Portable Battery Charger

[BruceM]

Bob- That's great= the float indicator signal would be just the ticket to trigger an auto shutdown.


Lloyd,
Charge complete is normally detected by dropping charge current while at the absorption voltage, and a timeout function is used in many 3 stage chargers in case the absorption phase goes on too long.

The absorption voltage isn't fixed, it varies with battery temperature. 

How do you sense charge completion with just a fixed voltage switch and timer relay?

[Lloyd]

Charge completion results in float voltage stabilized 13.2-13.4 temp depending, on 12 volts, set your time delay for 15-30 min at at what ever you chose for float.

The balmar uses time delay, for it's stages, so do many inverters, as a safety override.

Lloyd

[Geno]

Geno,
I have 4 6volt Trojan golf cart batteries wired to 12v......maybe the 4.5hp diesel he sells would be enough and I might get an auto alternator instead maybe not.......Is your alternator double or 1/2 the engine speed?

2 hp should be enough for 4 Trojan's. Are they the 225 amp hour T-105's? If so I don't think they should be charged at more than 150 watts each.

The alternator is double speed.

My next test will be to put the stock rectifier back in, put an automotive 24 volt regulator on the alternator and give it sense voltage from a couple small 12 volt UPS batteries I have. If it works I'll have a steady 26-27 volt output from the alternator which I can use to feed the Flexmax. I'm pretty sure Bob mentioned elsewhere that the stock rectifier doesn't go into avalanche until around 30 volts and that was with a lot more power going through it than I'll ever see.

Thanks, Geno

[mobile_bob]

keep your eyes open, these come up on ebay from time to time
they are made for an inverter, but
can have an external rectifier bridge, and external regulator and charge a 48 volt bank at whatever voltage
you want.

good for nearly 5kwatt of charging

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=330410509900&ssPageName=ADME:B:EOIBSA:MOTORS:1123

bob g

[Geno]

*Somebody* got a great deal on that one!

I'll keep my eyes open.

Thanks, Geno

[mobile_bob]

Somebody??



bob g

[Geno]

I got the external 24 volt regulator installed yesterday and I finally have a nice steady 26.5 volt output to feed the Flexmax. I ran the Flexmax up to 14 volts/55 amps/780 watts output and it worked very well. The engine pulls the load nicely at an rpm somewhere less than deafening.

Thanks, Geno