Electrical Guru's -

[drmiller100]

hmmmm......
Ok then.

How about this. I have 4 batteries in series. Can I build a non grounded alternator, and a switching mechanism to charge one battery after another?

So, I'd charge the first battery with the alternator for 2 seconds, switch to the next, etc.

I'm thinking about using a set of 4 or 5 lead acid batteries in series to run a golfcart motor (cheap).
Then use a small onboard gas engine with alternator/generator to extend the range.

[Ryland]

How large of a battery pack do you have that you want to charge it at 50 amps?

You can buy a 45amp 48v charger for electric fork lift batteries for about $1,000 used 250CII by HOBART BROTHERS CO - Buy or Repair at PLCCenter - PLCCenter.com
And they weigh around 150 pounds.
I always figured that charging my batteries was something that I wanted to do carefully because my pack in my car cost $900 and I want to get as many years out of it as I can.

If you want a proper cheap 48v charger, check out golf cart chargers, they come in either 36v or 48v.

[oil pan 4]

My varrac weighs under 10lb and I bet you could find one used on ebay for less than $100. Also you could use it to charge any voltage stack of batteries up to about 170 or so.

[Ryland]

Originally Posted by drmiller100

Can I build a non grounded alternator, and a switching mechanism to charge one battery after another?

I'm thinking about using a set of 4 or 5 lead acid batteries in series to run a golfcart motor (cheap).
Then use a small onboard gas engine with alternator/generator to extend the range.

Automotive alternators put out higher voltage if you remove their voltage regulator, at that point the voltage either needs to be regulated by how fast it is spinning or by a modified voltage regulator and I'm pretty sure that there are people selling modified voltage regulators for the home built "wind turbines".

If you want to use a golf cart motor you either need the rest of the drive axle's differential to support the drive end of the motor or you need to build a new face plate for the motor and get a splined shaft to fit in to the drive end of the motor, if you or anyone else has a project that they need a splined shaft like that for, send me a message because if all goes well I'm hoping to get a price quote on having some made at a local shop that does CNC machining, I already have a hand full of them that have the other end fit in to the drive shaft of a Honda CX500 or Honda Goldwing and I have the CNC file to make them, but I don't have a price yet nor do I have solid ideas on variations that other people might want.

[moorecomp]

Originally Posted by drmiller100

I have 4 batteries in series. I want to charge them at once with 120 volts.
Seems to me 12.6 times 4 equals 50.4

Seems to me alternators normally charge batteries at 14 volts. So, it seems to me if I charged at 60 volts DC, I would be pretty close to perfect.

So if I take 120 volts, and stick a diode in it the right direction, I'm gonna kill one leg of the AC current, and have 60 volts peak charging my batteries.

Obviously it is not this simple, so what am I missing?

120 vac, or your "normal" house current, only has "1 leg". If you look at the sine wave, it goes up to 120v+ and then down to 120v-. A diode cuts out the negative side of the wave and you end up with only peaks of 120v+, not 60v.