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Thursday, March 16, 2023

Amateur Radio Mobile and Electric Vehicles


Operating amateur radio equipment while mobile in a motor vehicle can be challenging. Traditionally twelve volt DC systems have predominated among automotive manufacturers of gasoline and diesel powered vehicles. We’ve become proficient at modifying automotive electrical systems to provide required power for transceivers, auto-tuners and linear amplifiers. Recent interest in next generation electric vehicles (EVs) might require we more carefully consider equipment selection and their electrical load requirements.

Mobile power for equipment has always been straight forward. Selecting battery capacity, alternator and wire size accommodates most higher current twelve volt requirements. Gas or diesel power was always there to power and charge the system. Next generation EVs change the power equation as battery charging is no longer sustained during vehicle operation but only occurs when plugged into a fixed charging station. This means accessory electrical systems (stereo, air conditioning/heating etc.) operate on battery power during vehicle operation and can effectively limit vehicle range between charges. Amateur radio equipment can potentially limit an electric vehicle’s range by additionally taxing the power system (my Icom IC-7300 can draw twenty five to thirty amps while transmitting). It’s interesting to note that amateur radio equipment manufacturers are introducing fully featured systems operating at QRP power levels (the Icom IC-705 is one example). The popularity of QRP operation aside, the IC-705 seems well suited for mobile hams sporting electric vehicles.  See the link:

We might consider conservation a sign of the times but consider your neighbor who might have a killer stereo system in his car or a ham friend with a vehicle powered up for field day. Americans need mobile power!

With the advent of EVs automotive electrical systems have evolved. Tesla (and most) electric vehicles utilize a high capacity lithium ion battery to power the car’s drive train but also feature a twelve volt auxiliary battery system to power conventional mobile electronics and accessories. A DC to DC converter ports power from the lithium ion drive train battery to charge the smaller twelve volt battery. In its original design Tesla used a conventional twelve volt lead acid cell for the auxiliary battery. Later models now feature a twelve volt lithium ion battery providing more current capacity but at a higher price of $450-500. Hams might utilize the twelve volt power system for equipment but must be careful not to exceed fused power and wiring harness capacity. Before installing anything it’s a good idea to consult your auto dealer on power routing and RF interference/interaction concerns (if any).

Balancing electrical loads on EVs can be challenging as power consumption for traditional accessories (and ham gear) can reduce vehicle range.  Estimating your ham gear power load (watt/hours) you can approximate any reduction in vehicle range by using the power loading table below as a guide. See the link:[2] https://avt.inl.gov/sites/default/files/pdf/fsev/auxiliary.pdf

Some Chinese EV manufacturers are offering battery changing stations (as opposed to charging stations). When your vehicle battery is near depletion and needs charging you stop at a station and swap your battery for a charged one. The advantage is no waiting, no charging and no worries of battery replacement cost. This poses a different economic alternative for EV owners. You never need to replace your battery but pay a monthly fee to access battery exchange stations. Nio vehicles boast a five minute battery swap and eliminate lengthy charging times. See the link:
[3] https://www.caranddriver.com/news/a33670482/nio-swappable-batteries-lease/

My mobile solution was to purchase a hybrid vehicle. My Ford Fusion Hybrid has a similar lithium ion battery and lead acid twelve volt auxiliary system but its gasoline engine sustains electrical operation while charging the batteries. I recently replaced the twelve volt battery upgrading it from 390 cranking amps to 1,200. During HF QSOs with 100 watts the battery voltage remains constant.

In my opinion hybrid vehicles are the best interim green solution as electric vehicles and the power grid evolves. If you’re a ham considering the purchase of an electric vehicle find the best fit for your requirements.

Mobile safe everyone. Wishing you good DX.

Best regards,
 
Thomas D. Jay, 
W4TDJ




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References and acknowledgements:

[1] Icom, Web Site

[2] Idaho National Laboratory, Web Site

[3] Car and Driver, Web Site