‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Sunday, June 27th, 2021 at 7:41 AM, Gene Heskett <ghesk...@shentel.net> wrote:
> On Sunday 27 June 2021 07:41:35 fxkl47BF via Emc-users wrote: > > i'm gonna explain my screwup here because this group of folks has a > > very diverse range of expertise. enough kiss'n up. if you know of a > > list that would be more appropriate please let me know. i've had a > > desire for some time to build a gasoline powered battery charger. i've > > seen it done several times and thought no big deal. my first thought > > was to use a 3 hp engine and a 100 amp one wire alternator. but since > > i already had a 6.5 hp engine i decided to go with that and an > > alternator like this > > https://www.ebay.com/itm/NEW-CS130-ONE-WIRE-RED-ALTERNATOR-FOR-CHEVROL > > ET-GMC-CHEVY-220-AMP-1-WIRE-1100665-/283190864732?hash=item41ef7dab5c. > > i also added an ammeter like this > > https://www.ebay.com/itm/301111474999?hash=item461ba47b37:g:hYUAAOxy4f > > VTEuR6. i finished it and was ready to test. i pulled a big battery out > > of my tractor, connected a 1000 watt inverter, and about an 800 watt > > load. i cranked the engine and connected it to the battery. ammeter > > showed about a 7 amp load. i switched on the inverter and it went to > > about 9 amps. i switched on the load and it went to about 75 amps. the > > engine was straining. i disconnected the the alternator from the > > battery so the load could draw down the battery. after about one > > minute i reconnected the alternator. the ammeter jumped to about 110 > > amps and it promptly stalled the engine. i tried several times with > > the same results. all of my feeble calculations led me to believe that > > a 6.5 hp gasoline engine was more than enough to power a 220 amp 12 > > volt alternator. either my 6.5 hp engine is more feeble than my brain > > or my calculations are way off. thanks for any feedback. > > I think that formula might be in the Machinists Handbook but mine isn't > handy. In any event that 6.5 hp engine is too puny to pull that 220 amp > alternator at full output as thats 3.19 kilowatts at around 14.5 volts > to the battery. And thats w/o any wiring losses. i always used a rule of thumb 2 gasoline hp per 1000 watts and 746 watts = 1 hp i was very liberal with my calculations 15 volts * 220 amps = 3300 watts 3300 / 746 = 4.423 (3300 / 1000) * 2 = 6.6 either way i figured i had enough _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
