westend wrote:
BFL,
Are you sure about this? I used to do a fair bit of vehicle recovery where sending power to the inoperable vehicle was the goal. When I had the battery charging recovery unit (220 amp alternators), there was nothing that could beat it. Even a set of jumper cables allow a good bit of power into a discharged battery through a 120-130 amp alternator. It would be fulfilling to see actual measurements of the power transferred between the two options over time.
I was careful to say that the inverter- powered charger had to do at least the same initial charging amps as the jumper method.
It is possible that you could restore more AH with fat jumpers and a good alternator than with a small amp smart charger, even though the jumper amps will taper.
I have some data from my old 7-pin /jumper cable trial, but not sure if that is what is wanted. I used the Trimetric as my ammeter.---
First I ran the trailer battery down to 50% so it would be sure to accept whatever amps either method would produce. 105amp alternator.
A. I confirmed the battery would accept 35 amps by trying it with a 35 amp Vector charger. So that means it would do constant 35 in bulk for a time until the battery reached Vabs, then amps would taper.
B. Battery drawn back down from that, and on 7-pin, engine off, amps at trailer-- 0.3
Time 1611-start engine-amps 10.1
1612- amps 8.5
1613-amps 7.5
1615- amps 7.1
1617-amps 6.5
C. Battery drawn down again, and with 12 ft #10 jumpers,
Start--20 amps, then tapering quickly as above 18.1 amps, 17.0, etc
That was with engine idling. Tried a comparison at 2000 revs vs idle:
17.5 amps revving, 17.0 amps idle.
D. Battery back down, and with 25 ft #1 cu-al jumpers
Start 35 amps and immediate tapering same as above except with more amps.
So---the 35 amp Vector would beat the fatter jumpers starting at 35 amps because no initial tapering with the Vector.
However- with even fatter/shorter all copper jumpers, it might have kicked off at higher than 35 amps so then you would need to run a proper AH restored in same time contest, which the jumpers might win, despite their tapering amps.
