Brightwire J4 · Portable jump starter · 12V
Dead battery at 7 am? Start it yourself.
A slim jump starter that lives in your glovebox. No second car, no cables across the street, no waiting for roadside help.
- Free US shipping · 3–5 days
- 30-day money-back
- Secure checkout
In stock · ships from the US- 20kmAh
Battery capacity. Also a power bank
- 2.5L
Starts petrol engines up to 2.5 litres
- ~1min
From flat battery to engine on
- 3in 1
Jump starter, power bank, flashlight
See it in action
Three moves, then you drive.
One box. Three ways out of trouble.
Starts your car without a second one
Works on 12V petrol cars up to 2.5 L, plus motorcycles, snowmobiles and small boats.
- Red and black jumper clamps included
- Battery indicator shows the charge left
Charges your phone on the way
The 20000 mAh battery has a USB output for your phone, tablet or headphones on road trips and camping weekends.
- USB output for phones and small devices
- Recharges with the included USB cable
Light when you need it most
Breakdowns rarely happen in daylight. The built-in LED lights up the engine bay so you can see where the clamps go.
- Built-in LED, no extra torch needed
Will it start your car?
Set your engine size and fuel type. You'll find the engine size on your registration document or in the owner's manual.
A 1.6 L petrol engine is within the J4's range.
The details
- J4J4 unit20000 mAh battery with LED flashlight
- +/−Jumper clampsRed and black, plug into the J4
- USBUSB cableFor recharging the J4 from any USB charger
| Battery capacity | 20000 mAh |
|---|---|
| Jump start voltage | 12V |
| Compatible engines | Petrol / gas up to 2.5 L |
| Works with | Cars, motorcycles, snowmobiles, small boats (12V) |
| Ports | Jump starter socket, USB output, Micro USB input |
| Extras | LED flashlight, battery indicator |
| Shipping weight | 454 g / 1 lb |
| Brightwire J4 | Jumper cables | Roadside assistance | |
|---|---|---|---|
| Needs another car | No | Yes | No |
| Time to get going | About 1 minute | 10–30 minutes | 45–90 minutes wait |
| Charges your phone | Yes | No | No |
| Cost | $59 once | $20–40 once | $80–150 per year |
Holiday deal · Ends Dec 25
Winter is coming. Be ready.
Car batteries lose up to a third of their power in freezing weather. Keep a J4 in every car this winter, or put one under the tree. For delivery before Christmas, order by Dec 14.
Questions
Not sure it fits your car?
Send us your car's make, model and engine size. We reply within 1 business day.
Does it work on diesel engines?
We don't recommend the J4 for diesel engines. They need more starting power than this model is rated for.
When will my order arrive?
Orders ship from our US warehouse within 1–3 business days and arrive 3–5 business days later. You'll get a tracking number by email.
How do I charge the J4?
Use the included USB cable with any USB phone charger. Charge it fully before the first use; the battery indicator shows when it's full.
Can I leave it in the car?
Yes, in the glovebox through autumn and winter. Lithium batteries don't like heat, so bring it inside on hot summer days and recharge it every 3 months.
Is it safe for my car's electronics?
Yes, when you follow the clamp order: red to positive (+), black to bare metal or negative (−). Connect the clamps before you switch the unit on.
How do returns work?
Email us within 30 days of delivery with your order number. Send the J4 back unused with all accessories and we'll refund you. If it arrives damaged or faulty, we'll replace or refund it.
