Expected use time out of a power pack before recharge?

Overland-X5

New member
I apologize if this has been asked before, but I couldn't quite find the answer I was looking for when searching.
Now I know the answers are going to vary, so I'm not looking for exact numbers, just more of a rough idea.
Question 1: For those of you that run a PowerPack/battery station in your vehicle or on your trailer, approximately how long does your battery(ies) last if, lets say, you are running a small fridge, maybe some lighting at night, and maybe the random electronic device?
Question 2: What is the approx. length of time with 1 90amp hour battery vs 2 90 amp hour batteries. (precisely double the length of time? or does it vary?)
Question 3: What is the preferred method of charge? (generator or solar). Does solar take too long?

Thanks in advance!
 

hour

Observer
Q1 would depend on...everything
Q2: with a new 90 amp hour non lithium battery, you have ~45 amp hours of usable power before you're deeply discharging it which will affect its longevity. My giant fridge/freezer combo (62 quart) consumes 29 amp hours in 24 hours - 36*F both compartments, in peak summer heat where it's still mid 80's at 3am. So probably 48 hours with any 40some quart more common sized refrigerator. Maybe more if you get a super efficient$ one from ARB etc, or a tiny fridge.

You should be able to find the power consumption of any fridge you're interested in either in the product description, reviews, or deep googling. You might even find a nice chart that tells you how long it should run at a given set temperature and specified ambient temperatures. Whynter (my fridge mfg) has a chart of this on their website for each fridge. Then subtract that from about 45ah usable. Though you may be wise to not discharge to 50% every day. If you had two 90ah batteries (180ah) in parallel, you'd have 90ah usable. So in my case I could run my fridge for 72 hours in the middle of summer before I hit 50%

Both charging methods speed depends on the size of the charger / overall setup. More panels and a charge controller that can support them = faster charging. Bigger 120v->12v charger, faster charging. Generator could run at any time and put out consistent power if you can tolerate the noise. Not the case with solar. Say if you have a 5 day camping trip and a fridge that will run 3 days on a 180ah battery before hitting 50%....

1) You could get an adequately sized battery charger and run it off generator one afternoon during the middle of your trip, then deal with it when you got home
2) You could get an undersized solar setup, but satisfactory to put enough juice in to the batteries during every afternoon of the trip (pending no consecutive bad weather days) and if calculated right, last until you got home
3) You could get an adequately sized solar setup and maintain the battery over the trip
4) You could charge the battery with your vehicle's alternator with a dual battery setup or DC to DC charger and maintain the battery over the trip running the car
5) You could do any combination of the above

If using small LED lights that's pretty much a drop in the bucket if they're on at night, even less if on during waking hours when its dark. If you have giant LED spot lights or light bars that you want to leave on, that's different, but you could still find the watt draw for them by same means as finding fridge data.

Random electronic device doesn't really mean much, but phone chargers and even laptop chargers, not very significant. It's not a constant load and your battery will fill on the device. If fans, probably not much. You should still be able to find the consumption of these devices if you google a bit
 

Overland-X5

New member
Thanks for the detailed response! That answers a lot of questions. I'm slowly working on putting stuff like this together and I'm trying to get a good feel for what I'm going to start out with and then eventually build to in the future. And yes of course, I can always charge the batteries off the vehicle which is a good idea. Generator seems real nice all the way around if you can tolerate the noise, but it seems like solar is the Ultimate Backup to have provided you have good weather.
 

hour

Observer
Thanks for the detailed response! That answers a lot of questions. I'm slowly working on putting stuff like this together and I'm trying to get a good feel for what I'm going to start out with and then eventually build to in the future. And yes of course, I can always charge the batteries off the vehicle which is a good idea. Generator seems real nice all the way around if you can tolerate the noise, but it seems like solar is the Ultimate Backup to have provided you have good weather.

Worth noting that your battery (assuming standard auto/marine/deep cycle - which like to be at 100% charge as often as possible) will begin to slow down on what it can accept from any charge source as it gets more full. So say you're running a 25 amp (~300w) 12 volt charger on your generator and charging up your 90 or 180ah battery. It might accept all of that power initially, but not the entire time. The process can drag on getting it to full while you're listening to a generator.

With even a small portable solar setup you could get the majority of the charging out of the way with the generator+120v charger and when it stops being able to put in enough power to warrant the noise and gas... cut it off and let solar do the rest.

If you already have a generator and take it with you + run it periodically anyway you may want to just start off with a 120v battery charger. If you find yourself cruising around daily when out on trips you could add in the vehicle charger. If you find yourself stationary more often and get sick of the generator, supplement or replace with solar. I don't think a one time purchase of a quality big 12v charger would really be wasted, so that's a simple solution provided the generator is always around. And you can plug it in when you get home. I wouldn't bother with a 5-10amp charger, make use of the gas you're burning even at its idled down no-load speed (inverter generator). That (10a charger) is like 15% load tops on the generator which is making noise all the same.
 

Swiftone

Member
Ok I will jump in. I have a 40 ah LiFeP04 power box I made. Running a Dometic CXF28/with cover I used about 32 ah in a 48 test. I consider (and was told by the manufacturer of the battery) I could draw down to 90 % or 36 AH on that battery.

That remaining 4 ah would power some lights and charge up a few personal devices.

Disclaimer: the CXF28 is new to me. I have no real world idea how it would do on the road being used as food/drink storage. Realistically it will be plugged into my trucks power system and if parked for over a couple of days I would have a 100 watt panel charging the battery. I also have a Dometic CF-35 that my son "stole" from me that draws a bit more power but he keeps it running 24/7 with a 20 ah LiFeP04 and a 100 watt panel.
 

67cj5

Man On a Mission
If you are using it for camping then a 100-120Ah Deep cycle battery with a 100w solar panel will do the job, personally I would aim for 2 X 115/120Ah Batteries because you don't want to run them below 50%, Without a solar panel they would run a fridge for about 5 days, but The thing to do is fully charge them at home then fit them to the trailer or what ever they are going in, Then hook up a 100/150w solar panel and you should have way more than enough power, the secrete to it is keeping the panel in full sun each day because a panel of that size will put back what you have used over night in around 2 to 4 hours.
 
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67cj5

Man On a Mission
As a side Note, If and when you buy a fridge "DON'T" run your fridge direct from the generator because as they Rev up to compensate for the load being used or when they run out of fuel they will Rev Up causing a voltage spike and that is the main Killer of Fridges, You "CAN" use the built in charger that most generators have to charge the battery or Plug in a normal charger to the generator to charge your batteries but make sure the fridge is running from the batteries because they will Act as a Buffer so any spikes the Generator sends out will be absorbed by the Batteries protecting the fridge at all times, no matter if you use the little built in charger on the generator or use a normal mid powered plug in charger, All of the generator companies make claims that their products are safe for sensitive items etc But they are not and they will kill a fridge, Sooner or later, Ok.

Hope that helps,
 

67cj5

Man On a Mission
Well that f'n sucks
Yeah it was an Engel Engineer that warned me about that, He said that generators are the cause of about 80+% of their repairs,

He was the one who told me about running the fridge from the battery while charging it via the generator because the battery acts as a buffer.
 

luthj

Engineer In Residence
Quality inverter gens don't have voltage spikes like that. Older style direct output units can, depending on if they have buffer circuitry.
 

67cj5

Man On a Mission
Quality inverter gens don't have voltage spikes like that. Older style direct output units can, depending on if they have buffer circuitry.
No that's not right at all, It does not matter if they have AVR and pure sign wave or Both, Don't be fooled in to thinking that just because a person buys a $2000 generator that this problem Only applies to cheap generators because it Don't, They All Do It, The Guys from Engel don't make this up and just as many fridges have died because of Honda generators as have with other brands, This Issue is Not Brand or Price specific, Believe what you want but you have been warned, Yours might be safe for a week or a month or even a Year but It will happen and it is not a matter of IF it happens it is a matter of When it Happens.
 

luthj

Engineer In Residence
AVR direct output generators are not the same as an inverter gen. Inverter gens can have voltage spikes, but they are quite rare. In an inverter gen the output is isolated from the windings in the gen itself.

There is an inherent risk with running on any generator, but the situation you describe is not common. In fact I have only seen 2 firsthand accounts of this happening.
 

67cj5

Man On a Mission
AVR direct output generators are not the same as an inverter gen. Inverter gens can have voltage spikes, but they are quite rare. In an inverter gen the output is isolated from the windings in the gen itself.

There is an inherent risk with running on any generator, but the situation you describe is not common. In fact I have only seen 2 firsthand accounts of this happening.
Like I said believe what you wish, The Engel engineer showed me a pile of fridges that were waiting for parts because of generators killing them and they were not all killed by the same brand of generator, Most generators are stable to within 1 or 2% or less,

All generator companies claim that their products are safe for sensitive equipment even though it is untrue, The Engel Engineers say Don't Do It and ARB warn you about the types of generators etc but according to Engel modern AVR and Pure Sign Wave Generators are still not safe when it comes to fridges and if you must use one then run the fridge from the battery and run a charger to the battery from the generator and not from the 110/240v AC socket,

If you think otherwise then that's up to you, My ARB manual warns you that some generators are not suitable and that Some generators fitted with AVR and Pure Sign Wave inverters are suitable, But considering the Cost I have invested in my Fridges running them Via a generator is not a risk I am prepared to take due to the cost involved or having a Trip cut short, And considering it was an Engel Engineer who made me aware of this problem confirms the risk involved.
 

shade

Well-known member
AVR direct output generators are not the same as an inverter gen. Inverter gens can have voltage spikes, but they are quite rare. In an inverter gen the output is isolated from the windings in the gen itself.

There is an inherent risk with running on any generator, but the situation you describe is not common. In fact I have only seen 2 firsthand accounts of this happening.
Feels like a glitch in the Matrix, doesn't it? :)

Don't want to damage your electronics? Don't use crap generators & inverters. Pretty simple, and you don't have to spread disinformation in the process.
 

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