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Re: (ET) HL-Controller vs The E-meter

Basically it states that the capacity of a battery under load is not a static or linear number. A T105 battery for example can deliver 205ah over a 20 hour period. However if you discharge it over a 1 hour period, it will only be able to deliver about half it's 20 hour capacity. This dynamic is called the puekert factor, and is different for different types of lead/acid batteries.
That said, the problem with lead acid batteries is that you have to put more charge into them than you take out. Partially because we discharge the batteries at more than a 20 hour rate (unless you drive the tractor really slow) But also because batteries are not 100% efficient: You have to put more energy into them than you take out.
The E-Meter in this case is correct: You are not putting in enough power to offset the amount one is taking out.
The other issue is equalizing the batteries: Because they are in a series string, they tend to discharge at slightly different rates. The solution to this is to overcharge the batteries; that way all of them get a full charge.
When you overcharge, you get a warm battery and the electrolyte bubbles. Overcharge for too long and you wind up drying out the battery. This is why you can't leave the charger on full blast forever: The batteries will overcharge and dry out. It's also why you have to add water from time to time.
The problem with a single voltage controller is that you can either set it to run at a voltage which will equalize the batteries, but over time (few days) you will wreck the batteries by drying them out and warping the plates. You can also set the peak voltage lower, but then the batteries will never fully charge, and will sulphate over time.
Given all that, the Elec-Trak people chose the best option for the time: Overcharge the batteries, but put the charger on a timer to keep them from drying out too quickly. They even put recommended charge times, since new batteries need to be equalized longer than older ones.
My solar tractor solution uses a two stage charger as well: It bulk charges up to one voltage, then tapers off the charge at a higher voltage (45 I think). Even so I run the transformer once a year just to make sure it all works properly.
The Landis type controller is a nice idea, but simply going out to your tractor every month or two and running a charge is probably a lot better for your batteries. 

Chris


Rob Brockway wrote:


Can anyone explain Puekert number?
Rob 

oleoranch aaahawk com wrote:
Jim, your calculations are good on paper but in real life when I use the tractor starting with a Full battery I can run for about 2 hours. This brings the battery down to about 80% DOD. With the Landis controller in the charger, plugged in all day and night when I start using the tractor the next day I can only run for about 20 minuets before the tractor slows WAY down from weak batteries. The E Meter confirms this "Battery at 0%" condition. You are correct that the E Meter is difficult to program. It takes me several tried to get is set to the tractor. R. ; > 
!
  I think that the E-meter and the Harry Landis Controller may be mutually 


exclusive (I say never having tried it).

The e-meter has a lot of great features but all the programmable
parameters can make it tricky to use. So bear with me for a longish
explanation...

When the tractor is in use, the e-meter counts actual Amp-hours used
(although the % remaining 'fuel' gauge is corrected based on Puekert
number, but that is another story). So far, so good.
When the tractor is charging, the e-meter shows *corrected* amp-hours put back into the pack. This correction is based on the "Charging Efficiency" (CEF) that the e-meter calculates based on past charge cycles. For instance, if the CEF is 90% then when 10 actual amp-hours are returned, the e-meter will show that 9 amp-hours have gone in. I won't tell you how many years of using an e-meter it took for this detail to penetrate my skull.
The CEF is recalculated with each complete charge cycle. A complete cycle (or "reset to zero") requires 5 conditions to be met: 1) At least 10% of the batteries capacity must be used (so very shallow discharges don't count) 
2) 100% of the KWhrs removed must be returned by the charger
3) The pack voltage must rise above the 'charge voltage' parameter (say 40 volts) 
4) The current must fall below the 'charge current' parameter (say 4.4 
amps)
5) Conditions 3 & 4 must be met for ***at least 5 minutes***.
With a standard battery charger, the charge cycle starts off with a high current (say 20 amps) and the pack voltage starts slowly rising as the battery charges. As the bulk of the charge gets done, the voltage rises more quickly as the current falls quickly. If the charge parameters on the e-meter are correctly set, the meter sees a complete cycle and is happy. Out of the box, the e-meter starts with a CEF of 90% and then updates this value each cycle as it learns about the particular battery pack.
If the charger keeps going after the e-meter sees it as full, positive amp-hours are accumulated, but as soon as you start driving/mowing it jumps back to zero and starts counting negative as it should.
Now add a Landis controller to the charger. As I understand it, the charger no longer runs continuously until done, but rather cycles on and off. On an empty battery the off time is short, and becomes longer as the battery reaches full charge. So now even when all the KWhrs have been returned to the battery pack, the 5 conditions for a reset may not be met - particularly #5 that requires the conditions to hold for at least 5 minutes. 

The result may be that the e-meter never sees a "complete" charge
cycle, so it doesn't reset to zero properly and it doesn't recalculate the CEF. Or worse yet it occasionally does see a reset after sitting on the charger for days and ends up calculating a horrible charge efficiency.
Some options to get the e-meter to reset to zero on complete cycles might be:
- Make sure the 'charged voltage' is below the final voltage of the charger & HLC combo; make sure the battery capacity is set correctly
- Increase the 'charged current' parameter from say 2% to 4% of the pack capacity, so the charge current doesn't have to fall off as far
- Change the time to meet the charged parameters from 5 minutes to 1 minute (F05) 

- Manually set the CEF (F06) - "not recommended" per the instruction manual
Could also set the e-meter to count KWHrs in/out, which are not corrected in any way (F04) and use the human brain instead of the e-meter brain to track things. 

I'll be curious to hear the results of any experiments.


oleoranch aaahawk com wrote:


  I have several "Landis controllers" and I had one on a tractor
with an E Meter.  The E Meter keeps track of all battery functions
including ah out and back in.   With the Landis controller the
charger was never able to replace all the ah I has used.  Even
if I let the tractor sit plug in for 2 weeks. The Landis controller
is fine for maintaining full batteries for long periods of sitting
but will never fully recharge the batteries if you use the tractor
on a regular basis.
R.


_________
Jim Coate
1992 Chevy S10
1970's Elec-Trak
http://www.eeevee.com



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