Big Red

Big Red Covered with Snow Again

It didn't take long for winter to return. While I don't have any plans to go anywhere today - I'm canceling my trip to Central New York for now - I don't feel like knocking the snow off my truck or heading anywhere today. 

Taken on Friday October 30, 2020 at Big Red.

Solar Charger Scam

While lithium batteries are fairly good, I can tell you an advertisement for an 80,000 mAh USB battery bank is a scam. 80 amp hours even at just 5 volts, is 2/5th of a kilowatt hour — which is a lot of electricity to store in a little battery.

The 50 lb lead acid batteries in my truck — each only have about 50 amp hours of usable capacity (to be fair, at 12 volts). Trust me, you’re not going to take a 50 lb battery to the beach to charge your cellphone.

What are they doing to make this claim?
1) First off they’re measuring amp hours at the nominal voltage of the lithium ion batteries at 3.6 volts, ignoring losses in the boost converter, and that 1 amp at 3.6 volts is only 0.72 amp at 5 volts. But discount by the 80% with loses in the boost converter, so you are at .57 amp at 5 volts.

2) A really good 18650 cell — like a pricey one used in an electric car or high end laptop might have 3.5 amp-hour capacity. So the best case scenario if there is three really good 18650 cells in this unit, it could put out 10.5 amp hours or 10,500 mAh if your interested in inflating numbers.

3) But with loses in the boost converter, and the fact that when you increase voltage you decrease amperage, your talking about 5.98 amp hour or 5,980 mA hour if you want to sound impressive. But I doubt the Chinese cheapout 18650 cells in this put anywhere near that capacity.

So yes, these solar chargers are a scam. The solar cells themselves put out maybe 20 – 30 mAh of capacity, so don’t expect much charging unless you have days in the direct sun.

Working out of my truck has me

Working out of my truck has me …

  1. Really notice how much wildlife there is out there and the many patterns of the clouds.
  2. Pay much more attention to the weather, notice the impacts of clouds and sun on solar panel and electricity production.
  3. Be aware of how much energy my little 100 watt panel can actually produce on a nice day.

I am watching the voltage start to sag a bit in my truck, but I have good faith that I’ll make it to five o’clock

I am watching the voltage start to sag a bit in my truck, but I have good faith that I’ll make it to five o’clock. The sun angle is declining now that it’s almost four o’clock and the skies have clouded up. But my battery bank is full and my laptop is fully charged, so I think I won’t go dark for another hour. #trucklife

Energy hog

It’s the relay ⚫ that’s the big energy hog 🐽 …

I used to think that it was the starting and accessory batteries 🔋 with their different charge depth fighting that was causing the starting battery to loose charge when both batteries were connected in Big Red. But it turns out after reading on the internet, the relay that connects them is quite power hungry, pulling 400mA per my volt meter or about six watts whenever the relay is live. Doesn’t sound like much but six watts adds up over time. It takes a fairly powerful electromagnet to securely latch the relay when live to ensure that it doesn’t bounce loose on rough roads or have poor contact leading to arcing ✨ and burnt contacts.

The electricity use is fine and not possible to prevent unless I replaced the relay with a latching relay of some sort. Not a big deal when the big olf alternator is putting out 135 amps but something to consider with the solar panel that only puts out like 2 amp in the winter and maybe 5-7 amp on a sunny summer day. Also definitely something to consider when I eventually have an off grid property of my own.