Welcome to our next installment of the technician’s log. Today we are going to talk about inverters and battery chargers, which are essential items in every modern cab. Why? Well, for a few reasons. Just one example includes when you are parked at a truck stop. A proper inverter and charger will help keep the batteries on your trucks topped off in the morning. Also, when putting a truck out of commission for a while, a charger can make sure the battery can start the truck when put back in commission.
Furthermore, the inverter part of the inverter/charger combo will make AC power available in all receptacles inside the sleeper cab. It is extremely important to have a reliable source of onboard AC power for sensitive equipment such as CPAP and other essential electronics.
Many fleets are going over every pound with a fine-tooth comb in order to boost payload and fuel economy. And with such an emphasis placed on fuel economy these days, can you really blame them? How much weight does such a device typically add? Not enough to put a huge dent in fuel economy. So, what have you got to lose?
Inverter and chargers come in various form factors. The best types offered through major truck manufacturers come in a compact, lightweight footprint weighing roughly 12-13 lb. In the grand scheme of things – meaning overall payload – this weight is almost negligible. Even more, you don’t really have to worry too much about maintenance.
You can generally integrate servicing into standard maintenance program. For example, every time the oil is changed, you can run a quick service on the inverter or charger. These devices are quite hardy, so it shouldn’t take much to ensure everything is in proper working order. But if you really want to step up your game, you will invest in an inverter/charger combo that requires no maintenance. A high-level device will actually improve your overall maintenance situation by decreasing the load on your battery.
You also want to look for a device that is equipped with a failsafe. Does it have any protection features such as overload, over temperature, under or over voltage, or low battery voltage protection, which help increase the life of an inverter? Speaking of the life span, do you know what to expect? Should it be three years? More or less? Furthermore, how does duty cycle impact lifespan?
Look for a device that has a minimum 2-year warranty. A good inverter and charger combo should run you about 8-10 years if it is well taken care of as the duty cycle is not too intense. Still, quality inverters will resist spikes and overloads and stop before its internal components and circuits are exposed and ultimately damaged. They should have protection features built-in so that they can withstand heavy duty cycles for longer periods of time.
Why an Onboard Charger is Critical
A quality inverter with a built-in charger offers many features – onboard AC power, the ability to use shore power to charge batteries, and pass through incoming shore power to operate hotel loads when parked at truck stop. In fact, an inverter/charger enables a truck driver to enjoy the comforts of home while on the road.
A sleeper with any of the following additions would benefit from an inverter/charger:
- TV
- CPAP
- Refrigerator
- Microwave
- Induction Cooktop
You also need to consider compliance. You want a device that meets UL458 and TMC RP163 requirements for safety, quality and reliability.
When it comes to compliance and reliability, the old adage, ‘you get what you pay for’ comes into play. Quality inverters should have a ‘Regulatory Listed’ approval – such as UL or ETL with UL458 rating. This means the inverter was inspected and approved by an independent agency, which safeguards against issues with electricity. UL458 is the listing for inverters and chargers in mobile applications. They must meet strict vibration, environmental, and thermal requirements that non-UL458 units do not.
TMC’s RP163 calls out this UL listing for all inverters and chargers installed in a truck. What’s more, TMC’s RP160 that discusses DC and AC wiring in a truck has requirements that are automatically met by UL458 listed inverters. The main point being that the neutral and ground are bonded together within the inverter. Inverters that are not UL458 listed do not do this as it allows the inverter to be made at a much lower cost.
Buying an inverter that is not Regulatory Listed tells someone ‘buyer beware’. These types of products quite literally shock users, plus they often can’t internally protect themselves against power surges. So, what can you do to maximize life and ensure your inverter/charger combo doesn’t pose a danger to your truck drivers?
First, we do not recommend a truck driver doing self-installation. Remember, you’re dealing with electricity. So, if you’re not comfortable handling wiring at your house, you better not try it in your rig. Therefore, it is best to ensure the shop technicians are doing the work, rather than the front-line truck drivers.
If you’re working on a 12-volt lighter plug or a 300W inverter for the laptop, installation should prove to be no problem. But, for larger inverters it’s important to understand fusing, voltage-drop calculations, and knowledge of applicable safety standards. We cannot stress enough how important it is to get it right the first time.
There is a bevy of things to consider when installing an inverter, starting with ‘where it should go’ and making sure there is adequate ventilation to allow heat to dissipate. You also must look at wire sizing and the distance between the inverter and plug-ins which can be put in the sleeper; plus, the distance between the battery and inverter.
We really recommend either an OEM install (factory assembly line or pre-delivery inspection) when you purchase a new truck, or have the installation done by an authorized dealer. The OEMS have installation down to a science and it’s done on the line to rigid specs. Truck and aftermarket dealers also have the experience, so it’s worth spending a few extra bucks to have the installation done right, the first time.
Your Essential Inverter Checklist
Now that you have learned everything there is to know about inverters and inverter/charger combos, you will want to have a checklist handy when you make your recommendations to fleet management or procurement. First up, access size. It is easy to think you need the biggest and baddest inverter, but when you are looking at a range from 300 to 5,000-watts, you could easily make a mistake and purchase an inverter that isn’t right for you. Always make sure you check the wattage number and assess it for your needs.
There are also two different types of power pushed through inverters. The first is sine wave and the second is modified sine wave. While both work well in a truck environment, you want to use a sine wave device if you are running sensitive electronics off the system. Whether it be a CPAP device or otherwise, you don’t want to be worried about inconsistent voltage or spikes or drops. You want the power to react just the way it would at home for those devices.
Modified sine wave is good for other devices where consistent power flow is not necessary. Most electronics will work fine with modified sine wave, you just don’t want to take the chance that it may short out sensitive devices.
When it comes to the inverter or charger combo you choose, you want to ensure you and everyone else in your shop is comfortable with installation and maintenance. Remember, you are working with electricity. You must be aware of wire sizing and distance between the inverter and plug-ins. Also, what is the distance between the battery and the inverter?
The best option is to have the OEM install if you can, or have it installed by an authorized dealer. Don’t hesitate to spend a few extra bucks to ensure the installation is done right. This is especially true if you are using an inverter/charger combo. Many inverters will run the batteries down to 10.5 volts, which will allow truck drivers to run their devices longer in the cab. Important to note, however, is that the LVD feature is required to start the truck with an inverter. Or you could run two dedicated deep-cycle batteries and connect them to the inverter.
Whatever you choose to do, inverters are an important part of any in-cab ecosystem. To keep your truck drivers happy, you need to ensure your shop understands how they work, how to install them, how to maintain them, and what recommendations need to be made when purchasing them. Do your due diligence, and you are bound to make the right choices for your fleet.