Back in the dark ages !

[wanderingbob]

I believe that I was taught that all things being equal, that stranded wire would carry more current than solid wire ? Is that true or am I being misled ?

[deadticket8]

Hey Wandering Bob! That's my style of travel too. I will install 300 watts of panels with 200 AH batteries. Like to wander, boondock, see some sights. I dont want to spend what would be a large down payment on a condo so I can live like I am in a condo! But Lithuium is new to me. Sure seems like they are more cost effective than wiring 6 volt flooded batteries in series. I am learning! Happy trails to you and yours!

[Chum_lee]

^^^ Plus, in USA residential applications, (which generally use romex solid core wire within the walls) where does the temperature match what is typical in an automotive engine bay or along an exhaust system? (catalytic converter) That's right, . . . . in oven/rangetops, water heaters, compressors, furnaces etc., which all use multi strand wire internally, even though they are permanently installed in a residence.

Ambient temperature is important!

Chum lee

[valhalla360]

jkwilson wrote:

Tvov wrote:
I was always told that solid wire conducts / allows more electricity / power. That is why houses are wired with "romex", solid wire, instead of stranded wire like extension cords. Considering how difficult romex is to work with, everyone would prefer stranded wire if it would work better.

Well, that is the simple explanation given to me by electricians!

Solid wire is cheaper to make and easier to connect in household wiring. Stranded wire is better where flexibility is important such as lamp cords or in vehicles.

How many 7.0 earthquakes does the average house go thru per year and how many equivalent events happen in your average RV.

For most practical purposes, once the house wiring is in place, it will never move again to any meaningful degree. Bouncing down a road at 60mph, your RV wiring is undergoing hours long 7.0 equivalent earthquakes every time you travel.

The smaller diameter of the individual strands results in far less work hardening and fatigue damage compared to solid wire.

[S_Davis]

wa8yxm wrote:

johnhicks wrote:
I've read that charging lithiums with an ordinary alternator can smoke your alternator. Investigate before doing that.

0

There are many myths designed to scare you into not improving your life.

Alternators come in two flavors.. both are current limited and the myth is since Iithiums can take a rapid charge they will draw more than the alternator can deliver and burn it out... Nope. alternator knows what it can deliver and won't exceed that amount.

Li's however do take a slightly higher voltage.. Oh that could pop a diode.. Again nope.. it won't.

It might not exceed its max amperage but they can over heat and burn up trying to put out max amperage at idle, unless they have temperature protection. I charge a pair of 280ah LifeP04 batteries and they will take all the amperage I can throw at them until about 95% SOC when they start tapering off the amperage.

[ktmrfs]

jkwilson wrote:

PastorCharlie wrote:
More wires give more surfaces for current to travel on. Finer the strands the greater number of surfaces. Considering the same size of wires.

Current does not travel on the wire surface until the frequency gets to about 20 KHz. It is not an issue for power.

Well, no skin effect exists for ALL frequencies above 0 Hz. (DC). It's just that for it to be noticeable for many conductor sizes it needs to be pretty high frequency. However, Power companies need to deal with skin effect even at 60Hz. given the size of conductors they use.

[wanderingbob]

The original poster here ! I want to thank you all for your help . What I am in the process of doing is installing a 200 amp lithium battery and the proper converter . We consider our selves as " travelers " , not campers , not boondockers . We tend to spend the night where ever we are when we get ready to stop , maybe Walmart but could be just as easy a church lot , police station , hospital , cemetery . What we were hoping to achieve by going with lithium is the ability to run the furnace or a couple of fans all night with out running the batteries down . We travel in a Ram 2500 with a topper , under the topper is mounted a 3400 watt generator , a 35 gallon water carrier , 2 electric bikes and a pancake compressor . We like back roads and stop at all small museums , yard sales , towns with funny names , historic sites , battlefields . We just wander and will go to a campground every 5 or six days . Planning a 5 month trip next summer/fall . Thank you all again . I have owned RVs for 40 years but this " new Tech " is confusing to an eighty year old .

[wa8yxm]

johnhicks wrote:
I've read that charging lithiums with an ordinary alternator can smoke your alternator. Investigate before doing that.

0

There are many myths designed to scare you into not improving your life.

Alternators come in two flavors.. both are current limited and the myth is since Iithiums can take a rapid charge they will draw more than the alternator can deliver and burn it out... Nope. alternator knows what it can deliver and won't exceed that amount.

Li's however do take a slightly higher voltage.. Oh that could pop a diode.. Again nope.. it won't.

[time2roll]

Wire carrying capacity for DC and 60hz electricity will depend on circular mils (copper cross section) not stranded or solid. Also depends on insulation heat rating and if the wire is bundled in a sheath such as NMB, in conduit, or in free air. However this ampacity rating would be used for fuse selection. Selecting the right wire will also depend on the length and amp load to avoid excessive voltage drop. Usually one or two sizes larger will be appropriate vs minimum for ampacity.

Also smaller wire will tend to allow more ampacity per circular mil of copper as there is more relative surface area to dissipate heat. Need to study a wire vs ampacity chart. Very high frequency AC will have some "skin effect" but nothing to think about in an RV.

May not need a shunt (battery monitor). If the battery has bluetooth it may already have an internal shunt. Voltage is still an indicator of remaining capacity although voltage is very flat from 25% to 75%. Depending on the usage and charging patterns the system may stay above 50% and mostly get ignored.

Alternator is only subject to overload/heat damage if the connection is short, fat and no fuse. More likely to have lower than desired charging vs overcurrent situation. Many jump on a DC-DC charger when it is not really needed. Install the battery and measure the situation before adding more equipment.

I pulled my trailer 5 hours today and my alternator is fine. My internal BMS was indicating 99% full. (no harm in a short charge unlike the old lead-acid)

[Boon_Docker]

johnhicks wrote:
I've read that charging lithiums with an ordinary alternator can smoke your alternator. Investigate before doing that.

Charging a couple 100 ah batteries will not hurt the alternator.
It's when you try charging a large battery bank that exceeds the alternator capacity that you run into problems.

[C_Schomer]

I had two electrician uncles... both long gone, now! They said stranded wire ran a little cooler. Whatever, but I still go by the regs. Craig

[wa8yxm]

The answer is not as simple as yes/no
At DC the answer is NO
At RF the answer varies with frequency.

[johnhicks]

I've read that charging lithiums with an ordinary alternator can smoke your alternator. Investigate before doing that.

[Chum_lee]

wanderingbob wrote:
I believe that I was taught that all things being equal, that stranded wire would carry more current than solid wire ? Is that true or am I being misled ?

You were taught correctly, but the difference is negligible. What matters more is the operating temperature of the wire. The cooler the wire is, generally, the more current it will carry. (less voltage drop) Stranded wire, because it has more surface area per foot than solid wire can shed or gain heat more easily than solid wire depending on the ambient temperature and the insulation. Stranded wire has much more flexibility (resistance to vibration) than solid core wire of similar gauge, that's why you generally see its use in aerospace, automotive, and industrial applications.

As the temperature approaches absolute zero (-460 degrees F) wire conductors approach zero resistance. They become superconductors where current flows with little to no voltage.

Chum lee

[wanderingbob]

Guy next door sez that I should not let the alternator on my truck charge my lithium while driving . Is he a dummy ?