PaulRainbow
Well-Known Member
A decent controller should still see the battery voltage and that's all of the battery data it can ever see.
Solar panels - can I use more than one charge controller?
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A decent controller should still see the battery voltage and that's all of the battery data it can ever see.
roaringgirl
Well-Known Member
Yes, all of mine do, even the incredibly cheap ones!
noelex
Well-Known Member
In general, as I indicated in my earlier post it is rare to have conflicts of any consequence. However, it is not true that there are never any issues regarding conflict.
The two biggest issues to watch out for are:
1. Incorrect absorption time.
Even if the controllers are set to the same parameters, manufacturing and calibration differences will mean the voltage set points will be slightly different. As a consequence, in some circumstances the solar controllers can run down their absorption timers sequentially rather than together. The net result is a much longer absorption time (up to double with just two controllers) than was intended. This will slightly overcharge the batteries if it occurs.
2. Inadvertent activation of the tail current setting.
Not all controllers feature a tail current setting, but if they do this should be disabled with multiple charge sources unless you are leaving the boat with little draw for long periods (such as winter layup). The tail current feature can cause one controller to shut off charging prematurely.
If these problems do occur, providing the controllers are reasonably adjustable the conflicts can usually be resolved.
The two biggest issues to watch out for are:
1. Incorrect absorption time.
Even if the controllers are set to the same parameters, manufacturing and calibration differences will mean the voltage set points will be slightly different. As a consequence, in some circumstances the solar controllers can run down their absorption timers sequentially rather than together. The net result is a much longer absorption time (up to double with just two controllers) than was intended. This will slightly overcharge the batteries if it occurs.
2. Inadvertent activation of the tail current setting.
Not all controllers feature a tail current setting, but if they do this should be disabled with multiple charge sources unless you are leaving the boat with little draw for long periods (such as winter layup). The tail current feature can cause one controller to shut off charging prematurely.
If these problems do occur, providing the controllers are reasonably adjustable the conflicts can usually be resolved.
davierobb
Well-Known Member
I haven't tried it but if you watch the video then I believe the issue he describes can occur and its worth protecting against. The fact that the manufacturers have designed controllers to interconnect makes me think that the technical experts also see this as a real issue.
At the end of the day if you're happy with your system and think it's working OK then no need to change.
noelex
Well-Known Member
Interconnecting and synchronising the charge sources will result in a slightly more accurate charge algorithm, but the improvement is only slight.
Greater improvements are gained by interconnecting the battery monitor and charge control devices. Once the charge control devices gain information about the current entering the battery (typically from the battery monitor), the transition between the absorption and float stages becomes more accurate. This option is offered by several companies and is the primary motivation, together with better integration of lithium batteries, for designing communication protocols in charge control devices.
If you are setting up a complex system with equipment from one manufacturer, these comununication options are worth considering .
With the popular Victron solar controllers it is very simple to set up communication between between two or more solar controllers. While the improvements are small, it is an option that is worthwhile turning on. It can be done with Bluetooth communication so no extra cables or costs are involved.
For slightly more trouble and cost (about £30 from memory) you can gain more accurate battery voltage and temperature information. This is the set up I use. For slightly more cost and complication, communication with the battery monitor and battery charger can be installed, but you need all Victron equipment. The ultimate is option is to also incorporate communication of all these devices with the alternator regulator. This is difficult to incorporate, but it can be done.
One caution is that very complex charging systems have many failure points. They are not always sensible. A simple system with multiple stand alone charge sources still works well if properly adjusted.
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