gibson air conditioning How much will an air conditioner affect my battery range?

Darth Geneus

I am considering adding air conditioning to a purely electric vehicle. The vehicle gets about 30 miles of real world range, not 35 like the link states. I have the specs of the batteries and the air conditioner, but I don’t know the math required to calculate how much the AC will limit the range. My mental math tells me that it will nearly cut it in half :/

Please help, it sucks being in Texas without AC.

GEM e2 Purely Electric Vehicle / NEV / LSV

http://www.gemcar.com/models/default.asp?ID=481

Trojan 30XHS Deep Cycle Battery

http://www.trojanbattery.com/Products/30XHS12V.aspx

Gibson Air Conditioner GAC102P1A

http://ac-review.com/models/air-conditioner/gibson/gac102p1a.html

Answer by billrussell42
The AC runs from 120 VAC at 8.2 amps, or a power of 984 watts. You will need an inverter to convert DC volts to 120 VAC at 2 kW (extra to enable the motor to start). the losses in the inverter will bring it to about 1100 watts. At 12 volts, that is about 90 amps. At 72 volts, that is about 15 amps. It will be difficult to find an inverter that runs from 72 VDC.

The car itself runs from a set of batteries that supply 72 volts, and the battery in your link is a 12 volt battery, so my guess is that you have 6 of these batteries in series.

The batteries each supply 25 amps for 225 min, which is 94 amp-hour. OR, 75 amps for 57 min, which is 71 amp-hour. So the battery is good for somewhere between 71 and 94 amp-hour.

The batteries and the AC alone will lsat about 100 amp-hour/15amp = 6.7 hours

But beyond that, we have to make guesses, as the battery life driving the wheels depends on speed, conditions, and other factors. Range is listed at max 35 miles, but no speed noted. Assuming a slow speed of 15 mph, that is 2.3 hours.

Using that number, and an average number for the battery of 80 amp-hour, that means the current used for average driving is 80 amp-hour/2.3h = 34 amps. Adding the 15 amps for the AC, that increases to 49 amps, which reduces the time to 80 amp-hour/49 = 1.6 hours. At 15 mph that is 24 miles.

So with lots of guesses, we get range reduced from 35 to 24 miles.

edit, other ans is correct, this AC can be a lot smaller. And smaller means lighter. The weight of the unit also will impact your range. You may need a custom designed inverter to run from 72 volts.

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