Comment by charlesju | Hacker News Reader

Comment by charlesju | Hacker News Reader

Here is the much more portable and expensive version of this kit.

Anker PowerHouse to store the energy. 400 WH which is about the same capacity as the deep cycle battery listed, but this is lithium based so it's much lighter (9.3 lbs vs about 30 lbs for the deep cycle version). $500 https://www.amazon.com/Anker-PowerHouse-Generator-Alternativ...

Foldable 80W solar panel. $190 https://www.amazon.com/ALLPOWERS-Foldable-SunPower-Technolog...

Extension cord for solar panel to battery. $8 https://smile.amazon.com/gp/product/B00FTFYH0U/ref=oh_aui_de...

Evaporative Cooler instead of building your own. $112 https://smile.amazon.com/gp/product/B007SNQ4FM/ref=oh_aui_de...

$810 for the total package. The benefits are that you get to use a lithium-based battery which is 20 lbs lighter, you can use a foldable solar panel which is more portable, and you buy a pre-assembled evaporative cooler which has nice features like swinging. Mainly this is a good solution for those that just want to press buttons and set up their configuration in a few hours otherwise the kit seems like a good option too.

I used this configuration at burning man and the battery was permanently charged even with the cooler on the whole time. I needed another shade structure for the tent to keep it down a couple more degrees but I was able to sleep until noon with this set up and be totally off grid and have enough power left over for lights and music.

FYI, I've seen prices for the Anker Powerhouse in the $300's on Slickdeals: https://slickdeals.net/newsearch.php?src=SearchBarV2&q=%22An...

Is there a major difference between lithium and deep cycle lead acid batteries with respect to battery life versus amount of discharge per usage or is it a wash?

There are indeed several major differences. The first one that comes to mind is to get the most cycles out of a lead acid battery, they recommend not discharging it below 50% capacity. Lithium ion batteries are usually good to 85% - 90% discharge.

And on the other hand shouldn't be fully charged. Only going to 90% capacity does wonders for their lifetime.

How do they compare on temperature ranges?

Yes, but you're still talking hundreds of charges to 100% for a Li-ion before you lose capacity. A regular charge to 90% and then only charging to 100% on the odd occasion you need the little bit extra gives you the best of both worlds.

Do even a handful of deep discharges on a lead-acid battery and you'll kill it.

Like you, I built a similar system for BM this year, but based it around two 48v Li-ion ebike batteries (550 Wh and 1000 Wh).

BMSBattery (China) sells a 48v 30AH Lipo battery pack [1] for $530 + $120 shipping, with delivery in 2-3 weeks. That's 1440 Wh! And the battery includes a "BMS", circuitry that prevents under/over-voltages, over-temperature, cell balancing, and allows for simultaneous charging and discharging. This last feature is really useful if you are using the battery with a solar setup and want to be able to source loads bigger than your panels can supply from time to time.

If you need batteries ASAP in the bay area, you can get similar products from AA Portable Power Corp / Batteryspace.com [2] located in northeast bay (caution - these do not include BMS so no simultaneous charging+discharging).

So, if you are spending $500 for the battery, you can get much higher capacity (Wh) Li-ion batteries around the same price point from suppliers serving the diy ebike market.

Caveat is that these batteries are typically in the 36-48v, so depending on your application, you may need to add a buck converter (to regulate voltage down to 12v or 5v) or a boost/ac inverter for 120v. Sometimes having a higher voltage can lead to some efficiencies vs lower voltages - can use thinner wires, less power loss over same wire lengths, voltage converters / inverters may be more efficient.

"DROK"-brand voltage converters are around $30 on amazon[3].

If you want to charge your 36-48v Li-ion battery, try the $38 MPT-7210A "Docooler® MPPT Solar Panel Battery Regulator Charge Controller 10A"[4]. If you have two ~20v panels, wire them in series so the panel voltage going to the charge controller is ~40v; it won't have to work as hard to boost the voltage for battery charging and will be more efficient.

[1]: https://bmsbattery.com/ebike-battery/715-high-power-48v30ah-... [2]: http://www.batteryspace.com/lithium-26650-battery-pack-50-4v... [3]: https://www.amazon.com/s/ref=sr_nr_scat_10967761_9119938011_... [4]: https://www.amazon.com/gp/product/B01HCL7LEW

What did you do with that much power? Did you go for the AC or fridge?

We added a pedal-assist ebike motor to our camp's quad bike (2x2 tandem; 4 passengers).

The high Ah capacity was to support using the motor and accessories (atv soundsystem, lots of "dotstar"-style LED strips) periodically throughout the day and night.

We had two batteries and two sets of solar charging systems: a large, heavy 270-watt panel at camp and 2x 100-watt flexible panels for the bike.

Bike panels extended the range of the bike through a combination of powering accessories during the day, recharging the battery (when not using the motor), and reducing the load on the battery by providing supplemental power directly to the motor controller (when using the motor). "750" watt motor, ~200 w of solar, so not really possible to drive without also using the battery.

Meanwhile, the spare battery is charging at camp and also available for light loads like phone charging and some lights at night.

Every day or two we swap the batteries such that the bike has the more fully charged one.

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