Using solar to charge batteries

[seadog59]

I don't have power at my dock so I bought an 18 watt solar panel and hooked it up to both my starting and deep cycle battery on my fishing boat. I installed the recommended controller in between to prevent over charging. I wired the solar panel to the controller and then come off the controller with 4 wires...a positive and negative to to each of my batteries. I leave it hooked up all the time while I am away from my cabin for a week at a time. I am in north central Minnesota where the sun is not as strong as more southern climates. My charging battery is a traditional marine lead acid battery and my deep cycle is a trojan AGM (expensive) battery. Everything seemed to be working fine but when I took in the boat last fall I noticed the sealed Trojan AGM battery had a hole the size of a pencil in the top of the battery at one of the end cells. Trojan factory said that the battery must have been overcharged. Does anyone have any experience with solar to charge their batteries? Sounds like my controller is bad but how do you know? Should I be checking my batteries with a volt meter and only charging them when the voltage is below? I appreciate your feedback.

 

[Rancherlee]

Re: Using solar to charge batteries

It will be really hard to overcharge a battery with a single 18 watt panel. At MOST it only putting out 1.5Amps. I would however check the voltage across the terminals when the sun is at its brightest at 1pm, If is over 14.4V then you might be cooking it.

 

[seadog59]

Re: Using solar to charge batteries

I checked my controller, it is a Northern Industrial (same place I bought the solar panel) with a 7 amp load max, cut out is 14.2V cut in says 13V. Doesn't seem like it should be a problem. I appreciate your thoughts.

 

[Silvertip]

Re: Using solar to charge batteries

Vandals perhaps? Did the hole look like it was made from the inside out or outside in? Is it perfectly round like it may have had a plug in it and gassing had forced it out. Have the battery load tested. If it's ok, seal the hole and go boating.

 

[seadog59]

Re: Using solar to charge batteries

I couldn't tell from the hole if it was made from the inside or outside...I assume inside. Trojan told me they are made to break there if they are going to break. I took it back and got a new battery. I'm just not sure I want to charge it with solar.

 

[solar7647]

Re: Using solar to charge batteries

I do enviromental testing on Solar Modules for a living. With the set up you have as long as that controller is kicking off at the proper voltage it should be fine. It sound like more of a battery issue perhaps previous damage that just got worse. Was there any issues with the other battery? To see if the controller is working properly force 14.2 v and see if it cuts out, if it does deffintly a battery issue. Stay with the solar charger, its a good way to save some money and some coal from being burned every little bit helps. Good luck!

 

[flargin]

Re: Using solar to charge batteries

I couldn't tell from the hole if it was made from the inside or outside...I assume inside. Trojan told me they are made to break there if they are going to break. I took it back and got a new battery. I'm just not sure I want to charge it with solar.

Seadog.
Don't know if I read this correctly, but it sounded like you took one solar charge controller and split the leads to charge both batteries? If so, this may be a problem... you have one AGM and one wet cell battery. They don't charge the same, you may have actually overcharged the AGM this way. You may want to use 2 solar charging systems, one for the AGM and one for the Wet cell.

 

[seadog59]

Re: Using solar to charge batteries

Good point...that is exactly what I did, one controller charging two batteries...one wet cell and the other AGM. I wonder if I can install a second controller at each of the batteries rather than buying a second solar panel?

 

[Chris1956]

Re: Using solar to charge batteries

Seadog, You simply cannot damage a battery with 18 W of charge. This is a trickle charge, which does no more than keep a fully charged battery "warm". Your battery was either defective or vandalized.