Trickle charge generator battery

[checkthisout]

I have a voltage reference line running from the solar batteries out to the generator shed. The generator control uses these lines to simply monitor the solar battery voltage so it knows when to start.

I would like to trickle charge the generator battery using these wires. They are #12.

Would a resistor and diode do the trick? If so, what size resistor should i use to limit the current to say 5 Amps? (System is 12 volts).

The diode would keep energy from flowing out of the generator 12v system. The resistor would limit the current flowing from the solar battery to the generator battery while it's voltage drops during cranking.

Is this good? A better way?

[Mike90250]

the generator control lines will not be able to carry charging current to your battery. I suggest ( and use ) a "Noco Genius" battery charger of the right size for the battery. But you do do have to plug it in.

[SunEagle]

I have a voltage reference line running from the solar batteries out to the generator shed. The generator control uses these lines to simply monitor the solar battery voltage so it knows when to start.

I would like to trickle charge the generator battery using these wires. They are #12.

Would a resistor and diode do the trick? If so, what size resistor should i use to limit the current to say 5 Amps? (System is 12 volts).

The diode would keep energy from flowing out of the generator 12v system. The resistor would limit the current flowing from the solar battery to the generator battery while it's voltage drops during cranking.

Is this good? A better way?

Well a 12V battery is really looking for about 14 - 15V to charge so IMO limiting the voltage may also limit the charging capabilities.

Maybe having a separate solar panel and charger for charging the battery

[checkthisout]

Well a 12V battery is really looking for about 14 - 15V to charge so IMO limiting the voltage may also limit the charging capabilities.

Maybe having a separate solar panel and charger for charging the battery

I'm only looking to "Float charge" or maintain the battery, not charge it. The generator's alternator charges the battery at about 15.4 volts. I can see the generator battery voltage drop slowly over time and just want ensure it remains charged. (It's a small battery).

Its ridiculous but I have a panel and old charge controller ready to go but not hooked up yet. I was thinking of adding the panel to my regular system and dropping its voltage. 2s4p from 3s3p.(different topic).

If you wanted to limit current flow in a 12v circuit, how would you do it?

[checkthisout]

the generator control lines will not be able to carry charging current to your battery. I suggest ( and use ) a "Noco Genius" battery charger of the right size for the battery. But you do do have to plug it in.

They don't control the generator, it's just two wires that hook directly to the solar battery and go out to the generator so the box at the generator that controls the generator knows what the battery voltage is. They also supply voltage to a light in the Gen shed.

How would you limit current flow in a 12v circuit in the most simple manner possible?

[checkthisout]

I just realized that a trailer brake disconnect battery setup has the exact setup I need. They prevent current from flowing out of the trailer battery into the vehicle and prevent too much current from flowing to the trailer battery from the vehicle. Exactly what I need!

I probably have an old one laying around work I can steal the circuit board out of.

[SunEagle]

I'm only looking to "Float charge" or maintain the battery, not charge it. The generator's alternator charges the battery at about 15.4 volts. I can see the generator battery voltage drop slowly over time and just want ensure it remains charged. (It's a small battery).

Its ridiculous but I have a panel and old charge controller ready to go but not hooked up yet. I was thinking of adding the panel to my regular system and dropping its voltage. 2s4p from 3s3p.(different topic).

If you wanted to limit current flow in a 12v circuit, how would you do it?

A solar panel used to trickle charge will only work with a small wattage/amp panel (usually about 5 to 10 watts) . A larger panel may cook the battery since there isn't any control system to lower the voltage going to it. A small battery will over charge a lot quicker then a standard battery.

[checkthisout]

A solar panel used to trickle charge will only work with a small wattage/amp panel (usually about 5 to 10 watts) . A larger panel may cook the battery since there isn't any control system to lower the voltage going to it. A small battery will over charge a lot quicker then a standard battery.

Panel and old charge controller.

[SunEagle]

Panel and old charge controller.

If you mentioned the specs of the panel and CC then half of my comments could be ignored.

[Mike90250]

Or, now with a fuller understanding, that you want to parallel your generator battery with your house battery, select a pair of 20A fuses to protect the 12ga wire at both ends, when the solar recharges the house battery, it will top off the genset battery. Any diodes will reduce the voltage to nearly useless.

[checkthisout]

Or, now with a fuller understanding, that you want to parallel your generator battery with your house battery, select a pair of 20A fuses to protect the 12ga wire at both ends, when the solar recharges the house battery, it will top off the genset battery. Any diodes will reduce the voltage to nearly useless.

This would allow the genset battery to run down with the solar batteries which would actually make the problem worse.

It would also expose the solar batteries to the 15.4v output of the generators charging system and unlimited Amps would be able flow throw the #12 cable out of the solar batteries while the generator is cranking.

The 12v to 12v controller for trailer brake or house batteries appears to be a good solution. Thanks.

[checkthisout]

If you mentioned the specs of the panel and CC then half of my comments could be ignored.

270 Amp panel, 40 Amp cc.

Battery is like smaller than a motorcycle battery and Gen charges it at 15.6 volts.

[SunEagle]

270 Amp panel, 40 Amp cc.

Battery is like smaller than a motorcycle battery and Gen charges it at 15.6 volts.

I figure you mean 270 Watt panel.

Depending on the Vmp rating of that panel ( probably around 36VDC) the Imp may be around 7.or 8 amps. That can cook a battery that is less then 60Ah which is much bigger then a small motorcycle battery.

At least you have a CC which will help keep the battery charged and safe.

[checkthisout]

$8.00 solution. And no DIY!

Hopkins 20007 Break Away Battery Charger https://www.amazon.com/dp/B0049MF1Z4...ing=UTF8&psc=1

[sdold]

That looks like a good simple way to do it.