels are producing quite a bit of power (approximately 15.9v / 8.2a). However, after minute or two, this drops down drastically to about 19.2v and 1.9a and remains fairly constant around this level. The battery is now fairly well charged at 14.2v 2.7a, although took a bit to get there. I would have thought that the controller would show that the panels are putting out a much higher amount of power (as it did initially). Clearly there is enough sun here in Los Angeles to produce more power and the panels are putting out that power, but when it gets to the controller it seems to be cut down somehow. My question is whether the display on the controller with respect to the panels is only showing what it is using to charge the battery, which may be lower after it is up and running, seeing that the battery is mostly charged already. However, this display of lower power was also showing when when the battery was less charged at 12.4v. If you don’t mind, I would very much appreciate your thoughts on this issue. I’m wondering if there is something wrong with the controller. Everything is brand new, just installed a couple of weeks ago.
Also, I’m debating to add a 3rd panel to ensure that the battery is charged fast enough while I’m using it. I use it for a TV, charging several other RC batteries and some light tools (dremel, heat gun, soldering iron). Not sure if that is misguided, but figured I’d mention.
Last question, is it normal for the battery power to show that it is fully charged at about 14.7v during the day when the panels are getting sun, but then it drops down to 12.7v at night without any power. Is there some sort of resting energy, although the battery is fully charged. That is another issue that I’m not sure about. In other words, why does the battery show fully charged with the solar controller charging, but then not fully charged when at night resting; both without having any power draining from tools or the TV?
Thank you for your help and consideration in advance.
Here’s my issue, when I connect the battery to the controller first and then the panels, the controller shows that the panels are producing quite a bit of power (approximately 15.9v / 8.2a). However, after minute or two, this drops down drastically to about 19.2v and 1.9a and remains fairly constant around this level. The battery is now fairly well charged at 14.2v 2.7a, although took a bit to get there. I would have thought that the controller would show that the panels are putting out a much higher amount of power (as it did initially). Clearly there is enough sun here in Los Angeles to produce more power and the panels are putting out that power, but when it gets to the controller it seems to be cut down somehow. My question is whether the display on the controller with respect to the panels is only showing what it is using to charge the battery, which may be lower after it is up and running, seeing that the battery is mostly charged already. However, this display of lower power was also showing when when the battery was less charged at 12.4v. If you don’t mind, I would very much appreciate your thoughts on this issue. I’m wondering if there is something wrong with the controller. Everything is brand new, just installed a couple of weeks ago.
Also, I’m debating to add a 3rd panel to ensure that the battery is charged fast enough while I’m using it. I use it for a TV, charging several other RC batteries and some light tools (dremel, heat gun, soldering iron). Not sure if that is misguided, but figured I’d mention.
Last question, is it normal for the battery power to show that it is fully charged at about 14.7v during the day when the panels are getting sun, but then it drops down to 12.7v at night without any power. Is there some sort of resting energy, although the battery is fully charged. That is another issue that I’m not sure about. In other words, why does the battery show fully charged with the solar controller charging, but then not fully charged when at night resting; both without having any power draining from tools or the TV?
Thank you for your help and consideration in advance.
), I certainly use voltage to get an idea of the battery state. But as pointed out, don't confuse charging voltage with battery resting voltage. Once you remove the charging source, the battery voltage will begin to settle down to its resting voltage. But there are things like surface charge and other stuff that affect this process. Basically, you would need to let it rest with no load for quite some time before you get to its true resting voltage. For a 12V battery, I think 12.6-12.7V is a good ballpark value for "full." Google "battery soc chart" and you'll get a lot of charts for how full the battery is based on state of charge (SOC). 
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