xda charging in car problem

[Ish]

hi all

i'd like to ask your opinion on what this fault

i purchased a xda2 which i use in my car with a gps reciever & satnav software. the cable i use is in the pic below. it connects to the ciggy lighter and then powers the gps box and powers/charges the phone at the same time.

http://www.gpsforless.co.uk/product_images/602.jpg

the problem is that if the battery is below about 35% and i plug it into the car charger and turn on the gps stuff the battery doesn't charge eg. battery showing 18%. i plugged it into car charger and turned on gps stuff. drove 20 mins home and battery was showing 8 % by the time i got home even though the battery status thing shows as charging.

BUT

if the battery is at about 70 % and i use it in my car with all the gps stuff it charges fine.

does this point to a faulty battery or something more serious :cry:

thanks for any input.

[sunny127]

It is all about the mA. check out the mA specifications on the cable. 500 mA output is too low. 1000mA is ok.