More battery questions

[TheBeastie]

Well I am getting a bit further on. I now know, rather than suspect, that I need to move all my distribution stuff out of the battery box to fit the two batteries, so will get working on that once I can find a good solution.

However this morning's Q-1 is about Anderson connectors. I want to fit one to the front of the seat box to use for tyre compressor and also jump leads. I expect use of jump leads to be occasional since I am not a breakdown truck so would 175 amp connectors be adequate? Also should I feed them from the battery with thinner, and slightly more flexible 170amp cable or would I be better using the thicker 300 amp cable?

Q-2 relates to home made busbars - if I create a "block" of copper from old copper pipe do I need to use brass nuts and bolts for the connectors or will normal Screwfix BZP ones do? I suspect it is partially to do with conductivity and partly to do with corrosion but am not a metallurgist and would prefer not to lose all my electrics at the wrong point due to the busbar having corroded away.

Thanks

Malcy

[110WestCape]

Hi Malcy,

Suggest you test the compressor under load and then decide what guage cable to use to the Anderson plug unless it is specified in it's manual. Same can be done for the jumper leads although I would not recommend a sound connection that would be more difficult to remove in an emergency. IIRC car batteries are tested to approx 400A from a design spec perspective. 175A connectors seems way sufficient for the compressor purpose. 300A would be overkill. A far as jumper leads ...... cannot say would have to test the resistance on the cable as well as the amps.

Q-2: you suspected correctly.

Cheers

Wikus

[TheBeastie]

Thanks

Very helpful. I think the compressor will be fine since it runs on supplied byt relatively minor (30 amp) cables at the moment so no fears re: 175 amp connectors for that but the jump leads is a bigger one. Most seem to fit 175amp but some say you need the 350amp so I was trying to clarify.

I have now solved the busbar issue by finding a distribution board with +ve and -ve busbars incorporated so I am saved that one!!

Best wishes

Malcy

[LandyManLuke]

It doesn't matter how often you use the jump leads, what matters is the current through them when you do.

Starting currents can be huge, I would go with the larger anderson connectors and decent sized cable, 30-35mm^2.

Glad you've decided not to bodge some copper pipe into a bus bar, the proper units are not that expensive.

[110WestCape]

Agree with LandyManLuke. The CCA (cold crank amp) rating of your battery should give you a good steer, it's usually indicated somewhere on the battery. The main battery (used to start your vehicle) operates completely different to an aux battery (usually a deep cycle) in the sense that the main battery can provide larger bursts of amps for short periods in time.

The aux battery (if it's a deep cycle) takes longer to charge in smaller increments and likes to be discharged frequently and on a gradual basis. Usually not beyond 10,5V. Thereafter it shortens the battery life.

The larger diameter cables are required for the high amp operations and the anderson connected to it should match the battery CCA rating to be safe.

Thicker cable = reduced resistance (ohms) and should prevent the cables getting hot or even starting a fire. High Amps = high current flow rate, Volts = current pressure. Think of it as blood running through your veins.

Cheers

Wikus

[TheBeastie]

OK

Thanks guys

I am now convinced and will need to invest in the 350amp connectors. I was also concerned how I might get the bigger cables sitting neatly between the exit from the battery box and the connector itself since they are not very flexible!

Best wishes

Malcy

[SteveBo]

Could go bigger (only joking) http://www.torberry.co.uk/pdf/DS-SBE700REV02.pdf

However, some of these are finger proof and have mounting holes so you may be able to mount the female connector permanently on the side of your battery box (facing downwards) to avoid having stiff cables poking out? Then just plug the male connector on your cables when you need it.

I'm thinking of a distribution/fuse board on an extension lead for camping power supply and a set of jump leads for emergencies either of which can be plugged in when needed.

[TSD]

However this morning's Q-1 is about Anderson connectors. I want to fit one to the front of the seat box to use for tyre compressor and also jump leads. I expect use of jump leads to be occasional since I am not a breakdown truck so would 175 amp connectors be adequate? Also should I feed them from the battery with thinner, and slightly more flexible 170amp cable or would I be better using the thicker 300 amp cable?

The current handling of Anderson connectors is directly related to the cable size due to contact heating. Fatter cables are better at removing heat from the contacts. The 175A connectors are rated to over 500A for 15 seconds when fitted with 0 gauge cable (50mm2).

Use the fattest cable you can (on battery side and jump lead side) and the 175A connectors will be fine for most peoples use of jump leads. Get the ends crimped on properly too, no smashing them on with a hammer and punch

[wormhole]

The current handling of Anderson connectors is directly related to the cable size due to contact heating. Fatter cables are better at removing heat from the contacts. The 175A connectors are rated to over 500A for 15 seconds when fitted with 0 gauge cable (50mm2).

Use the fattest cable you can (on battery side and jump lead side) and the 175A connectors will be fine for most peoples use of jump leads. Get the ends crimped on properly too, no smashing them on with a hammer and punch

Just for reference, I have a ex-AA jumpstart setup to install which uses the 175A connectors