Electrical Help

[hiddentalnt]

Hi All,
Winter is nearing an end and I'm itching to get camping. Before I do I have a few electrical plans in mind that I would like to complete. We have a Kodiak 243BHSL that we purchased last year and we mainly boondock. I would like to upgrade the electrical to make this a little easier but I plan on phasing my upgrades. I have installed 2 x 6v GC2 in a truck side toolbox with room for 4. This spring I plan on doing the following:

- install Victron BMV712
- install inverter (small MSW)
- install WFCO T30
- install ice cube relays on converter and AC

So the plan and questions...

I don't want to keep opening up my trailer, so while I have the bottom exposed I would like to install wire capable for future upgrades. For example, I have not decided how large of a pure sine inverter I need, but I am planning for a max 1000W. In addition, I am not convinced I need to replace my WFCO8955, but I don't want to have to upgrade my wires in the future.

By big question is what is the acceptable voltage drop for inverters and converters. The converter is currently approximately 15' back in the trailer (base of the bunks in the rear). I would like to keep this location understanding it means bigger wire. I can find into on voltage drop by load... But nothing for the acceptable range for a converter to still deliver full charge. I want the wire to be sufficient if I decide an upgrade to a Progressive Dynamics converter is worth the upgrade (which the BMV712 will help determine).

Similarly, I plan to locate the inverter under the bed. I am trying to avoid the storage bay as I feel there is a higher chance of damage with the frequency of access. The bed storage is used a little less frequent, but it is further. Same question, what drop is acceptable for an inverter? Do I base this on continuous or peak loading. I don't plan on any big loads, maybe a very infrequent microwave (900w) or hair dryer (low wattage)

Last question related to the converter, I read conflicting charge information. I read that chargers will only send what the batteries suck... If I get a higher amp unit, it will only send what the batteries can take before ramping down. I am considering this as I may add batteries in the future if I determine 2 are not enough.

Thanks in advance...

[marjoa]

I do appreciate your diligence to detail.

But, it's my experience that long posts like this, with many questions don't bear much fruit. Folks have a hard time following along and grow impatient to read all the details.

FWIW...try to focus your questions one at a TIME.

JMO...maybe someone will chime in.

Good luck my friend.

Oh....did I mention...

[twinboat]

You want short cables to the inverter.

A 15 ft run will require very large 12 volt cables. Its much cheaper to run 14/2 w ground, romex from the inverter that's installed near the batteries.

Hair dryers can draw up to 1500 watts, not a low watt device.

A low battery, less then 50% charged will take what the charger is capable of putting out.
Once it gets up to 70% or so, internal resistance will start to drop the amps it takes. That's why smart chargers charge then up to 14.6 volts. It helps push in more amps.

The problem with most chargers is that they sense the charging voltage at their output terminals. The charger control may see 14.6 volts, but the battery isn't getting it due to voltage drop in the small gauge wires.

The closer the charger is and the larger the cables are to it, the faster you will charge your batteries.

Inverter/chargers do a good job at charging because they use the same heavy inverter cables, to charge the batteries with.

You could run something like 4/0 cable from the batteries to the under bed area. From there tie in both the inverter and converter. You should fuses each item under the bed and a fuse out by the batteries.

[hiddentalnt]

Thanks for the feedback...I guess I didn't realize how long the post was...just kept writing.

To summarize everything...
What is acceptable voltage drop for converter? For inverters?

[twinboat]

Originally Posted by hiddentalnt

Thanks for the feedback...I guess I didn't realize how long the post was...just kept writing.

To summarize everything...
What is acceptable voltage drop for converter? For inverters?

1 % or 2% max, the same as solar, for a fast charging system.

[Persistent]

A 1000 Watt sine wave inverter may draw 85 amps. Wire gage needs to be 4 AWG for up to 20 feet. A larger gage would be more efficient.
Battery charging is more sensitive to long runs and many connecters. A 50 amp converter charger at 16 feet requires 8 AWG for safe use, but much more for fast charging.
A better design is to have the batteries, charger, and inverter within 2 feet of each other. Make the long run 6 or 8 AWG to the 12 volt service distribution panel.

[Persistent]

Voltage specifications for converter, chargers, and inverters like every other appliance can be obtained from the manufacturers.

[twinboat]

Originally Posted by Persistent

A 1000 Watt sine wave inverter may draw 85 amps. Wire gage needs to be 4 AWG for up to 20 feet. A larger gage would be more efficient.
Battery charging is more sensitive to long runs and many connecters. A 50 amp converter charger at 16 feet requires 8 AWG for safe use, but much more for fast charging.
A better design is to have the batteries, charger, and inverter within 2 feet of each other. Make the long run 6 or 8 AWG to the 12 volt service distribution panel.

20 ft of 4 gauge, at 83 amps, has a 6.8% voltage drop, according to the calculator I used.

That leaves 11.78 volts at the inverter and does not take into account the surge current most inverters offer.

After a few minutes the inverter may be alarming you of low voltage.

My 1000 watt inverter suggests a 150 amp fuse or breaker. I calculate, and use wire for at least that amp draw, using 2% voltage loss.

[Persistent]

A 2000 watt sine wave inverter may draw 160 to 200 amps. That requires 1/0 to 3/0 wire at 16 feet.
Fast charging a bank of 6 CG batteries with a monster charger requires the charger to be next to the batteries.

[garym114]

Calculator for voltage drop given the AGW cable size and length of the cable. Calculator is at the bottom of the page.

https://www.powerstream.com/Wire_Size.htm

[twinboat]

Originally Posted by Persistent

A 2000 watt sine wave inverter may draw 160 to 200 amps. That requires 1/0 to 3/0 wire at 16 feet.
Fast charging a bank of 6 CG batteries with a monster charger requires the charger to be next to the batteries.

Yet they recommend a 250 amp fuse.
You can't fuse higher then the amperage the cable can safely handle.

Underestimating the cable size results in low voltage issues with inverters.

Here is a chart from Xantrex.

[theoldwizard]

Originally Posted by hiddentalnt

I don't want to keep opening up my trailer, so while I have the bottom exposed I would like to install wire capable for future upgrades. For example, I have not decided how large of a pure sine inverter I need, but I am planning for a max 1000W.

I am not sure why you want to hold off with this upgrade until later, but installing an inverter/charger/transfer switch NOW (instead of later) will make things MUCH EASIER.

I recommend on of these Samlex inverter/charger/transfer switch all-in-one. Not cheap, but they are simple to install with all connection made at the same point. Other companies make similar devices.

By installing this combination unit, you can get rid of your current converter and just wire your DC distribution panel directly (via a fuse of course) to your battery bank.

[hiddentalnt]

Originally Posted by theoldwizard

I am not sure why you want to hold off with this upgrade until later, but installing an inverter/charger/transfer switch NOW (instead of later) will make things MUCH EASIER.

I tend to stay away from combination units in general...maybe I'm just paranoid. Cost is usually comparable going with individual units, and if a single unit fails replacement is easier to swallow. Also, if I want to increase my inverter size or change battery type I can upgrade as necessary.

In my case, I have a converter, I'll install a small inverter and a ATS. This allows me to upgrade my inverter next season.

[hiddentalnt]

Originally Posted by twinboat

Yet they recommend a 250 amp fuse.
You can't fuse higher then the amperage the cable can safely handle.

Underestimating the cable size results in low voltage issues with inverters.

Here is a chart from Xantrex.
Attachment 233546

Thanks, I found that chart on their website. I wish they would of added that additional line "we recommend voltage drop less than X%" but I think I will plan around 2% as you suggested.