Can a 250A Busbar and Neg post replace a battery

[budgie348]

If I was to remove the first battery of my domestic Bank and replace it with a a 250A Busbar for the positive terminal and 10mm stud commoning post for the Negative terminal, would it be acceptable?

 

I want to replace my domestic Bank of batteries with a 660amp traction battery. The traction batteries will be on the starboard side of the engine hole on the swim and the 250A busbar and neg post will be on the port swim, I want to do it this way as it will save me having to put extra tails on all the wiring that went to the first of the domestic batteries. Is this an acceptable practice?

 

I originally had 3 X 200 amp Gel Batteries, 1 on the port swim and 2 on the starboard swim.

[Gibbo]

Nothing wrong with that as long as you insulate it all properly. Electrically it's fine. You might want to seriously consider putting a fuse in the positive close to the battery (but not in the battery box), just in case.

[budgie348]

Thanks Gibbo, One further question if I may, is 250A Busbar big enough or should I go to 600A?

[Gibbo]

Thanks Gibbo, One further question if I may, is 250A Busbar big enough or should I go to 600A?

 

That depends what current you intend drawing from it. You can't really pull 600 amps because that would flatten your batteries in about 15 minutes. If used within normal limits you're not going to be pulling more than 250 amps from a 600Ahr battery so 250 will be fine. Fuse it at 200 amps then you know you're safe.

[RLWP]

I haven't seen either, is it easier to work with the bigger bar? I'm thinking about size, stud diameters and so on

 

Richard

[paulcatchpole]

A quick attempt at thread hijacking whilst the experts are around...

 

My 350A ANL fuse blew yesterday, when I loaded it up with about 20A. It's outside, though under the deckboards, and I wonder if weather exposure had done something to weaken it? It's never seen much more than 150A through it, and only for short periods, though does see the charging load of 60A, tailing downwards, quite often.

 

Any thoughts?

 

PC

[Gibbo]

I haven't seen either, is it easier to work with the bigger bar? I'm thinking about size, stud diameters and so on

 

It is if you have fingers like sausages

 

Any thoughts?

 

Moisture definitely damages fuses. So do slightly loose connections (they heat up). But even without those, fuses age. Eventually every correctly sized fuse will fail, even with no overload.

[paulcatchpole]

Moisture definitely damages fuses. So do slightly loose connections (they heat up). But even without those, fuses age. Eventually every correctly sized fuse will fail, even with no overload.

 

Hmm, well, that would look to explain that then. It does look to have gone a bit manky in the damp. I'll have to devise a better cover for it.

 

Ta!

 

Something for the OP to think about, if he's putting fuses in damp places for this battery relocation...

 

PC

[smileypete]

A quick attempt at thread hijacking whilst the experts are around...

 

My 350A ANL fuse blew yesterday, when I loaded it up with about 20A. It's outside, though under the deckboards, and I wonder if weather exposure had done something to weaken it? It's never seen much more than 150A through it, and only for short periods, though does see the charging load of 60A, tailing downwards, quite often.

 

Any thoughts?

How are the inverter and charger cables protected? Just by the 350A fuse?

 

cheers,

Pete.

[paulcatchpole]

How are the inverter and charger cables protected? Just by the 350A fuse?

 

cheers,

Pete.

 

Yup... That 350A fuse is (just) on the boat side of the domestic isolator, in the 90mm^2 run to the bus bar in the electrical cabinet, where the charger and inverter cables are connected.

 

Inverter is 1500w continuous, charger 60A. I've not seen more than 150A steady on the ammeter, though agree that transients will be higher than that.

 

PC

[smileypete]

Yup... That 350A fuse is (just) on the boat side of the domestic isolator, in the 90mm^2 run to the bus bar in the electrical cabinet, where the charger and inverter cables are connected.

 

Inverter is 1500w continuous, charger 60A. I've not seen more than 150A steady on the ammeter, though agree that transients will be higher than that.

Sounds like the inverter and charger cables should be fused where they connect to the bus bar, with something appropriate to their cable rating.

 

Otherwise a short in the charger cable could draw up to 350A, which could be far more than the cable rating.

 

ETA: The instructions for the inverter and charger might require a fuse of a certain rating to protect them, so your fuse protects the cable and the equipment.

 

cheers,

Pete.

Edited July 5, 2011 by smileypete

[paulcatchpole]

Sounds like the inverter and charger cables should be fused where they connect to the bus bar, with something appropriate to their cable rating.

 

Otherwise a short in the charger cable could draw up to 350A, which could be far more than the cable rating.

 

ETA: The instructions for the inverter and charger might require a fuse of a certain rating to protect them, so your fuse protects the cable and the equipment.

 

cheers,

Pete.

 

Fair point, though the cables to charger and inverter are rated 330A DC at 30% duty cycle, or 180A continuous.

 

I'm happy that the fuse will blow before the cables give up, in a >350A situation like a dead short.

 

PC