Question, I have a Victron charge controller and two Battleborn lithium 100 amp hr batteries. When the charge controller is on the batteries show 13.60 volts. Putting a meter on the batteries show the same. With the charge controller off it shows 12.70 volts. Meter on the batteries show the same. No matter how long I leave the charge controller on or off the batteries read the same. If I try to charge the batteries the charge controller tells me that the batteries are full. But again when the charge controller is off the batteries read 12.70. How do I know what is the correct number???
What charge controller. What other information do you have, charge current would be very important for troubleshooting. 12.7V is very empty, if your controller is too small then it may not be able to refill the batteries very quickly and 13.5V will not charge quickly. Are the batteries turned on to accept charge, some batteries can have charge turned off by Bluetooth so this would create the symptoms you see. What charge settings do you have on the controller.
Thank you for replying. I have a Victron 75 15 charge controller. I have one 200 watt panel on the roof of the camper. I also have the Victron IP65 to help charge the two 100 Amp hr batteries. I guess my question is why would the batteries read on a meter with the controller off 12.7 and the batteries read 13.6 with the controller turned on. Would I charge the batteries with the controller off in order to get them up to 13.6 ?
OK, the batteries on their own without any charging will be showing a voltage based on what state of charge (SOC, = how full they are). An approximate table is given below, there are lots of these on the web and specific batteries can be slightly different, I am using this as an example.
12.7V is down at the 15% SOC, i.e. your batteries are pretty much empty if they are working properly.
You have 200W of solar and a 15A controller, so in perfect bright mid day summer sunshine the most current you will get into the batteries will be 15A. If your batteries are currently 15% full, they need to be filled with 85%, you have 2 x 100Ah batteries, so 200Ah and you need 85% of this = 170Ah. Charging at 15A will take 11.5 hours of mid day summer sunshine. If you are currently cloudy winter day it will take much longer. You give no clue as to where you are, important info for solar charging.
When the controller is on, you have some sun and the controller does some charging. To charge the batteries, i.e. force electricity into the batteries, the charge controller needs a higher voltage than the batteries to push the electricity in (think water in pipes needing to be pumped up in pressure to flow into a tank). This is why the voltage rises to 13.6V. However, this shows that you do not really have enough charging power, it really should get higher than this, towards 14.2V or 14.4V when the batteries are full.
I think you have got into winter time wherever you are with less sunshine and your batteries are just running very low and you do not have enough sunshine to fully charge them. Running like this for long periods may result in the cells in the batteries going out of balance. I suggest you get a shore line hook up and give your batteries a full charge.
Thank you for your help. One other question. Should I charge the batteries with the controller turned off. Leaving the controller on the controller is showing the batteries are 100% and goes into float mode.
You can charge them with the solar controller still running. Something is amiss because your charge controller on its own does not report SOC. If it goes to float then it must get the voltage much higher. Your information is confusing because it is at odds with itself. The controller going to float but the battery being at 12.7V without the controller suggests a deeper problem per my first post. When you measure the battery voltage with your meter are you checking on the terminals on the battery itself or the terminal on the solar controller labelled battery.
it is very hard to diagnose remotely from limited info.
My son checked the voltage with the meter on the battery terminals at each battery and both were the same voltage. To me what was odd was with the meter on the batteries and the charge controller turned on both the batteries and the charge controller were reading 13.6 and 99% full. Using the meter at each of the battery terminals with the breaker turned off between the solar panel and charge controller the voltage was 12.7 on both the battery terminals and the charge controller. I have the Victron IP65 on the batteries but it too is in float mode and is saying the batteries are full. I understand it’s next to impossible to diagnose with with the information I can provide but I very much appreciate your help. At this point I’m not sure what to do.