Inspiron 1525 - What size/type plug does it have - Need to know for DC-DC regulator use

I am currently sailing around the world.  I just purchased a Dell Inspiron 1525 laptop for use on the boat.  I am looking at purchasing a DC-DC regulator to be able to keep the laptop powered on at all times but not draw any more power than is necessary to conserve batteries.

I need to know the type or size of plug (the little power plug that plugs into the left side of the 1525).  The manufacturer of the DC-DC regulator lists the compatible notebooks for the various plugs which are included with the regulator.  However, the 1525 is not on the list.  I am thinking it's because the 1525 is new, but perhaps it's because the 1525 uses a plug which isn't included with the regulator.  Can someone tell me the size of the plug, or if the plug is the same as some other Inspiron laptop (such as the 9100 or the 5100 or ...).

Here is the a partial list of compatible computers shown:

Compatible Notebook list

New Dell plug (5.1mm x 7.4mm, K plug): Dell Inspiron 8600, 9100

Dell plug (F plug): Inspiron 2000, 2100, 2500, 2600, 2650, 3700, 3800, 4000, 4150, 5000, 5100, 7500, 8000, 8100 series, Latitude C Series ( Not compatible with C400 or C840 series) & CP series

1.4mm x 6.5mm (E plug): Fujitsu Lifebook A,B,C,E,i,L,P & S Series (not compatible with E-6600), Panasonic toughbook Series all models, Sony Vaio SR,GR & VX series, Sony Vaio F,FX,FXA, GRX, R505 & Z505 Series

3.0mm x 6.3mm (D plug): Toshiba Satellite 1200, 1400, 1500, 1600, 1700, 1800, 2000, 2100, 2200, 2400, 2500,2600, 2700, 2800, 3000, 4000, 5000, 5100 & 5200 Series ( Not Compatible with Satellite 4330, 4500 Series) Toshiba Satellite Pro 400, 4200, 4300, 4600, 6000 & 6100 Series, Tecra Series for all models, Portege 300, 320,610, 620, 650, 660, 2000, 4000 & 7000 Series, 7140

2.5mm x 5.5mm (B plug): Dell Inspiron 3000, 3200, 3500, & 7000 series

I have called both Dell sales and Dell technical support, and neither of them has been able to provide me with the information I need to know if the DC-DC regulator I am wanting to buy will working with my Inspiron 1525.  Can anyone help?

Thanks!

Dar*Dar