Calculate installed cost per usable Ah or Wh and lifecycle for true cost of ownership. You will probably find that drop in LiFePO4 is cheapest, followed by FLA, followed by SLA followed by "solar generator" (GoalZero, etc.). At least that is the conclusion that I came to when planning my house battery install last year.
At what point do you install a dual battery system? (1 Viewer)
- Thread starter Nooooooooob1
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That's one way to break things down into a metric, but not sure that tells the whole story at least for a solar generator. I'm sure you know that they come built in with everything along with the battery. It's probably useful to repeat what comes built in, because when doing a custom batt install, each component is a not so insignificant cost, along with the associated heavy and expensive interconnects and hardware. Component size for installs can also be a challenge considering how much physical size each component may take.
It's very possibly cheaper and smaller as part of a solar generator, when all aspects are taken into consideration.
1) Battery Management System
2) Display
3) Charge controller
4) 120V Inverter
5) DC to DC charger
6) AC to DC charger
6) Various input and output ports: cig, anderson, USB, USB-C
It's also an integrated user friendly design with validated operation and performance. This may be hard to come by when homebrewing, unless one is pretty skilled and aware of detailed considerations.
It's very possibly cheaper and smaller as part of a solar generator, when all aspects are taken into consideration.
1) Battery Management System
2) Display
3) Charge controller
4) 120V Inverter
5) DC to DC charger
6) AC to DC charger
6) Various input and output ports: cig, anderson, USB, USB-C
It's also an integrated user friendly design with validated operation and performance. This may be hard to come by when homebrewing, unless one is pretty skilled and aware of detailed considerations.
1world1love
SILVER Star
Neither here nor there. But a nice cost breakdown
I run my Dometic cfx3 55 on my Rockpals 500w 24 hours a day for a couple of days a pop. I can easily top it off using a 12v or solar because it never goes below 60%. I have often considered a dual battery setup but as long as my portable is working, I will hold off.
Can Portable Power Packs Replace Dual Batteries? - Expedition Portal
Portable power packs have come a long way, but are they finally ready to replace hard-wired power systems in off-grid vehicles?
expeditionportal.com
I run my Dometic cfx3 55 on my Rockpals 500w 24 hours a day for a couple of days a pop. I can easily top it off using a 12v or solar because it never goes below 60%. I have often considered a dual battery setup but as long as my portable is working, I will hold off.
FrazzledHunter
SILVER Star
Replying to my own post here because I did find what looks like a high quality commercial DC boost converter by Victron. Their 25A model retails for $526.00. I don't think this expense is worth it as draining the AGM 2nd truck battery to charge the Yeti 1500X is an edge case I think. But it was fun researching what's out there.Got it. I didn't know what these things might be called if they existed at all. I'd ideally want one that would allow me to charge quickly so I'd dream of one that could do 150+ watts. Thanks!
Edit: I'd only do this If I had to as flattening an AGM battery ain't too good for it.
REF:
Victron: Buck-Boost DC-DC Converter 25A / 50A / 100A
Amazon: Victron Energy Buck-Boost 25A DC-DC Converter ORI303025000
Victron also makes other charge converters which appear different in that they support charging phases i.e. boost/bulk, absorption and float.
REF: Victron DC-DC converters
Victron also sells these DC DC chargers which can act as a converter as well. Several different models available to address needs. Also can be paralleled for a large bank.
Amazon product ASIN B0851TPKV7
FrazzledHunter
SILVER Star
Right - they were mentioned in my post. Those Orion units appear to be specialized toward direct charge of batteries by providing a 3 part charging profile: boost, absorption and float. The application I was referring to was one of an unregulated voltage of approx. 8-13V from a discharging AGM secondary battery IN to a constant 13.8V OUT.
The whole problem is I wanted to be able to charge my Yeti 1500X by draining the 2nd AGM battery. BUT the Yeti 1500X will not charge unless it has 13.6+V DC IN which I didn't know until I first hooked it up to my 2nd battery and it wouldn't charge at all. A check of the voltage on the 2nd battery was approx. 12.5V. Start the engine and it charges just fine because the REDARC BCDC is supplying 14.6V volts to the second battery. Turn the engine off and the 2nd AGM battery of course discharges to charge the Yeti 1500X. So far so good until the 2nd AGM battery hits 13.6V and all charging to the Yeti abruptly stops!
NUTS.
No problem I thought: just get a gizmo that takes a variable DC voltage IN and a puts a constant DC voltage out. I figured these units would be expensive but not THAT expensive. So my second AGM battery will not be used to charge the Yeti 1500X after all. It will however, be used for its original intended purpose of providing a jump start or powering things like lighting that can tolerate a declining voltage as the battery drains.
I'll get constant regulated 12 VDC and 120 VAC from the Yeti 1500X; that's the main reason I have it and one of the reasons it's so expensive.
This is what I am running. It's a fantastic DC-DC charger. It even detects engine vibration to enable charge cycle. I never considered a use case for this until I saw someone put a trickle charger on the starter battery (effectively increasing the voltage to trigger charging) and it drains the starter battery completely. Fortunately, I found one on ebay much cheaper than than retail.
FrazzledHunter
SILVER Star
I get it. This thread has a video of how things can go sideways then you put a trickle charger on the main battery when it's hooked up to a REDARC BCDC charger.
REF: RedArc BCDC help - https://forum.ih8mud.com/threads/redarc-bcdc-help.1216511/page-2#post-13830320
I'd love to get that 25A Victron buck boost. Must...resist...pressing...buy...button...
CharlieS
GOLD Star
Fwiw, that 13.6v shutoff is designed to protect the battery you are charging from and is working as designed. It is a feature, not a bug. The Redarc BCDC chargers do the same thing.
FrazzledHunter
SILVER Star
I understand that. The whole idea was to see what was required to get around the "safety feature" that prevented me from draining the 2nd AGM battery.
So true. To each his own. I have added a few things this past year that 5 years ago I would have rolled my eyes at. Hot water heater is one item and the air mattress was another. The hot water is a lux item that I wish I added years ago. No more greasy half cleaned dishes and everyone loves a hot shower after 3 days. Smaller dogs don't freak out when you try to rinse them off. Still don't see the need for a fridge, too much space, too expensive and I don't bring things that need to be refrigerated. If I lived further south I could absolutely justify a fridge.
But back to the original post. At what point now, with efficient cheap solar power, do you need a dual battery set up. You can run a winch, compressor, motor, all exterior lights (most are LED now) off of one battery with no issues as long as the motor is running. The extra electric needs for the leaf blower, blender, charging devices, pump the air mattress, run a water heater are all handled by a solar system with battery bank for $700-1100 and no headache. Toss in a jump box for dead batteries.
I can be really stupid. I ran dual batteries for years but when solar got decent I made the switch. Never had a problem with AUX power with solar? So if you can save money and have a reliable system that is simple to set up and user friendly and meets all your electric needs why go thru the headache and cost of a dual battery system. Is it the full fridge with freezer that justifies the dual battery when everything else runs fine? Bragging rights to show off your two batteries? At what point in 2021 does the duel battery justify the cost and complexity where the vehicle stops working properly that can be avoided using a solar set up for accessories?
KISS. Keep It Simple Stupid.
Markuson
SILVER Star
We all have different needs & I will eventually add solar.
But…
-Thee’s a reason Tesla Walls are selling for big bucks.
-Because solar doesn’t provide capacity in the dark when people want light, power, charge and run all sorts of things. Without substantial battery power at night, solar is just a dead piece of tech that sits idle at night.
Solar is great in bright, direct sunlight…but that’s when most of us drive and don’t need it).
After the ling drive and through the night, we charge, light things up, run various equipment, or keep stuff frozen in hot weather…on battery.
If traveling, and you have to park in a structure…or under sunlight obstructions of various kinds in a forest, valley or urban…solar doesn’t power anything.
If, on the other hand, you drive all night…
…and sit around all day? Solar is perfect. -But most travelers do the opposite.
I agree that most may not see huge benefit from dual batteries. But some of us truly do.
I get it. I reside in an area that is mute for solar. It's grey skies for most of the year and thick forest. But for me the solar panels work great. I do not need the dual battery any more. The solar panel keeps the extra battery charged in the back. That keeps everything charged that I have and runs the few items we use for 40 hours with no sun. I don't turn the rig off when using the winch, compressor or exterior lights. So it's all one battery.
I hate to see folks go all gang busters with unnecessary mods. Save the money and complications for something else that is needed. Not an advanced set up like a dual battery. A small percentage of people really need two batteries. If your doing 15-30 days of vehicle camping a year on light to medium trails it's just over kill.
Again I have no fridge/freezer or anything else that is running 24/7
Spend the money on a good DC-DC setup and a decent battery. Solar doesn't really make sense IMHO. Considering a simple 20amp DC charger will produce a full 240W anytime/anywhere and it only costs about .5 gallon an hour if you are stationary and nothing when you are on the move. It's hard to make a case for half of your rooftop real estate additional electrical equipment and a solution that will only work part of the time and very rarely output advertised wattage.
Markuson
SILVER Star
Yep. I have similar reservations about solar. I’m running a Redarc 50 amp for my aux battery now and it leaves my old IBS manager faaaar behind.
I hear ya on the roof real estate too. I really don’t like to put other items on my roof rack anyway, so a single solar panels would be minimally fiddly for me. Plus with the Redarc already to set up to control a raw panel, there would be very little fiddling. We’ll see.
Markuson
SILVER Star
Many of these arguments tend to end up falling into the ”You don’t really NEED it” answer.
Here is my thinking on that…
I run many of my power items…not because they are absolutely essential, but because they are nice to have and great to use.
Not talking survival here.
Talking fun and convenience.
When I can pass out ice cream to an entire trail group on a long day 105 degree heat?
It’s just nice.
When I can keep cold things cold all week without finding ice, draining water, or creating ice-water soup?
It’s just nice.
If you want to talk absolute necessity…our LCs aren’t necessary either.
But they are nice…so we spend the big bucks and enjoy using them.
It’s not so dissimilar with ready power. I add it on my limited budget because its worth it to me to regularly use it.
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Lots of great points here and I agree with your conclusion. I think for many, it's as much want for all the perceived capacity, versus actual need. Much has changed recently with the advent of portable battery powered devices and much greater efficiency across the board. Heck, LED lights draw practically nothing. I camp with many people regularly, and even with tons of toys, we all make it through each night just fine. Many friends that have fridges, run on the single stock battery as fridges don't have a lot of power demand through cooler nights.
Funny thing is that traditional dual batt setups, still only give 1 batts worth of juice for any device. They're more setup for a separation of concerns in the form of starter vs aux batt. Yet with the right system design and setup, with low voltage cut-offs, having enough power to start can be a non-issue without separation. Then there's the safety net of modern lithium jumpers.
Solar is definitely where it's at if anyone follows van life or RVs. With portable solar briefcases offering even greater flexibility.
Now for real power users that do need dual batteries worth of reserves, and real ampacity support of dual batts - I propose the KISS dual batt configuration without the complexity of DC-DC chargers, fuse buses/wiring/interconnects:
KISS Dual Battery Upgrade
There’s been a lot of discussion on batteries and battery systems. Here’s my attempt to offer an easy button. The task of a battery first and foremost is to offer power and reserve capacity. There’s many battery setups and systems talked about. But perhaps some of those are solving a problem...
forum.ih8mud.com
RobW0
GOLD Star
I have solar on my dual battery Redarc setup. With my LC always outside, it allows me to keep my fridge freezer running 24/7 even when I don't drive my LC for a few of days.
Agreed. My last truck was a Tacoma that was my daily driver and set-up for weekend warrior camping trips. I installed a big, Group 31 AGM, battery in place of the OEM starter battery. It’s a simple solution and it never let me down.
It ran a couple driving lights, USB aux ports, ARB fridge, and some LED work lights in the camper shell. More than enough capacity in that 31 for a long weekend in the desert. Like you said, one has to be conscience of their battery level while camping, but it takes a lot (or a mistakenly left on accessory (lights)) to drain a Group 31 with the accessories listed by the OP. Most 12v fridges are extremely power efficient and they also have a low voltage cut-off feature to save the battery from dropping below 11.2-12v (depending on where one sets the cut-off). A small 12v folding solar panel could be used to top off the battery for longer stationary periods.
For peace-of-mind, I kept a little lithium ion jump pack for emergencies. Though, I never used it to jump my truck.
FrazzledHunter
SILVER Star
Which Fridge/freezer do you have? I just got a Dometic CFX3 75 liter dual zone. It draws about 40 W with the compressor running and 0-1W otherwise. What I really like is you can dial in your battery protection voltage where the unit will shut off to 10.1/11.2/11.8V. That means it will totally flatten the 2nd AGM battery before shutting off if I choose to let it.
One thing that's high on our list for things to take camping is a volt meter.
