Is it OK to connect to under bonnet battery terminal?

[Lankylad]

I have a 2005 Citroen Xsara Picasso 2.0 hdi and I want to fit an extra 'permanently live' auxiliary power point. I don't really want to 'piggy back' a connection to a fuse as I don't want to compromise any of the car's systems. I am wondering is it be possible to attach an inline fused positive connector to the under bonnet battery terminal (it has a nut and washer) and a negative connection to a suitable earthing point. If this is feasible, would it be safe? I love my 'piccy' and I don't want to cause any problems. i would be grateful for any help in this matter. Many thanks!

[GiveMeABreak]

Depending on your needs I would actually advocate the first option. Use a specifically designed 'piggy back' fuse connector that replaces the original fuse and then allows a second (fused) feed. This will provide the original fused protection and an additional fuse for the intended connected equipment. As long as the load is within the limits you will be fine. You won't compromise any of the car's systems this way so long as you choose a fuse that allows sufficient current for your needs.

I wouldn't recommend tying in additional wires from the engine fuse box as this will mean disturbing the electronics. What is it you are connecting and what are the current requirements?

[GiveMeABreak]

There are different electrical systems on these depending on BSI only or with Comms 2000 relay unit. Once you confirm what current you need, pop your VIN up and I can suggest a suitable fuse and location.

[wheeler]

Theres no reason why you can connect to the under bonnet positive connection as long as its fused. I too though would second using piggy back fuses, there may even be a vacant fuse slot that meets your needs inside.
If it is to power something inside the cabin then getting the cable back inside can be the problem, if not done correctly it can be a big problem.
Are there no threaded studs on the quick release battery terminals under the seat you could connect to?

[Lankylad]

Thanks for all your comments. I feel more confident now to go ahead with the piggyback approach now that I know it won't compromise anything. I want to install an auxiliary power socket to plug a '6w solar power maintainer' into it as I really don't do enough mileage to keep my new Silver battery fully charged as these batteries do not like the charge running down. The solar power Maintainer will be inputting about 0.345ah so there will be very little power involved. I really would appreciate advice on which fuse to use in the piggyback though. Thanks again!
Ps.. I do not want to use an Obd2 adapter to connect up

[GiveMeABreak]

Pop your VIN in that case.

[Hell Razor5543]

It may not need to be piggy backed. One IT service provider I used to work for used Citroen Xsara Picassos for their field service engineers. They received their call details through a specialist piece of equipment that was powered from the cigarette lighter. Unfortunately these Picassos (54 reg), when they went into economy mode, did not disconnect the cigarette lighter. If an engineer forgot to unplug this kit when he got home he would need to jump start the Picasso in the morning. If this is the case with YOUR Picasso you could just connect the solar cell via the cigarette lighter without making any wiring modifications.

I know that, on my 2004 C5, the cigarette lighter does not turn off. I know this because I have forgotten to disconnect the dash cam overnight, and it is still running the following morning.

[GiveMeABreak]

Many of these are BSI controlled - so the power to the cigarette lighter is switched off by the BSI after a time limit.

[Hell Razor5543]

But some are not, including (as stated) my personal C5 and the 54 reg company Picasso.

[van ordinaire]

So America is even more of a nanny state than us, because for years now ignition fed cigar lighters have been mandatory, less an unaccompanied child in a parked car, sticks his fingers in the socket.

As for piggybacks, originally I thought they were really smart - but not found a vehicle yet that will allow you to replace the fusebox cover with one in place.

No problem connecting direct to battery, in fact preferred practice for high draw items, that's what the commonly found extra terminals are for.

[GiveMeABreak]

Thanks for all your comments. I feel more confident now to go ahead with the piggyback approach now that I know it won't compromise anything. I want to install an auxiliary power socket to plug a '6w solar power maintainer' into it as I really don't do enough mileage to keep my new Silver battery fully charged as these batteries do not like the charge running down. The solar power Maintainer will be inputting about 0.345ah so there will be very little power involved. I really would appreciate advice on which fuse to use in the piggyback though. Thanks again!
Ps.. I do not want to use an Obd2 adapter to connect up

Stick to a piggy back.

[Lankylad]

To Marc... My vin is VF7**************[VIN obfuscated, can be read by forum staff] and the solar power input will be about 0.345ah. I really would appreciate help on which fuse to piggyback. Thank you very much!

[GiveMeABreak]

The fuses you need are in the cabin fusebox. Here is a scalable SVG diagram and the relevant fuses - pick one that meets your needs, but when using a piggy back fuse, always enure the accessory fuse is not too high for the equipment you are using as they may supply a higher fuse than needed.

Fuse Number	Amps	Equipment
F13	20A	Heated Seats
F14	15A or 30A	Accessories Socket or Caravan Socket
F15	20A	Rear Electric Windows
F16	40A	Anti-pinch Electric Window
F17	15A	Audio System

Here are the above fuses which I have highlighted on the extract from the above in yellow:

[Lankylad]

Thank you Marc, you have been brilliant. Your assistance has been superb. I cannot thank you enough!