12 volt newbie

[surly]

Trying to determine if a lithium power bank (http://www.aspectsolar.com/) would be sufficient to run my fridge over a weekend (or longer). Its cheaper and more portable than a dual battery set up so I thought it was worth considering. Upon performing the calculations it seems, for my purposes, the power bank is wimpy and or my fridge is a pig (possibly both are true).

Currently we only have the fridge to worry about but I would like to add some camp lights for cooking and general nighttime mischief. I haven't gathered the specs from my starter battery but regardless of the capacity I'd like to run house items off a dedicated power source so we aren't stuck somewhere. Our rule number one: Don't break the Jeep

Given that I am just "getting into 12 volt appliances" I would appreciate any feedback on my stupidity and or ignorance below. I'm trying to figure out as much as possible without asking too many annoying questions.

Fridge draw = 4.5 Ah @12V
Power bank = 250Wh

4.5Ah * 12V = 54Wh
250Wh / 54Wh = 4.62 hours fridge time
Or
250Wh / 12V = 20.833 Ah
20.833Ah / 4.5Ah = 4.62 hours fridge time

Thanks for any feedback folks!

 

[unseenone]

Nothing dumb about asking questions, that's why we're all here.

In order to run your fridge, if it's like either of mine, figure it will need to run 21 hours out of 24. At least in 80-90 degree heat. I recently ran two fridges, in the shade with the insulation shells on them. Combined they used 70Ah or 70 Amp hours in 24 hours. I suspect you have a bigger one, so let's say it's 3.5*21 or 73.5Ah for 24 hours. I suspect that actual amps used is less than the rating. This assumes you start with it full and cold. I figured out the actual use with a meter, pictured on some of the threads.

You will be able to add back into the equation the solar charge during the day, assuming you have some sun, and we can calculate how much you can put back in. Based on the size of the panel that comes with it. I'm seeing something in the 4-5 amp range with a 90-100 watt panel in idea conditions. (not the unit you asked about)

250Wh / 12 * .70 = 14.78Ah is a more conservative number .. This does not Jive at all with the anecdotal stories of amazing performance you'll read in the threads below. I'd say to browse through the following 4 threads, and check back here if you still have questions.

The first three discuss the unit you asked about, or it is touched on in some detail, worth a look;

http://www.expeditionportal.com/for...compressor-and-inverter?highlight=aspectsolar

http://www.expeditionportal.com/for...in-a-dual-battery-setup?highlight=aspectsolar

http://www.expeditionportal.com/for...ondary-battery-or-solar?highlight=aspectsolar

http://www.expeditionportal.com/for...Temp-ARB-50qt-100-watt-solar-panel-Not-enough


Just as a point of reference, I'll post the specs from their web site;

Battery Capacity 12.8V 20AH, 250Wh LiFePO4 (Lithium Iron Phosphate)
OUTPUTS
USB (4 Sockets) 5V 2A Max
12V DC Socket 12V ± 20% 10A
AC Universal 100 Watt Modified Sine Wave
INPUT
DC 15V 4A (For charging and daisy chaining)

DEVICE WATTAGE Power Duration w/ Full Battery

Mobile Devices, Chargers, Small Fans, GPS, LED Lighting, ...............................10 25 Hours
CPAP Machines...................................................................................... 20 12.5 Hours
LED Televisions, Video Game Consoles, Radios, DVD Players ............................30 8.3 Hours
<snip>
Multiple Devices Charging Simultaneously ....................................................80 3.1 Hours
............................................................................................................90 2.8 Hours
Maximum Output 100 2.5 Hours

*my note, the max draw in amps in 2.5 hours is 8.33Amps according to their own documentation.

 

[Omar Brannstrom]

Hi

I ordered the new Goal Zero Yeti 400, maybe that could be better. It aint so big and can be charged in the vehicle or via solarpanels. I like the plug and play thing. I also have Goal zero led lights and solar panels.

It has 400Wh

http://expeditionportal.com/field-tested-goal-zero-yeti-400/



http://www.goalzero.com/p/165/goal-zero-yeti-400-solar-generator

 

[Omar Brannstrom]

Iam not an expert but I understand LiFePO4 has it benifits compared to a AGM battery.

Anyway I see that energybar has a 100w Modified Sine Wave, I have read that Pure sine wave is better for delicate electronics and the Yeti have that and is on 300w

 

[surly]

I see that the Yeti uses a traditional batter where the Aspect Solar solution uses LiFePO4.
Would that difference make the power difference more even?
From what I've read the Yeti capacity is less than stated. So I'm thinking if you can only use half the 33Ah the battery has you might get more, or as much, juice from Aspect Solar?

Anyway. Goal Zero was something else I was considering. I even checked out Paul Buffs latest Vagabonds.

 

[Omar Brannstrom]

Hi

I did not know Aspectsolar when I bought the Yeti and I dont have it yet.

You might be right that aspect solar with LiFePO4 and 20 ah might get more juice than the Yeti 400 with 33 ah. The energibar cost less, smaller and lighter and faster to charge via the vehicle and so forth.

And the EP-55 Portable solar panel with case looks great and are at better price that the goal zeros and it has a built in stand.

I read that somebody asked Goal Zero if not the yeti 400 would come with a LiFePO4 battery and they sad that it would cost to much?


My 2 nomad solar panel is only at 20watt each and can be chained together to be come 40watt. Cost much more than the EP-55 but are smaller and lighter. I use one Nomad to directly charge my tablet or android phone directly through the USB contact on the Nomad, very nice.

Some larger laptops can peak to about 150w, so the inverter is maybe to small? on the energybar and it is a modified sinus wave, maybe not so god for delicate electronics.

I do like that the yeti have 2 AC universal, me and my buddy can charge our camera batteries at the same time.

I dont find any of them really perfect. It would be nice if Yeti 400 came with a LiFePO4 battery instead but it might cost to much at this date.

Intresting is that Christophe Noel wrote about the Energybar here in 2013

http://expeditionportal.com/gear-scout-aspect-solar-energybar-250/

But still he choosed the Yeti 400, could be that he alredy hade Goal zero stuff from before

http://expeditionportal.com/field-tested-goal-zero-yeti-400/

 

[surly]

I should probably ring both companies and see what they have to say about the actual usable capacity.
If I get anything other than marketing babble I'll share it here.

 

[Omar Brannstrom]

Hi

This looks cool, but a hefty price

http://www.portablesolarpower.biz/c.../lfp-20-portable-solar-power-generator-system

 

[surly]

Called Aspect Solar and basically what they had to say was their unit would or should offer the rated power due to the battery type.
Free to return within 30 days in like new condition with all packaging etc.
I'm considering giving it a try.