2 batteries vs 1? (aka cold beer for cheap)

M

monkeyodeath

Member
Swiftone said:
I have posted this in the past, but a 20 AH LiFeP04 plus a 100 watt panel has kept my sons CF-35 at 39 degrees 24/7 over the past month or so in Southern CA heat. If you already have the panel, a 20 ah LFP battery is a not much more...flat roof mount panel, cheap Renogy PWM 10 amp controller and the fridge.
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Mind if I ask what battery or where you got it?

I think that one of the reasons I was scared off lithium was seeing $950, 100ah batteries for sale and assuming that's what I needed.

But if it's possible to use a smaller and cheaper one with good results, that's great and I could be willing to spend more for a longer-lived battery that takes up less space and weighs less. Not that it's necessarily my top concern, but weight does matter, and 140# of golf cart battery is a lot for a little truck. Especially as I do a fair amount of wheeling in mine and would like to keep as much ground clearance as possible.
 
J

john61ct

Adventurer
The vehicle should ideally be equipped with proper charge sources independent of its location.

Purchasing the deep cycle bank so that it matches the alternator output would be a frugal approach.
 
S

Swiftone

Member
monkeyodeath said:
Mind if I ask what battery or where you got it?

I think that one of the reasons I was scared off lithium was seeing $950, 100ah batteries for sale and assuming that's what I needed.

But if it's possible to use a smaller and cheaper one with good results, that's great and I could be willing to spend more for a longer-lived battery that takes up less space and weighs less. Not that it's necessarily my top concern, but weight does matter, and 140# of golf cart battery is a lot for a little truck. Especially as I do a fair amount of wheeling in mine and would like to keep as much ground clearance as possible.
Click to expand...

I used a Bioenno power 20 ah, Renogy 10 amp PWM controller and a Dometic CF35 in my sons jeep. Panel is a 100 watt Renogy. Battery is tucked behind the fridge in the last picture. All wiring is 12 ga. I may switch it to a MPPT controller for the winter sun now that I know the concept works.

Couple of thoughts:
Son is a diabetic and this is for healthy lunches and snacks while at school. Not beer :(
It has been installed 5 weeks so far and run 24/7 without a break
He is not in the fridge a lot - mainly for lunch and snacks before work. Using it for a beer fridge will most likely tax the power draw a bit more.
The first 3 weeks it was installed we had 100 degree plus weather and it was sitting in the car with no ventilation.
This fridge as tested (using a in-line meter with fridge installed in his jeep) drew .85 ah per hour. I was told I could expect 90 percent from the battery or 18 ah. This gives me theoretically about 21 hours without sun... Your results may vary.

 
M

monkeyodeath

Member
Cool, thanks for showing!

I think my use will be somewhat limited as well. Typically my trips are hiking/canyoneering trips where the fridge sits closed most of the day and night. The only time I really would be opening it is for breakfast food and dinner food/beers.

One more question...

If I decided to have a FLA house battery (golf cart batteries or something similar), and put the battery on a quality charger at home, would this help extend its life?

I know that my alternator's not going to top off these batteries as much as they like, but I'm wondering if, after I get home, I keep the battery on a charger, that will help maintain their lives a bit better.
 
J

john61ct

Adventurer
How or where does not matter.

Keep them topped up, right at 100% Full as per mfg specs, if you want maximum lifespan,

every few weeks is fine.

True for **any** lead
 
67cj5

67cj5

Man On a Mission
Swiftone has a good basic setup in his Lads Jeep and he could possibly get away with a 50w panel,

I think you are worrying too much, My mates in Aus go bush for a month at a time prospecting and all they have is a couple of type 31's 115Ah / 100Ah batteries and a 100 to 150w panel and it runs their trailers fridge and lighting and charges their detectors etc, Thing is out in the desert yes the fridge will chew more power but you will get a lot of hours of Sunlight to compensate the off set,

A 100w Panel can put out around 70Ah per day under UK summer conditions and about 5Ah per day in the winter time. So if you are In the US deserts and High Country then you are easily going to get that kind of power return, So I would grab a couple of type 31's and with that panel you should have power to spare,

So your 200w panel is going to almost double that, remembering that under most conditions a 50w panel will keep most fridge batteries powered for weeks on end, 100w will give you an edge, 200w is going to give you power to spare.

I have 2 X 115Ah Type 31's plus a spare in a Battery Box and I have a XD85 / 85Ah Duel Purpose as my Starter,

I ran my ARB 47L / 50 Qt from one of the batteries last winter in Temps of 16*c / 60.8*f and One XD 31 / 115Ah Battery ran the fridge for 6 and a half days and it was still above 50% before I called it time on the battery Test, If you can keep your fridge in a Cool spot while your away you will double your battery time, During my test It only used 120.9w and just over 9Ah in a 24 hour period, So keep it simple,

I hope that helps and good luck. ?
 
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Photobug

Photobug

Well-known member
You don't have to do it all right away alternator charging vs solar. It depends on how much you hang out in one place vs drive. If you drive more add a power from the alternator situation. If you drive somewhere and hang out for a few days then add as much solar as you think you need, you can add more panels as needed and add alternator charging if you want later. IMO, maybe because I have already done solar, it seems like the easiest addition. A second battery, a MPPT or PWM controller, 20 feet of wire and a solar panel. A solar system is also portable can be taken from one vehicle to the next, where an alternator charging source is hardwired to the vehicle.

My primary charge is always at home. After a trip is done and before the next one. Charging on the road is just to keep the ions flowing. The charging at home is also for maintenance purposes.


monkeyodeath said:
Cool, thanks for showing!

I think my use will be somewhat limited as well. Typically my trips are hiking/canyoneering trips where the fridge sits closed most of the day and night. The only time I really would be opening it is for breakfast food and dinner food/beers.
Click to expand...

What no breakfast beer?
 
M

monkeyodeath

Member
67cj5 said:
Swiftone has a good basic setup in his Lads Jeep and he could possibly get away with a 50w panel,

I think you are worrying too much, My mates in Aus go bush for a month at a time prospecting and all they have is a couple of type 31's 115Ah / 100Ah batteries and a 100 to 150w panel and it runs their trailers fridge and lighting and charges their detectors etc, Thing is out in the desert yes the fridge will chew more power but you will get a lot of hours of Sunlight to compensate the off set,

A 100w Panel can put out around 70Ah per day under UK summer conditions and about 5Ah per day in the winter time. So if you are In the US deserts and High Country then you are easily going to get that kind of power return, So I would grab a couple of type 31's and with that panel you should have power to spare,

So your 200w panel is going to almost double that, remembering that under most conditions a 50w panel will keep most fridge batteries powered for weeks on end, 100w will give you an edge, 200w is going to give you power to spare.

I have 2 X 115Ah Type 31's plus a spare in a Battery Box and I have a XD85 / 85Ah Duel Purpose as my Starter,

I ran my ARB 47L / 50 Qt from one of the batteries last winter in Temps of 16*c / 60.8*f and One XD 31 / 115Ah Battery ran the fridge for 6 and a half days and it was still above 50% before I called it time on the battery Test, If you can keep your fridge in a Cool spot while your away you will double your battery time, During my test It only used 120.9w and just over 9Ah in a 24 hour period, So keep it simple,

I hope that helps and good luck. ?
Click to expand...

Thanks, this is good to hear. Easy to get a bit too into the weeds and overthink things. It's not like I'm trying to run a microwave in the middle of a 2-week trip.

Right now I am leaning towards grabbing or building a 40ah Lithium battery and keeping that in the back of the truck with the fridge. Then I'll slap a solar panel on top of my hardshell RTT and hook that up to the battery/MPPT.

I like the lithium battery because mounting an underhood battery on my truck requires removing the (admittedly worthless) ABS pump and re-plumbing the brakes. And I'd rather have a lighter battery if I'm going to be loading it in and out of the truck often.

This way, I don't have to worry about the fridge killing the starter battery, and don't have to fuss with a permanent mount for the house battery, which will only be used when I'm packing the fridge.

I figure I'll eventually run a cable on a battery isolator to the bed of my truck and plug the external battery into that so I can get some extra juice when I'm driving.

---

Oh, and I'm more of a mimosas with breakfast guy ?
 
67cj5

67cj5

Man On a Mission
I would try to go a bit bigger on the battery, Maybe 60/65Ah using lithium just to give you a bit of spare power for night time use, 85Ah would be my minimum just because I use Lead Acid batteries which would give me about 42Ah to play with,

Even with a Lithium Battery you could make this as basic as can be and it would still work If you wanted to, Using just crocodile clips etc, It does not have to be some singing all dancing setup to enjoy your time away, And once you have done it a few times and worked out any changes you like to make that's the time to go to the next step,

Good luck and have fun ?
 
S

Swiftone

Member
monkeyodeath said:
Right now I am leaning towards grabbing or building a 40ah Lithium battery and keeping that in the back of the truck with the fridge. Then I'll slap a solar panel on top of my hardshell RTT and hook that up to the battery/MPPT.

If it helps with your decision I also have a 40 ah LiFeP04 (also a Bioenno Power) I use with a Dometic CFX28 and I have gotten 40 hours easy with normal use i.e. getting drinks and food and zero recharging in the Ca coastal heat.

To clarify: Son has a 20 ah/Dometic CF 35/100 watt flat panel. Runs pretty much 24/7 (but we will see what happens with the winter sun) I have a 40 ah/Dometic CFX28 (newer/more efficient) no panel and I easily get 40 hours when weekending and normal use.

I figure I'll eventually run a cable on a battery isolator to the bed of my truck and plug the external battery into that so I can get some extra juice when I'm driving.

This is also a thought on my sons Jeep if winter sun does not cooperate. Or we could just unplug the fridge on his short days and let the battery catch up. Trying to keep it simple.

Oh, and I'm more of a mimosas with breakfast guy ?

Sorry coffee the way my mom taught me to eat it - with a knife and fork. :eek:
Click to expand...
 
Photobug

Photobug

Well-known member
monkeyodeath said:
Right now I am leaning towards grabbing or building a 40ah Lithium battery and keeping that in the back of the truck with the fridge. Then I'll slap a solar panel on top of my hardshell RTT and hook that up to the battery/MPPT.

Oh, and I'm more of a mimosas with breakfast guy ?
Click to expand...

Mimosas are good.

I like your plan, but going to agree with some of the other suggestions given recently. I chose a 60ah lithium for my battery box, I don't run a fridge yet as I have not figure out where to put it. So figure 60ah gives me a day or two of reserve without solar. It is also very light at 17 lbs. I am using the same style battery as Swiftone but slightly larger.

www.bioennopower.com

12V, 60Ah LFP Battery (ABS, BLF-1260AS)

User Manual – BLF-1260AS | Material Safety Data Sheet – LiFePO4 Product Overview The Bioenno Power Lithium Iron Phosphate (LiFePO4) Battery Model BLF-1260AS is a compact, high-capacity 12V 60Ah battery engineered for high-load, long-runtime applications. With its sealed ABS case and built-in...
www.bioennopower.com

Another consideration is adding a permanent cheap FLA battery into your truck bed, weight does not matter if you don't have to carry it so much. You can get a group 27 battery at Costco for $90, with the same capacity of the $600 lithium.
 
M

monkeyodeath

Member
Hmmm.

I can assemble a 50ah lithium battery for a bit under $300. But it's pretty tempting to do the $90 Costco battery, as well.
 
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