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Lithium-Ion Battery Powered Tools – a Toolstop Guide

Posted by Toolstop Katy on 22nd Jan 2016

Lithium-ion is a family of rechargeable battery types boasting one of the best energy densities, no memory effect, and a slow loss of charge when not in use.

That makes it absolutely perfect for our power tools. 
But what about some of the terminology and technology within and associated with this family?

Let’s break it down a bit.

Memory Effect

No, we’re not talking about that dull moment of wonder where you wake up on a Sunday morning and have no clue how you got there.

Memory effect is the problem that (it’s alleged) nickel cadmium rechargeables have whereby they hold less and less charge, depending on use.

For example, if a ni-cad battery is charged without being fully discharged, the theory goes that the battery “remembers” that it’s got a smaller capacity for charge than the manufacturer intended.

This means your ni-cad battery will be less and less efficient, charge-by-charge. That’s “memory effect”.

Not so with lithium-ion batteries.

You can drop them on the charger no matter what their current state of discharge, and they’ll eat until they’re completely full again.

They also tend to charge faster and have greater life-spans than, say, ni-cad batteries. For example, Makita claim that they can achieve a “massive 2000+ cycles” from their lithium-ion batteries because of their Optimum Charging System.

That’s a lot of tea break power ups.

Self-Discharge Rate

Another advantage of lithium-ion batteries is their self-discharge rate. No, we’re not talking about another post-Saturday-night-on-the-tiles phenomenon. Rather, rechargeable batteries slowly release their charge. This happens over time when their not put to use.

So, for example, you leave your Bosch GSB18VE2Li 18V Cordless li-ion RobustSeries Combi Drill in the van for two weeks over Christmas.

The battery still has a fair bit of charge left in it. When you get back to the job site after the New Year you’ll still be able to use the tool because the lithium-ion batteries will have held on to most of the charge you left them with.

It’s estimated that lithium-ion rechargeables will self-discharge about 5-10% of their charge per month, compared to around 30% per month on ni-cads.

Perfect for those of us who forget to slap our tools onto the charger at the end of the day.

Weight a Minute

Operator fatigue is a pest, correct? When we’re using a heavy corded power tool repeatedly throughout an 8 hour day on the job site we end up knackered.

We then work slower. And we get paid less.

Being able to work quickly without that fatigue in our hands, wrists, arms, shoulders and backs is important and this is where our favourite family of rechargeables once again has changed the world of power tools.

Lithium-ion batteries are, traditionally, lighter.

For example, an 18v lithium-ion battery will weigh the same as a 12v Ni-MH.

Think that through; more power, less weight. This is vital when you’re using power tools above shoulder height for any lenght of time.

This is a breakthrough in the world of power tools that has, whether or not we’ve realised it, changed the way we’re able to work. Less operator fatigue for more power. Bonuses all round.

Choosing Well

So, choose your manufacturer carefully, as each of the big brands has it’s own “flavour” of lithium-ion rechargeable battery and associated technology

Keep it Cool

Of course, efficiency of battery is vital, and we’ve already seen how the lithium-ion family are leaner in size, more dependable in the charge, but what about staying cool “under the collar”?

Heat is the enemy of batteries, so managing the through-put of heat generated within a rechargeable battery pack is very important. The hotter a battery gets, the shorter it’ll live.

To enable each cell in the battery to be cooled, the unit needs to be designed in such a way that air flow around the battery is maximised.

For example, Makita have engineered their LXT lithium-ion batteries in such a way as to keep them at a cool temperature while charging. They claim that their battery pack design “allows each cell to be kept at an optimum temperature which extends the battery life”.

Makita has a huge range of tools that are powered by these 18v LXT batteries. And with a charge time of only 22 minutes for the 3Ah batteries, these are well worthy of consideration. As of late 2013 Makita announced the addition of 4Ah 18v li-ion packs which charge in 36 minutes, one of the fastest charging 4Ah batteries on the market as of January 2014.

Bosch claim that their Premium Lithium-Ion technology provides a “400% longer lifetime” for the battery. This is due to the engineering of their units using Electronic Cell Protection. ECP constantly monitors the cells of the battery, stepping in to prevent overheating, but also overload and total discharge.

And when the company released their first 4Ah battery, it was named “CoolPack” due to some very important cooling technology built into the battery and charger. Click here to learn all about CoolPack batteries.

Our friends at Metabo have consistently impressed us with their lithium-ion battery technology, and they even offer a 3 year warranty on their batteries, which is pretty much unheard of in the industry.

They’re so confident in the performance of their family of lithium-ion batteries due to their Electronic Single Cell Protection technology.

They’re also the first power tool manufactuer to give you 5.2Ah 18v li-ion batteries!

We’ve discussed this before, but to summarise, Metabo have created a battery management system to make sure you get the best from your lithium-ion battery.

For example, ESCP monitors each individual cell and status while working and charging. Plus, their chargers are fan cooled. This means the lithium-ion cools quickly and feeds quickly, all at the same time.

Metabo boasts that they “only use the highest grade lithium-ion cells available, with the highest power density ratings”.

DeWALT overhauled it’s range of 18v li-ion powered tools when it launched the XR technology system, later upgrading the batteries to 4Ah capacities, and again to 5Ah in 2014.

The XR system manages and monitors the charge of the battery, the health of the cells, making sure no damage can be done the tool or battery while you work.

It’s pretty clear that the manufacturers are taking your investment in lithium-ion technology seriously.

5Ah is Now The Norm?

In 2014 we’ve seen virtually all of the major power tool manufacturers roll out 5Ah 18v battery packs, promising longer runtime than ever before.

We’ve written about it on the Toolstop blog, so check out these articles for all the details from Makita and DeWALT.

The Future is Here

There’s no doubt that lithium-ion battery technology is evolving how we use power tools. Gone are the days where we needed to be close to a power point and tethered to an electrical cord in order to drill through a concrete wall.

Now we’re going cordless, but we’re doing so with power tools that are lighter, more efficient, more reliable, longer-lasting and more powerful than ever before.

And it’s all thanks to lithium-ion rechargeable batteries.

In Summary:

  • Lithium-ion is a robust, reliable form of battery for power tools
  • Run-times from li-ion batteries is getting longer thanks to higher capacities
  • New battery technologies means better reliability