USB-C "Chargeverter"

[Shimmy]

In light of @Battery Bob's thread, https://diysolarforum.com/threads/c...inverter-sizing-calculator.71247/#post-905111 I am wondering if there are any good (commodity) solutions for combining 1-2 LFP cells (say 200-300Ah total) and some power electronics to give modest 5-12VDC power for small loads.

I am thinking that there might be value for something like half of a 12V/100Ah battery with 12V and 5V ports that could be easily charged by a USB-C charger... if it can be half the cost and significantly lighter. To that end, an inverter would likely be out.

A case could be made for a similar device that is dedicated to just backing up a refrigerator.

 

[SeaGal]

USB-C would not be so good for charging, being only 5V. Max power is also 100W which would still be 20A.

Edited to add: ignore that - not only 5V (thanks @Vigo)

 

[Vigo]

So my VERY weak understanding of USB-C is that the only way they get up to 100w is by going up to ~20v? I guess there is some communication in the protocol about what the recipient device can use as far as voltage or wattage, similar to the j1772 ev plug maybe? Like i said, VERY weak, passing knowledge, might just be totally wrong.

But either way, USB-C is a tiny connector format and while it may be able to do 100w, i'd personally be dubious about it being able to sustain that in anything less than perfect conditions (ie imperfect connections like we see with mismatched MC4 brands etc plus 'wear' on terminals from repeated connections/disconnections of connector).

I personally would rather use a larger (and simpler) connector format that was going to be used way under its current limit so that it could 'degrade' quite a ways before it actually impacted performance. My .02.

 

[SeaGal]

So my VERY weak understanding of USB-C is that the only way they get up to 100w is by going up to ~20v? I guess there is some communication in the protocol about what the recipient device can use as far as voltage or wattage, similar to the j1772 ev plug maybe? Like i said, VERY weak, passing knowledge, might just be totally wrong.

That makes more sense - and that's what I love about this site - learn something new every day.

 

[Brucey]

That makes more sense - and that's what I love about this site - learn something new every day.

Perhaps something like this:

And then charge by connecting charger to one of the Anderson connectors.

https://www.amazon.com/Redodo-Battery-Charging-Intelligent-Suitable/dp/B0BD85M67Z

 

[Brucey]

USB-C would not be so good for charging, being only 5V. Max power is also 100W which would still be 20A.

Edited to add: ignore that - not only 5V (thanks @Vigo)

To get to 100W output it switches to 20V at 5A if I'm not mistaken

 

[Shimmy]

USB-C can easily do 35-70W, so for an application where 300-600Wh is desired it is a reasonable match. It gives enough power and energy to charge a family's devices and internet for a day, along with some rechargeable lanterns and the like.

Two 100Ah LFP cells and power electronics to run a basic BMS and buck/boost converter gives you something about 10lbs and 8x8x4", that should be able to be made for ~$200. I just haven't seen such a product on the market.

 

[Shimmy]

Looks like the Ecoflow River series essentially does everything I was looking for, albeit a little bulkier than I had hoped but at a pretty reasonable price point in the scheme of things.

 

[Brucey]

Looks like the Ecoflow River series essentially does everything I was looking for, albeit a little bulkier than I had hoped but at a pretty reasonable price point in the scheme of things.

I have two river 2s. Just be aware they can get pretty loud with their cooling fans with even a small 50W AC load or when charging via the solar input or grid etc. When just using the USB c/a ports it's basically silent, it tends to discharge to 98% then charge back up.

Hard to beat for around $200 if the 300W output limit is acceptable.

 

[Shimmy]

I have two river 2s. Just be aware they can get pretty loud with their cooling fans with even a small 50W AC load or when charging via the solar input or grid etc. When just using the USB c/a ports it's basically silent, it tends to discharge to 98% then charge back up.

Hard to beat for around $200 if the 300W output limit is acceptable.

Do you know if it can start a standard/full size refrigerator compressor? Just looking for a frame of reference, as I know the Wh rating is insufficient to really do much. Thanks for the detail about noise... that is one of the things I like about a pure DC approach.

 

[webbbn]

I've seen a few proposals in the past for making a DC power standard in homes, but they never seem to go anywhere. There are, of course, issues with wire sizing and such for higher-power devices, but there are so many things these days that could benefit from a low-voltage DC standard that I think it has to happen some day.

I see a post that I made a few months back listed below as one of the similar threads to this, that only got one reply, so maybe it's a pipe dream.

 

[Brucey]

Do you know if it can start a standard/full size refrigerator compressor? Just looking for a frame of reference, as I know the Wh rating is insufficient to really do much. Thanks for the detail about noise... that is one of the things I like about a pure DC approach.

I haven't tried but I'm thinking it's going to overload with the surge when compressor kicks in. The Wh capacity can be extended pretty cheaply with a 12V 100Ah LFP battery connected to the solar input, as long as you are ok with around 100W charge rate and having to charge the 12V battery with a separate charger.

 

[Vigo]

I have a 400w 'travel' inverter that would start my home fridge sometimes, but not all the time! I think 600-1000w is a safer bet to start a household fridge, but honestly there's no downside to going bigger other than upfront cost. For example, my 5000w modified sine wave harbor freight inverter only pulls like 7-12w 'idle draw' but it will start a 13000btu ac or probably about 10 fridges at once. It was a little more upfront but it's not really costing me anything in energy consumption to have it sit there being overkill. So i would just buy an inverter that is DEFINITELY big enough (say, a 2000w inverter to power a fridge + odds and ends) and just eat the up front cost to live in confidence that it will never fail to start the compressor. My .02.

 

[Shimmy]

I think 600-1000w is a safer bet to start a household fridge, but honestly there's no downside to going bigger other than upfront cost.

It's for my 87 year old mom, so physical size and weight is an issue. It can be dealt with though.

 

[Watts Happening]

I suppose my question is why not just build a 12v battery using off the shelf cells, then a standard “high power” 12v USB-C charger? Seems simple enough?

 

[Shimmy]

I suppose my question is why not just build a 12v battery using off the shelf cells, then a standard “high power” 12v USB-C charger? Seems simple enough?

I was looking for something smaller initially, and had hoped that a two-cell 100Ah battery would better fit the need, using just DC outputs. At the price point though for some of the smaller systems though it is easier to just buy a $300 integrated product that throws in a 300W inverter.

 

[Brucey]

It's for my 87 year old mom, so physical size and weight is an issue. It can be dealt with though.

River 2 is relatively light and portable so shouldn't be too much of a problem. For her fridge that may be a better application for a diy project, something bigger/less portable that can handle the start up surge and a bigger battery to give you solid runtime.

 

[Brucey]

Perhaps a licetti battery box?

AC Battery Box - LICITTI

WORLDWIDE SHIPPING!!! Los Angeles ,New Jersey,Georgia,Illinois,Canada, Germany,United Kingdom,Romania,Greece in stock!!! Strong ABS+PC with flame-retardant rating UL94 V-0 Pure Sine Wave Inverter Easily see battery status with large digital display Multiple port types allow you to connect a...

www.licitti.com

 

[Vigo]

For an 87 yo mom i would probably buy an off the shelf solar generator with the LEAST feature rich menu to navigate. Nothing small is parallelable unfortunately, at least as far as ac out. But if you had something like a DC fridge you could easily parallel the 12v dc outs. Just thinking easy to carry.

 

[Shimmy]

Perhaps a licetti battery box?

Interesting, thanks.

For an 87 yo mom i would probably buy an off the shelf solar generator with the LEAST feature rich menu to navigate.

She's tough, but even a 15lb box is more than I would want her moving around. Whatever I do needs to be set-and-forget.

I think I will be getting her a River2 Max or Pro for above the fridge and a River2 for her office... or something comparable.