Category: Electrical

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Road-Tripping with a Tesla Model 3

Tesla Model 3 Standard Range Plus

In April of this year, I decided to take our 2021 Tesla Model 3 Standard Range Plus on a road trip from our base in Boca Raton, Florida to Connecticut. The round-trip totaled about 3300 miles, so I learned a lot about the car and how to use it along the way. Before setting out, I subscribed to Full Self Driving/Advanced Autopilot for one month ($199.00) to give it a try, and see what all the hype is about. The car was operating on the latest software update at the time.

Range and Charging

You may wonder if I am crazy for taking a car with a listed 265 mile range on a trip of this length. It turns out that the range was not an issue at all – ever. The Interstate 95 corridor is well populated with Supercharger stations, and has been for many years. New stations are being built as well.

Trip planning is easy as pie. Enter your destination on the touchscreen (or use voice commands), and the car automatically plans your route, as well as charging stops along the way. The ETA includes driving time, traffic, and charging stops, however the estimate is highly optimistic.

Before leaving Boca Raton, I set the car to charge the battery to 100% before leaving home. We have a level 2 charger at home, using a second dryer-type outlet. With this setup, home charging happens at about 30 miles of range per hour. I let the car recalculate the route to my first night hotel, and the charging stops all changed based on the starting level of charge. My first stop was planned at about the 180 mile mark, in Titusville FL. This was to be my very first experience with a Supercharger.

Wow! That was easy. Just pull into a Supercharger parking space and plug in. That’s it. My credit card was charged automatically (a whopping $12.25) when I disconnected. At this point I noted that the estimated charging time displayed on the navigation screen in the car was not quite accurate. On average, Supercharging took about 10 percent longer than the estimate. My average stop was about 20 minutes long. The planned Supercharger stops are based on running the battery down below 20%, then recharging to about 80%, because in this range the battery can accept the fastest charge rate.

One of the amazing features of the Tesla navigation system (using cellular connectivity) is that the car knows how many open Supercharger spaces are available in real time. At one point along the trip, the planned Supercharger station was nearly full as I approached, and the car automatically selected a different charging station. Awesome! I never once had to wait for a charging space to open up.

Let’s talk about battery range. Our 2021 Tesla Model 3 Standard Range Plus had a range of 264 miles when the car was new. That range has diminished by about 10 percent as of now. This is not a big deal for us (and normal for the mileage), because we rarely take trips longer than about 50 or 60 miles round trip. For the road trip, keeping the battery charge level between 20% and 80% means I was stopping roughly every 150 miles. For me, this was just about the time I would need a restroom, drink, a snack or meal, and stretch my legs. My gasoline powered vehicle can go longer between stops, but I rarely make it that far.

Speaking of restrooms, it turns out many Supercharger stations are not near public restrooms. Some are located in far corners of shopping center parking lots, or behind strip malls. Others are in the parking lot of a sit-down restaurant, where the meal takes longer to get than the car takes to charge. At one stop in Virginia, the Supercharger station was at the far end of a large shopping plaza parking lot, and it was a long walk to find a coffee shop where I could use the restroom. It would be nice if the Supercharger stations situated like this displayed some form of “This Way to Restrooms” sign. Further, the charging station details in the navigation display should mention available services, but did not at the time of the trip.

Full Self Driving

The navigation system in the Tesla Model 3 is very good, and easy to use. My only complaint is that all audible prompts are completely silenced when using the phone. This caused me to miss turns more than once during the trip, as the only notification of a coming turn is on the center display. If I were to use Apple’s navigation system on my phone, upcoming turns are announced with one beep for a left turn, or two beeps for a right (I may have this reversed – I can never remember). The beep tone is enough to get me to glance at the screen so I know which way to go. Tesla needs to improve this.

Using the Navigate on Autopilot feature of the Full Self Driving suite has its good and bad points. It is marvelous to let the car keep pace in traffic, stay in its lane, and automatically change lanes when needed for an interchange. I used this feature extensively on the long first day of my trip.

I made a rookie mistake and allowed the car to plan my first overnight stop about 900 miles from home. This would take 12 hours according to the navigation system. It turned out to take closer to 16 hours due to traffic, construction, and taking a few stops that were longer than what was needed for charging. I must say, however, that I was not exhausted from the trip. Allowing the car to carry the tedious burden of staying centered in your lane and not plowing into the car ahead of you is very relaxing. Mind you, I stayed alert the whole time. Autopilot makes driving much less fatiguing.

What Full Self Driving does well:

  • Keep the car centered in the driving lane
  • Keep a safe distance with the vehicle ahead
  • Changes to the correct lane for highway interchanges or off ramps
  • Merge into slower moving traffic

What Full Self Driving does poorly:

  • Merge into faster moving traffic
  • Merge lanes – car centers in lane
  • Speed limit changes
  • Stop-and-go traffic
  • Traffic light control

When the vehicle you are following is driving slower than the speed you have set, the Autopilot has the option of changing lanes to pass the slower vehicle. There were time when this was downright frightening! We have all been stuck in a lane that is going 20 MPH slower than we want, so we drop back a bit, wait for an opening, and stomp on the throttle while merging. Advanced Autopilot DOES NOT STOMP! Nor can it see very far behind. At the time of the trip, Advanced Autopilot was programmed to change lanes first, then GENTLY accelerate up to the speed setting. More than once, the car was crossing the lane line into fast moving traffic, then chickened out when cars came into view of its myopic rear-facing cameras. It would then lurch back into the lane from which it was trying to merge. This made me feel like I was giving driving lessons to my teenagers again! I turned off the auto lane change feature.

In most areas along Interstate 95, the right hand shoulder painted line becomes a dashed line at merging on-ramps. In other areas, the shoulder line stops at the on-ramp, and tricks the Autopilot into thinking that the driving lane is now 20 feet wide. The car then centers in this newly tapered lane. As stated before, the Autopilot does very well at centering the car in the lane. In this scenario the car drives like an idiot savant. To avoid this, I tried to stay in the second lane if there were at least three lanes.

When it comes to speed limit changes, the center display indicates this by briefly enlarging the speed limit sign icon in the upper left. There is no tone or other alert, and the Autopilot does not make any adjustments. Without user intervention, this can lead to annoying other drivers, or a speeding ticket. Neither are good things.

When driving in stop-and-go traffic, the Autopilot does not creep with traffic smoothly. Rather, the car accelerates, then applies the brakes in a jerky fashion, ensuring the discomfort of the passengers. I much prefer to drive manually in these cases.

Sometimes when approaching a significant slowdown of multiple lanes of traffic, Tesla Autopilot will ignore the speed of the cars in adjacent lanes, and only pay attention to the vehicle ahead. There were times when this resulted in the Tesla going 20-30 MPH faster than the cars in the adjacent lane. This is putting way too much faith in other drivers not to do something unexpected. This is dangerous.

When driving with Autopilot engaged on roads with traffic lights, the Traffic Light Control feature becomes very annoying. The car will alert the driver to the presence of the traffic light, then proceed to stop regardless of the status of the light. This feature was turned off immediately.

Courtesy to Others

When driving at night, one of the nice features of a Tesla is automatic high beams. When driving on highways, this can be turned off to avoid blinding other drivers. However, when driving on Autopilot, auto high beams cannot be disabled. In congested areas, this is not usually a problem. When driving through the Carolinas at night, auto high beams have a tendency to greatly annoy other drivers, forcing me to disengage the Autopilot so I could disable the auto high beam feature.

Conclusion

Overall, my wife and I are very happy with the purchase of our 2021 Tesla Model 3 Standard Range Plus. The car looks good, is comfortable and fun to drive, and is much cheaper to operate than any gas-powered car. I am glad we did not pay up front for Full Self Driving, because Tesla has a way to go before Full Self Driving will be worth the money.

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Air Conditioning without a Generator

Have you ever wished you could sleep comfortably without the droning of a generator keeping you awake? It is now possible thanks to the high storage capacity of Lithium (LiFePO4) batteries. Our service department recently completed a new system installation on a Leopard 440 catamaran that allows the cruisers to run the entire electric service panel from two inverters. Now, the owners can run both air conditioners, water heaters, microwave oven, 12 volt battery charger, and more, without running the yacht’s generator. Here is how we accomplished this:

We chose Victron Energy’s Quattro inverter/chargers as the heart of the new system. We added 48 volts worth of Lithium batteries (total about 20 kWh capacity), along with 2.2 kW of solar so the owners can keep generator use to a minimum.

It is getting crowded in here!

Since this particular Leopard 440 is equipped with twin 30 amp shore power connections, we opted to use two 5000 watt inverter/chargers – one for each shore power leg. We configured the Quattro Inverter/Chargers in a master/slave setup that allows the battery management system to handle the power flow. We chose Victron’s 24 volt Smart Lithium batteries to keep connections to a minimum. The 48 volt battery system allowed us to keep cable sizes down, which allowed us to run all cables through the factory conduits – a big help with keeping everything secure!

One BIG caveat with choosing a 48 volt battery system is the availability of switches, fuses, and breakers that can handle the voltage. Don’t make the mistake of using equipment rated for just 48 volts! While the NOMINAL VOLTAGE of the system is 48 volts, the ACTUAL VOLTAGE is between 53 and 58 volts!

Rather than upgrade all the boat’s existing 12 volt systems to 48 volts, we chose to add monitoring to the 12 volt house bank. Now, all the systems are monitored in one place! We kept the installation simple by using the existing 12 volt battery charger to keep the house bank full.

The Victron Cerbo GX with touchscreen display provides clear, graphical information on what is happening with the system.

We selected LG 375 watt panels for the solar arrays. We designed the solar strings in series for maximum charging efficiency, and separated the port and starboard panels into two strings. A custom stainless steel frame keeps panel shading to a minimum.

Please contact us if you have questions, or would like a quote for going silent.

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Battery Bank Sizing for Your Inverter

How to choose the ideal battery bank size for your inverter

The Battery Bank Sizing Guide from Xantrex is a very useful tool to determine the size of your inverter and battery bank. However, some additional information is always helpful. Here is what I have learned from personal experience:

  • Your inverter should be sized based on the total simultaneous load to be applied (including motor start loads)
  • Your battery bank should be sized based on your total daily amp-hour demands (inverter and DC loads)
  • Your battery bank should never be discharged by more than 50% of it’s rated amp-hour capacity, or your batteries won’t last long!
  • Your battery bank will be TOO SMALL!

My reason for this harsh assessment is based on the fact that static (unloaded) battery voltage is entirely different from dynamic (loaded) voltage. This is due to internal resistance of batteries, and the surface area of the plates. The voltage supplied by any battery is reduced as the current draw increases. Additionally, the amp-hour capacity of any battery drops as the current load increases.

There is one more important factor for battery bank sizing:

  • Your battery bank must be sized based on the maximum expected current draw, and depends on the battery type. The maximum charge/discharge rate for various deep-cycle battery types is:
    • Traditional lead-acid batteries: 20-25% of amp-hour capacity
    • Gel cell batteries: 30-35% of amp-hour capacity
    • AGM (absorbed glass mat) batteries: 35-40% of amp-hour capacity (check your cable sizes!)

As you can see, the battery type can make a big difference in battery bank sizing based on maximum current load. Try out our Marine Battery Load Calculator to help determine your ideal battery bank size.

A fully charged starting battery loaded at half its rated CCA capacity (load test current) will only put out about 9.7 VDC at 80°F. The voltage of a deep cycle battery will drop even more under similar load conditions. Keep in mind that most inverters will trip off to protect the batteries when their voltage drops to 10.5 V or less.

Xantrex provides a fine example of using a circular saw that uses 1500 watts of power. Their example indicates that the saw would only use 2 amp-hours at 12 volts if run for one minute. (Xantrex’s example ignores the inefficiency of the inverter). The point made by Xantrex is that while the saw uses 1500 watts, the total run time is short, so it uses very few amp-hours. If your battery bank is sized based on using this current draw for just a few minutes at a time, you appear to be in good shape. This may not be the case. My point is that the saw uses 1500 watts!

A 2000 watt inverter powering the circular saw will draw about 1667 watts (at 90% efficiency) from the battery bank. At 12 volts, the current draw is 139 amps. Using our Marine Battery Load Calculator, you would need a 700 amp-hour bank of deep-cycle flooded batteries! A battery bank with 400 amp-hours capacity doesn’t stand a chance of supporting a 2000 watt inverter load without help, but it can be done.

Don’t let me scare you away from an inverter just because the battery bank sizing can be complicated. A modestly sized battery bank will work great to power an inverter under most conditions. If you have an occasional need for high-wattage power, you can meet the current demand by simply running your engine – even if your alternator is not rated for the total current draw. The current supplied by your alternator will make your battery bank appear much larger to the inverter, and be enough to run a substantial load for a short time.

In the circular saw example above, your power supply (battery bank and alternator) needs to provide 139 amps of 12 volt DC current while the saw is running. This can be accomplished with a 400 amp-hour flooded battery bank assisted by a 60 amp alternator.

The lesson learned is that a large inverter is a very useful piece of equipment. Your battery bank does not need to be huge if your highest loads are only used occasionally. Base your battery bank size on the loads that will run on a regular basis.

Battery Bank Sizes Based On Battery Type

Flooded (Wet) BatteriesFlooded (Wet) BatteriesGEL BatteriesGEL BatteriesAGM BatteriesAGM Batteries
Inverter SizeMax Amps @ 12VBatt Only Batt +100A Alt Batt Only Batt +100A Alt Batt Only Batt +100A Alt
3000 W 278 A 1390 A-H 890 A-H 1120 A-H 720 A-H 840 A-H 540 A-H
2500 W 231 A 1160 A-H 660 A-H 930 A-H 530 A-H 700 A-H 400 A-H
2000 W 185 A 930 A-H 430 A-H 740 A-H 340 A-H 560 A-H 260 A-H
1500 W 139 A 700 A-H 200 A-H 560 A-H 160 A-H 420 A-H 120 A-H

As you can clearly see from the table above, using your alternator to help your battery bank under peak loads makes a huge difference in the size of battery bank you need. Please note that the battery bank sizes above were calculated based on powering the INVERTER ONLY. Your battery bank size should be based on your total power usage and your charging schedule.

Happy Cruising!

Tim Allen

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Power Tools Off-Grid

Corded or Cordless Tools – Which are Better for Cruising?

Before we went cruising on our catamaran “Unbound,” I shopped around and bought a set of cordless power tools to bring along. I thought this would be the greatest thing since sliced bread. Like many people, I had worked on projects away from convenient power. You know the projects – building the kids’ gym set in the back yard, attaching a bracket to a wall from a ladder, hanging a mirror. Many of us have done these things.

One morning, after a couple weeks aboard “Unbound” I took on the project of mounting a GPS display near the helm. I needed to drill four holes. I grabbed my trusty cordless drill and … it was dead. I plugged it into the charger and turned on the inverter. Fifteen minutes later the inverter control panel was yelling at me (with yellow and red lights) that the batteries were too low! Now to crank up an engine to charge the battery bank, so I can drill four holes.

According to the label on the drill’s one-hour battery charger, it uses 65 watts at 120 VAC. The charger puts out 2 amps at 16 VDC. That’s 32 watts, so the charging efficiency is less than 50%. Our Xantrex inverter/charger is about 90% efficient at supplying 120 VAC, so to charge the drill’s battery for one hour uses about 6 amp-hours of house battery current.

Now let’s look at drilling those holes with a regular, old-fashioned corded drill. My Milwaukee drill (in storage at the time) is rated at 3.5 amps at 120 VAC, under full load. Now, I was drilling fairly small holes through fiberglass, so lets say it would draw 2 amps (240 watts). Each hole took about 15 seconds to drill. That’s one minute at 240 watts, at 90% inverter efficiency – 22.2 amps at 12 VDC. The total battery drain would have been only 0.37 amp-hours! That’s only 6% of the power used for the cordless drill! And, I wouldn’t have had to wait an hour to do the job.

If your getaway plans include a tool kit with cordless power tools – don’t waste your money! Their batteries are almost never charged when you need them, so you have to run your inverter or generator for an hour to charge them up (if you remembered to get the fast charger) before you can get started with your project. A cord-type power tool is ready all the time, and you only need to run your inverter while you are using it. Corded tools also take up less space (no bulky batteries or chargers). Saves time and house battery amps!

True off-grid life is different! Whether on a boat or in an RV, or in a mountain cabin, electricity usage off-grid is totally different. The number three priority for any cruiser (after safety and water) is battery power. Without it we have no communications, navigation, lights – or engines!

Update:

Battery technology for power tools is constantly changing. The latest Lithium Ion batteries hold their charge for a very long time. With this in mind, cordless tools get a second chance on board. I love the power and consistent tool speed that the new batteries offer. However, I don’t like the surprise when the battery is discharged – the tool just stops without warning!

The charging efficiency of Lithium Ion batteries is similar to the NiCd battery example above. If you are seriously pinching amp-hours, you may still want to use your corded tools.

Happy Cruising!

Tim Allen