Question can I use two 25 amp fuses for a 50 amp wire? (1 Viewer)

[Fisher23]

I have a wire that will use from 30 amp to 50 amps.
Then I have a fuse block that can have 100 amps max BUT each fuse can only be up to 30 amps.

Can I parallel two 25 amp fuses to the single line that will use 30 to 50 amps ?

I would think it would be equally balance the amps. SO I'm thinking it's ok ..just not conventional.

I am using 6 AWG wire.

 

[peesalot]

Nope, thats not right, the electricity does not split the load evenly between the two fuses, if you need 50 amps I would use a breaker as thats getting alot of power for a pop fuse. Curious, what drawing this 50 amps ?

 

[Fisher23]

Thanks,

AC 12 volt unit .. Eco Flow Wave 2

 

[e9999]

In a vacuum, so to speak, you would think it would be OK, cuz yes, the current would split if the fuses are good. In real life, though, I would not do that as there may be issues. For one thing, the 2 fuses / circuits may not be identical and then the current would not split equally, but OK, that may not be critical. More seriously, potentially, though, imagine that one of the fuses would blow, cuz you're at 25A there, say, now suddenly you'd have the full 50A go to the other fuse circuit. If that is rated for only 30A, the fuse would hopefully blow but the full circuit would experience the 50A and something else could burn up as well. Now, you're out not only the fuse but also the fuse block, potentially. Not very likely admittedly, but not a great idea altogether, IMO. Better to keep things clean and simple, I think.
On a related note, 6ga is typically good for around 50A and a bit more, IIRC, depending on insulation, but this may be cutting it close if your wire is not good quality or if the fuses don't react quickly. I'd check that. Don't think that fuses are clean cut affairs that blow instantly at the specified value, there is a fair bit of uncertainty there. And with breakers, there are significant time lag considerations as well.
I'd just keep the wire separate from the fuse block and use the proper fuse / breaker. Lots of options.

 

[peesalot]

Curious what batt set up you will run and what the results(run time) you get ? Please post what you discover.

 

[Fisher23]

I didn't really think about circuits being exactly identical.. until it was mentioned.

I ordered a breaker.

On DC 12 Volts it pulls down 460 watts at max mode and 198 watts on econo mode.
I found when testing it is best to run max for about 1 hour pull down the temp then switch to normal or econo mode.
Then a 100 ah battery will last about 1 hours 40 minutes run time on MAX or 2 hours 55 minutes Normal mode or 6. hours 20 minutes on Eco mode.
I have 288 ah so that will easily cool for 8 hours. I may add another battery.

I also have a small 2000 watt gen set for backup power. It runs 23 hours on a 20lb propane. I don't normally take it with me but it's an option.

I already tested all this out.
I tested the RougeRV 4000 btu AC vs the Eco Wave 2 which is 5000 btu

The RougeRV dropped the temp 9 degrees while the Eco Wave dropped it 15 degrees.
I had to pay return shipping on the RougeRV as there was nothing wrong with it.. just didn't meet my needs.

Running off the inverter the AC unit used 16% more amps. It is better running of the 12 volt. It uses XT60 connectors for the DC.
The real world test of mine the amp hours were weird and didn't seem to compute as expected.
Took a 99.83 AH battery. Ran at 460 watts until it turned off at 17. hours.
(460 watts / 12 volts ) x 1.7 hours = 65 amp hours used?
BUT
(198 watts / 12 volts) x 6.5 hours till it turned off) = 107.25 amp hours. used

I think it didn't compute as the AC must turn off at a lower voltage on econo mode vs max mode. I just check times and didn't check the voltage.

The AC is 5000 btu and pulls down the temp about 15 degrees, so at 92 it dropped to 78 during the day.

Then at night it dropped down to 85 and the tent dropped to 70.

I do have a lithium battery question but will post on a separate thread.

 

[peesalot]

Perfect, thanks for recording all that, it helps as a reference. Are you using Li batts ?

 

[Fisher23]

Yes. Lithium For 3 reasons, mostly because they charge back up so much faster, they produce voltage for longer, and a bonus the weight is less.
The Li are the same price and less than a good deep cell now.
Deep cell 66 lbs Lithium 22 lbs
Price a good Deep cell is $250 vs. Lithium $160 to $199 for 100 amp hours. There has been a huge price drop.

The Eco Flow Wave 2 can also heat the tent-trailer but I got a Vevor diesel heater that I'm going to install for heating.
Electric Heating is not cost effective.

 

[george_tlc]

One other big plus with lifepo4 batteries vs lead acid (deep cycle, agm, etc etc) is that they can be discharged to BMS cutoff and then recharged over and over, 100's or 1000's of times. The lead acid stuff doesn't take kindly to that. So, a 100AH lifepo4 battery can deliver a true and undamaging 100AH. While a lead acid you really don't want to go much below 50%, so your 100AH lead acid is really only 50AH...

It's just that most lifepo4 batteries aren't heavy amp delivery capable, so not for engine starting. winching, etc. Great as a aux battery to run fridges and stuff when camping and topped up via a DC : DC charger (from the main battery/alternator) and/or solar.

cheers,
george.