Battery Load for Accessory Simulation

[Dyno22]

I am trying to simulate accessory loads in a vehicle on a test stand. The problem I am having is I need a large load of 2500-3000 Watts. I would like to have it variable such that it is selectable for light, medium, heavy, approx. 1000W per circuit. Do you have any suggestions on possible load configurations? I was thinking of some sort of resistor bank or light bulb bank but it might start to resemble Las Vegas at full load.

 

[melone]

Can you use the actual vehicle loads, i.e. alternator, headlamps, A/C, etc.? Are there size, space, cost constraints?

 

[IRstuff]

3000 Watts?

That's 250 amps, which is akin to the starter motor load. What else on a car draws that much current? Your headlights don't draw more than about 30 amps. So, you'd need somewhere between 8-20 headlamp pairs. If you individually switch each lamp in/out, you'd get a variation in load.

TTFN

 

[Dyno22]

Not really. My work is being done in a test cell that handles the power, cooling, braking, etc. functions. This particular test I am doing though, requires the use of an auxiliary car battery that I am required to exercise by loading and charging it. My constraints are minimal.

 

[busbar]

 
A straightforward approach may be seven 1-ohm 225-watt vitreous-enameled resistor per kilowatt of load. Duty is not mentioned, but consider 14AWG MIIL type-E (teflon) hookup wire from each resistor to the paralleling point. Each resistor will dissipate 144 watts at 12 volts, but also 190 watts at 13.8V [charging at 2.3V/cell]—down to 100 watts per resistor as the battery discharges to 10V (~1.7V/cell.) [A 1-hp fan may be a good idea.]

 

[ScottyUK]

A phonecall to one of the manufacturers of industrial resistors (as distinct from electronics components) such as Cressall or Eaton might pay dividends.

Cressall in the UK have a fairly small minimum order value and stock a lot of spiral resistor banks capable of handling high currents pretty much off-the-shelf. 3kW is a small rating in their terms, but they have been helpful in the past with oddball resistor values for DC motor time starters and the like.

250A from a car battery seems unreasonably high. The battery itself will get hot delivering this sort of current for a long period. What do you hope to determine from the tests?



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