5 ms·

It’s at 76% now. In 53 minutes since the post it has gone down 4%. So say roughly 5% per hour as a back of the envelop calculation. That’s roughly 20 hours on a

It’s at 76% now. In 53 minutes since the post it has gone down 4%. So say roughly 5% per hour as a back of the envelop calculation. That’s roughly 20 hours on a full charged cycle. It would be good to know if there is a fast charge capability of the battery and how long would that be. An hour of full sun a day? Or two hours of partial sun?

eyelidlessness 5y ago
It’s on the HN front page, I don’t think I’d extrapolate anything from its current power usage.
- dsizzle 5y ago
  Ha. We better read it while we can!
  - r-w 5y ago
    Or, in keeping with the spirit of the post: think long-term and give the battery a chance to rest, then read it later :)
  - NaturalPhallacy 5y ago
    Quick, everyone in!
  - mcv 5y ago
    Maybe this should have been posted on a sunny summer's day.
ronsor 5y ago
One can only blame HN traffic for its sudden decrease.
- vstm 5y ago
  Well the sun has probably set in Barcelona too, this won't help either.
  - rzzzt 5y ago
    Indeed, there is a row in the "Power demand" table saying "Solar panel active: no".
- superjan 5y ago
  I clicked the link, curious what the what the power reading would be now. Now I feel guilty.
deleted 5y ago
[deleted]
agilob 5y ago
Avg. CPU load is 99.5%
invalidator 5y ago
They are using a 168Wh battery and a 30W panel, so a naive first approximation would be 168Wh / 30W = 5.6h to go from 0% to 100% capacity. In reality: * The panel won't be pointed squarely at the sun most of the day * The sun won't be high-noon-bright most of the day * Lead-acid is about 80% efficient (perhaps 90% at low state-of-charge, dropping to 60% at high SOC) * Lead-acid chemistry is sluggish. It can charge pretty quickly to 80% (a 168Wh battery will easily accept the full 30W up to that point), but the acceptance rate decays asymptotically toward zero as the battery approaches 100% capacity. No matter how powerful the charger, going from 80% to ~98% takes about 6-8 hours. * 0% state of charge is about 10.5V, but lead-acid cycle life falls dramatically with deeper discharges. To reduce wear on the battery, they designate 12V as 0% charge and shut down at that point. This means they're only using 50% of the 168Wh capacity, but it also means they hit the sluggish part of the charge cycle sooner. Summing up the above, with perfect-noon-sun conditions generating the full 30W, the charge curve will be roughly: 3h from 50% to 80% SOC (0%-60% indicated); 6h from 80% to 98% SOC (60%-100% indicated); a few more hours for the last 2%. Realistically it will get the majority of the charge by early afternoon, and the slow trip from 80%-98% will complete sometime in the early evening. At that point the panel will only be producing a few watts, but it's still enough to finish trickle charging to 100%.
tgtweak 5y ago
A 30W panel would need about 6 full hours of sun to fully charge that battery from 0-100. Lead acid can charge fairly quickly and can suck up that 30W input pretty easily.

eyelidlessness 5y ago

It’s on the HN front page, I don’t think I’d extrapolate anything from its current power usage.

dsizzle 5y ago
Ha. We better read it while we can!
- r-w 5y ago
  Or, in keeping with the spirit of the post: think long-term and give the battery a chance to rest, then read it later :)
- NaturalPhallacy 5y ago
  Quick, everyone in!
- mcv 5y ago
  Maybe this should have been posted on a sunny summer's day.

ronsor 5y ago

One can only blame HN traffic for its sudden decrease.

vstm 5y ago
Well the sun has probably set in Barcelona too, this won't help either.
- rzzzt 5y ago
  Indeed, there is a row in the "Power demand" table saying "Solar panel active: no".
superjan 5y ago
I clicked the link, curious what the what the power reading would be now. Now I feel guilty.

deleted 5y ago

[deleted]

agilob 5y ago

Avg. CPU load is 99.5%

invalidator 5y ago

They are using a 168Wh battery and a 30W panel, so a naive first approximation would be 168Wh / 30W = 5.6h to go from 0% to 100% capacity. In reality: * The panel won't be pointed squarely at the sun most of the day * The sun won't be high-noon-bright most of the day * Lead-acid is about 80% efficient (perhaps 90% at low state-of-charge, dropping to 60% at high SOC) * Lead-acid chemistry is sluggish. It can charge pretty quickly to 80% (a 168Wh battery will easily accept the full 30W up to that point), but the acceptance rate decays asymptotically toward zero as the battery approaches 100% capacity. No matter how powerful the charger, going from 80% to ~98% takes about 6-8 hours. * 0% state of charge is about 10.5V, but lead-acid cycle life falls dramatically with deeper discharges. To reduce wear on the battery, they designate 12V as 0% charge and shut down at that point. This means they're only using 50% of the 168Wh capacity, but it also means they hit the sluggish part of the charge cycle sooner. Summing up the above, with perfect-noon-sun conditions generating the full 30W, the charge curve will be roughly: 3h from 50% to 80% SOC (0%-60% indicated); 6h from 80% to 98% SOC (60%-100% indicated); a few more hours for the last 2%. Realistically it will get the majority of the charge by early afternoon, and the slow trip from 80%-98% will complete sometime in the early evening. At that point the panel will only be producing a few watts, but it's still enough to finish trickle charging to 100%.

tgtweak 5y ago

A 30W panel would need about 6 full hours of sun to fully charge that battery from 0-100. Lead acid can charge fairly quickly and can suck up that 30W input pretty easily.