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 > Voltage drop on inverter

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phemens

Montreal, Canada

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Posted: 08/12/19 04:49pm Link  |  Quote  |  Print  |  Notify Moderator

Samlex manual says surge rated to 466 amps, so I guess I’d better go with 500a on the fuse. I don’t see much in the way of Class T fuses at 500 on Amazon or am I missing something? See plenty of ANL.
The wiring is fine, I have a run of maybe 1.5 feet of 4/0 from batteries to inverter. I assume i’m Ok with 2/0 between the batteries, would really rather not have to redo all the 2/0 I already made.
Itinerant1, it’s hard to tell from your photo since your cables are all so well managed along the batteries, you’re running 3/0 everywhere?

* This post was edited 08/12/19 04:57pm by phemens *


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bigfootford

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Posted: 08/12/19 05:02pm Link  |  Quote  |  Print  |  Notify Moderator

Gave up on reset-able breakers a long time ago. A 200 amp breaker passing 100 amps was dropping over .1 volts. I use. The fuses.


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bigfootford

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Posted: 08/12/19 05:03pm Link  |  Quote  |  Print  |  Notify Moderator

Dup post.

Itinerant1

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Posted: 08/12/19 05:10pm Link  |  Quote  |  Print  |  Notify Moderator

Yes, neg side batteries to shunt to neg buss, inverter. Pos side batteries to seleniods (part or the ems/cpu), pos buss, classt T, inverter.

Copper bar connecting all batteries in parrel.

* This post was edited 08/12/19 05:27pm by Itinerant1 *

pianotuna

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Posted: 08/12/19 05:23pm Link  |  Quote  |  Print  |  Notify Moderator

.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp hours of AGM in two battery banks 12 volt batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

LittleBill

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Posted: 08/12/19 06:13pm Link  |  Quote  |  Print  |  Notify Moderator

based on the reading from the marine website. it says to fuse for the size of the wire, not for the load on the wire. fuse can cause a voltage drop even when working properly, never thought of that till he mentioned it.

glad to see the voltage drop test worked for you, it found something for me as well. just learned about it a year or 2 ago, and i thought i knew alot of about electricity.


Fuse tutorial.

"#1 Fuses should be sized to not exceed a continuous current of more than 80% of the fuse or breakers rating. Doing so will lead to short fuse or breaker life and the potential for nuisance trips. It also leads to excessive voltage drop across the fuse.

#2 When sizing for charging systems it is often best to use a fuse that more closely approaches the maximum ampacity of the wire. Doing so will still protect the wire but will also result in less voltage drop across the fuse. In other words it will be helpful, from a voltage drop perspective, to use the largest size fuse the wire can handle. Doing so will minimize any added voltage drop across the fuse."





phemens

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Posted: 08/12/19 07:59pm Link  |  Quote  |  Print  |  Notify Moderator

If I understand correctly from those charts, the recommended maximum ampacity for 0000 gauge wire is about 300 amps, but the inverter recommends 466 at maximum surge rating. 80% of that is about 372 amps. So I guess I should aim for 400?

time2roll

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Posted: 08/12/19 08:10pm Link  |  Quote  |  Print  |  Notify Moderator

phemens wrote:

Samlex manual says surge rated to 466 amps, so I guess I’d better go with 500a on the fuse. I don’t see much in the way of Class T fuses at 500 on Amazon or am I missing something? See plenty of ANL.
The wiring is fine, I have a run of maybe 1.5 feet of 4/0 from batteries to inverter. I assume i’m Ok with 2/0 between the batteries, would really rather not have to redo all the 2/0 I already made.
Itinerant1, it’s hard to tell from your photo since your cables are all so well managed along the batteries, you’re running 3/0 everywhere?
Wire is fine. I would go 250 or 300 amp on a class T as it takes a bit of time to open depending on the overload. 200% of rating takes about 60 seconds to open.

[image]

ANL is much faster so maybe 350 to 400.

[image]

These are Blue Sea graphs


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Itinerant1

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Posted: 08/12/19 08:14pm Link  |  Quote  |  Print  |  Notify Moderator

This is from your inverter manual.

[image]

BFL13

Victoria, BC

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Posted: 08/12/19 08:17pm Link  |  Quote  |  Print  |  Notify Moderator

phemens wrote:

If I understand correctly from those charts, the recommended maximum ampacity for 0000 gauge wire is about 300 amps, but the inverter recommends 466 at maximum surge rating. 80% of that is about 372 amps. So I guess I should aim for 400?


If 80% is 466, then you want ampacity of 582.5 for the wire and fuse for that. It is just silly IMO. Your max amps from running say the microwave -130a plus the kettle 90a, and the toaster 90a is 310 and then the furnace comes on for another 10 and run the tap for another 10 so call it 350 to go crazy.

The Vector manual seems to suggest the "surge" rating of the inverter somehow comes from the slow blow ANL fuse. Not sure about that, but the wording seems to say that. If the actual surge ability is from the fuse's time to blow, why should you fuse to the surge rating of the inverter? I don't get it.

Also the wire gauge relates to the length of the wires. Beware of not allowing for both pos and neg return "distances". Those tables are bad for not making clear which length is being counted.


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