Power station build - choosing battery

[HarryN]

Your life will be a lot easier if you purchase pre-made Li batteries.

The savings of home built vs buying a commercial battery are not as significant as they once were.

The biggest mistake most people make in building a power station, including the commercial offerings, is far to low of battery capacity. As an example, your original post would need something more like 4 x 100 amp-hr @12 volt equivalent to work reliably. That is approaching 75 - 100 kg by the time it is all in the box.

 

[Rednecktek]

Your life will be a lot easier if you purchase pre-made Li batteries.

Easier? Yes, maybe. As fun? Not even close!

 

[Jahlovje]

Your life will be a lot easier if you purchase pre-made Li batteries.

The savings of home built vs buying a commercial battery are not as significant as they once were.

The biggest mistake most people make in building a power station, including the commercial offerings, is far to low of battery capacity. As an example, your original post would need something more like 4 x 100 amp-hr @12 volt equivalent to work reliably. That is approaching 75 - 100 kg by the time it is all in the box.

I guess I have to agree with you. A 300ah done DIY would cost me roughly 700 usd, an equivalent 300ah (the cheapest I can find) is 640 usd.

So much for my research

And I do agree with you Rednecktek, it must be fun, and I'm looking forward to making holes in a tool box, but when it comes to electricity, it's fun if you know what you're doing, for me it's just insecurity and stress

 

[HarryN]

Yes, but look at how much you are learning just by doing the research - it is a lot.

The renogy rovers are an exceptionally poor mppt charge controller. The reason is that they have very high standby power draw - even at night, and the real world operation does not match the manual very well. Also if your battery ever goes low and trips the BMS, the rover cannot recover it, as it pulls it's operating power from the battery - not from the sun.

I built my portable power station using a bogart engineering PWM solar controller and the monitoring, but victron also makes nice controllers.

I am a fan of 24 volt systems if you can swing it.

A lot of DC refrigerators come in 24 volt or dual 12 / 24 volt.

USB ports are similar - many will run on 12 or 24 volt.

 

[HarryN]

It is worth considering the idea of building your power system in two different boxes.

Box 1 for the DC portion, batteries, USB, DC connections, chargers, perhaps some SB 50 or larger connections to power the inverter.

Box 2 for the AC related items, or even just have the inverter mounted in the vehicle and plug it into box #1 as needed.

This is a good way to simplify it all in terms of budget, space constraints, and weight distribution.

 

[Jahlovje]

Yes, but look at how much you are learning just by doing the research - it is a lot.

The renogy rovers are an exceptionally poor mppt charge controller. The reason is that they have very high standby power draw - even at night, and the real world operation does not match the manual very well. Also if your battery ever goes low and trips the BMS, the rover cannot recover it, as it pulls it's operating power from the battery - not from the sun.

I built my portable power station using a bogart engineering PWM solar controller and the monitoring, but victron also makes nice controllers.

I am a fan of 24 volt systems if you can swing it.

A lot of DC refrigerators come in 24 volt or dual 12 / 24 volt.

USB ports are similar - many will run on 12 or 24 volt.

Would you mind helping me understand, why a 24V system is better, or even why it is intended to use?
I have no idea what even differentiates them

 

[Bluedog225]

Volts times amps equals watts.

Per math, higher voltage means fewer amps.

Fewer amps can be carried by smaller wire.

Smaller wire, fuses, etc can be meaningfully cheaper.

Many go to 48 volt for this reason.

 

[Jahlovje]

So If i'm lets say building a 24v system:
a 100ah 12 volt, is equivalent to 50ah.

Any "changes" looking for 2000w inverters? a 2000w 12v system is 2000w 24v system, all the same?
(sorry, this is childs play for you guys, I apologize!)

 

[Andrewr05]

So If i'm lets say building a 24v system:
a 100ah 12 volt, is equivalent to 50ah.

Any "changes" looking for 2000w inverters? a 2000w 12v system is 2000w 24v system, all the same?
(sorry, this is childs play for you guys, I apologize!)

Nope, a 2000w 24v inverter will output the same 2000w of 120/240v power.

 

[SupraSPL]

Amazon has an Ecoworthy 60A MPPT for $129. The best value MPPT as far as I can tell. It takes the BT-02 Bluetooth module which is $20 from ecoworthy. Also sold as "Bateria" if you prefer white color. They are both rebranded iPanda esmart4, 150V solar input and work on 12V 24V 36V or 48V batteries.

I measured 93% conversion efficiency with 40V solar panels on 12V batteries but it is hard to measure be cause the solar voltage varies constantly. I measured 95%+ efficiency using them as 36V to 24V buck battery chargers which is easy to measure because of steady current. Standby power is 1.5W.

 

[SupraSPL]

I just saw they have a 100A 250V version now for $236 branded isunenergy and Im pretty sure also uses the BT-02 Bluetooth module

 

[Jahlovje]

This is a lot of information for me
Spent like 6h of researching and looking prices and making a list, but then I was just like - again, what are my needs

I'm definitely going with this option:
- When at campsites, just plug the damn induction cooker into the grid
- When off grid, just buy the damn 80$ gas cooker and suck it up

That left me with the following:
- Two phones
- One laptop/tablet (probably tablet, you're on vacation)
- A fridge that runs constantly
- A couple of battery powered flood lights (for fine dining at nights)
- an electric scooter that needs recharging once a week if even

I basically need the inverter just for that scooter. And a 1000W inverter will be enough, and if later in life, I need more, I can always upgrade.

To me, it makes a lot more sense, to get as bigger the size battery as possible, just to be able to run these things for as long as possible (a week max, but less), without the use of solar (at the moment), because the biggest usage is the fridge.

I'm leaning towards this 12V:
300ah battery
Victron MPPT 100V 50 Amp (in the future it only has to get me through, filing solar)
1000W renogy inverter
Redodo 40 ACDC charger

as my main setup.
Solar panels (in the future).

I can top up my powerstation before going on a trip, and worst case scenario (when I run out of power), I can always put the powerstation on my electric scooter, sit on it, a scoot to the nearest grid (joke) (meant to say, buy the damn panels, and hook it up)

Makes sense?

And by the way, I appreciate every single comment, you guys are legends!

What would be a cheaper alternative to the above in 24V?
2x 100ah in series is already cheaper.. and more Wh..

​

 

[Andrewr05]

I've been running into that issue for years now.
But I enjoy researching things as much as I do bargain hunting, as much as I do putting it all together when I get it.

But that's also how you end up saying "Well... for only $20 more you can get X product rather than Y but than for only $50 more than that that you ca........"

It's a slippery slope.

Spent like 6h of researching and looking prices and making a list, but then I was just like - again, what are my needs

 

[Bluedog225]

Works good. And fast.

 

[Andrewr05]

Works good. And fast.

Those do indeed work wonderfully, I've cooked a crap ton with mine.

And the canisters are relatively cheap too.

 

[Bluedog225]

Yep. And they come in stainless and with good carrying cases. Though mine fills up the trailer with CO much faster than I would have guessed. The meter starts to climb immediately. Absolutely open the door and window.

Canisters are cheapest at the Chinese markets.

 

[HarryN]

Would you mind helping me understand, why a 24V system is better, or even why it is intended to use?
I have no idea what even differentiates them

Some examples:

Solar charge controllers are rated by the maximum input voltage from the solar panel array, and the maximum output current to the battery or fuse block.

So for instance a bogart solar charge controller is rated for 30 amps out into the pack. Same with a victron 100 / 30.

In a 12 volt system, ( 30 amps ) x ( 12 volt ) ~ 350 watts max panels it can support.

In 24 volts pack, ( 30 amps ) x ( 24 volt ) ~ 700 watts of panels can be supported with the exact same hardware and wiring.

If you wanted to support 700 watts of solar panels in a 12 volt system, you would need to purchase a much more expensive, much larger charge controller.

( 700 watts ) / ( 12 volts) ~ 60 amps, so at least a victron ___ / 50, which is much more expensive and heavy. Heavier, less flexible wiring, etc.
_______________

USB port output capability.

Newer phones and devices can charge faster via usb than before.

In order to do this, the voltage of the USB is higher than the original ~ 5 volts.

The USB ports on the market that can do this tend to need 24 volts to get there vs if you feed them with 12 volts, they usually can't go higher than traditional USB port charge rates.

 

[HarryN]

In terms of your battery capacity:

A single 300 amp-hr, 12 volt battery. ( 300 amp-hr ) x ( 12 volt ) ~ 3 000 watt-hrs.

Two each, 100 amp-hr , 12 volt batteries. ( 2) x ( 12 volt ) x ( 100 amp-hrs) ~ 2 000 watt-hrs.

It does not matter if you wire them as 12 volt or 24 volt, the capacity is the same.

Imagine that you have two cans of beer. If you put them both flat on the table or stack them on top of each other, it is still two cans of beer. The only difference is the height and is narrower.

 

[Jahlovje]

In terms of your battery capacity:

A single 300 amp-hr, 12 volt battery. ( 300 amp-hr ) x ( 12 volt ) ~ 3 000 watt-hrs.

Two each, 100 amp-hr , 12 volt batteries. ( 2) x ( 12 volt ) x ( 100 amp-hrs) ~ 2 000 watt-hrs.

It does not matter if you wire them as 12 volt or 24 volt, the capacity is the same.

Imagine that you have two cans of beer. If you put them both flat on the table or stack them on top of each other, it is still two cans of beer. The only difference is the height and is narrower.

Thank you!

So in general terms, capacity is capacity, but regarding other stuff such as solar (MPPT), I could get a 30a not a 50a victron, and USB ports are more efficient.

Plus, I save some money on the wires.

Thank you!

 

[Dave911]

These work well:

https://www.amazon.com/gp/product/B0BVD2J4NM/ref=ox_sc_saved_title_7?smid=AYGOM05UUYR95&psc=1

These just showed up and they probably work fine as well: This is the mini size which is relevant if you want to package this thing.

https://www.amazon.com/gp/product/B0CRB118TG/ref=ox_sc_saved_image_8?smid=AURQPK7EE3FR8&th=1

The Redodo's test out fine as well. Both have a 5 year warranty if they are still around 5 years from now.
I am pretty sure the same company makes both. The manuals are nearly identical, the cases are identical, etc.

These batteries are rated to put out at least 100 ah at 12 volts. So that is 1200 watt hours or 1.2 kwhr. I have a number of these and they all test to at least 102 ah. Some have been just over 105 ah. That's on a tester that draws about 13 amps.

I have had 3 induction hot plates. You will only use 1500 watts if you are bringing gallons of water to a boil.
Otherwise you will be at 1000 watts or less. My plates are 1500 watts and I think I have used the high setting once, only to burn what I was cooking.

If I was going to do what you propose I would stick with packaged batteries. You can't make the case, buy the BMS, buy the cells, wire it and make it into a durable battery on your own for less. Plus these have a warranty of some type. If you make it, you warranty it!

 

[Whats_per_question]

To understand, you believe I would be ripped off?

Late to reply again sorry, but yes, I believe the probability of getting exactly what you paid for when you are a one-time purchaser are very low. "one-time purchaser" is not a slight or pejorative, its just a fact that you won't be on anyones top-buyer list like a retailer or wholesaler might be, so a seller who has invested little in their reputation or brand would not be losing much if they disappointed you.

There is an exception to this; long standing sellers with a good reputation are a different class of seller. They trade on their reputation in forums like this. @Rednecktek seems to be endorsing @Docan AmyZheng if i'm reading the post correctly, and if that's the case maybe Docan is one of those 'high reputation' sellers. High reputation sellers have invested a lot of time and effort into their brand. Their brand may just be their username, or it may be the company they represent. They build their brand by delivering exactly what they say, and your part of the deal is to say this on a public forum - you win by getting what you paid for, they win by building their brand.

I can only speak for NZ in general. The "wisdom" passed on through society is that (figuratively) everyone lives in a small town, and cheaters will get found out and will eventually lose. This is terrible wisdom to pass on when the internet became ubiquitous, and the "cost" of being found out as a cheater is to ditch your aliexpress sellers account and start a new one. There is no entry fee on Aliexpress - just the sale commission fee. The cost of cheating on a trade is maybe an apology email, maybe a partial refund. The profit is enormous in comparison to the cost

 

[Jahlovje]

Late to reply again sorry, but yes, I believe the probability of getting exactly what you paid for when you are a one-time purchaser are very low. "one-time purchaser" is not a slight or pejorative, its just a fact that you won't be on anyones top-buyer list like a retailer or wholesaler might be, so a seller who has invested little in their reputation or brand would not be losing much if they disappointed you.

There is an exception to this; long standing sellers with a good reputation are a different class of seller. They trade on their reputation in forums like this. @Rednecktek seems to be endorsing @Docan AmyZheng if i'm reading the post correctly, and if that's the case maybe Docan is one of those 'high reputation' sellers. High reputation sellers have invested a lot of time and effort into their brand. Their brand may just be their username, or it may be the company they represent. They build their brand by delivering exactly what they say, and your part of the deal is to say this on a public forum - you win by getting what you paid for, they win by building their brand.

I can only speak for NZ in general. The "wisdom" passed on through society is that (figuratively) everyone lives in a small town, and cheaters will get found out and will eventually lose. This is terrible wisdom to pass on when the internet became ubiquitous, and the "cost" of being found out as a cheater is to ditch your aliexpress sellers account and start a new one. There is no entry fee on Aliexpress - just the sale commission fee. The cost of cheating on a trade is maybe an apology email, maybe a partial refund. The profit is enormous in comparison to the cost

Thank you for this in-depth reponse! Appreciated!