Posted January 16, 2021

Hybrid power system buyer's guide

Selection tips on hybrid power systems from Powr2.

Many fleet managers are considering purchasing battery and hybrid power systems for the first time. Given that it is new technology, many buyers have no unbiased information upon which to evaluate vendor offerings.

Powr2 has developed a short check list of the criteria that should be evaluated when looking at these products:

The battery is the most expensive component and the most important one to ensure you understand. There are many different battery chemistries and thousands of suppliers of batteries each claiming to have the best product. If you want an asset that will be a good investment for your fleet, you need to check off a few points:

Ask your supplier:

  • What battery chemistry is used?
  • Who is the manufacturer and country of origin?
  • What safety certifications do the batteries have? Ask to see copies of the certificates.
  • How many cycles are they rated for and to what depth or discharge?

Lead-acid batteries used to be popular but given their weight, form factor, limited depth of discharge, low cycle life and slow charge time, they are not a good choice for a rental product.

Li-ion batteries are now the most common as they have a very good energy density and if looked after correctly, will last a very long time.  However, there are many types of Lithium batteries – you can learn about them here.

ProTip: Select a battery from a reputable manufacturer that is approved for use in your country. Having the UL or CE mark is not enough – insist on seeing the certificate!

The inverter or power conversion system will be responsible for taking the incoming AC power from grid or generator and converting it to DC to charge the batteries. It also transfers that stored energy from the battery from DC back to AC on the output.

Inverter Checklist:

  • Brand and warranty?
  • Peak-power and continuous-power output?
  • Pass-through current?
  • Power-assist mode?
  • Official integration with the battery being used?

The pass-through current is an important question as this can limit the size of generator that can be pair with the hybrid system?

PredoTip: While most inverter manufacturers claim to be battery-agnostic, they usually have a list of batteries that are officially “Integrated” with their system. Ensure the battery and inverters are officially integrated and recognized.

Solar is becoming a more common request on sites as clients wish to reduce their carbon footprint. Check that any system you buy has the ability to charge from solar or at least easily add this functionality in the future.

ProTip: Solar is measured in KWP (Kilowatt peak). Ask your supplier for the KWP of the system.

The Energy Management System (EMS) is the brain that ties all the other pieces together. When done right, this will make the product easier for the operator to use and easier for the fleet manager to manage.

The EMS should consist of a human interface (screen) on the physical product AND a fleet dashboard (cloud-based) that tracks the performance of each machine.

Some inverters/PCSs come with an EMS. This can be a limitation and the functionality is tailored to the needs of the Power rental industry.

  • Does the asset have an independent EMS?
  • Does it have a Touch screen HMI?
  • Does it have a fleet management dashboard?
  • Can the HMI be customized?
  • Can the EMS integrate with my own fleet management software?
  • Is the EMS programable to my fleet and user needs?

ProTip: The EMS is a very powerful tool. If your vendor has its own system, that bespoke programming can be a great advantage for special projects or events. It can also allow advanced functionality like paralleling of Multiple Hybrid Systems.

Usually, the smallest part of the cost, but the canopy, as with any fleet product needs to look good not only when new, but for years to come. Coating systems should be considered.

Forklift slots should be large enough for industrial forklifts and lifting eyes.

Suppliers should have the ability to provide custom colors and client decals.

ProTip: A galvanized base frame proves to be much more durable and prevents forklift damage and rust. 

Safety is top priority at all times but especially when you are working with potentially deadly electricity.

Ask your supplier for details on build quality and testing protocols. Also ask for any advanced safety features they may have fitted.

With new technology comes the need for training. This is training for all levels of the business from sales to operations to maintenance. Especially since the pandemic, it is important that your supplier is able to provide training and support.

  • Initial technical and sales training
  • Train the trainer
  • Ongoing technical support
  • Warranty and parts availability

Battery technology is here to stay and we’re on a path to see a push for clean power options and electrification. It’s important to make knowledgeable decisions based on best available data.

Fleet buyers may be hesitant due to the pace at which the technology is changing, but today’s technology is at a stage where tomorrow's improvements will not make it obsolete. Instead, gradual improvements , especially in battery energy density will lead to cost decreases per KWH over time.