Liftgates help deliver more freight faster and prevent driver injuries, but they do require an electrical connection between the tractor and the trailer to give the liftgate batteries the power they need to function properly. There are three potential options to accomplish this:

The “Eh” Solution: Single Pole Connection

A single pole connection does provide power to the trailer. However, the ground connection is made through the 5th wheel, which often makes the ground connection intermittent and unreliable. An unreliable connection means that the liftgate batteries are being run to a deeper cycle and cycled at a lower state of charge, which in turn causes significantly decreased battery life.

In addition to the issue of an unreliable connection, the distance of the liftgate batteries from the front of the trailer also poses a battery life problem, which we will discuss in the next section.

A Better Solution: Dual Pole Connection

A dual pole connection is superior to a single pole connection in that it has a dedicated ground circuit. This eliminates the intermittent and unreliable connection fault found with single pole connections. However, it maintains the issue posed by the distance between the liftgate batteries and front of the trailer.

So, let’s back up for a minute and talk about the batteries that provide the power through the dual or single pole connection to the liftgate batteries—that is, the tractor batteries. When installing a battery bank, it’s important to hook them all up properly, or else you minimize the battery life of the batteries.

For example, in a 4-battery bank, the batteries must be connected like this:

This is because this configuration allows all four batteries to be used equally so that one battery is not under any more strain than any of the other batteries.

If the batteries are hooked up like either of the images below, the battery on the end of the chain will have a significantly shorter lifespan than the other batteries.

It is proven that even when batteries are close together, their life cycle is affected by whether the electrical load is equally distributed among all the batteries in the bank.

So, now that we’ve reviewed proper battery hookup, let’s hop back to charging liftgate batteries through a dual pole connection.

Basically, adding a liftgate makes your battery bank look like this:

That extra-long set of cables between the tractor and the liftgate batteries brings with it the extra challenge of voltage drop. The voltage drop means that the liftgate batteries aren’t getting as much “juice” from the alternator, which in turn means the batteries are run to a deeper cycle and cycle at a lower state of charge, which again means significantly decreased battery life.

To sum up, yes, a dual pole connection will work to charge your liftgate batteries—but you will have to replace the liftgate batteries long before they reach their maximum life cycle.

The Best Solution: Dual Pole with Charging System

The inefficiency in the long stretch of cables between the tractor and liftgate batteries can be easily eliminated by boosting the voltage before it reaches the liftgate batteries.

This is where a charging system comes in—it can be either a traditional charging system, or a solar charging system.

A traditional charging system is placed before the liftgate batteries to boost the voltage with a DC/DC converter, like shown:

Alternatively, a solar charging system provides power directly to the liftgate batteries without having to be routed through the tractor as shown:

In summary, a charging system in combination with a dual pole connection will eliminate the downsides of using either a single pole connection or dual pole connection by itself by allowing the liftgate batteries to get the charge they need.

Where to get a Charging System

Purkeys provides several charging options, based on your application and needs. Our premium liftgate charging systems save you space on the front of your trailer, protect your batteries, and save you money in the form of reduced road calls, reduced battery costs, and driver retention. Click here for more information: