Renogy DC-DC Test Results-UPDATE 4 (Better!)
Updates 23 June--new test with Renogy input exposed for voltage readings
Update 25 June more readings
Update 4 - 27 June-- fewer amps with fat wire were noted this time!
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I have the 20 amper Renogy with a 105a alternator in the 2003 truck. The Renogy is in the truck camper near the house battery bank (200AH) and input to the Renogy is via (thin) 7-pin wiring for pos path and neg path.
To run the test I inserted an analogue 60 amp ammeter in the pos path from truck to camper close to where the 7-pin connects to the camper's 7-pin. Camper batts at 50% SOC so lots of time to stay at constant amps in Bulk to run the test.
Truck engine bay heated up during the test (idling with hood up) and truck engine battery voltage came down over time. Noted in test results.
Trimetric monitor for camper batt readings and digital meter for truck input readings
Trimetric showed 12.2v and -00.3a before test. I will give output amps as what the Tri said plus the .3 so 18.8 + .3 = 19.1 Renogy output to battery bank, eg.
Truck and Renogy on at first with 7-pin. Truck batt 13.94 after a few minutes (14.5 start), voltage tapered more as warmed up over 45 minutes.
19.1 amps out at first, then tapering as truck warmed up. (bad--I will have to do some work on that)
When Renogy turned on, output amps ramp up so not instant full amps. (good IMO)
Results:
Truck batt 13.72v, at ammeter 9.88v, 30 amps Tri and 12.8v/ 16.8a tapering amps.
Then 13.63/9.86, 30a and 12.8/15.8,
Then 13.55/9.83, 30a and 12.8/15.2
Renogy unit stayed cool to the touch for whole 45 minute test.
So now the big question is--What happens if you use fatter wiring between truck batt and Renogy compared with the 7-pin????
Using a 25 ft fat wire set of jumper cables (not sure of AWG--ISTR #2 cu-al)
Pos path change only, neg path still via 7-pin:
13.32/11.84 (big jump there!) and Tri showing 12.8/19.1 (big jump in amps there!) still 30 amps on ammeter.
Added neg path half of jumper cables
13.53/13.01 (ha!) 12.9 (battery coming up by now) /19.1 a no tapering.
Checked Renogy output at the unit 13.00v, and Tri says 12.9 so that's ok.
So there you have it for what happens with fatter wire from truck to Renogy No change in Renogy draw still 30 amps, but way better output amps. Adding neg path no change in output, so there is a voltage drop that is not worth improving looks like.
Update 25 June more readings
Update 4 - 27 June-- fewer amps with fat wire were noted this time!
-----
I have the 20 amper Renogy with a 105a alternator in the 2003 truck. The Renogy is in the truck camper near the house battery bank (200AH) and input to the Renogy is via (thin) 7-pin wiring for pos path and neg path.
To run the test I inserted an analogue 60 amp ammeter in the pos path from truck to camper close to where the 7-pin connects to the camper's 7-pin. Camper batts at 50% SOC so lots of time to stay at constant amps in Bulk to run the test.
Truck engine bay heated up during the test (idling with hood up) and truck engine battery voltage came down over time. Noted in test results.
Trimetric monitor for camper batt readings and digital meter for truck input readings
Trimetric showed 12.2v and -00.3a before test. I will give output amps as what the Tri said plus the .3 so 18.8 + .3 = 19.1 Renogy output to battery bank, eg.
Truck and Renogy on at first with 7-pin. Truck batt 13.94 after a few minutes (14.5 start), voltage tapered more as warmed up over 45 minutes.
19.1 amps out at first, then tapering as truck warmed up. (bad--I will have to do some work on that)
When Renogy turned on, output amps ramp up so not instant full amps. (good IMO)
Results:
Truck batt 13.72v, at ammeter 9.88v, 30 amps Tri and 12.8v/ 16.8a tapering amps.
Then 13.63/9.86, 30a and 12.8/15.8,
Then 13.55/9.83, 30a and 12.8/15.2
Renogy unit stayed cool to the touch for whole 45 minute test.
So now the big question is--What happens if you use fatter wiring between truck batt and Renogy compared with the 7-pin????
Using a 25 ft fat wire set of jumper cables (not sure of AWG--ISTR #2 cu-al)
Pos path change only, neg path still via 7-pin:
13.32/11.84 (big jump there!) and Tri showing 12.8/19.1 (big jump in amps there!) still 30 amps on ammeter.
Added neg path half of jumper cables
13.53/13.01 (ha!) 12.9 (battery coming up by now) /19.1 a no tapering.
Checked Renogy output at the unit 13.00v, and Tri says 12.9 so that's ok.
So there you have it for what happens with fatter wire from truck to Renogy No change in Renogy draw still 30 amps, but way better output amps. Adding neg path no change in output, so there is a voltage drop that is not worth improving looks like.
