Best way to wire for an automotive trickle charger?

pyroman

I am looking to wire in a 10w solar panel for a trickle charger for storing a vehicle for the winter and summer months. The charge controller I am looking at (just a basic unit off of Amazon for $10) says that the battery has to be installed before the panel to prevent damage to the charge controller. What would be the best way to wire to prevent charge controller damage for use when the battery is disconnected? Or are there basic units that have a reverse charge diode that allow for easy removal without damage? I thought of using quick disconnect connectors like you would use for a trailer plug or maybe a toggle switch?? The controller will be partially exposed to the weather, it will be under a carport.

BB.

Many charge controllers need to be connected to the battery bank first to get their electronics going--And for some units, select between 12 volt and 24 volt battery bank (automatic voltage detect).

A "typical" "12 volt" solar panel can run Voc (voltage open circuit) around 20 volts or so... And that can either "confuse" the controller (a little leakage current sets the controller to 24 volts) or damage the controller output (i.e., 20 volts on circuits designed for 12 volts).

A diode between the panel and the controller will not really do anything.

The "right" answer is to kill the solar panel panel power first--Then Make/Break the battery terminal connections.

Of course, there are a lot of solar charge controllers out there--Perhaps somebody here can recommend a "bullet proof" charge controller? (may cost more than $10).

-Bill

mcgivor

As suggested, get in the habit of connecting the battery first, then solar. Upon disconnect, solar first then battery, this applies to 99.99% of charge controllers, a good rule of thumb, even the cheap $10 units are sufficient to maintain a battery with a 10W panel, as long as it gets sun without shadows during the day, without loads.

PNjunction

The addendum to that is that before storing the vehicle, be SURE the battery is already fully charged!  That requires an ac charger.

If you don't, all the little 10 watt panel w/controller will do is offset the natural self discharge, or parasitic load(s).

So if the battery is REALLY only 90% charged, the little maintainer will do just that - maintain it at a 90% charge level and the battery sulfates anyway!  Oh yes, you might put a voltmeter across the maintained battery, and witness what appears to be a healthy voltage, but this is only a superficial surface charge.  Sulfation and/or walk-down is happening anyway.

The difference between a "maintainer", and a charger needs to be understood.  Essentially, if your charge source is not at least .05C of the battery's rated capacity, it is a maintainer.  And as such, if your battery is not already fully charged, it will dutifully maintain it at a partially discharged state, negating your efforts.