Dual battery opinions

[Chad D.]

With a fridge in mind, I am leaning toward the twin battery setup for a few reasons.

1) Peace of mind, knowing that my starting battery will not be depleted if I don’t keep up on charging well enough from time to time.

2) Easy jump start from auxiliary battery if the main battery peters out.

3) Full time power to power outlets fed from the auxiliary battery. (Why doesn’t Toyota give us an outlet that stays hot without the key???)

Vehicle is 2018 Tundra. I’ve only looked at the Genesis Off-road system, which looks really slick. Not super huge batteries, but I think they’ll be adequate for my needs.

Thoughts on this option, vs. other ideas? Cost is always a factor, but I am not concerned about the $1,100 if this is the right plan. Looks totally idiot proof, and I won’t lose any space. I do not want to put batteries in the back seat or in the bed. I use this truck for more than camping, so I need to keep everything open...

If there is no clear winner, does anyone know of a current discount code for Genesis? I am ready to get this moving...

Thanks!


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[rayra]

Are you 'handy' at all?
Here, go browse this topic and then decide if you still think $1100 for a dual battery setup is at all reasonable -
https://www.expeditionportal.com/fo...eap-isolated-dual-battery-setup-for-50.77503/

/I mean I know DIY doesn't mesh with this place's revenue model, but ffs, $1100??

 

[Chad D.]

To be fair, nearly $600 of that is in battery cost...

Thanks for the link! I will go check it out. I am handy, and not a bad fabricator. However, I have been leaning more toward plug and play lately, as I just don’t have the time that I used to.

This is the kit I’m eyeballing:




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[Chad D.]

Thats as easy as remove a relay and fit a jumper in place of its contacts.
Or...Rather than a jumper, to the load side of that relay contact, apply 12V from an alternate battery.

Now you’re talking! I assume it’s a single relay for all of the 12v outlets. Low on the dash, in the console, and between rear seat heat vents... I’ll dig into locating that relay and swapping the feed. ‘‘Twas just a little gripe, but should be a very simple fix!


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[DiploStrat]

This subject has been beaten into the ground and I have three potentially useful documents on my website, that said:

-- Dual batteries to save yourself from killing the camper battery is a bad idea. Size your camper battery for your needs, so that you cannot kill it.

-- Charging a lead acid battery properly depends on time, amperage, and voltage. If the voltage of your vehicle is right, then properly sized wires with a switch or a relay and you are all set. If not, you may need a battery to battery charger (B2B) or some device to adjust your voltage.

-- Time is the biggest issue. You will probably need shore power or solar to keep your batteries healthy.

A dual battery system is not the goal, merely one way to achieve the goal.

All the best!

 

[Chad D.]

This subject has been beaten into the ground and I have three potentially useful documents on my website, that said:

-- Dual batteries to save yourself from killing the camper battery is a bad idea. Size your camper battery for your needs, so that you cannot kill it.

-- Charging a lead acid battery properly depends on time, amperage, and voltage. If the voltage of your vehicle is right, then properly sized wires with a switch or a relay and you are all set. If not, you may need a battery to battery charger (B2B) or some device to adjust your voltage.

-- Time is the biggest issue. You will probably need shore power or solar to keep your batteries healthy.

A dual battery system is not the goal, merely one way to achieve the goal.

All the best!

I appreciate the input DiploStrat. We’ve wandered a tad off course, but that’s OK.

I’m not expecting this to prevent killing the auxiliary battery. I’m also on board with the necessity of properly charging whatever system I wind up with.

I was looking for input on the specific dual battery setup from Genesis Off-road, and seeing if there was any other specific systems that I should consider that would also retain all of the usable space inside the cab and bed. As well, I would appreciate any known, currently valid, discount codes for that particular site.

This wasn’t intended to become a thread regarding the validity of a dual battery system.


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[DiploStrat]

Sorry, was responding to your three numbered points.

Can't help you with the Genesis. Don't have a Tundra but I do know that some Toyotas only get up to 13.9v, which is a bit low.

Best wishes!

 

[Ducky's Dad]

I just watched the Genesis video, and it does look like s slick and sanitary installation. Lots of convenience, but at a high price. I have an '08 Tundra and finding space for a second battery is a challenge. My short term solution is a Grp 31 in the stock position while I figure things out. Genesis uses a pair of Grp 25s which are only 65ah each, so you get the redundancy of a dual system but not a lot of capacity. Given my experience with Odysseys, I'd probably opt for Northstars.

 

[DaveInDenver]

Genesis uses a pair of Grp 25s which are only 65ah each, so you get the redundancy of a dual system but not a lot of capacity. Given my experience with Odysseys, I'd probably opt for Northstars.

The dual system I run replaced a stock Toyota with a pair of group 25/35 Odyssey PC1400. You gain redundancy and a single high end group 25 is more than sufficient IMO as a replacement primary battery. What you lose is capacity when running a long term discharge mainly.

My stock True Start 27F was rated 710 CCA and 165 minutes reserve capacity. A single PC1400 is rated 900 CCA and 130 minutes. True Start are probably made by Interstate and being intended just for starting they don't give a 20 hour capacity spec, but it's probably around 90 or 100 amp hours if pushed. So clearly there's no substitute for the volume of lead and acid. But a pair of 25/35 is around 130 amp-hour so you do gain overall. So in a strict sense you would have just as much capacity for a winch session.

I gained about 30 lbs total with a pair of Odysseys over the stock battery and it takes up a bit more space in the stock location. Point I'm making is as a main/backup solution I decided it was acceptable. I would suggest that going this route you take the time to wire everything to the main and truly leave the aux as backup to really gain the benefit of a redundancy. In the case of a winching I'd personally isolate the aux battery and rely on the alternator sooner with the gain being that if I toast my main battery winching I won't be stuck.

 

[dreadlocks]

You can always downsize your starter battery, I use a small deka (ETX16) on my v6 race car and it has no problem starting it up..

also consider putting a Solid State LVD (like Victron Battery Protect) on your aux battery to prevent over-discharging it.

 

[DaveInDenver]

An ETX16 should have no issue starting any engine (and assuming no winching) but I'd still want to configure a more traditional dual battery system that splits loads in that case. There's no one perfect approach but I'm a fan of the primary/backup vs. starting/house when pulling a large group 24 or 27 in favor of two. In my plan the main battery has to reasonably substitute for the stock battery and all the normal loads to leave the second battery unused as much as possible.

 

[dreadlocks]

I see your point, but on a motor vehicle you always have an engine+alternator so I dont put that much value in overall capacity.. as long as house battery can keep things going between drives your good, if you put a massive battery in it and then dwell in one spot for a long time then you need to drive it even longer to get it recharged.. When we did 2-3 week vacations car camping we moved every other day or so unless we really found a place we loved, when we moved it normally it was not far..just a little further down the coast or to the next nearest park.. only our first and last days of travel involved a full day on the interstate.

If you need the capacity, I'd do a dual house battery out of 6v and then a small dedicated starter/jumper battery.. would not take much more room/weight than a dual battery setup, and you can use all that lead capacity without worrying about getting stranded in BFE.

 

[DaveInDenver]

Using a small starting and large house is a perfectly valid approach. In my scheme I'm not expecting to stay put relying on stored power alone, at least for longer than overnight. I do require solar or running the engine fairly frequently in an extended stop since I don't have a "house" battery as traditionally defined.

But I also don't have the loads typically requiring something that complex, basically only the fridge could be called a house load. I don't have lights or anything else that runs on electrical in camp. I do have radios of course but when used in camp, say when I'm tinkering with HF or out for an SOTA or Field Day, I have a separate power system I use for that based on a group 27 marine battery.

So for the purpose I do calculations based on having 65 amp hours, not 130, e.g. my dual battery approach is about protecting against failure, be that vehicle damage or simply inattentiveness on my part. The times when I've been left unable to start couldn't have been avoided just having a slightly larger capacity, so the way I've approached it works for how I use it.

 

[Chad D.]

This has turned into a great conversation! Thanks everyone for thoughts and ideas.

To fit my personal needs, which are to source a reliable and safe method of having dual batteries in a newer Tundra without sacrificing usable space in the cab or bed, I have pulled the trigger on the Genesis system with Odyssey batteries.

I do not stay camped in a single spot for long, and will not likely run much more than the fridge on the auxiliary battery. I’m sure I’d be fine with one large battery, but I want the ability to self recover if I do kill it...

Should arrive early next week, and I’ll get it all wired up. I’ll then need to provide a circuit to the rear for 12v.

Hope I like it...


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[Chad D.]

Ok. All parts for the Genesis kit are here. Look great! Very clean work.

Install? Not yet.

Took out factory battery, and unbolted the fuse/relay box so I could slide it back a bit. This kit requires the box to shift if your Tundra has LED headlights, which my Platinum has.

Can’t get the box far enough back... seems to interfere with the brake line hardware. I’m calling Shane (Genesis fella) to see if there is a trick. It’s gonna be rad once I get past this hurdle...


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