Cold Starts, Batteries & Jump Starters
The Best Jump Starters for Cold Weather
Every one of these is a lithium pack, and lithium delivers least current when it is cold. That is not a reason to avoid them - it is a reason to know where to keep one.
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Quick picks
The short answer, before the detail. Tap any row to jump to that write-up, or go straight to the listing to check today's price.
A jump starter is a battery you carry so that a dead battery does not end your morning. The specification everybody compares is peak amps, and it is worth understanding what that number is and is not before you spend anything on it.
Peak amps, and what it actually means
Peak amps is the maximum current a pack can deliver for a very short burst. It is not the same thing as cold cranking amps, which is a defined, standardized measurement made at 0F over thirty seconds. Peak amps has no equivalent standard, which means it is not directly comparable between manufacturers and it is not a cold-weather figure.
The number that is genuinely useful is the published engine rating - up to 6.0L gas and 3.0L diesel, up to 7.0L and 4.5L, and so on. That figure is the manufacturer telling you what they will stand behind, and it is what we rank on.
Note the last column. Not one of these manufacturers publishes an operating temperature range on its listing, which for a product sold specifically for cold mornings is a conspicuous absence. Check the manual for the pack you buy before you rely on it at 0F.
The lithium problem, stated plainly
Lithium cells deliver less current at low temperature. A pack stored in a cold trunk has been sitting at outside temperature all night and is at its weakest on exactly the morning you bought it for. Store it in the cabin, not the trunk.
This is the same physics that makes a phone die at 20 percent on a cold day, and it is the single most important thing to know about this product category. Nobody selling these leads with it.
It is not a reason to buy something else. Lithium packs are small enough to keep in a glovebox, they hold charge for months, and they work. It is a reason to keep the pack where the car is warmest and to charge it at the start of the season.
Some packs now include a pre-heat function that warms the cells before attempting a jump. Where a maker publishes that, it is worth having. The trade-off against lead-acid packs and plain cables is in lithium vs lead-acid.
How much pack do you actually need
- Four-cylinder commuter car: the GB40 at 1000A. It is smaller, cheaper, and its 6.0L rating is far beyond what your engine needs.
- V6 or small V8, or you live somewhere genuinely cold: the GB50. Headroom matters more in cold, because thick oil and a weak battery both eat current at once.
- Diesel: the GB70 or the Alpha85. A cold diesel is the hardest crank in ordinary use, and the 3.0L diesel ceiling on the GB40 is a real limit rather than a cautious one.
- You always have somebody to ask: heavy-gauge cables, and keep the money. They have no battery to go flat and no cold derating.
Using one safely
- Check the pack is charged BEFORE you need it. Charge it in October and again mid-season - a pack at 30 percent in the cold may not have enough left.
- Turn off the ignition and all accessories on the dead car.
- Red clamp to the positive terminal, black clamp to the negative terminal or to an unpainted metal ground point on the engine block.
- Switch the pack on. Modern units will refuse to deliver current until they detect a correct connection, which is what spark-proof and reverse-polarity protection mean.
- Crank for no more than a few seconds at a time, and wait between attempts. Continuous cranking overheats the starter motor.
- Once it starts, remove the clamps in reverse order and drive for at least twenty minutes so the alternator can put charge back.
Do notjump a battery that is frozen, cracked or leaking
A discharged battery can freeze, and a frozen battery can rupture under charging current. If the case is bulging, split or visibly leaking, or the battery has been sitting flat in deep cold, do not connect anything to it. That one is a tow, not a jump.
A jump start is not a repair
A jump gets you moving. It does not fix whatever flattened the battery, and if the battery is old the same thing happens tomorrow. The two usual causes are a battery at the end of its life and something in the car drawing current while it sleeps.
If you are jumping the same car more than once, the battery is the actual purchase, and why cars do not start in the cold explains what is going on underneath.
The picks, one at a time
We haven't tested these
No lab, no borrowed units, no free samples. What we did do: pull every published spec into one table and work out what the numbers mean on a cold morning. Everything below traces to a published spec sheet, a manual, or a standard we can point you at - and if a figure isn't published, we say so instead of estimating it. The full method is here.
1. Best overall
NOCO Boost GB40 1000A UltraSafe Lithium Jump Starter
The one most people should buy. 1000A, rated to 6.0L gas and 3.0L diesel, and small enough to actually live in the glovebox where a jump starter is any use.
Best for: Most gas cars
What the maker publishes
- Peak current
- 1000A
- Engine rating
- Up to 6.0L gas, 3.0L diesel
- Jump starts per charge
- Up to 20, per NOCO
- Safety
- Spark-proof connections, reverse polarity protection
- Extras
- USB-C power bank, 100-lumen LED with seven modes
What works
- Small enough to store in the cabin, which matters because a jump starter in a cold trunk is a jump starter with less charge
- Spark-proof and reverse-polarity protection turn the scariest part of jumping a car into a non-event
- Doubles as a power bank, so it earns its space the other 364 days
What doesn't
- Lithium cells lose deliverable current as they get cold, which is exactly the condition you bought it for - keep it inside, not in the trunk
- NOCO does not print an operating temperature range on the listing, so check the manual for your climate before relying on it at 0F
Skip this if: you drive a diesel truck. 3.0L of diesel is the published ceiling and a cold diesel is the hardest thing on this list to crank.
2. Best for bigger engines
NOCO Boost GB50 1500A UltraSafe Lithium Jump Starter
Half again the current of the GB40 for the same handling. Cold cranking is where headroom stops being a spec-sheet number and starts being whether the engine turns.
Best for: Bigger engines and colder mornings
What the maker publishes
- Peak current
- 1500A
- Engine rating
- Up to 7.0L gas, 4.5L diesel
- Jump starts per charge
- Up to 30, per NOCO
- Safety
- Spark-proof connections, reverse polarity protection
- Extras
- 200-lumen LED with seven modes including SOS and strobe
What works
- Headroom is the point: a cold engine is thicker oil and a weaker battery at the same time, and both eat current
- 30 jumps per charge means it survives a season of lending it to neighbors
- 4.5L diesel rating covers most half-ton diesel pickups
What doesn't
- Costs meaningfully more than the GB40 for capability most sedans will never use
- Same lithium cold-performance caveat as every lithium pack here
Skip this if: you drive a four-cylinder commuter car. The GB40 is smaller, cheaper and enough.
3. Best display
HULKMAN Alpha85 Portable Jump Starter, 2000A
A 3.3 in screen showing charge state and error codes. At 6am in the dark, a device that tells you why it is refusing to do anything is worth the extra bulk.
Best for: Seeing what is going on
What the maker publishes
- Peak current
- 2000A
- Engine rating
- Up to 8.5L gas, 6.0L diesel
- Jump starts per charge
- Up to 60, per HULKMAN
- Display
- 3.3 in screen for status, battery level and errors
- Operating temperature range
- Not published by the maker
What works
- The screen removes the guesswork that makes jump starters frustrating - it tells you whether the clamps are wrong or the pack is flat
- 60 jumps per charge is the highest published figure here
- 8.5L gas rating covers anything you are likely to be standing next to
What doesn't
- A screen is another thing to fail, and cold LCDs get sluggish
- No published operating temperature range on the listing
Skip this if: you want the smallest thing that works. NOCO makes a smaller pack and you will be more likely to keep it in the car.
4. Best for diesel
NOCO Boost GB70 2000A UltraSafe Lithium Jump Starter
2000A and a 6.0L diesel rating. If your truck has two batteries and a block heater cord, this is the size that stops being optional.
Best for: Diesel trucks
What the maker publishes
- Peak current
- 2000A
- Engine rating
- Up to 8.0L gas, 6.0L diesel
- Safety
- Spark-proof connections, reverse polarity protection
- Extras
- USB power bank, integrated LED
- Operating temperature range
- Not published by the maker
What works
- 6.0L diesel is a real rating, and cold diesels are the hardest crank in normal use
- The extra capacity is also margin for a battery that is further gone than you thought
What doesn't
- Big and heavy compared with the GB40 - it is a trunk item, and cold trunks are bad for lithium
- Overkill and overpriced for a car
Skip this if: you do not own a diesel or a big-block V8. You are paying for amps you will never draw.
5. The no-battery option
Heavy-Gauge Booster Cables (4 or 6 AWG)
Cables have no battery to go flat and no cells to lose current in the cold. Their weakness is that they require a second car, and at 6am in an empty lot there is not one.
Best for: Never needing a charge
What the maker publishes
- Gauge
- Lower number is thicker - 4 or 6 AWG for a car, 2 AWG for a truck
- Length
- 16 to 25 ft is the useful range
- Cold performance
- Copper does not lose capacity in cold; PVC insulation stiffens
- Charge required
- None
- Requires
- A second running vehicle
What works
- Nothing to charge, nothing to maintain, and no cold-weather derating on the conductor itself
- Far cheaper than any lithium pack
- Will still work in ten years, sitting in the same trunk
What doesn't
- Useless without a second vehicle and a willing driver
- Thin cheap cables are genuinely dangerous - they get hot and they will not carry cranking current
- Insulation stiffens in deep cold and the cables become unwieldy
Skip this if: you park alone or commute at odd hours. That is exactly the situation cables cannot solve, and it is the reason jump packs exist.
Questions people actually ask
What is the best portable jump starter for cold weather?
For most gas cars, a 1000A pack with a published engine rating well above your engine size. What matters more than the model is where you keep it - lithium cells deliver less current when cold, so a pack in the glovebox beats a bigger one in the trunk.
Do jump starters work in cold weather?
Yes, with reduced output. Lithium cells deliver less current at low temperature, which is why storage matters: a pack that spent the night in the cabin performs noticeably better than one that spent it in the trunk.
How many amps do I need in a jump starter?
Compare the published engine rating rather than peak amps. Peak amps has no standardized test behind it and is not comparable between brands, whereas a rating of up to 6.0L gas or 3.0L diesel is the manufacturer stating what they will stand behind.
Where should I store a jump starter in winter?
In the cabin - a glovebox or under a seat - rather than the trunk. Cabin temperatures are milder overnight, and a warmer lithium pack delivers meaningfully more current on the morning you actually need it.
Can a jump starter damage my car?
Modern packs with spark-proof connections and reverse-polarity protection will refuse to deliver current until they see a correct connection, which removes most of the risk. What you should never do is connect anything to a battery that is frozen, bulging or leaking.