fuse size and type

[MikeB]

I have tried to find an answer but haven't. How to determine fuse size with 1500w inverter and 4 6v batteries in series for 24v output, 2, 12v 150w panels in series. Also what type of fuse is best or sufficient..I'm assuming the blade type automotive in line fuse is ok.

Thanks,

Mike

[SunEagle]

I have tried to find an answer but haven't. How to determine fuse size with 1500w inverter and 4 6v batteries in series for 24v output, 2, 12v 150w panels in series. Also what type of fuse is best or sufficient..I'm assuming the blade type automotive in line fuse is ok.

Thanks,

Mike

Mike

First off those automotive fuses are not usually rated much above 12volts so they won't work for your 24volt battery system. You will need to get DC fuses rated 24volts or more.

Quick calculation for fuses would be to divide the equipment wattage rating by the voltage. So for 1500watts it could pull ~ 63 amps at 24volts. A minimum fuse would be sized by multiplying the amps x 1.25 or 63 x 1.25 ~ 80 amps.

The fuse is there to protect the wire so if you choose a 100amp fuse then you wire must be able to handle 100 amps.

BIG CAUTION. Most inverters have a max wattage rating so you could draw almost double that 63 amps (for a short time) if that inverter has a 3000 watt max rating.

[MikeB]

Mike

First off those automotive fuses are not usually rated much above 12volts so they won't work for your 24volt battery system. You will need to get DC fuses rated 24volts or more.

Quick calculation for fuses would be to divide the equipment wattage rating by the voltage. So for 1500watts it could pull ~ 63 amps at 24volts. A minimum fuse would be sized by multiplying the amps x 1.25 or 63 x 1.25 ~ 80 amps.

The fuse is there to protect the wire so if you choose a 100amp fuse then you wire must be able to handle 100 amps.

BIG CAUTION. Most inverters have a max wattage rating so you could draw almost double that 63 amps (for a short time) if that inverter has a 3000 watt max rating.

Yes it does have 3000W max voltage. I am using #4 wire for the battery jumpers and from batteries to the inverter. Please excuse my ignorance, so what type of fuse do most folks use. I will be using 100 amp fuse....I just don't know what type, with a reasonable cost, to use.

thanks, I really appreciate it. I'm just about ready to put it all together on the little cabin in NW Arkansas.

Mike

[SunEagle]

Yes it does have 3000W max voltage. I am using #4 wire for the battery jumpers and from batteries to the inverter. Please excuse my ignorance, so what type of fuse do most folks use. I will be using 100 amp fuse....I just don't know what type, with a reasonable cost, to use.

thanks, I really appreciate it. I'm just about ready to put it all together on the little cabin in NW Arkansas.

Mike

Probably one of the better fuse & fuse holders is made by Blue Sea. They fit right on the battery terminals and are rated over 50vDC. Another one which is similar is made by Bussmann CBBF type.

There are others. Just make sure they are rated for 24volt or better and have the ability to connect the wire size you are going to use with the proper terminations.

[MikeB]

Probably one of the better fuse & fuse holders is made by Blue Sea. They fit right on the battery terminals and are rated over 50vDC. Another one which is similar is made by Bussmann CBBF type.

There are others. Just make sure they are rated for 24volt or better and have the ability to connect the wire size you are going to use with the proper terminations.

I've been gone for a few days and just wanted to say thanks very much for the info.

Mike

[SunEagle]

I've been gone for a few days and just wanted to say thanks very much for the info.

Mike

You are welcome. Let us know what type of fuses you get.

[Pat Padden]

Circuit breaker in lieu of fuse?

I am also new to this. I'm wondering if a 100amp circuit breaker would work as well in this situation? Like the unit below:

http://www.rockfordfosgate.com/products/details/rfcb100

[SunEagle]

I am also new to this. I'm wondering if a 100amp circuit breaker would work as well in this situation? Like the unit below:

http://www.rockfordfosgate.com/products/details/rfcb100

Pat

It is hard to tell from that link what the voltage rating is for that circuit breaker or if it is DC rated.

The circuit breaker should be rated for DC voltage and while it should work, but sometimes they do not perform as well as a fuse.

I use both fuses to protect my wiring and a circuit breaker as a way to open the circuit without having to pull the fuse out of it's block.

[Pat Padden]

Pat

It is hard to tell from that link what the voltage rating is for that circuit breaker or if it is DC rated.

The circuit breaker should be rated for DC voltage and while it should work, but sometimes they do not perform as well as a fuse.

I use both fuses to protect my wiring and a circuit breaker as a way to open the circuit without having to pull the fuse out of it's block.

SE. This is a circuit breaker used for automotive sound systems. So it's rated for 12v DC. Do you think that it would be appropriate to use a breaker like this in a 24v or 48v DC PV system?

[SunEagle]

SE. This is a circuit breaker used for automotive sound systems. So it's rated for 12v DC. Do you think that it would be appropriate to use a breaker like this in a 24v or 48v DC PV system?

I do not feel that breaker is good for anything above 12v dc. So I wouldn't use it.

[Pat Padden]

I do not feel that breaker is good for anything above 12v dc. So I wouldn't use it.

Thanks loads.

[MikeB]

You are welcome. Let us know what type of fuses you get.

I got the terminal fuse, Blue Sea 100 amp. Everything is working great. Thanks for all the info from the good folks here.

Mike

[SunEagle]

I got the terminal fuse, Blue Sea 100 amp. Everything is working great. Thanks for all the info from the good folks here.

Mike

You are quite welcome. Glad I could help you.

[Drifter_sa]

What about fuses used in trucks with 24v systems, would they be ok I wonder?

[inetdog]

What about fuses used in trucks with 24v systems, would they be ok I wonder?

They should be OK for a 12V system, depending on where you use them. For example trying to use them in a DC combiner where the open circuit voltage can be higher would not be a good idea unless you look at the fuse specifications and find a higher DC voltage listed.