How Big a Jump Starter for a Diesel? Amps, Lithium and 24V Sorted

Your diesel will not turn over on a flat battery, and you want a jump starter that will. Choose by the maker’s engine rating rather than peak amps, then match the type and voltage to your vehicles and how often you use it.

The booster and jump starter range at PartsForMachines has nearly 70 jump starters and boosters from Sealey, Sykes Pickavant, SIP, Draper, EcoFlow and Chicago Pneumatic. They run from glovebox lithium packs to wheeled 12/24V units for trucks and plant.

How Big a Jump Starter Do I Need for a Diesel?

Size it on the maker’s diesel engine rating, not peak amps, and leave a margin, as ratings vary. A 1200A lithium jump starter such as the RS1200 is rated for an average 6-litre diesel, yet the 23722, with the same peak and cranking amps, is rated for diesels up to 4 litres. Diesel ratings are usually lower than petrol ones, so check that figure.

The test matters too. The POWERSTART500 gives 4400 peak amps, 1700 amps cranking at 20°C and 700 amps cold cranking at -18°C. Compare like with like, and for winter starts, size on the cold cranking figure.

Lithium Pack, AGM Booster or Capacitor: Which Should I Buy?

Choose lithium for a light pack that lives in the cab, AGM for regular starts in a workshop or fleet, or a capacitor booster for long storage or hard frost. The RS1200 weighs 0.695kg, while AGM boosters such as the SPEEDLINE5000 can weigh over 22kg.

Batteryless capacitor boosters have no battery to wear out. A compact capacitor booster such as the 07003 draws the charge left in a flat battery in about 90 seconds, and is rated from -40°C to 65°C. SIP rates the 07107 at over a million cycles, with unlimited shelf life.

Can Jump Starting Damage a Modern Car’s Electronics?

It can, so follow the handbook’s procedure, use any jump-start points it names, and choose a pack or leads with spike protection.

With a pack, the usual order is: switch off lights and other electrical loads, clamp red to the positive terminal, then black to an earth point away from the battery, and only then switch the pack on. Afterwards, switch it off and remove the clamps in reverse. For extra protection, choose a booster with built-in surge and spike protection, such as the PBI2212GS, which uses a fusible link in its output cable.

12V or 24V: Which Booster for Trucks, Tractors and Plant?

Match the booster to the vehicle’s system voltage. If you are unsure, check the handbook: a 24V system often uses two 12V batteries in series, but some 12V machines have two batteries wired in parallel. Set the voltage before you connect, and never boost a 12V machine on 24V: it can ruin the starter, ignition and other electrics.

Switchable packs are often about half as strong at 24V. A switchable 12/24V jump starter such as the RS125 gives 3000 peak amps at 12V or 1500 at 24V, and is rated for 6-litre diesels at 12V but 3-litre ones at 24V.

What Should I Check Before I Buy?

• the largest engine you need to start, and the maker’s diesel rating, not just peak amps
• system voltage: 12V only, or a switchable pack for 24V trucks and plant
• type and weight: lithium for the glovebox, AGM for the workshop, capacitor for long storage and frost
• protection: reverse-polarity and short-circuit protection, an on/off switch so you connect before power flows, and spike protection
• leads and charging: clamp reach, and whether it recharges from the mains, a docking station or in the vehicle

Browse the booster and jump starter range, or contact the PartsForMachines team by WhatsApp, telephone or email with the vehicles, engine sizes and voltages you need to start.

Product options, delivery options and returns terms are shown on each product page. A 30-day return policy applies to eligible items.

Frequently Asked Questions

Can a jump pack start a vehicle with a completely dead battery?

Some can, with an override or pre-boost mode. An ultracapacitor booster such as the 341300SP has an override mode to start an engine with no battery fitted, and the 13749 pre-charges a deeply discharged battery. Use override only as the pack’s instructions describe.

How long will a jump pack hold its charge in storage?

Check it before you rely on it, as holding time depends on the type. Sealey says the LiFePO4 SL32S holds charge up to five times longer than lead-acid packs. Batteryless capacitor boosters have no battery to go flat, and charge just before use.

How do I charge a capacitor booster?

From the flat battery, a supplied charger or a backup battery, depending on the model. The 07003 charges from the flat battery but needs more than 6V in it; the 07103 has its own charger, and the 341300SP can use a backup lithium battery.

Will a jump starter work in freezing weather?

Yes, if it is rated for the cold. Capacitor boosters such as the 07001 work down to -40°C, and some lithium packs, like the 13751, have a pre-heat mode for low temperatures. For winter use, compare cold cranking figures rather than peak amps.

Why do some car handbooks restrict jump starting?

Because procedures differ between cars, and the wrong one can damage the electronics or battery. Some handbooks name special jump-start points, and some makers say certain hybrids and electric cars must not be used to jump start another vehicle. Follow your handbook first.

Is a jump pack better than jump leads or a new battery?

It is more convenient than leads: a pack needs no second vehicle, so you can start a vehicle on your own. It will not cure a failing battery, though; if you keep needing a jump, have the battery and charging system checked.

Is a jump pack safe if the clamps touch?

Only if it has short-circuit protection, and even then keep the clamps apart. The RS1200 guards against short circuits, overloading and reversed polarity, and packs with an on/off switch, such as the RS1312HV, let you connect before power flows.

Do the lead length and thickness matter?

Yes. The clamps must reach the battery or jump-start point, and heavy-duty boosters often have longer, thicker cables. Compare 385mm leads on the RS1200 with 2m x 35mm² cables on the POWERSTART500 and 1.9m x 50mm² on the CP90600.

Can a booster also power accessories or save the vehicle’s settings?

Many can. AGM boosters such as the SPEEDLINE5000 can act as a 12V power source or memory saver, and the PRS6400 has a fused 12V socket for accessories such as mini compressors. Lithium packs usually double as USB power banks for phones.