How many amps does the starter motor need (what AWG jumper cables?) (2 Viewers)

[jasonrohrer]

For my 2001 LX470.

I'm about to buy a set of these:

Spartan Power Heavy Duty Jumper Cables 4, 2 & 1/0 AWG

Made in the USA, Spartan Power heavy duty battery jumper cables come with powerful clamps that provide power to both sides of the jaws.

spartanpower.com

But what AWG is required? I think the 20 ft ones would be more useful, and then I'm looking at a voltage drop calculator:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

But I don't even know what voltage at the end of the span would be sufficient (so what amount of drop is tolerable).

And all this depends on how many amps the starter will pull. I saw someone selling a replacement starter motor that seemed to be rated at 1.4 kW.... does that sound right?

This is assuming that I'm starting MY truck from a donor vehicle, with its 4.7L v8, which is a "big" engine. I'm assuming I won't be trying to use my truck to start even bigger vehicles.

Of course, I also want to get the smallest cables that will work, for storage size, weight, etc.

 

[GTV]

I ditched my cables and got one of these. It stays plugged in at the bottom of my center console so it's always ready.

https://www.amazon.com/gp/product/B015TKUPIC/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

 

[jLB]

There may be multiple variants, but the last starter that I purchased, claimed to be 2kw. If I’m not mistaken that would be ~166A.

As mentioned above, a jump box is more convenient in most cases.

 

[Andrewzlc100]

I ditched my cables and got one of these. It stays plugged in at the bottom of my center console so it's always ready.

https://www.amazon.com/gp/product/B015TKUPIC/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

And its on sale! Great deal

I still have yet to use mine after 2 years of having it

 

[Joe422]

Yea, the Noco jump packs work great. Good idea to on keeping it topped off all the time, ready to go.
No more turning cars around so the jumper cables can reach.

 

[GTV]

Yea, the Noco jump packs work great. Good idea to on keeping it topped off all the time, ready to go.
No more turning cars around so the jumper cables can reach.

And the best part is you can jump your own junk.

 

[Land Shark]

I’m definitely in the jump box crowd. So much I have them in all my vehicles and my kids

 

[jLB]

And the best part is you can jump your own junk.

Something about your wording, makes that sound rather painful!

I’m definitely in the jump box crowd. So much I have them in all my vehicles and my kids

My first NOCO was a 3000a model, which is probably complete overkill, and it’s become the garage & long road trip jump box. Soon after, every car in my family got a 1000a unit. Sadly all of them have been used more to jump other people’s vehicles, BUT I haven’t lost my voltage regulator to helping some dumbass jump start his car, that can’t tell a + from a -, while using a jump box

 

[BnvS]

To answer some of OP questions. For a V8 typically the starter is looking for 200 to 400 amps of draw to start. That's a big variable because all depend on the condition of your engine, condition of your starter wires, starter contacts, and temperature your trying to start your car in. In colder climate your starter is going to demand more energy to start than in summer.

If your just looking to not be stuck then buying a LiIon Jumper pack rated for v8 would be better as they can deliver a lot of Amps in a small package.

But of your like me and have a portable winch. We'll then you want the best thickest cables to deliver the most Amp from the batteries to run that winch which take a lot of Amps to operate. But even then no more than 1/0 is necessary. Most of the time 2 gauge should work as well.

 

[Mark W]

The starters in the FZJ80s (yeah I know this is not the '80s forum, but I happen to know those starters were rated at 1.6KW (2.0 for the 95-59 "arctic starter" and "2.6KW" for the 93-94 arctic starter. Assume 12.0 for the voltage and that gives you 216.6 amps for the heaviest duty of the 3 and 133.3 for the standard starter

Do not ditch your cables just because you have a lithium battery "jump box". In my world the most likely reason to need to get or give a jump is due to extreme cold complicating your starting. Pull your lithium battery jump box out of the trunk in cold weather (does not need to be sub-zero, just cold) and it will laugh at you and give you nothing. Sure, you can take it in the house and set it on a heater vent for an hour. Kinda a pain in the ass if you actually need to go somewhere. If you are out and about... warming it up so it will function might suddenly be a big deal.

A lithium battery jump box is great to have, I have one in each of my rigs. But it is not a magic pill. A great complement, or arguable an alternative, is a capacitor powered jump box. These have no battery and are basically an inert chunk of electronics when they are stashed way awaiting use. When your battery is dead it is seldom 100% dead. Just weak. maybe very very very weak. The capacitor box can suck the very low voltage power out of the battery. Slolwy. Real slow if the battery is real weak. It stores up the energy, converting it to the needed voltage and tells you when it is ready. You hit the key and that 5-20 minutes of 5-2 volt trickle that it sucked from the battery is dumped to your starter as 12V high amp boost. I had to see it to believe it.

AND... I am pretty sure that it can suck the power out of a lithium jump box that is too cold to jump your rig by itself. Have not tried that yet, so I am not 100% certain. But the pair seems like the perfect backup if you might be in a situation where you HAVE to get your rig started (Say... a rig waiting at the trailhead in sub-zero temps...)

Neither will be an ideal solution if you are fighting starting issues such as a flooded engine or something that requires a LOT of cranking and dinking around with the rig to get her to start and run. In a case like that, there is little as comforting as a good set of cables and a friend or patient stranger with a running rig.


Mark...

 

[badlander]

Regarding cable size, it isn't really that important. When you are jumping starting a car the cables are mostly charging the battery rather than powering the starter. The battery powers the starter. Smaller gage cables may just take a few more minutes to get the batttery charged enough to power the starter with enough rpms to fire up the engine.

 

[BnvS]

Regarding cable size, it isn't really that important. When you are jumping starting a car the cables are mostly charging the battery rather than powering the starter. The battery powers the starter. Smaller gage cables may just take a few more minutes to get the batttery charged enough to power the starter with enough rpms to fire up the engine.

I guess this depends on how you use the cables. Most people dont wait to charge the battery and then jump start the car. They usually just put the cables on.. give the donor car a raise and jump start the car.. in that case having bigger cables does help.

but @badlander your right.. going overboard with cable size may be overkill. Just depends on your final usecase.

 

[hoser]

I carry both lithium jump pack and cables. The jump pack won't always start a super dead battery.

@jasonrohrer I was looking at the features of those cables you posted and noticed:

• DOUBLE YOUR POWER! Spartan Power’s unique heavy duty clamps have a copper ribbon which connect each sides of the clamp so BOTH jaws provide power to the battery when starting.

So, I promptly took my jumper cables out and tested the continuity between both jaws of my clamps. No continuity! I now realize my clamps are inferior! haha. ONLY two little teeth are making the connections at the battery. Well, they sell the clamps by themselves ($20/pr).

 

[BnvS]

I carry both lithium jump pack and cables. The jump pack won't always start a super dead battery.

@jasonrohrer I was looking at the features of those cables you posted and noticed:

• DOUBLE YOUR POWER! Spartan Power’s unique heavy duty clamps have a copper ribbon which connect each sides of the clamp so BOTH jaws provide power to the battery when starting.

So, I promptly took my jumper cables out and tested the continuity between both jaws of my clamps. No continuity! I now realize my clamps are inferior! haha. ONLY two little teeth are making the connections at the battery. Well, they sell the clamps by themselves ($20/pr).

View attachment 3552497

@Houser You can probably get copper sleeves and install it on your jaw clamps....I found 1m 10mm tinned copper braded sleeve for $4 bucks shipped. Linky. double your power baby..

 

[hoser]

@BnvS That's certainly a good alternative. Hmm....