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Open Roads Forum  >  Tech Issues

 > Voltage drop on inverter

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phemens

Montreal, Canada

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Posted: 08/12/19 08:20pm Link  |  Quote  |  Print  |  Notify Moderator

Agreed, that’s why I was mentioning 500 amp fuse earlier, but then the discussion on wire ampacities and off we go. I seriously learn a whole bunch every time I browse here, but it might drive a normal person off the cliff [emoticon]
I can go either 500 amps ANL or 400 amps on a T class. Haven’t found a reasonable option for 500 amp T class yet.


2012 Dutchman Denali 324LBS behind a 2006 Ford F-250 V10 out of Montreal
1 DW, 1 DD, 1 DS, 2 HD (Hyper Dogs)
1Kw solar, 400 AH LIFePO4, Yamaha EF2000 gen, Samlex 3000w Inverter

pianotuna

Regina, SK, Canada

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Posted: 08/12/19 08:21pm Link  |  Quote  |  Print  |  Notify Moderator

I believe a calculator is a much better choice than a table:

https://www.southwire.com/calculator-vdrop


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.

phemens

Montreal, Canada

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Posted: 08/12/19 08:26pm Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

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.


To clarify, the inverter manual recommends 500a. The Samlex Manuel does not suggest the surge is based on fuse. Agreed that I never will likely approach the limits of the inverter, but the fuse melting (300a ANL in Blue Seas block from previous inverter) while I had the hot water heater running on inverter has me thinking twice... given a negligible price difference at 400 amps in a heavy duty T class fuse and holder, that’s where I would go unless someone can convince me otherwise,

time2roll

Southern California

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

phemens wrote:

Haven’t found a reasonable option for 500 amp T class yet.
I think your battery would give up before the 500-T opened.


2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
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pianotuna

Regina, SK, Canada

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Posted: 08/12/19 11:28pm Link  |  Quote  |  Print  |  Notify Moderator

phemens I have one class T fuse on each battery bank rated at 350 amps. I never use heavy loads without both banks strapped together.

Since you have two LI batteries in parallel, you could, in theory, put one 350 on each positive post.

MEXICOWANDERER

las peñas, michoacan, mexico

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Posted: 08/12/19 11:43pm Link  |  Quote  |  Print  |  Notify Moderator

Telephone and talk to Blue Seas Systems. They have their act together when it comes to supplying what you need. Phone: +1 800-222-7617

A direct continuous short can blow your batteries to shreds. Ignite your inverter and a bunch of other nasty deeds.

They say and I agree CLASS T fuses are the proper way to fuse ANY inverter. I learned this 30 years ago from Trace Engineering. But Blue Seas will set you straight.

Circuit breakers have a specific use for a specific application and PROTECTING ELECTRONICS is not on that list.

Hope this helps

phemens

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Posted: 08/13/19 05:41am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

phemens I have one class T fuse on each battery bank rated at 350 amps. I never use heavy loads without both banks strapped together.

Since you have two LI batteries in parallel, you could, in theory, put one 350 on each positive post.


I have a total of 5 batteries to wire up. Someone (might have been you!) was suggesting wiring them in 2 banks (1 of 2, 1 of 3) and then joining at the bus. You have your banks separated because they're different capacities/age? Mine are all same (100AH) and same Mfg date.

Right now I was putting them all in parallel and fusing before the positive bus. I'm assuming I don't need a separate fuse to the inverter in that setup.

phemens

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Posted: 08/13/19 05:42am Link  |  Quote  |  Print  |  Notify Moderator

MEXICOWANDERER wrote:

Telephone and talk to Blue Seas Systems. They have their act together when it comes to supplying what you need. Phone: +1 800-222-7617

A direct continuous short can blow your batteries to shreds. Ignite your inverter and a bunch of other nasty deeds.

They say and I agree CLASS T fuses are the proper way to fuse ANY inverter. I learned this 30 years ago from Trace Engineering. But Blue Seas will set you straight.

Circuit breakers have a specific use for a specific application and PROTECTING ELECTRONICS is not on that list.

Hope this helps


I did speak with someone at Blue Seas, they agreed that a class T 400 amp fuse would be sufficient for my setup, that's what I ordered.

LittleBill

Scranton, PA USA

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Posted: 08/13/19 05:55am Link  |  Quote  |  Print  |  Notify Moderator

phemens wrote:

MEXICOWANDERER wrote:

Telephone and talk to Blue Seas Systems. They have their act together when it comes to supplying what you need. Phone: +1 800-222-7617

A direct continuous short can blow your batteries to shreds. Ignite your inverter and a bunch of other nasty deeds.

They say and I agree CLASS T fuses are the proper way to fuse ANY inverter. I learned this 30 years ago from Trace Engineering. But Blue Seas will set you straight.

Circuit breakers have a specific use for a specific application and PROTECTING ELECTRONICS is not on that list.

Hope this helps




I did speak with someone at Blue Seas, they agreed that a class T 400 amp fuse would be sufficient for my setup, that's what I ordered.


Remember you also need to know the insulation rating of your wire, if its 200c that wire is rated at 510 Amps, there are 2 things you need to look at wire gauge and insulation rating. voltage drop over distance determines what gauge wire to use as well.

remember you can always parallel fuses to get the rating protection you want ( 2x 250A) to get 500 etc..





pianotuna

Regina, SK, Canada

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Posted: 08/13/19 06:52am Link  |  Quote  |  Print  |  Notify Moderator

Hi phemens,

There is only one way to wire an odd number of batteries together in a balanced manner. Please see method #3 at this site:

http://www.smartgauge.co.uk/batt_con.html

My first battery upgrade was to seven marine batteries totaling 875 amp-hours. One bank of 4 and one bank of 3, for reasons of physical space. Having them switched allowed me to charge one bank, while using the other. It also allowed me to equalize the banks with 1/2 the solar panels. With the cost of solar (5.50 per watt) at the time, it made sense to be able to switch them.

Given that LI's need for balance may be greater than lead acid--I would certainly make the effort to do method number three. Feed wires to the bus bar need to be identical lengths. Do not "stack" all the feeds on one bolt. I suppose a "sandwich" would work with one connection on top of the bus, and one beneath the bus.

bolt-->feed wire-->bus bar-->feed wire-->nut.

and

left bolt feed feed, middle bolt feed draw, right bolt feed feed.

the draw wire would go to a second bus where all the various loads are connected.

It would be nice to find a round bus bar or 3 inch copper washer.

I would use T class fuses on each positive battery post.

phemens wrote:



I have a total of 5 batteries to wire up. Someone (might have been you!) was suggesting wiring them in 2 banks (1 of 2, 1 of 3) and then joining at the bus. You have your banks separated because they're different capacities/age? Mine are all same (100AH) and same Mfg date.

Right now I was putting them all in parallel and fusing before the positive bus. I'm assuming I don't need a separate fuse to the inverter in that setup.


* This post was edited 08/13/19 07:35am by pianotuna *

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