HJ60 power inverter issues

Interestingly when i plug in my Engel fridge it works well (but unsure whats happening inside the fridge incase if its slowly damaging it). but for now i cant even charge the camera and nor even operate or charge laptop.

I will try getting direct connection from battery.

Is there a way to ramp up the power, i had heard about dual battery systems, or do i need a powerful alternator?

I would say Ross M is spot on the money.

Try it direct or use thicker wiring. The fridge will draw about 5A max. However the inverter could easily draw 10, 20 A or more. Even with say a laptop.

If you intent to use the inverter for any period when not going, then a second battery will be a must. They eat amphours like crazy.

G'day Naveed M
If you intend to charge and use a Laptop it is better to use a 12 convertor for Laptops.
This device availabe from Jaycar and Auto stores converts 12v dc to around 19v dc as is used in most Laptops. This means only one conversion of dc power to the desired dc voltage.
If you intend to use the Laptop long term the use of an invertor changes 12v DC to AC then supplies the Laptop power supply with 240V AC. The Laptop supply then Inverts it again down to a lower voltage from the 240V AC to 19v DC.
It looks like this: 12V DC - 240v AC 240v AC - 19v DC. This is causing more losses and if battery amp hours are at a premium then the double conversion will use much more.

While travelling if you have a GOOD supply to a suitably positioned invertor it can be used to power a battery charger to charge your batteries while driving. You get the losses but the battery charger will get the extra battery up to full charge unlike many dual battery systems. I say this because some people have and invertor and a multi stage battery charger already.

Be AWARE a 12v to 240vAC invertor is an innocent looking bit of kit but it can KILL if there is wrong wiring somewhere, be careful.

Incorrect or faulty connections means the score board reads:
Owner /operator nil v Invertor 1

Many modern devices have switchmode style internals to make these power conversions eg. 240vac to 12dc and they are designed for full wave AC not the modified crap wave as many 12 to 240 invertors are. Many Laptops and sensitive camera chargers will not start on the non sine wave power and can easily be destroyed. Check the use before going away and use FULL SINE WAVE invertor if possible. More efficient and kinder to the gear.

I was thinking of opting for a much cheaper solution....

Put another identical rating battery in parallel in Engine bay. This way i can have 12 V with double rating amps.

The only issue will be alternator which on most SUV's is strong enough to charge both batteries when engine is running.

Is there a way to have manual hand system with a meter on board on dashboard which enables to connect the 2nd battery to alternator once the primary battery is fully charged and then disconnect by a hand switch system once 2nd battery gets fully charged