Can I still get 12V from two 12V batteries in series

[cajucito]

A dedicated extra 12v Battery very close to the windlass is the best solution charged from the 24v system using a regulator. No long 12v Heavy cables. Tapping 12v off the 24v system is a definate no no as the windlass is a high power item especially under load when breaking out. I had probs with my bow thruster for a long time , when I fitted an extra battery right next to the thruster it solved every problem I ever had. Having a dedicated battery on heavy load devices such as windlass electric winches or thrusters is a great idea as it isolates the rest of the system from low voltage dropouts when the 'big current' device comes under heavy loads. Thrusters can draw several hundred amps.

[Zil]

In my good old days, we converted hot rods from 6v to 12 volts. Changed the generator, the bulbs, but run the 6 volt starter on 12 volts. Some early Ford V8s were set up with a solinoid on a 12v battery to just power the 6 volt starter. Would spin faster, but did not have other problems.

[rwidman]

Originally Posted by Zil

In my good old days, we converted hot rods from 6v to 12 volts. Changed the generator, the bulbs, but run the 6 volt starter on 12 volts. Some early Ford V8s were set up with a solinoid on a 12v battery to just power the 6 volt starter. Would spin faster, but did not have other problems.

The heater blew good too!

[Cadence]

Originally Posted by Zil

In my good old days, we converted hot rods from 6v to 12 volts. Changed the generator, the bulbs, but run the 6 volt starter on 12 volts. Some early Ford V8s were set up with a solinoid on a 12v battery to just power the 6 volt starter. Would spin faster, but did not have other problems.

You forgot the coil.

[hellosailor]

Except, starter motors are high impulse motors. And high impulse motors are very very different from electronic instruments or much of anything else. You can overvolt many motors with no damage, if the power is applied briefly enough. But sooner or later, the excess voltage also overheats them and burns them out. The same way that the normal voltage will burn them out, if it is applied for just a little too long.

It's like giving dog chow to a goldfish. Probably would work for a while. Just isn't the best way to raise prize goldfish.

[jordiebsocal]

Make sure the 24v charger is not charging those batts when you are powering your 12v windless off them, or you will fry it.

[Kipper1258]

I have the reverse problem. I want to install a 24V thruster on a boat that has a 12V system. I am thinking of installing a second 12V battery in series with the start battery as shown is this wiring diagram.



My questions.

1. Has anyone done something similar to this and did it work?
2. If so, what did you use for the diode to prevent a short circuit on the charging circuit? I think a 50 A bridge rectifier may work, using the DC output terminals as the diode.
3. What sort of reverse current was there through the diode and did that cause any flattening of battery issues?

An obvious solution is to install two extra batteries and a 12-24v charging system. I'd like to avoid that if possible.

[FlyingCloud1937]

A better solution.

Originally Posted by FlyingCloud1937

Going to require some additional HD wire pulls, but a solution is at hand without moving the bats.
Lloyd

texasindustrialelectric.com

Originally Posted by Kipper1258

I have the reverse problem. I want to install a 24V thruster on a boat that has a 12V system. I am thinking of installing a second 12V battery in series with the start battery as shown is this wiring diagram.



My questions.

1. Has anyone done something similar to this and did it work?
2. If so, what did you use for the diode to prevent a short circuit on the charging circuit? I think a 50 A bridge rectifier may work, using the DC output terminals as the diode.
3. What sort of reverse current was there through the diode and did that cause any flattening of battery issues?

An obvious solution is to install two extra batteries and a 12-24v charging system. I'd like to avoid that if possible.

[Cadence]

Originally Posted by Kipper1258

I have the reverse problem. I want to install a 24V thruster on a boat that has a 12V system. I am thinking of installing a second 12V battery in series with the start battery as shown is this wiring diagram.



My questions.

1. Has anyone done something similar to this and did it work?
2. If so, what did you use for the diode to prevent a short circuit on the charging circuit? I think a 50 A bridge rectifier may work, using the DC output terminals as the diode.
3. What sort of reverse current was there through the diode and did that cause any flattening of battery issues?

An obvious solution is to install two extra batteries and a 12-24v charging system. I'd like to avoid that if possible.

You would be shorting across your gen. output.

[Kipper1258]

Originally Posted by Cadence

You would be shorting across your gen. output.

Yep. Suppose that's why I'm not an electrical engineer. Thanks.

[Kipper1258]

Originally Posted by FlyingCloud1937

A better solution.

Thanks. What I am looking for. One more question, any issues with this type of parallel switch for driving a thruster. Looks like it also looks after the charging side of the second battery.

[FlyingCloud1937]

No problem, as long as your charge back amps don't exceed 45amps. The relay/combiner is rated at 1500 amps intermittent. I doubt your thruster would exceed 150 amps.

Lloyd

Originally Posted by Kipper1258

Thanks. What I am looking for. One more question, any issues with this type of parallel switch for driving a thruster. Looks like it also looks after the charging side of the second battery.