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Fuse/ fuseholder, Isolator and cables for battery connections


superdiy
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As per the topic title I'm searching for these items for another installation. Since I'm not in a big city my supplier choices are limited and I prefer online shopping, but seems that not many of the online shops keep these things in stock.

 

For my own installation I bought 100A fuseholders (which can be used for isolation as well) and fuses from RS - it was about 30% more expensive compared to my other option, the ACDC equivalent, but at that stage ACDC did not have stock and had no idea when they will have stock again. I used 25mm2 house wire as battery cables, but it is not a pleasure working with those.

 

Locally I can only get 25mm2 welding cable, but welding cable is not available in different colours for the same size - I preferably want red and black. The different cable sizes are identified by different colours e.g. 25mm2 is blue, 35mm2 is grey and 50mm2 is red.  I can also get inline fuse holders and fuses locally, but no isolators.

 

Can anyone recommend, preferably an online store, which should be able to supply above-mentioned.

 

Preferably fuse holders like these:  http://za.rs-online.com/web/p/rail-mount-fuse-holders/7038579/

 

Thanks  :)  

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I also wanted red and black but could not find any and i live in Pretoria. So i brought red and black shrink sleeving and used that to identify positive and negative. You can buy them at any decent electrical store even Chamberlins sell them.

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I also wanted red and black but could not find any and i live in Pretoria. So i brought red and black shrink sleeving and used that to identify positive and negative. You can buy them at any decent electrical store even Chamberlins sell them.

 

A very long time ago I bought nice thin stranded 25 mm^2 red and black cable from a place in Pretorius street, just before you get to Prince's Park Avenue. I think they were called MegaWatt or something like that.

 

That is one serious fuse setup you have there. Very impressive.

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I also wanted red and black but could not find any and i live in Pretoria. So i brought red and black shrink sleeving and used that to identify positive and negative. You can buy them at any decent electrical store even Chamberlins sell them.

 

I saw a few people doing the heatshrink thing.  I'll try a few other local places today, else I'll also go the heatshrink way.

 

I like your "bus bars".  :D

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The 2 buss bar are there so when i install more batteries i can just connect. I already drilled and tapped 6mm thread.

 

If you eventually do connect more batteries in parallel, just put a fuse in series with each string in case something goes wrong in one of the strings. The fuse rating of the fuse in each string should obviously be less than the rating of the main fuse(s) between the battery bank and the inverter e.g.

main fuse = 100A and 2 strings in parallel - each string should have a 50A or 63A serial fuse

main fuse = 100A and 3 strings in parallel - each string should have a 32A or 40A serial fuse etc. etc.

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The 2 buss bar are there so when i install more batteries i can just connect. I already drilled and tapped 6mm thread.

 

If and when you ever connect more batteries, use the same type and gauge cable and try to have the same total length of cable for each parallel string in order to have the same resistance and thus the same voltage drop across the cabling in each string - it will help to keep the batteries balanced.

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Hi SD

I understand the red and black main wires from the strings to the bus bar being the same length. I've done the same.

What is happening with the bridge cables in the strings? Are they different lengths? There seems to be a pattern, but I don't catch it.

Can you please explain?

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Hi SD

I understand the red and black main wires from the strings to the bus bar being the same length. I've done the same.

What is happening with the bridge cables in the strings? Are they different lengths? There seems to be a pattern, but I don't catch it.

Can you please explain?

 

It all comes down to the fact that the "total length of cable" in each string needs to be the same to have the same total resistance across each string's cabling. In the drawing I've just added some length to some of the bridge cables to try and explain the fact that the total cable lengths must be the same. I'm sorry if that confused you.  :)

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Hi Everyone

One thing to be aware of is, any uninsulated battery terminals, especially when they are close together, become instant welding machines if you happen to 'drop a spanner in the works'!

A bit of shrink sleeving over those Bus Bars could save you some heartache and avoid a fireworks display.  Don't be fooled by low voltage there is still massive current.

A

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Hi SD

I understand the red and black main wires from the strings to the bus bar being the same length. I've done the same.

What is happening with the bridge cables in the strings? Are they different lengths? There seems to be a pattern, but I don't catch it.

Can you please explain?

Just a thought, having 1 cable 300mm longer may cause a voltage drop of 0.1V, is the voltage of each battery exactly the same ?.

Connecting to the busbars pulls the voltage in line.

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Just a thought, having 1 cable 300mm longer may cause a voltage drop of 0.1V, is the voltage of each battery exactly the same ?.

Connecting to the busbars pulls the voltage in line.

 

Connecting to the bus-bars pulls the voltage OF THE STRING in line, but since the resistance of the cabling in the strings are unequal the currents running through the different strings while charging or discharging will also differ and the batteries will be charged and discharged at different rates, effectively utilizing the string with the least resistance the most and the string with the highest resistance the least. That puts the strings out of balance.

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