Hi Steve. Sounds like you have been having fun. Yes, you can stuff a battery by overcharging. Trek covered this well in my thread from a week or so back
www.seabreeze.com.au/forums/Sailing/General/Small-Solar-controllers/

Oh BTW you were reading Volts, not amps.

Thanks guys. Ill need to sort out this charging etc. Saw no whalesuntil deciding to head in. Saw a big tail breach surface then 2 whales breaching and being nutcases for a bit. Awesome!

Sectorsteve said...
Thanks guys. Ill need to sort out this charging etc. Saw no whalesuntil deciding to head in. Saw a big tail breach surface then 2 whales breaching and being nutcases for a bit. Awesome!

On Saturday we went from botany bay to Jibbon saw 10 whales in 4 different pods

MichaelR said...
Excellent day out Steve.

Regarding your charging. Yes, you can overcharge and kill a battery. However, a normal car or bike alternator will charge at roughly 13.8 volts at any speed above idle. The outboard you have will have a built in voltage regulator, this regulator gets the voltage load back from the charge cables and regulates how much charge the alternator sends back to the battery. At least, that's the layman's explanation.

If your regulator wasn't working, your voltmeter would show a much higher voltage than 14, which is still fine.

Thanks michael. So are you saying that theres a kind of safety system in there somewhere? What about from the panel? Im all paranoid now since frying the last battery (left inverter on) so im disconnecting the solar panel when i leave the boat.

we talking about excessive bat. charge or discharge ?
Sure leaving bat. loaded / invertor, bilge pump, ligh or any load /
without maintaning adeqate charge meantime ....it will kill the battery.
opsite running any engine even outboard never harm the bat.
the same solar with controller.
fully charge bat. happy battery.
why disconnect solar....there is no controller in the line.

The question is really does the outboard alternator have a charge regulator. I checked the spec sheets for my new 6hp Tohatsu and it doesnt say. Probably, if it is a larger motor it would have one, but the little ones guess you would have to ask the manufacurer or find a workshop manual.

When the fridge was running it was 12.5. But after motoring a while i switched fridge off and the battery showed 14 VOLTS. its just a 40ah century deep cycle

Sectorsteve said..

MichaelR said...
Excellent day out Steve.

Regarding your charging. Yes, you can overcharge and kill a battery. However, a normal car or bike alternator will charge at roughly 13.8 volts at any speed above idle. The outboard you have will have a built in voltage regulator, this regulator gets the voltage load back from the charge cables and regulates how much charge the alternator sends back to the battery. At least, that's the layman's explanation.

If your regulator wasn't working, your voltmeter would show a much higher voltage than 14, which is still fine.

Thanks michael. So are you saying that theres a kind of safety system in there somewhere? What about from the panel? Im all paranoid now since frying the last battery (left inverter on) so im disconnecting the solar panel when i leave the boat.

Steve, all battery charging systems from engines will have a voltage regulator. Alternators, or stators as some call them are simple power generators that generate a power curve depending on their revolution speed, if there was no regulator, the voltage would increase to many hundreds of volts. The regulator/rectifier is in place to regulate the voltage your battery and engine receives from the alternator/stator to roughly 14 volts. This is the voltage required to continually charge a 12 volt battery.

Using your panel will only show you some of the story and is only good for on the go monitoring, but if you are showing 14 volts its a good thing. If it was off the dial, then the regulator in the outboard has failed and would need attention. If it's showing lower than 12 fully loaded with fridge and lights, then it's also going to need attention.

From what you've explained so far, it seems like you have nothing to worry about with your engine overcharging.

With your solar, you will need to get a multi-meter and check how much power it's generating in full sun. You can google the method for this, because there are a couple of things to look out for. Here is the first hit I got. www.selectsolar.co.uk/cat/171/testing-your-solar-panel-regulator

Have fun, and thanks for making me think about my aging solar panels :-)