I just got a similar unit about a week ago, and you won't likely know what's
inside until you open the case.

The Schumacher Instant Power 400 Peak Amps model IP-55 has a 12V 5Ah battery
and an internal charging circuit (AC transformer, circuit board, LEDs
red-yel-grn).

On the back of the unit, there is a flip-up set of (2) blades that fit a
standard NEMA 120VAC extension cord female connector. Any AC cord is just
connected to the 2 blades for charging.
The manual states that an optional 12V cord is available for charging from a
car lighter-socket "while driving" (inserted into the front DC power outlet
socket), which won't actually work well unless connected "while driving"
while the vehicle alternator is operating and the output voltage is about
13.8-14.2V.
Cable p/n 38-99-001564, which doesn't seem to exist.. not found on their
site or by Goog search.
A warning cautions that the unit's internal charge limiting circuit is not
applied when the adapter cord is in use, and the charge-level LEDs aren't
functional/reliable, so.. the user needs to disconnect the adapter cord and
check the level of charge frequently when using the charging cord, also
never used in excess of 4 hours, never unattended - risk of explosion or
fire, and disconnected when the engine is not running.

The unit's internal battery is connected directly to the big, external
battery terminal clamps, so one needs to avoid contacting the clamps to
anything conductive, or each other.
The front DC power outlet is connected directly to the internal battery,
with a 15A self-resetting circuit breaker in series.

Charging thru the front power outlet socket on these types of power-packs
should only be performed by use of an actual smart/automatic battery
charger.. one that will charge at a low rate (~1A maximum for a 5Ah battery
or C/0.2 rate) and capable of automatically stopping the charge cycle when a
fully charged state is attained.

--
Cheers,
WB
..............


"Adrian C" wrote in message
...

http://i912.photobucket.com/albums/a...r/IMG_3573.jpg

A neighbour has dropped in with his discharged and dead "RAC Portable
Power Station and Engine Starter" which he obtained without the necessary
DC charger. The starter is a dayglo orange heavy thing with a handle and
says it can crank 400 Amps.

Anyway, written on the front of the DC input socket, it claims it needs
16V - so I've got it charging up of one of my laboratory supplies set at
that.

Initially connecting it up, it was was drawing about 100mA. After 5 hours
it's now drawing 400mA. Must have some 'inteligence' in it.

So I'd guess a 16V 500mA adaptor (or thereabouts) would be a suitable
replacement. But to check if anyone has one of these, could ye check
what's written on the mains adaptor? And can find for reference the user
instructions?

Thanks.

--
Adrian C