Bongo wiring

[pikey]

I have fitted a wellington LB kit and now want to run my 12v fridge off it. The cable for the fridge at the moment goes straight from the fridge to the SB. I have a few (stupid?) questions about this which it would be great if someone could answer?

- Reading the fridge Waeco fridge manual it suggests that a 6mm cable is needed to connect the fridge to the battery about 3-4 metres away. Is that right? Sounds like quite a thick cable for a 70w fridge.

- Should there be a fuse between the battery and the fridge? If so, what rating is recommended?

The vehicle is fitted with electirc hookup at the moment which goes straight to some 3 pin sockets. Is there any reason I shouldn't use a transformer in one of those sockets to power the fridge when the bongo's on electric hookup?

Could I likewise use a battery charger in one of the sockets wired to the leisure battery to keep it topper up? If so, is there any particular make, model, type, rating of charger needed? Is a special charger needed or just a standard charger like one would use to charge the battery out of the vehicle?

Thanks for any help anyone can give me.

[g8dhe]

- Reading the fridge Waeco fridge manual it suggests that a 6mm cable is needed to connect the fridge to the battery about 3-4 metres away. Is that right? Sounds like quite a thick cable for a 70w fridge.

That sounds about right, you have the motor start current to account for which is quite a bit higher than the average current once running.

- Should there be a fuse between the battery and the fridge? If so, what rating is recommended?

Yes you do need a fuse it should be mounted as close the the L/B as possible, the Fuse is to protect the cable, not the device, a 6mm² cable should be fused for about 30 Amps at most, personally I would fuse it at 20 Amps if its only going to feed the fridge.

The vehicle is fitted with electirc hookup at the moment which goes straight to some 3 pin sockets. Is there any reason I shouldn't use a transformer in one of those sockets to power the fridge when the bongo's on electric hookup?

I hope it doesn't go directly to the outlet sockets! It needs to run thru a small distribution box with switching and MCB at least!
The small garage types are ideal (click for details of a suitable one);

Could I likewise use a battery charger in one of the sockets wired to the leisure battery to keep it topper up? If so, is there any particular make, model, type, rating of charger needed? Is a special charger needed or just a standard charger like one would use to charge the battery out of the vehicle?

In theory yes a battery charger would do, but a lot of modern chargers have some "intelligence" in that they expect the load to be a battery, in reality you need a DC power supply to run the circuits and charge the battery as well, this should be connected to the second circuit of the above consumer unit (protected by its own MCB) and then the 12v output will feed the L/B in parrallel with the L/B loads via something like a PMS3 or Zig Marque 1 switching panel. Zig do suitable power supplies etc. http://www.zig-electronics.co.uk/products.htm

[Kincaid]

- Reading the fridge Waeco fridge manual it suggests that a 6mm cable is needed to connect the fridge to the battery about 3-4 metres away. Is that right? Sounds like quite a thick cable for a 70w fridge.

That sounds about right, you have the motor start current to account for which is quite a bit higher than the average current once running.

- Should there be a fuse between the battery and the fridge? If so, what rating is recommended?

Yes you do need a fuse it should be mounted as close the the L/B as possible, the Fuse is to protect the cable, not the device, a 6mm² cable should be fused for about 30 Amps at most, personally I would fuse it at 20 Amps if its only going to feed the fridge.

The vehicle is fitted with electirc hookup at the moment which goes straight to some 3 pin sockets. Is there any reason I shouldn't use a transformer in one of those sockets to power the fridge when the bongo's on electric hookup?

I hope it doesn't go directly to the outlet sockets! It needs to run thru a small distribution box with switching and MCB at least!
The small garage types are ideal (click for details of a suitable one);

Could I likewise use a battery charger in one of the sockets wired to the leisure battery to keep it topper up? If so, is there any particular make, model, type, rating of charger needed? Is a special charger needed or just a standard charger like one would use to charge the battery out of the vehicle?

In theory yes a battery charger would do, but a lot of modern chargers have some "intelligence" in that they expect the load to be a battery, in reality you need a DC power supply to run the circuits and charge the battery as well, this should be connected to the second circuit of the above consumer unit (protected by its own MCB) and then the 12v output will feed the L/B in parrallel with the L/B loads via something like a PMS3 or Zig Marque 1 switching panel. Zig do suitable power supplies etc. http://www.zig-electronics.co.uk/products.htm

Geoff, read the above and wondered if you could give a bit more info. I have been using a RING 8amp smart charger to recharge the LB when on hook-up. It seems to be working as I'd hoped, selecting the correct amp level to top-up the battery. Re your post above is this the wrong way to do this and should I really be picking up a DC power supply then?

[g8dhe]

I have been using a RING 8amp smart charger to recharge the LB when on hook-up. It seems to be working as I'd hoped, selecting the correct amp level to top-up the battery. Re your post above is this the wrong way to do this and should I really be picking up a DC power supply then?

Its not necessarily wrong, but it depends on how the charger has been programmed to work. Most modern chargers have three differing phases;

• 1st phase is a constant current charge - this is to get the biggest charge in to the battery as quickly as possible (some chargers will have a switch to select the capacity of the battery others make a simple assumption) this will normally run for around about 5-10 hours and the charger will watch the voltage, when it reaches about 2.3v to 2.45v per cell (6 cells = 13.8v to 14.7v)
• after this the current is reduced to maintain the voltage, this phase is called the Topping charge as it represents about the last 30-40% of the charge and is quite an important feature if you want to get the most out of the battery in terms of long life, during this phase the current is watched and once the charging has in affect stopped i.e. its full and the charging current is less than 0.5-1 Amps then
• the charger goes over to the final phase called Float charge, at this point the charging voltage is reduced to around about 2.25v to 2.27v (about 13.6 volts in total) at this level the charger can continue for ever, its really only putting in enough current to cover the internal discharge rate.

Now the problem is if you are running a charger of the type above, and then you start drawing current to run lights, radio etc then the charger can be totally fooled into thinking that the battery is undercharged or overcharged depending on how much current is drawn at what phase the charger thinks it should be using! The result is normally a lot less life for the battery
A simple DC power supply set to 14.2 volts and connected directly to the battery is a pretty good option for the type of use where the vehicle is being used during the day (i.e. charged from alternator at above 14.3 volts) then during the evening and night on a campsite the battery will get its desirable Topping charge. If your on a campsite most of the time and not running about in the Bongo during the day then a slightly lower voltage say 13.9 to 14.0 volts would be better as this means its approaching the Float charge level which is just maintaining the battery at optimum.

So I wouldn't say its right or wrong, if your able to control the current and ideally the voltage within the limits above then you will get the most from the battery in terms of its 2-3 years nominal lifetime, if your out by say ±10-20% in current terms then you might loose 6 months to a years worth of life from the battery. But its NOT an exact science by any means!

[Kincaid]

Geoff - thanks for the info, much appreciated. I've had look on ebay and found this
http://cgi.ebay.co.uk/Logic-RC-12v-Powe ... 1043wt_922 looks a lot cheaper that the zig unit -does this seem a better way to go than the smart charger?

[g8dhe]

Yes I would say that if you don't already have a unit of either type then this would be suitable, having the display is a nice feature but not essential for this use so there might be something even cheaper, as once setup the voltage wouldn't need changing. Having the current limit is also a good idea as you can set it for say 10 Amps and the not worry about any excessive currents. Incidentally when setting the charging voltage measure the voltage AT the battery itself with no other loads connected, not at the power pack itself as there will be a voltage drop down the cable.

[pikey]

Thanks for your advice Geoff. There is a fuseboard between the electric hookup and the 3 pin sockets in the van. I have now bought one of these:

http://cgi.ebay.co.uk/Logic-RC-12v-Powe ... 1043wt_922

I have a zig marque 1 unit already fitted to the bongo. What's the best way to connect the power supply to the battery and zig marque 1 so it powers all the devices connected to the marque 1 and charges the leisure battery at the same time? Do I connect the positive of the power supply to an inline fuse then to the positive in terminal from the l/b on the zig marque 1 and the negative straight to the leisure battery?

Thanks again for your help.

[g8dhe]

OK well if you have a Zig 1 fitted then, hopefully you didn't already have a Zig power supply X70 or X80 power supply already fitted? Because otherwise you have just duplicated it with the other PSU!
Here is a diagram of the connections you need to make the +12 Volts from the PSU needs to connect to the common wire running the length of the Zig 1 connecting all the fuses / switches to the 3 way switch at the left hand end which controls which battery (or none) is selected, the 0V (negative) of the PSU needs to attach to the common earth this is normally available as a connector block somewhere behind the Zig unit (its not part of the Zig however). The diagram is below (click it for large image), the relevant part for you is up in the top Right hand corner and the left hand side;

You won't have the stuff in the lower right hand corner, thats specific to my vehicle, nor will you have the Low Voltage Cut Out Relay.
It is important that you check that the Wire from the VAN setting on the Zig 1 goes to the L/B via a fuse (probably in-line type) mounted close to the L/B itself, 15 Amps will be fine.
Also the same goes for the CAR setting back to the S/B again a 15 Amp fuse should be mounted close to the battery itself.
Note also that the wiring colours are not standard, those shown are merely the colours I used on mine!

Do shout if any of it doesn't make sense

[pikey]

Thanks Geoff.

No, it doesn't have a zig psu. I bought the bongo a couple of years ago and it had the s/b connected to the zig and the electric hookup, fuseboard and sockets.

Since then I have added the l/b which only powers the lights, 12v cig lighters and stereo via the fuseboard near the steering wheel and now I want a) the l/b to power the pump and fridge through the zig and for the l/b to be charged from the hookup.

It looks like the wire from the battery +ve to the zig car setting +ve isn't fused! Guess I need to sort that!

If I connect the psu to the common wire, will it charge the s/b when the zig is switched to car and the l/b when switched to van? Will the pump and fridge be on permanently (assuming hookup plugged in) even when the zig is on the middle setting (rather than the van or car settings) if the psu is attached to the common wire?

The fridge is grounded to a bolt on the chasis behind the fridge - is that the common earth for the PSU too?

[g8dhe]

Yes please fuse the wire from the L/B ! The switch on the Zig will indeed allow you to charge or draw load from the S/B if its set that way. Regarding the Fridge and pump if they are switched via the Zig then they don't have to be on permanently but they will draw power from the PSU if switched ON and EHU is on otherwise they will draw from which ever battery is selected.

Regarding earthing, yes use the chassis of the vehicle, but I always install my own 0v wire as well running from L/B to S/B then on to the Zig unit and to the common earth there. This is seen by some as over kill but having worked on and used radio transmitters in vehicles for a long time the quality of chassis connections and more importantly the unseen connections between chassis members causes LOTS of problems, so I always use my own earth wire using as thick a cable as possible to thread thru the vehicle something like 6mm² or even 8.5mm² as it will be carrying current back from several circuits - you only need to do it once and it avoids problems in the future, but yes it does add to the expense but not that dramatically. One other thing is if you need to make more than a couple of crimp connections then its well worth buying a decent crimping tool rather than one of the cheap ones http://cpc.farnell.com/_/ht-301/insulat ... dp/TL08620 is quite suitable and not that expensive, then keep it in the vehicle!

[maxi_77]

- Reading the fridge Waeco fridge manual it suggests that a 6mm cable is needed to connect the fridge to the battery about 3-4 metres away. Is that right? Sounds like quite a thick cable for a 70w fridge.

That sounds about right, you have the motor start current to account for which is quite a bit higher than the average current once running.

- Should there be a fuse between the battery and the fridge? If so, what rating is recommended?

Yes you do need a fuse it should be mounted as close the the L/B as possible, the Fuse is to protect the cable, not the device, a 6mm² cable should be fused for about 30 Amps at most, personally I would fuse it at 20 Amps if its only going to feed the fridge.

The vehicle is fitted with electirc hookup at the moment which goes straight to some 3 pin sockets. Is there any reason I shouldn't use a transformer in one of those sockets to power the fridge when the bongo's on electric hookup?

I hope it doesn't go directly to the outlet sockets! It needs to run thru a small distribution box with switching and MCB at least!
The small garage types are ideal (click for details of a suitable one);

Could I likewise use a battery charger in one of the sockets wired to the leisure battery to keep it topper up? If so, is there any particular make, model, type, rating of charger needed? Is a special charger needed or just a standard charger like one would use to charge the battery out of the vehicle?

In theory yes a battery charger would do, but a lot of modern chargers have some "intelligence" in that they expect the load to be a battery, in reality you need a DC power supply to run the circuits and charge the battery as well, this should be connected to the second circuit of the above consumer unit (protected by its own MCB) and then the 12v output will feed the L/B in parrallel with the L/B loads via something like a PMS3 or Zig Marque 1 switching panel. Zig do suitable power supplies etc. http://www.zig-electronics.co.uk/products.htm

Agree with much but would suggest that as the cable size is more about voltage drop than current capacity you fuse it to suit the appliance. Then it will protect the internal wiring of the appliance.

My smart charger on my boat doubles quite happily as a DC power supply and there are no problems. A separate power supply and charger is not needed, though I would suggest a smart charger would be best to get the LB charge as close to 100% as possible.