24v alternator for solar

[ice2484]

I am trying figure which 24v alternator to use for solar? There are some that put out 100 amps at 24v but how wondering how many amps can it handle continuous without burning up.

[inetdog]

I am trying figure which 24v alternator to use for solar? There are some that put out 100 amps at 24v but how wondering how many amps can it handle continuous without burning up.

I am at a complete loss to figure out how you would be planning to use a 24V alternator with a solar PV system.
Are you planning to build your own wind turbine to supplement the PV?
Is this a purely off grid system where you need reliable energy sources to keep from overusing your generator?
Or are you planning to add another alternator to one of your vehicles so that you can use it for emergency battery charging?
100A is way to much current to try to run any great distance between the alternator and whatever you will be loading it with. It would be manageable within the confines of an engine compartment for charging a vehicle starting battery.

[ice2484]

Just for emergency battery charging for 24v battery bank. Is going to be used with lawn mower engine that i allready have.

[inetdog]

Just for emergency battery charging for 24v battery bank. Is going to be used with lawn mower engine that i allready have.

That makes sense. As far as I know the alternator should be able to deliver its rated current continuously, but it may be relying on a stream of cooling air from the engine fan too, so I would make sure to provide some sort of cooling fan in the arrangement.

[Sunking]

Just for emergency battery charging for 24v battery bank. Is going to be used with lawn mower engine that i allready have.

You have some challenges. Over heating the alternator is the least of your problems. Properly sizing the engine and gear/belt ratio is the most important thing to get right.

One big challenge is the engine HP. On paper a 3 HP engine should work. Problem is every lawn mower manufacture lies big time on rated HP output. Second issue is every alternator must reach a minimum RPM to achieve maximum output. In a vehicle is no problem as most design the pulley ratio to generate maximum alternator power at idle RPM or slightly higher. Gear it too low and you will never reach maximum power. Gear it to high and you stall the engine. You will need to know engine Torque & RPM to get it right along with a governor to throttle the engine at the right RPM.

[Bala]

I ahve never set up a 24V one but have had a bit to do with 12V ones.

Cooling will not be an issue, they have there own fan,

2000rpm for an alternator will give you plenty of output, which is probably about 1000rpm in a car.

Petrol stationary engines give max HP at 3600 rpm, if you were to use a 3hp engine you may need to run at that.

generally about 5-6hp is used so you can run at a lower speed, less noise less fuel.

So off a 5-6hp engine you can run 1 to 1 ratio or direct drive and set the rpm you want that will give you enough output at the lowest possible rpm.

Biggest hurdle is that the regulator in any vehicle alternator is set to a float voltage, not what you want for charging stand alone batteries.

I once had the internal reg taken out of a bosch alternator and an adjustable external regulator wire so I could charge at a much faster rate.

This was on portable roadworks traffic lights, it was the next step after changing batteries every day and just before solar came in on them,

So unless you can set it up with a higher voltage set point on the reg you will have a lot of run time to charge up.

[bcroe]

Biggest hurdle is that the regulator in any vehicle alternator is set to a float voltage, not what you want for charging stand alone batteries.

I once had the internal reg taken out of a bosch alternator and an adjustable external regulator wire so I could charge at a much faster rate.

So unless you can set it up with a higher voltage set point on the reg you will have a lot of run time to charge up.

Vehicle alternators have a voltage sense wire. By reducing the voltage into it, you can make it charge
to a higher voltage. Much harder to make it charge to a lesser voltage. Bruce Roe

[Sunking]

You can replace any vehicle alternator reg to do anything you want. There are many manufactures at all price ranges. If it were me I would be looking for a 1 cylinder diesel engine made specifically to do what you want. They last forever. They operate at 1800 RPM's. No more, no less. It is the perfect engine for the application.

[Bala]

Vehicle alternators have a voltage sense wire. By reducing the voltage into it, you can make it charge
to a higher voltage. Much harder to make it charge to a lesser voltage. Bruce Roe

Glad you pointed that out, never even thought to post it even though I recommended it for a vehicle at work just last week.

A lot of late model vehicles are only charging 13.5v,

By putting a diode in the Voltage sense wire you can get the reg to charge higher.

They are avail commercially for some, they have put the diode into a blade fuse so you just replace the fuse in your fuse box,

but if you know what diode then it is cheap to do.

[Mike90250]

I am trying figure which 24v alternator to use for solar? There are some that put out 100 amps at 24v but how wondering how many amps can it handle continuous without burning up.

Solar uses PV panels and charge controllers.
Alternators are used with engines or water/steam turbines to create electricity.

Common automotive alternators will perform poorly in off-grid / constant load usage, as they are not designed for full load
output for long periods of time. They slowly overheat and their output starts to drop off. Look for a 150-200A 24V alternator from a truck or bus, something other than a standard car.

It takes about 2hp of engine to generate 1Kw of power. My 6hp diesel is rated 3Kw output.