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Portable Jump Starter Buying Guide: Selecting the Best for 12V and 24V Vehicles

Portable Jump Starter Buying Guide: Selecting the Best for 12V and 24V Vehicles

Updated July 2019

Get the jump on a flat battery

Rescue your vehicle from a sticky situation with a portable jump starter

No matter how diligent you might be in making sure your car battery is in good shape, there is always a chance you might find yourself with insufficient charge to turn over the engine. This can often happen while you're out camping or on a road trip, because unless you have a dedicated house battery, you're likely to be using your car battery to power portable 12V devices.

Luckily, you can bail yourself out using a portable jump starter. Check out this buying guide to learn about the features you need to consider.

Will 12V be enough?
Cars and motorbikes normally use a 12V electrical system, but boats and trucks need a 24V supply. So, if you're planning to use your jump starter as a backup system for a range of vehicles, it's worth investing in a unit that is suitable for both 12V and 24V systems.

How much cranking current?
The power needed to turn over the engine is referred to as cranking current. A small car with a petrol engine will only draw about 300A of peak load, so an entry-level unit will suffice. Larger vehicles such as vans and SUVs will need a higher cranking current, but even mid-range jump starters can turn over a 5L petrol or 3L diesel engine.

What's the capacity?
The amp hour capacity of your jump starter is mainly relevant if your battery is failing to hold charge and you're likely to need multiple jumps before you're out of trouble. Glovebox-sized units offer up to 18Ah, which is enough to restart your engine and recharge your phone afterwards.

What are the bonus features?
Get the most mileage out of your jump starter by choosing a unit with extra features such as laptop charging, a torch with a strobe function, or an onboard compressor to top up your tyres.

See below to learn more about dealing with a flat car battery.

Jump Starters Header

Selecting the right jump starter for your vehicle and how to use it

If you've been driving vehicles for a few years now then you've probably experienced an incident where your vehicle wouldn't start - through your own fault (like leaving the headlights on), or battery failure... Were you alone? Did you call someone for help or did you have to flag down a stranger? Were you late for something or someone, or did you miss out completely? No doubt you're keen to avoid that again! Statistically flat batteries are the primary cause of vehicle breakdowns (about 35%). In 2015, the NRMA attended 400,000 battery-related breakdowns - and that's just in NSW and the ACT alone!*

Why do batteries go flat?

Batteries have a limited lifespan. They tend to last between 3-5 years, depending on the make of the battery and the driving conditions it's been subjected to. Short distance driving - especially at low speeds - is terrible for batteries as they don't get a chance to fully recharge. It's also not uncommon for us to plug in devices such as mobile phones, car event recorders & GPS navigators, which all draw extra power from the battery. It's not a problem when the car is running, but can be when the engine is switched off! New cars do tend to alert drivers when electronics are left on - such as headlights - but they also tend to include lots of power-hungry features like heated seats, climate controlled air conditioning and headrest monitors. Put simply, one day your battery is bound to go flat.

How can I fix a flat battery?

If your battery is flat it will need to be recharged or replaced. You'll be able to tell if it needs to be replaced when you try to jump start it. Jump starting is when a secondary power source applies just enough charge to the electrical system in order to start the motor. Once you jump start the battery, you'll want to drive around for a while to replenish the charge. It should recharge itself fairly quickly. If you simply ran-flat because you left the headlights on, or some other similar incident, the battery should have no problems starting your car next time. If, after running your engine for at least 10-minutes, the battery won't start the car by itself and you need jump starting every time, we're sorry to say that it likely needs replacing.

Jump starters have come a long way!

To jump start a car, you used to need jumper leads plus a secondary power source (normally a battery on another vehicle) to connect the leads to. Today, self-contained jump starters are compact and more convenient! They ARE the secondary power source. Essentially a jump starter makes you totally self-sufficient out on the road. There's no need to call someone to come and help, or flag down a stranger in the hope they're the helpful type (and not the Hannibal Lecter type!). No wasted time waiting for help to arrive. No expensive call out fees if you're not a roadside assistance member. Just connect the leads of the jump starter to your battery, start the motor, disconnect the jump starter and drive off.

Getting the voltage just right...

When selecting a jump starter you need to make sure it has a voltage suitable for your vehicle's battery. Car and motorcycle batteries tend to be 12V, while large trucks and motorboats tend to be fitted with 24V batteries. Jaycar's 12/24V Jump Starter (MB3759) covers both bases, comes in its own carry case and can even charge smartphones, tablets & GPS navigators via the USB port!

Power Delivery

The next thing you need to consider is "cranking current". This is how much power you need the jump starter to apply to your vehicle's battery in order to get its motor to turn over. As an example, Jaycar's Pocket Size Jump Starter (MB3753) has a cranking current of 300A which will work on a 6-cylinder petrol engine/4-cylinder diesel engine. That's definitely ample for a Toyota Carolla or Mazda CX-5 for instance, but not for a Ford Ranger Diesel. Large 4x4s and trucks - especially diesel - would likely need a cranking current of 400+. Refer to your vehicle's engine specifications to work out what cranking current you need. If you're not sure, our staff are happy to provide advice.

Battery Type

This actually applies to the battery the jump starter uses and not the battery you're trying to use it on. Options include Lithium-ion (Li-ion), LiFePo4, SLA and Li-Po. Whilst it's probably not a key deciding factor, the battery type will impact the size of the jump starter, length of time between charges and how well it copes with charging and operating other things. Jaycar also sell a jump starter that doesn't have any battery at all! A capacitor based 12V jump starter uses a super capacitor to store energy. This technology means it stores energy perpetually - just charge it once then store away until needed.

Never heard of LiFePO4?

LiFePO4 (Lithium iron phosphate) batteries are becoming more common because of their efficiency. The ions are smaller and coated, enabling them to move faster than the ions of other Lithium batteries. They also don't break down with repeated use, making them longer lasting. Consequently a jump starter which uses a LiFePO4 battery will be more efficient than one that uses a Li-ion or Li-Po battery. You'll get similar outputs but they'll differ on battery life expectancy and recharging requirements. SLA (sealed lead acid) batteries are what you probably think of when you first think of batteries. As an older technology they're more cost effective than LiFe-PO4 batteries but they're also a lot bigger! More traditional Li-Po / Li-ion batteries are much lighter and more compact than SLA, so they're also a great alternative. When selecting a jump starter, consider how much you're willing to invest in the technology, how portable you want your jump starter to be (glove box vs. boot), and how often you expect to use the jump starter.

Amp Hours

This measurement indicates the volume of charge the jump starter's battery can hold - the larger the volume the less it needs recharging to provide multiple jump starts. However recharging after use is recommended to ensure long-life of the internal battery in the unit. It also helps determine how long auxiliary features (lights / charging etc) will run before recharging is required. Most jump starters will display the internal battery level for your information too.

Additional Features

Most of Jaycar's jump starters do more than just jump start your vehicle, so you're really getting bang for your buck! The 12V 700A Jump Starter (MB3758) provides 12/16/19V, 3.5A to run a laptop. It also provides a 3.0A USB Type-C outlet, and a 2.4A USB outlet. That covers a large majority of portable devices, including the car! It also features an integrated torch and warning strobe. Always keep in mind that the primary reason for having the jump starter is to jump start your vehicle so make sure you keep an eye on the amount of charge left as you never know...

If you're the type who wouldn't dare drive around without a spare tyre and jack, then why would you drive around without a jump starter? With the range of jump starters on offer these days, it makes sense to keep one handy. The team at your local Jaycar store can run through how you use your vehicle or boat to help you select the best one - visit us in store today!