I just recently purchased a Schumacher XP400 Portable Jump Starter from WalMart. It was a few cents less than $40. It is a nice simple Jump Start/Jump Box. The unit comes in the box just with the directions. I have read the directions which is always a good idea when purchasing anything. There are several warnings in the Owners Manual...I recommend reading it.
One warning states "Important: Charge Immediately after purchase and after each use and every 30 days to keep the Instant Power Internal Battery fully charged."
Schumacher XP400 Portable Jump Starter
Other tidbits I gleaned from the Schumacher XP400 Portable Starter manual:
Do not use the XP400 while charging.
If you overload the 12 Volt port there is a circuit breaker inside the XP400. It will reset itself after you disconnect the shorted or overloaded circuit.
The XP400 does not have an on/off switch so the cables are always live. Be careful to keep them from touching each other or from both touching the same piece of metal and shorting out.
On the front of the unit is a button that lights up either a red, yellow or green LED light. Green means the Jump Box is over 75% charged. The Yellow means a 50 to 75% charge and the red LED means less than a 50% charge and it is not a good Idea to use the Jump Box.
This picture shows the front of the Schumacher XP400 with the Cigarette Lighter Port.
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