Dual Battery Questions

Ducky · January 8, 2020

First I will say... Yes I searched... and well... I'm about to fire up MS Paint to diagram out what I need to do, but have some questions that are either vaguely mentioned, or I just might not get. *Takes a deep breath*

* I plan on running Winch, Offroad Lights and Communication.

1) Do I need the same kind of batteries? I'm assuming the factory battery plus a deepcycle would be a no no? I'd just replace both?

2) From #1... Do I need to do anything fancy if I replace the factory Battery? I know these newer trucks have sensors out the ass etc...

3) I know based on my searches/others, that the spare battery tray does not fit the same model of factory battery... it needs to be a smaller one? and is that okay to mix two different types?

4) Whats the deal with the funky ground on the factory battery? (That I assume I have) Do I need to do that for the 2nd battery as well?

gmcdawg · January 8, 2020

I've read the dual battery threads til absolute frustration and exhaustion. Lots of different opinions, and I doubt you will get a consensus. Having said that....

You won't find a deep cycle to fit in the second tray location, I don't think. Many say that having both batteries the same size and brand/etc is optimal, but in real world I don't think it's that big of a deal.

The second battery tray on my 2018 Sierra doesn't have the lip or the hold down threaded hole, but that's an easy fix with a tiny bit of welding, rather than spend the $$ on a new tray. The part # for the tray with all that can be easily found on those threads mentioned earlier.

I'm gonna put a battery in the secondary tray, after mods, and send power to the bed. Using an old fashioned isolater, and a battery that I have, if it dies in a few years no big deal, it isn't cranking the truck and isn't gonna power something I can't live without. I think some folks stress over this too much and overthink it. If it's isolated, it will charge and will be available for powering whatever is wired to it.

Snowcamo · January 8, 2020

I agree with the above. Batteries of the same size are ideal, but mixing agm and lead acid could cause charging issues in the long run due to the differences of the rates of charge and discharge. It is said that both batts need to ground through the current sensor. Mine don't and charge without issues. Also since the addition of my second batt i have yet to see the voltage on the dash drop below 14v even full tilt. Interesting...

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rbrjr1 · January 8, 2020

Why don't people just go with the same dual setup that the "interceptors" use?

I would think that they pretty much have all the kinks worked out since there is an absolute TON of electrical accessory drain on those vehicles..

Snowcamo · January 8, 2020

Why don't people just go with the same dual setup that the "interceptors" use?

I would think that they pretty much have all the kinks worked out since there is an absolute TON of electrical accessory drain on those vehicles..

Interesting you brought that up. I recemtly did a job for a city entity and asked why they were throwing away so many year old batteries. He told me they dont last the way they are setup.

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rbrjr1 · January 8, 2020

it could be the way they use them, couldn't it? I would think a cops charging system is as extreme duty as it gets..

Snowcamo · January 8, 2020

it could be the way they use them, couldn't it? I would think a cops charging system is as extreme duty as it gets..

Agreed. I figure its the use of lead acid vs agm. They utilize duracell lead acid batts.

Over the years I have found that AGM rules when it comes to high drain or extended. Battery drain intervals. It's hands-down the best way to go if you have to worry about an additional battery drain outside of the factory capabilities. At times at the AGM is the most underrated misunderstood bat when in all seriousness it is the leader of the two types, used.

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Ducky · January 9, 2020

Hrm, maybe I should just upgrade the factory battery for extra load and carry jumper cables (or one of those jumper units)

Is there anything to consider when changing factory battery, no factory trickery of "U will screw up your truck if you buy the wrong battery"

Or are there others with dual batteries that can explain what they did and how its doing?

davester · January 9, 2020

First, figure out what kind of amps your offroad lights and communication stuff will need. Those will be turned on for an extended period of time, so you need the alternator to be able to supply enough power for the rest of the truck AND these new items. The winch is generally used more intermittently, so it's reasonable to just throw in an extra battery, so you can use it a bit more, and then run the engine and the alternator slowly charges it back up.

Snowcamo · January 9, 2020

Hrm, maybe I should just upgrade the factory battery for extra load and carry jumper cables (or one of those jumper units)

Is there anything to consider when changing factory battery, no factory trickery of "U will screw up your truck if you buy the wrong battery"

Or are there others with dual batteries that can explain what they did and how its doing?

I suggest you upgrade the factory battery first. Also the ground to the frame. I take the knowledge from 1slow and nasty and pass it on to others as it works well for me. The factory alternator can handle a lot more if the battery(s) are capable of storing a charge. Lead acid batteries are not capable of doing so. The cost of the northstar and xs batteries is high, but its totally worth the cost in the end.

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Darmichar · January 9, 2020

You need to find something like this:

https://smile.amazon.com/gp/product/B00BFVHDNA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

That's a charge controller for a dual battery setup in a boat, allows mixing standard and deep cycle batteries (start & "house" on boats). I put one in the pontoon boat I had a couple years ago and it worked like a dream.

Clearly this won't work for you as it's only rated for 65A, but I'm sure higher amperage applications exist somewhere.

Allows the system to charge both batteries simultaneously and will discharge both until the "start"/existing battery reaches a certain voltage, then the controller disconnects it and relies on the "house"/added battery for power, reserving the "start" battery for starting.

Snowcamo · January 9, 2020

Here is the one I myself will purchase https://www.sonicelectronix.com/item_18726_PAC-SPR-200.html?from=3-701

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Ducky · January 10, 2020

So if I upgraded just the factory battery (1 Batt setup) What Battery is everyone recommend, back when I had my FJ, I used a Yellow Top, but I heard Optima has gone down hill.

The Optima I used with winch and the lights I plan on using and communication and didnt have any start up issues, so I don't think I HAVE to have a 2nd battery, but thought it would be nice... until i looked into this model of vehicle.

What's the reasoning of bypassing the factory ground? Is it that shady of a connection?

Snowcamo · January 10, 2020

Northstar is at the top right now. They make a group 48. That swaps right in. If your looking for the biggest the tray will fit with ease the 94r. You don't bypass it just replace it with larger wire to suit your needs

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Ducky · January 10, 2020

5 minutes ago, Snowcamo said:

Northstar is at the top right now. They make a group 48. That swaps right in. If your looking for the biggest the tray will fit with ease the 94r. You don't bypass it just replace it with larger wire to suit your needs

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NSB-AGM94R/L4 ?

Oh I see add secondary grounds for the stuff... will that cause any issues with the ground sensor not seeing everything? (Sorry I've just heard of something with the ground, not sure what it exactly does)