Battery Cable question

[Johna56]

Im relocating a battery about 3.5 feet from its current location. Ive been advised by the local shop that i can use bolt on splice sleeves to connect the original cables to the extensions, and that I can use a thicker gauge to reduce resistance. My neighborly home garage mechanic is telling me i could lose enough voltage in that setup to cause my plugs to misfire preventing the engine form starting. Is this correct that the loss in voltage will likely be noticeable? Thank you.

 

[plugsandsparks]

If you use decent crimp or bolt connectors and cable at least as thick as the original, there will be no problem. You will know straight away when trying to start the car. Once its running the alternator takes over anyway.
Batteries are moved all the time in competition cars, usually from under the bonnet to the boot. So its a well trodden route. BTW what car is it and where is the battery moving from - to

 

[Wilko]

Is this correct that the loss in voltage will likely be noticeable?

The answer really depends on how good a job is done. It sounds like the leads will be at least twice as long as the originals so if they are not upgraded then you may have issues in winter or as the battery ages. Keep in mind the original leads will have been sized down to hit a price and still work, they won’t be oversized ...

 

[Johna56]

Thank you for responding. The extensions are 4 gauge, about 2x as long as the lead, which are 6 gauge. I think the bolt sleeves are good quality. I took my time, soldered the ring terminals and shrink wrapped all the connections. The vehicle is actually a 2 stroke 800cc watercraft. cables and connections are tinned. I fabricated the cables this eve and am hoping to do the install this weekend. I guess ill find out then and post up. Thanks again .

 

[Wilko]

Hi - that’s an upgrade of 16mm2 to 25mm2, which hopefully will work for you. If you have problems it’s likely one more step up (to AWG 2 or 35mm) will fix it as that will give the same voltage drop as the originals.

 

[telectrix]

I would have replaced the existing leads wirth longer ones, maybe going up a size. then there wouldn't be joints to possibly cause high resistance after some time.

 

[Johna56]

Thanks for al the replies. The machine didnt start, but did turn over and over. A couple guys that know this engine say 10.3 volts isnt enough to start this engine. There is spark, but it's slow, like a spark every second or more. If i run one long power cable (no splicing), but leave the ground spliced, will i still likely see a reduction in the volts? I cannot physically reach the grounding point under the engine so its tough run a a single cable to that spot. I gotta take some course on electricity......

 

[ruston]

As @telectrix . I would try and avoid joins in the cable , especially as the nature of the the vehicle and vibration.. 800cc is not a great load in the life of suitable amp hour battery , the cables mentioned should be fine,

 

[Johna56]

Update....... starting issue was the cables. I went back to the original cables and its starting no problem. If I get back to this project, ill try direct 2 gauge cables. Thank you all.

 

[telectrix]

any joint in a cable can lead to a bit of high resistance. when the cable is supplying a large current as in starting an engine, it doesn't need much if a resistance to lead to volt drop at the load end, causing problems.yourstarter may crank the engine, but there may no be enough voltage left for the ignition circuit to fire up the motor.