Anyone use a small 12V marine battery as a house battery?

I think the problem to this argument on both sides is the cookie cutter everyone is trying to put everyone into instead of properly qualifying what type of behavior each case has.

For example it is not unusual on my long trips (10 day trips) to drive 6-8 hours a day covering ground to get to the next destination. But that doesn’t mean others wheel this way. Some may as Mitch mentioned barely move thus not allowing the house battery to charge.

I know I personally would t trust running my fridge and accessories off 1 battery and then be able to start my truck in the middle of no where. I want that extra assurance of the second battery. If I need to pull out my solar panel I will but I rarely need to.
 
I think the point Mitch is trying to make is that the majority don't need it and it's an unnecessary expense. That's my take and it is my personal experience with the FJ that I had. I just didn't need it. That said. I do have a 12AH sealed AGM motorcycle battery sitting in the garage that I may make a budget Goal Zero with.
 
Greg said:
I just got them so I can't answer how well they work. I did pick these because they are the same manufacturer that Overland Solar uses. Cleans with Windex. And the specs are right. My guess is that these are a previous generation. The current spec sheet has slightly better performance. It's a fairly hard plastic so it will a little effort to scratch them. One of the intended uses are to be glued to curved external vehicle surfaces.

I store them in an artist's portfolio. If it's good enough to keep paintings and drawings undamaged it should be good enough for the these.
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These are the latest Sunpower panels. They disappeared for awhile getting some issues worked out, but are back now. These are the same solar cells used in Renogy's Eclipse model panels, their most efficient panels. In short, these 100W panels are among the best you can buy right now. Renogy sells them for quite a bit more, but you're guaranteed that they are actually Sunpower panels and not labeled chinese knock-offs. There is a decent chinese made panel by Lensun (http://www.lensunsolar.com) they have foldable kits, semi-flexible kits, etc. I've used these and they work great. They offer the plastic back for portable use, and aluminum backed. Like any permanent installation, your biggest worry will be keeping them clean. With offroad driving, dust+morning dew=MUD=useless solar panel.

@Brett C I don't recommend that you run your accessories on ANY type of battery setup (single, dual, whatever) without help. People think that just because they put in a huge battery that suddenly they're carrying around a self-sustaining power system that will run for the full labeled life of the battery, and it just isn't true.

I don't feel that solar is the backup plan. I feel that solar is the PRIMARY plan. The battery is the backup plan during the night when I can't run my solar, or charge by any other method. I also carry a lithium jump pack as my safety net in case something went wrong. I think if you have a solar panel stowed away while the sun is shining, you're being foolish, and abusing your battery unnecessarily, but that's just my educated opinion. Unless you are taking proper steps to keep your battery topped off between draws, you WILL be replacing the battery before its time.
 
I basically more or less agree w/ Mitch's assertions. I also run a group 31 agm. Sometimes I'll be hunkered down for a few days, so I'll put up a folding solar panel that fits inside a cub pack. some days we'll be driving from 9 to 9. When the engine is running, the fridge is in fast freeze mode. When the engine is off at night, it's usually near or below freezing where we camp, so I don't have to run the fridge at night.

If we end up camping somewhere warm, all the food in my freezer is frozen, so it stays frozen for at least a 24-36 hr period. I keep frozen water and juice bottles up top, when they defrost I have a cold drink and the stuff on the bottom stays frozen.

If it's a hot day, the solar panel will take care of everything.

It's a simple numbers game.

My fridge runs at ~50watts, so I need a solar panel that can output at least 50 watts +additional for accy used (during the day or night like lights or charging AAAs for headlamps, flashlights, and Bluetooth speakers) on a partially cloudy day (this should be read as get a 100w panel), I make sure the back of my bed is ventilated so it doesn't try to cool down hot air.

If I want a steak at night, I pull it out in the morning and throw it in an insulated lunch bag with a couple of room temp water bottles. Unpeeled vegetables and fruit keep fine at room temp. Frozen fruit juices that are melted are great to have on subsequent days.

It's honestly not that complicated.

Rule of thumb for AGMs, use only 1/2 its power if you want to keep it around for a long time, ie only burn up to 50% of your capacity at a .1 or .2c rate unless you want to risk damage. Lithiums can use up to 75-80% without any ill effects but also cost way more in initial outlay. So in the same physical size and weight, you get way more energy density, but you'll also need specialized equipment to maintain.

A group31 AGM, a small solar panel, and a noco gb70 jumpstarter works fine for me when I can't push start my truck.
 
Mitch said:
These are the latest Sunpower panels. They disappeared for awhile getting some issues worked out, but are back now. These are the same solar cells used in Renogy's Eclipse model panels, their most efficient panels. In short, these 100W panels are among the best you can buy right now. Renogy sells them for quite a bit more, but you're guaranteed that they are actually Sunpower panels and not labeled chinese knock-offs. There is a decent chinese made panel by Lensun (http://www.lensunsolar.com) they have foldable kits, semi-flexible kits, etc. I've used these and they work great. They offer the plastic back for portable use, and aluminum backed. Like any permanent installation, your biggest worry will be keeping them clean. With offroad driving, dust+morning dew=MUD=useless solar panel.

@Brett C I don't recommend that you run your accessories on ANY type of battery setup (single, dual, whatever) without help. People think that just because they put in a huge battery that suddenly they're carrying around a self-sustaining power system that will run for the full labeled life of the battery, and it just isn't true.

I don't feel that solar is the backup plan. I feel that solar is the PRIMARY plan. The battery is the backup plan during the night when I can't run my solar, or charge by any other method. I also carry a lithium jump pack as my safety net in case something went wrong. I think if you have a solar panel stowed away while the sun is shining, you're being foolish, and abusing your battery unnecessarily, but that's just my educated opinion. Unless you are taking proper steps to keep your battery topped off between draws, you WILL be replacing the battery before its time.
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Not what I said at all, is it?

I simply addressed that making a cookie cutter system for everyone doesn’t work. Everyone’s style of off-roading is different. In my case driving 6-8 hours a day between camps does allow my alternator to charge my system and I have solar as back up (meaning to the alternator not the battery) for those rare times I’m in camp more than a day and a half.

Then went on to say for others who don’t drive as much as we do in a day solar should be the primary charging source but either way I do feel a second battery should be where the accessories are draining not the primary battery where if it fails will leave you stranded.
 
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@Brett C I agree that there is no cookie cutter install. I agree right up to the the point to where you mention secondary battery. While you may enjoy the piece of mind of having it, I'm here to tell you 99% of the time, you won't need it. And that 1% time that you do, can be addressed by an inexpensive jump pack and not a $1000 second battery (including costs of batteries, trays, installation, etc, probably more than $1K).

My experience has been that most people don't want to go the distance in regards to caring for their system. And MOST people fit in the category of Upgraded Primary Battery, Supported by Solar, Backed up by Jump Pack.

What isn't working is folks putting a secondary battery in, running their fridges full time/most of the time without solar or shore charging, and thinking that their alternator/upgraded alternator is going to handle the task, and then crying when their $400 battery dies in a year and a half. I don't know if they think just because it was professionally installed, that it's a perfect system, or what they're thinking, but it's happening enough that I feel I need to start putting the word out there, and put a stop to this thinking that if you don't have a dual battery you have to turn in your overlander card. And if your needs demand, you need to go all in to support that second battery.
 
well @Mitch you and I will just have to agree to disagree. Your single battery with reliance on a jump pack is a recipe for disaster in my opinion.
 
Greg said:
So what's a good upgrade battery for a 3rd gen taco?
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Brett C said:
well @Mitch you and I will just have to agree to disagree. Your single battery with reliance on a jump pack is a recipe for disaster in my opinion.
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6 Years so far. Brought the same system design over from my old 4Runner.

Granted, there have been various batteries in play during that time, but I'm going by how long I've been able to keep a battery at 100%. Disasters are avoided by knowledge in this case, not equipment.
 
31M-PC2150? That actually fits in a Tacoma? And 100AH? Nice.

I started looking after I posted at the 34M-PC1500.
 
Can 100AH be too much? Can I create a condition similar to the problem with a duel battery system that you mentioned?

To make the math simple. A person has a duel battery system consisting of 50AH batteries. Their usage pattern leaves the second 50AH battery undercharged. The reason why is unimportant it could be because of ignorance or it may be because of faulty equipment. e.g. their solar charge controller is broken. Again to keep the math simple. The result is one 50AH getting fully charged and the second only getting topped to 50%. Now that person has a single 100AH battery but their usage pattern has not changed. The result is that the 100AH battery hovers at 75%.

First. Is that math right? The math is linear but I suspect charging rate is more of a exponential decreasing curve as the battery voltage approaches the charging voltage.

Is there a difference in damage between a battery maintained at 50% vs 75%?

In either case I guess my take away to avoid this condition regardless of the battery system and math used is to start with your charging capacity first and build backwards.
 
This is why I feel my primary power source is my solar. My solar input exceeds my amp output throughout the day.

The battery, regardless of primary or auxiliary, is the reserve storage for use when the sun is down.

Yes a smaller AH battery is going to fill recharge quicker, theoretically, but it's also going to drain faster. My 100 AH battery is that size because if I HAVE to rely on it because there are no options, I have that freedom. Do I want to do that all the time? Nope, but it's nice to have the option.
 
Greg said:
Can 100AH be too much? Can I create a condition similar to the problem with a duel battery system that you mentioned?

To make the math simple. A person has a duel battery system consisting of 50AH batteries. Their usage pattern leaves the second 50AH battery undercharged. The reason why is unimportant it could be because of ignorance or it may be because of faulty equipment. e.g. their solar charge controller is broken. Again to keep the math simple. The result is one 50AH getting fully charged and the second only getting topped to 50%. Now that person has a single 100AH battery but their usage pattern has not changed. The result is that the 100AH battery hovers at 75%.

First. Is that math right? The math is linear but I suspect charging rate is more of a exponential decreasing curve as the battery voltage approaches the charging voltage.

Is there a difference in damage between a battery maintained at 50% vs 75%?

In either case I guess my take away to avoid this condition regardless of the battery system and math used is to start with your charging capacity first and build backwards.
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TBH, your case actually is extremely ambiguous.

A dual battery system consisting of:

  • 2x 50AH Batteries

Without stating:

  • How the batteries are connected (side by side, parallel, diode, via charger)
  • What is charging them (alternator, solar, shore power, dc to dc charger, another vehicle, generator, etc)
  • Use case (powering fridge, blanket, hair drier, washing machine, roadpro oven) / power usage
  • Type of vehicle and alternator (if any) equipped
Leaves a lot of variables that would change the situation and limitations of a particular system.

Also to be noted. If you're dedicating a single 50AH deep cycle battery as a house battery to be used when the engine is off, you'll only have 25AH of power (about 300wh) before you're damaging the battery after each cycle.

A group 31 makes a little more sense if you want to utilize more of the battery and to go w/ a low voltage cut-off and still have pow pow to start the vehicle when you're ready to bounce. Either that or be the kind of person who's always aware of how much power they use and turn off all the accessories when they hit the 50% mark. (But I mean who can do that perfectly every time?)
 
I’m curious how this single battery system works when you’re out and there is no sun to charge your batteries efficiently? Heavy cloud cover, rain or snow etc. so even with solar being your primary charging (which is fine) this is where my isolated draw off my larger battery for accessories come into play and knowing I can start the truck when I need to. If my accessory battery dies it simply kills my accessories not my starter battery and therefore possibly me. I see zero logic in not having a second battery allowing me to isolate my starter battery just to save a few dollars.
 
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Brett C said:
I’m curious how this single battery system works when you’re out and there is no sun to charge your batteries efficiently? Heavy cloud cover, rain or snow etc. so even with solar being your primary charging (which is fine) this is where my isolated draw off my larger battery for accessories come into play and knowing I can start the truck when I need to. If my accessory battery dies it simply kills my accessories not my starter battery and therefore possibly me. I see zero logic in not having a second battery allowing me to isolate my starter battery just to save a few dollars.
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I have a battery that can support that scenario just fine, and if for some reason I wasn't paying attention to conditions, I carry an Anti-gravity XP-10 lithium jump pack. And this system isn't just a "few dollars" cheaper than a dual battery setup, it's hundreds, if not over a thousand cheaper.

The typical setup that I've installed for a dual battery consists of this:
Off Grid Engineering Dual Battery Kit $675
Redarc DC to DC Dual Input $417
TWO Odyssey batteries $750
Installation Labor $500
Total $2342 without the solar kit
Unexpected cost every two years for not properly charging auxiliary battery $400

My setup
Pelfreybilt Tray $135
Odyssey battery $400
Slee terminal extensions $69
Renogy 100W Solar suitcase $389
Lithium Jump Pack $150
Installation Labor $250
Total $1393
 
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kalieaire said:
TBH, your case actually is extremely ambiguous.
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Well, my question wasn't really about dual battery systems. I think that's been pretty much covered. Perhaps the details I added were unnecessary so lets just skip them and go for the end results of the theoretical situation.

For whatever reason:
  • We have a situation that results in one battery hovering at 50% capacity in a dual battery system for extended periods of time.
  • Under the same conditions we a single battery system hovering at 75% capacity extended periods of time.
Build them however you want. In this head-to-head competition where both systems are placed under the exact same stress which system will crap out first.
 
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Except Mitch by your own words people don’t care for their systems so they don’t properly charge their second battery. Then by that viewpoint their anti gravity battery isn’t going to be ready when you need it and then you’re screwed. Also my dual battery setup cost about $500-600. Ctek D250 with Dekka Marine group 31 AGM and battery box. With the amount of money people spend on their rigs that’s cheap insurance to keep one of the things we always use (the truck) starting when I need it too.

2500 for a dual battery system is insane.

My antigravity is my redundancy so my truck drives out of the remote areas AAA can’t come get me. Just like my starter battery remains isolated so my truck can drive back out of remote areas. Most people spend a fortune on recovery gear in case they need it. This goes in that same area for me. A small investment to ensure my trucks not going to have a flat battery because my fridge drained it due to bad weather where we had to hunker down a few days.
 
Guy with IBS dual battery system for 8 years takes a sip of his Yamazaki, yawns, and moves on to the next thread... :rolleyes:

:popcorn
 
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