Please note that whatever the actual and particular math works out to be in the following example regarding copper cross section ....1 single wire of 4 awg would be superior to 4 parallel runs of 10 AWG, if 4 parallel runs of 10AWG would equal the same amount of copper 4 AWG. There are sites that will give the actual math as to how many parallel runs of XXawg in parallel......will equal one run of 4 awg................. I do not know off the top of my head
Also keep in mind that each of those four 10 AWG parallel runs should be fused individually at ~ 30 amps each, whereas one run of 4awg can be fused once at ~100 amps for less overall resistance.
Also note that much wire sold ,is rated as SAE gauge, which is significantly thinner than AWG, by 12 to 20% or so. Don't hold me to those exact numbers, just know 4 SAE gauge is noticeably thinner than 4 AWG, and marketers are born liars, and proud of it, so please do not believe their manipulations, or even product descriptions. Truth in advertising has never occurred and certainly hasn't tried recently. Anything but.
Some people like to get caught up in wire ampacity, or what it is rated to carry.
When there is a hungry battery at the end of a circuit, the thicker wire can allow much larger amperages to actually reach the battery, as voltage at the battery will be higher. Higher electrical pressure at both ends means higher amperage delivered. higher mperage delivered meas faster recharging. Faster recharging means that the next discharge begins at a higher state of charge. A higher average state of charge means higher battery longevity, and a higher to cycle per $$ ratio.
A higher cycle to $ ratio means more travelling budget available to you.
Thick copper is your friend when depleted batteries are involved, except when idling( not moving) to recharge, as it is possible the alternator might overheat or wear out prematurely from being maxed out and not having the ability to trnasfer the heat from itself via a fast belt driven spinning fan and vehicle speeds fast enough to flush hot air from underhood and keep alternator cooler.
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take note some (lesser $$) AGm batteries will say to limit charging amps to no more than 30amps per 100AH of capacity. Thick copper and a fast spinning cold alternator can exceed this limit for long enough for that warning to become very valid, and in this instance thinner copper can safely limit the starving battery from overeating and purging from both ends.
Usually alternators are more expensive than batteries. There are exceptions. A hard working alternator will wear out faster, especially at low speeds when battery is depleted.
Idling to recharge is usually very hard on an alternator. Avoid unless temperature data reveals otherwise, but safe to say idling to recharge a depleted battery is very hard on an alternator.
hHgher roms move the alternator fan spins faster. Higher vehicle speeds keep the underhood temps lower, keeping alternator cooler, allowing into produce more juice, for longer.
Many people make the mistake of saying XX AWg wire can only pass so much current, or will always be able to pass this much current, without realizing that the voltage at the battery end of the circuit is a huge factor in how much amperage the battery can ask for at that voltage. When a battery is depleted below ~80% , thicker wire between charging source and battery ensures that the battery can reach 80% significantly faster, regardless of what any ampacity chart says is possible. There is much BS online concerning wire cross section and the ability to recharge a depleted battery, the BS being from those who read an Ampacity chart without really understanding OHMs law.
The battery can also easily take a high amp recharge. High amp recharges are not 'ideal' or necessary or required(usually) when one has all the time in the world needed to recharge. but when the next discharge cycle begins late afternoon, the high amp recharge is less detrimental, compared to to beginning the next discharge at a lower initial state of charge, because someone's grandpa once said that a slow trickle charge is always best, no matter what.
The trickle charge mentality should be forgotten, disparaged, respectfully and perhaps quietly with prejudice on a daily deeply cycled battery.
Grandpa was wrong in this instance.
No need to tell him though, Grandma's been doing that since day one, give him a break.
Thick wire between depleted battery and charging source, Will pay for itself in battery longevity.
Somebody just ran a triathalon and is gasping for breathe. You gonna say breathe through this kinked cocktail straw instead of this doubled Mcdonalds soda straw?
Do not do the same thing to your depleted battery while quoting an Ampacity chart that says the cocktail straw is perfectly adequate and safe.
This post was made for general consumption, not to disparage anyone. No offenses intended.
Ampacity charts have sent many a battery recharger down a path of mediocrity and premature battery failure.
Pay more for adequately thick copper between chargign source and depleted battery now, or pay much more for recycled lead later and more often.
Your choice.
As usual, it is much easier to do it right the first time, than correct the issue hoping to get it right the next time.
'Good enough' has its limits, and more so when it comes to recharging a lead acid battery, which are all stubborn selfish little ?@^(&WWW's which really want a stupidly intense recharge regimen to even approach 'ideal' cycle life.
Cha Ching!
