Archerite
New Member
I have an experimental setup to try the different solar electrical components before I invest in a permanent installation. (see here for a bit more info on what I have)
The common recomendation is to prevent discharging an SLA battery below 50-80% but I am having trouble to determine when and how this percentage is reached. I know voltages change during charging but my battery remained at 13.2v for about a day after charging with almost no load. Only the victron smartshunt with Bluetooth active was connected.
Then I used a USB charger and the "State of Charge" displayed by the smartshunt app showed the expected drop to 85% and consumed Ah made sense too. Since it was a slow charging USB device I left it in over night because I knew it would stop when full and not drain my battery all the way. When checking this morning it was back at 100% State of charge at a 12.83 voltage!!! That was a big suprise since I thought the smartshunt also calculated the aps while charging the 12v battery that go back into the battery. I did specify a "charged voltage" as 12.8 so it was not exactly wrong....but still it's confusing!
Looking at voltage and state of charge values online I found that 12.7+ is considered 100%...but mine started at 13.2v after charging. Is this exact value different for each battery? What would be the lowest "safe" voltage to go down too? I read the battery's datasheet but it raises more questions than giving me an idea on how to correctly use the battery.
Sorry if these are dumb questions. Still very new to the solar and batteries thing here
Thanks
To start with I bought two Kung Long 12v SLA 7.2Ah. (WP7.2-12) on amazon for almost no other reason than that they were cheap and had prime. Since my primary goal at the moment is getting experience with the various components and I do not "need" to power anything from solar 24/7 yet these will do just fine I think. They allow me to test both series or parallel connected battery bank setup. For now I keep only a single one connected to the Victron MPPT at a time since I don't really know how to properly connect the batteries in parallel. As in do the voltages and Soc need to match exactly?
Since at this time of the year the sun is not that much available and I only have about 30 watts of solar panels, charging from solar alone is not exactly fast yet. Looking at charges and prices I decided to go for a Victron Blue smart 12V/5A charger since I can configure it to charge at 2A maximum that the batteries can handle. Also have a smart shunt connected to one of the batteries to get a percentage and current statistics but that's not related to my actual question.
Since at this time of the year the sun is not that much available and I only have about 30 watts of solar panels, charging from solar alone is not exactly fast yet. Looking at charges and prices I decided to go for a Victron Blue smart 12V/5A charger since I can configure it to charge at 2A maximum that the batteries can handle. Also have a smart shunt connected to one of the batteries to get a percentage and current statistics but that's not related to my actual question.
The common recomendation is to prevent discharging an SLA battery below 50-80% but I am having trouble to determine when and how this percentage is reached. I know voltages change during charging but my battery remained at 13.2v for about a day after charging with almost no load. Only the victron smartshunt with Bluetooth active was connected.
Then I used a USB charger and the "State of Charge" displayed by the smartshunt app showed the expected drop to 85% and consumed Ah made sense too. Since it was a slow charging USB device I left it in over night because I knew it would stop when full and not drain my battery all the way. When checking this morning it was back at 100% State of charge at a 12.83 voltage!!! That was a big suprise since I thought the smartshunt also calculated the aps while charging the 12v battery that go back into the battery. I did specify a "charged voltage" as 12.8 so it was not exactly wrong....but still it's confusing!
Looking at voltage and state of charge values online I found that 12.7+ is considered 100%...but mine started at 13.2v after charging. Is this exact value different for each battery? What would be the lowest "safe" voltage to go down too? I read the battery's datasheet but it raises more questions than giving me an idea on how to correctly use the battery.
Sorry if these are dumb questions. Still very new to the solar and batteries thing here
Thanks