40 replies to this topic

[Tulloch]

An 180-100W inverter would be more than sufficient, they are available for cars as well from about US$20-30 or less - 

 

So a pure sine wave inverter is not needed? I would have thought that would have been important...

[powerslide]

OK, so from the responses I can see, the only real issues with a petrol powered generator are maintenance (which really only amounts to that of a lawnmower), annoying other people with the noise (which I get, but it's not really my problem if I'm in a secluded area), and it's a bit inefficient to supply a small amount of power.

 

How do people power their laptops with a 12V battery?

My laptop is compatible with USB-C PD, I just have a 12V adaptor to USB-C PD  I plug into my battery box and works well. You can also buy specific laptop adaptors that do the 12V step up to 19V or whatever is required. But if your laptop is PD compatible you'd be silly to use anything else.

 

https://www.amazon.c...aps,270&sr=8-16

[powerslide]

So a pure sine wave inverter is not needed? I would have thought that would have been important...

If you are going to use an inverter to power your standard laptop power pack and charge your laptop battery, not only will you need a pure sine wave you will need a good quality one otherwise you will destroy your battery. Many a laptop have died from a cheap inverter.  

 

I would not use an inverter for this purpose look at a proper Laptop power supply that is 12V compatible or USB-C PD.

 

something like this 

https://www.amazon.c...,aps,379&sr=1-7

 

Using an inverter is going from DC back to a pseudo AC then back to DC in the Laptop adapter. If you are on limited power that is wasting a lot of energy in heat.

Edited by powerslide, 19 July 2024 - 01:23 AM.

[archiebald]

If you are going to use an inverter to power your standard laptop power pack and charge your laptop battery, not only will you need a pure sine wave you will need a good quality one otherwise you will destroy your battery. Many a laptop have died from a cheap inverter.  

 

I would not use an inverter for this purpose look at a proper Laptop power supply that is 12V compatible or USB-C PD.

 

something like this 

https://www.amazon.c...,aps,379&sr=1-7

 

Using an inverter is going from DC back to a pseudo AC then back to DC in the Laptop adapter. If you are on limited power that is wasting a lot of energy in heat.

Most notebook power bricks will handle modified sine wave with absolutely no issues.  There are multitudes of discussions on this very subject.

 

Besides, my recommendation still remains just buy a portable power station.  My 768Wh Ecoflow is overkill, I can run my mini PC based rig plus my notebook off it for two full nights of imaging, plus I can charge it from mains, solar or from the car while driving to and from my shooting location.  And then it is a power back up at home too.

[powerslide]

Most notebook power bricks will handle modified sine wave with absolutely no issues.  There are multitudes of discussions on this very subject.

 

Besides, my recommendation still remains just buy a portable power station.  My 768Wh Ecoflow is overkill, I can run my mini PC based rig plus my notebook off it for two full nights of imaging, plus I can charge it from mains, solar or from the car while driving to and from my shooting location.  And then it is a power back up at home too.

Don't get me wrong, I am not suggesting a generator is a better solution anyway... But over the years I have seen plenty of Laptop batteries quickly destroyed through the use of cheap inverters. If you are however talking about a recent laptop... surely it would be PD compatible anyway. If I had no alternative I may resort to using a Modified Sine Wave Inverter for a short period of time. But if I was designing a power solution for my rig and accessories, an inverter would not feature.

 

When I go away I have 2400Wh in batteries plus 320W in solar panels for running lights refrigerator and rig. I assume that the Ecoflow has self-heating of the LiFePo4 cells, otherwise you will not be able to charge it in cool winter locations. I have seen people with similar power stations (other brands), thought they were ok because they had solar panels but because temp was around 40 degrees they could not charge them, and having to run their cars during the day to heat them up and charge up the power station. 

[archiebald]

 

When I go away I have 2400Wh in batteries plus 320W in solar panels for running lights refrigerator and rig. I assume that the Ecoflow has self-heating of the LiFePo4 cells, otherwise you will not be able to charge it in cool winter locations. I have seen people with similar power stations (other brands), thought they were ok because they had solar panels but because temp was around 40 degrees they could not charge them, and having to run their cars during the day to heat them up and charge up the power station. 

Ecoflow River 2 Pro - LiFePO4

 

I don't think self heating is used in the smaller scale PPS's.  Seems to be in the 2000W+ range only. 

 

However, according to the specs for operating temperatures,

Charging from 0 degC to 45 degC

Discharging from -10degC to +45degC

 

I cannot imagine I'll ever need to be charging / discharging outside that range so it suits my use case perfectly.

Edited by archiebald, 19 July 2024 - 03:28 AM.

[powerslide]

Think that charging range is more wishful thinking than anything else. If it doesn’t have self heating the bms would have to turn of charging before it got close, otherwise it would damage the cells. Same for all LiFePo4 cells.

Yeah obviously comes down that certain solutions are suitable for certain situations. If you are more for warm weather trips probably never encounter it.

Last time I was out it was subzero overnight and if I didn’t have self heating it wouldn’t have been able to charge until after lunch, and maybe only for an hour.

And that was only the beginning of winter. Next trip will be 4 nights in B1 with a max temp around 6 degrees Celsius.


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[danny1976]

Ecoflow River 2 Pro - LiFePO4

 

I don't think self heating is used in the smaller scale PPS's.  Seems to be in the 2000W+ range only. 

The Bluetti B300s has self heating built-in and you can charge it below 0°C.

 

If someone knows another power station with this feature please tell.

[pedxing]

How do people power their laptops with a 12V battery?

I use a dc-dc boost converter set to 19v. You can get "car laptop adapters" that are essentially the same thing.

Its best if you can avoid inverters and the dc-ac-dc conversion penalty.

[archiebald]

Think that charging range is more wishful thinking than anything else. If it doesn’t have self heating the bms would have to turn of charging before it got close, otherwise it would damage the cells. Same for all LiFePo4 cells.

 

A) it works for me

B) A general search on LiFePO4 gives exactly the same temperature ranges, so I see no reason to believe the spec are "wishful thinking"

[archiebald]

The Bluetti B300s has self heating built-in and you can charge it below 0°C.

 

If someone knows another power station with this feature please tell.

...and the Bluetti 300S is a 3,000Wh class battery on Amazon at US$2,000 - 3,000...and it's only an add-on battery

 

Not the sort of thing you are going to be using to power your AP rig.

[powerslide]

The Bluetti B300s has self heating built-in and you can charge it below 0°C.

 

If someone knows another power station with this feature please tell.

My Customized power station is built off these.

 

https://au.renogy.co...ating-function/

 

For those of you that do not understand the limitations of LiFePo4 cells I suggest you do some research. Any decent Power Station BMS will disable charging before it reaches 0 because it's not that a LiFePo4 cell can't be charged at sub zero temps it's because if you do it will do irreparable damage to the cells reducing battery life.

 

So yes they will say that you can charge up to 0 degree, but it is their sensors that determine what the temperature is. Just because your weather station says its 4 degrees C does not mean that the power station will charge. 

 

Here is a Youtube on Canbat batteries out of Canada. 

https://www.youtube....gJySULk&t=184s 

Edited by powerslide, 19 July 2024 - 10:35 PM.

[archiebald]

Silly me, I thought the topic was about "portable" power supplies.

[rick80134]

There's some good info here.  For example, in Colorado in the winter (very clear skies, no moisture) it is often below 0c when shooting overnight.  So, if a LFePO4 batt has issues in sub-zero © temps, that's good information.  The gas powered, I don't consider as portable due to weight and fuel fumes in the vehicle on the way to the site, if driving.  If my rig needs 2000 kwh, and I want to be portable, I've got the wrong rig.

Silly me, I thought the topic was about "portable" power supplies.

[Phil Sherman]

There's some good info here.  For example, in Colorado in the winter (very clear skies, no moisture) it is often below 0c when shooting overnight.  So, if a LFePO4 batt has issues in sub-zero © temps, that's good information.  The gas powered, I don't consider as portable due to weight and fuel fumes in the vehicle on the way to the site, if driving.  If my rig needs 2000 kwh, and I want to be portable, I've got the wrong rig.

LiFePO4 batteries have two low temperature cutoff values, one for charging the other for discharging. As already mentioned, these batteries shouldn't be charged when their internal temperature is less than 0C. They can be safely discharged down to around -18C (0F). At low temperatures, like lead acid batteries, the capacity does decrease but no where as much as what's seen with lead acid batteries.

 

There are low temperature use solutions. One of the simplest is to put the battery into a close fitting styrofoam box. A DIY one made from two layers of home insulating foam with the non-reflective sides glued together will dramatically decrease thermal cooling of the battery. An extra layer on the bottom (conduction to the ground) and cover (radiation to the night sky) will also help. If this isn't enough, adding a low wattage 12V heater under the battery, powered from the battery,  should completely resolve this issue.

 

I did a quick search online for low wattage heating pads and found this one that runs on 5V and draws only 4W of power. There's lots of others powered from a USB port that draw up to 10W. This one, with its plug-in heating pads should be easy to adapt to a battery box. A DC-DC buck converter can provide the 5V needed or you could wire them in series with an added low value resistor to limit the current and power it directly from the battery. Another alternative would be a 12V pet heating pad.

 

https://www.walmart....b=0&athena=true

[powerslide]

LiFePO4 batteries have two low temperature cutoff values, one for charging the other for discharging. As already mentioned, these batteries shouldn't be charged when their internal temperature is less than 0C. They can be safely discharged down to around -18C (0F). At low temperatures, like lead acid batteries, the capacity does decrease but no where as much as what's seen with lead acid batteries.

There are low temperature use solutions. One of the simplest is to put the battery into a close fitting styrofoam box. A DIY one made from two layers of home insulating foam with the non-reflective sides glued together will dramatically decrease thermal cooling of the battery. An extra layer on the bottom (conduction to the ground) and cover (radiation to the night sky) will also help. If this isn't enough, adding a low wattage 12V heater under the battery, powered from the battery, should completely resolve this issue.

I did a quick search online for low wattage heating pads and found this one that runs on 5V and draws only 4W of power. There's lots of others powered from a USB port that draw up to 10W. This one, with its plug-in heating pads should be easy to adapt to a battery box. A DC-DC buck converter can provide the 5V needed or you could wire them in series with an added low value resistor to limit the current and power it directly from the battery. Another alternative would be a 12V pet heating pad.

https://www.walmart....b=0&athena=true

absolutely... but not easy/effective to adapt those methods to an enclosed portable power station though. My comments in the thread about Charging Was to make sure anyone purchasing such devices knows the limitation, if they will be running them in those kind of conditions.

If you wanted an all in one and charge in low temps, maybe wait until a suitable solid state based power station is available. I believe they will have lower charging temperature range.

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Edited by powerslide, 23 July 2024 - 05:05 PM.