Battery charger DC fuses

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Wilfred123

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Hi,

I have just fitted a new Victron IP22 30amp 3 output battery charger to replace a faulty Sterling unit. I want to add fuses in the cables that run from the charger to the batteries and was thinking that fuses of 40amps would be sufficient. I have seen that 12 volt planet sell 40amp standard size blade fuses which would fit into a standard fuse holder. Do people think that its acceptable to use blade fuses for this purpose or should I be looking at the more heavy duty midi link types?

Thanks
 
Technically no, these fuses have a breaking capacity of 1000A and the potential short circuit current is likely to be above that.
You are also looking at about 70mV of voltage drop, which will influence charge rate.

You are not trying to protect the battery from being charged too fast, you are presumably trying to protect the wiring from a short?

In practice, will you ever get a 1000A + short? Your call!
 
If the cable gets shorted for any reason, a 6mm or 10mm cable makes a nice electric fire, for a short time.
 
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I used a strip fuse because - and I stand to be corrected here, I couldn't find a blade fuse holder with ring terminals that could be mounted on a bulkhead. Didn't like the idea of a spade terminal blade fuse holder floating around on the cable.
 
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I was just installing fuses as its recommended in the instructions, as they are connected direct to the batteries I assume that fuse is required to protect from a short rather than anything to do with charging.
I thought that if a fuse was rated at say 40amps, this was its continuous rating and that it would blow at around 80amps. Is that not the case?
 
Wilfred123 said:
I was just installing fuses as its recommended in the instructions, as they are connected direct to the batteries I assume that fuse is required to protect from a short rather than anything to do with charging.
I thought that if a fuse was rated at say 40amps, this was its continuous rating and that it would blow at around 80amps. Is that not the case?
Click to expand...

It wont blow instantaneously at 80 amps

If you look for the spec you will find graphs of time taken to blow vs current.

Typically at 80 amps it will blow in about 2 seconds

at 800 amps it will blow in under 0.01 seconds
 
Wilfred123 said:
I was just installing fuses as its recommended in the instructions, as they are connected direct to the batteries I assume that fuse is required to protect from a short rather than anything to do with charging.
I thought that if a fuse was rated at say 40amps, this was its continuous rating and that it would blow at around 80amps. Is that not the case?
Click to expand...

You are correct.

Personally, i didn't fit fuses. My charger is very close to the batteries and the cables only pass through a wooden bulkhead. There simply isn't anything for them to short out to. If there was i'd obviously fit fuses and i'd fit blade fuses.
 
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