Timers that keep good time?

New_Mexico_Will

I use timers to kick several things on and off during bulk charging, like the water heater, laptop charger, etc.

Unfortunately, all that I have tried keep terrible time, and I have to adjust them once a week or so.

Can anyone recommend a 15 amp capable timer that actually keeps good time?

RCinFLA

If you get one that takes its timebase from AC mains, no battery backup, (assume you have grid) should be pretty accurate because power grid compensates any variance over time.  Only issue is if you lose power you get blinky.

Most clocks with 32.768 KHz clock crystals run slow because their designers don't take the couple of pF of PCB runners stray capacitance loading into account.  The crystals temp coefficient is an inverted parabola so the farther away from room temp the slower they run.

I have tweeked several clocks by changing their 10-12 pF xtal load capacitors.  But you need an accurate timebase to do so.

You miight find one that uses WWVB.  Typically named 'atomic' clock.

Photowhit

My family used a graybox timer at home for years and I installed one on a pool where I worked security. Once set, I don't think any of them had to be reset. Both were working off of grid electric. 

https://www.amazon.com/Intermatic-WH40-Timer-7-75-inches/dp/B00004W4XI/ref=asc_df_B00004W4XI/

mike95490

My inverter runs a bit fast, so all my clocks and timers run a tad fast too.  nearly any AC powered clock gets it's time from the 60hz power line.  Grid power, over a week or so, should be very accurate - but with changing loads day to day may vary a hair.

BB.

DC Timers/Clocks (some battery based) are usually the answer vs Inverter AC power (and the less than ideal 60 Hz--And MSW inverters sometimes "confuse" timing circuits):

https://www.solar-electric.com/fldctico.html

I have found that there are Digital AC timers that (appear) to use a crystal time base--Usually see something like this:

https://www.amazon.com/Century-Digital-Programmable-Packaging-Security/dp/B00MVF16JG

 The battery backup assures you stay on schedule even after a power outage. Our product has an internal battery that will last 3 months when not plugged into an electrical source. If the battery needs to be recharged, plug it into an electrical source and allow it to charge for 30-45 minutes. 

I have also had Digital Timers that have a couple watch batteries in a side compartment for the "loss of power" timer operation.

-Bill

New_Mexico_Will

Wow, lots of info I had no idea about. I'm off grid.  Ill be checking these out!  Thanks as always.