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Discussion Starter #21
Interesting, good to know. can't hurt to try. May not take much to resolve the issue.

as far as the core of the issue.. I wish I knew exactly. my best guess is the starter is poorly designed, but I have not found an alternative.I am running a pretty big battery(don't recall the group size, but it based on experience its on the bigger side) and the most expensive/heavy/highest CCA I could find in a traditional lead acid battery.

Its kind of a known issue for the Lambo Gallardo starters to suck, and I am using one (due to the gear box) in my car. For whatever reason a fresh topped off battery is OK, but anything less than that and it struggles. Even Gallardos (i have had two in my house hold) struggle with this.

In my case I have 1/0 + 1awg running from battery to starter, plus 1/0 ground. So a pretty solid amount of copper. Clearly I would prefer to solve the voltage problem (which I am not giving up on) but that will probably not be easy to solve.

Also I have a dedicated wire running from the battery to the amps/twk (4awg) that is only about 3ft long.
 

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You would likely benefit from using a decent agm battery like a hawker powersafe or an nsb90 and not having faith in a wet ‘old technology’ lead acid battery given your last statement

as an example doing db drag years ago, we used to use an nsb90 for 14kw measured over 3 seconds and it would drop to 10.7v, if I dropped to a single amp from the 4 I could keep the voltage over 12v easily on a burp (a burp is very similar to a starter motor in the sense that it’s a large current draw over seconds)
 

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Expensive doesn't mean best.... find the group size, brand, and post a picture of the mounted battery to see what available room you have.

When it comes to starters, a smaller battery with a bigger capacitor bank would work better. Need a picture of the battery, its group size, and 'elbow room' to see if you can use a 6-pack of 2500+F eaton/maxwells.

Better to run 1 or 2 group sizes smaller battery with bigger ultracapacitor. The instant surge from a capacitor would put ANY chemical reaction battery to shame.

Your option is to either isolate the JL and use a small ultracapacitor and diode checkvalve, run a larger ultracapacitor parallel to the battery, or both.

Are there any relays that trigger off all unneeded electronics to help start vehicle? Are you sure that the cranking voltage is causing the JL to reboot?

A Maxwell group 31 ultracapacitor weights ~20lbs. An AGM group 31 battery weighs 70lbs. This is a no-brainer if weight is an issue. Easier to lose 50lbs swapping batteries than living on slimfast.
 
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