# Test Rig



## locost_bryan (Aug 18, 2008)

How feasible would it be to design and build a test rig that could simulate an EV operating in the real NZ world?

I'm wondering whether this could then be used to test the manufacturers' claims for performance and durabilities, for components like controllers and batteries?

For example, durability does seem to be the major unknown with the new battery types. I wonder how easy it would be to design a test rig with say a 6 volt source and a proportional resistance load. Could you scale it down to test with a single battery or small battery pack (to keep test cost reasonable), and get realistic scalable results? Run it with a computer to control charge and discharge loads, with results gathered by a data logger?

Run the same test cycle for lead acid batteries (wet/gel/AGM), then LiPo and A123. Could you get comparable results, that wouldn’t be skewed by BMS or charger design?

For testing controllers or motors, you'd need a full-size test rig, perhaps using a large generator to simulate the load on the electric motor? Or perhaps access to a rolling-road dyno to test a functional EV?


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## carrott (Aug 19, 2008)

locost_bryan said:


> How feasible would it be to design and build a test rig that could simulate an EV operating in the real NZ world?


First you'd have to decide what is a real NZ world.



locost_bryan said:


> I'm wondering whether this could then be used to test the manufacturers' claims for performance and durabilities, for components like controllers and batteries?


I have 40Ah cells, assuming they provide 40Ah (I haven't quite finished my cycler) and you had a cycler that could charge and discharge at 40A, a single cycle would take at least 2 hours, so almost 3 months to do 1000 cycles.

My cycler will charge at 3A and discharge at maybe 100. I'm unlikely to do more than 2 cycles on a couple of cells. Have a look at ZEVA's cycler for some ideas.



locost_bryan said:


> For example, durability does seem to be the major unknown with the new battery types.


Cycle life is quite well known and is easy to test. Calendar life is much harder. The only reliable way to measure that is to wait, preferably while exercising the cells in the way you plan to use them.



locost_bryan said:


> For testing controllers or motors, you'd need a full-size test rig, perhaps using a large generator to simulate the load on the electric motor? Or perhaps access to a rolling-road dyno to test a functional EV?


A dyno would be the easiest way to do this, but you'd also be testing your batteries. If you want to measure endurance (can you drive on the motorway until your battery goes flat without your motor overheating?), well dyno time is expensive, not good for your tyres and you'd have to find a dyno that doesn't over heat first.

You could just drive on the motorway with some temperature sensors.


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## locost_bryan (Aug 18, 2008)

carrott said:


> First you'd have to decide what is a real NZ world.


The Dunedinites seem to think our hills are steeper than America's.



carrott said:


> Cycle life is quite well known and is easy to test. Calendar life is much harder. The only reliable way to measure that is to wait, preferably while exercising the cells in the way you plan to use them.


I've seen some postings claiming Thundersky's 2000 cycle claim is optimistic, and other comments about their durability claims. I have no idea how lead acid batteries compare (the battery in my wife's previous car expired the day after the warranty ran out ).

My thoughts about a battery test bench, was to see if a single battery could be tested to verify the manufacturer's claims, and if the results could then be extrapolated for a larger battery pack in an an EV.

Ditto for testing other components in a "controlled" lab test. I suspect building an EV and installing a good data logger would be the most cost-effective way to go. Otherwise, you'd be looking at something hugely expensive, like a car manufacturers test cell.


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## locost_bryan (Aug 18, 2008)

I would expect Waikato University to have these sort of test facilties for the UltraCommuter. 

Wonder if they've done any testing on the durability of the Thunder Sky batteries? They've had bad press in the past - wonder if they're up to spec now?


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