Charging system upgrades with smart alternator equipped trucks

[voyager1500]

Hi,   I have a 2017 silverado 1500.  I would like to set up a dual battery system, but i'm getting bogged down with all the info and technology on these new electronic systems.  Apparently you cannot use a traditional dual battery isolator on the new trucks with the smart alternators.  So I found numerous versions, but they all have widely varying descriptions so i'm finding myself spinning around and unsure of what I actually need.  there are smart isolators, but there are also dc to dc battery chargers for use in dual battery set ups.  what do I need ?  do i need both the smart isolator and a battery charger ?  or just one or the other ?  ugh...   I just installed a yellow top optima as my primary, and will add a smaller yellow top for the auxillary.  the brands I have found include: Redarc, Victron, smart gate, keyline, etc.  THe prices are all over the place.  I m certainly in no position to spend a thousand dollars to do this, so hoping i'm just confused with what I need and there is a simple resolution.   End result i'm looking for.......  dual batteries, isolating main from aux so that I can protect starting battery , while using aux to power accessories, then my alternator charges both while driving.  sounds simple right ?  

 

TIA

 

I also found a blue sea systems ACR unit that sounds like it fits the bill, but again, confused as if that is all i need, or ?????  

 

 

Edited September 13, 2020 by voyager1500

[VanguardK2]

Subbed as I am having the same issue...

Sent from my SM-G986U1 using Tapatalk

[bdbake01]

Not sure why this seems to confuse everyone?  Granted, electricity is my "day job", but still.  There's a LOT of bad info out there.  Where did you hear that a standard battery isolator won't work?  

[voyager1500]

Saw it in several spots.  something to do with the way the smart alternator varies voltage would not excite the charging ckt and the second battery would not get charged .  Thus requiring a special smart relay that could sense the voltage variations and also have an exciter ckt to make the smart alternator s charging ckt activate to provide enough voltage to charge both batteries.  Then somewhere else I read that you needed a dc to dc battery charger in addition to ensure that the second battery received 100% charge.  all while isolating the two so that the main battery would always be charged and protected from draining.  

[bdbake01]

6 hours ago, voyager1500 said:

Saw it in several spots.  something to do with the way the smart alternator varies voltage would not excite the charging ckt and the second battery would not get charged .  Thus requiring a special smart relay that could sense the voltage variations and also have an exciter ckt to make the smart alternator s charging ckt activate to provide enough voltage to charge both batteries.  Then somewhere else I read that you needed a dc to dc battery charger in addition to ensure that the second battery received 100% charge.  all while isolating the two so that the main battery would always be charged and protected from draining.  

No offense, but that's all poor advice.  These boards are full of people making random statements based on limited to no understanding of how the system(s) that they are making definitive statements about even work in the first place.  The only thing you need to do is make sure that the grounds from both batteries go through the factory current sensor.  That way the alternator's control algorithm will be able to detect when you're using current from either battery, which will prompt the voltage to increase - ie go into "charge mode" vs reduced voltage / float / etc.  This isn't perfect mind you, but having two isolated power systems that share a single charging source (alternator) will always have compromises.  But it will also work just fine, and you won't have some stupid complicated system that never works quite right.  

 

For these vehicles, I'm a fan of the WirthCo Battery Doctor.  Because of the method it uses to charge the secondary battery (technically a battery equalization), it will work extremely well with our charging system.  It also had a very handy manual paralleling function, and lots of built in protection.  It's also affordable.  You'll still want to make sure your battery grounds both run through the current sensor, but this isolator will help the OEM charging algorithm do it's job a bit better.  And since it charges via equalization, you don't run the risk of overcharging the non-depleted battery.  

 

https://www.amazon.com/WirthCo-20092-Battery-Doctor-Isolator/dp/B0058SGDFK/ref=as_li_ss_tl?ie=UTF8&linkCode=sl1&tag=nerdtechy-20&linkId=826133debec6908fb473f9ed2e973dc7&language=en_US&th=1

 

[voyager1500]

I found a video that explained it a little better.  So the traditional isolators will work, but work better on pre 08 vehicles without the smart alternators.  The DC DC battery charger is used on newer vehicles because it allows the second battery to get 100% charge.  THe charger will also have the isolation feature that will prevent the main batttery from draining when vehicle is not running.  The conventional isolator will not allow 100% charge and you will have less resere power than expected with whatever battery you choose.  Of course the dc dc set up is like 4 xs the cost of the old school isolators.  but guess it's the right way to go when your spending $500 plus on batteries.  Me and my dumb ideas...  

 

CHeck out this video, a bit long, but goes into detail on all these technologies and systems.

 

[gmcdawg]

bdbake01, can you provide a little more info on where and how to wire into the factory current sensor?  Where is it located.  Any pics of your install would be great!  Looking to do this too.

[aggets]

looking at a Victron DC to DC Charger. They have a 18 and 30 amp model. I am wondering if the 30 amp model would draw to much current from my factory alternator. Thank You.