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Manual Synchronisation & LinkLite Monitor

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I'm having a bit of an issue with my battery monitor.  I has always worked perfectly well in the past for instance, when the monitor 'Synchronise' function flashes, pressing the two outside buttons simultaneously has resulted in "Full" being displayed in accordance with the manual.

 

I have the van on 240V external power charging so I'm not relying on solar alone.

 

More recently, when the 'Synchronise' notification has been flashing, going through the process of pressing the two outside buttons simply results in the display showing 100% with both the A(mps) and the A/Hr reverting to 0.  Which is all good.  Or is it?  I must mention too that although the flashing 'synchronise' notification will stop flashing, this will be for about 20 secs max before it starts flashing again.

 

My reading on a very comprehensive US boating site indicates that 100% doesn't necessarily mean Full and explains that the 100% is only what the monitor algorithm will show by calculation but doesn't really mean the battery is fully charged.   Yeah, this may be splitting hairs but the algorithm apparently stores data from previous synchronisations and any errors that may have been accumulated in time like for instance synchronising when the two parameters of F01 and F02 are not met, can be responsible for this possible error.  The Americans call this the 'gotcha' effect.  'Course they do.

 

The boating site experts also recommend that one change various parameters in the Function menu like for instance changing the theoretical voltage of the battery to 15V and the charge current  to 1% (instead of 2%).  These parameters will never be met but it does prevent the charger from going into float mode before it should.  Here is an excerpt from that site:

 

The Link 20 has an "gotcha" that isn't real obvious. When charging, the Link 20 considers the battery to be fully charged when two conditions are met. First the charging voltage must be at or above the entered parameter and the charging current must be below the percentage of the bank capacity that is also an entered parameter. In my case those parameters were 13.2V and 2%. 2% is about 9.2A for my bank of 460Ah. When these two parameters are met, the Link 20 blinks the top green LED indicating full charge, resets the AH used to zero, and recalculates and stores the charge efficiency factor for future charging. This can happen even if the used AH are not counted down to zero.

Without realizing this was happening, my golf carts were being cheated of 10-20Ah at various recharge cycles during the month. Thus I thought my batteries were being fully recharged but actually they were reported to be full but were short. Over the month I calculated that they were about 140Ah down out of the 460Ah capacity. Thus I had a chronic undercharge.

This undercharge showed itself as a low terminal voltage in the morning, sometimes as low as 11.9V when the voltage was 12.4-12.5 or so when retiring for the night.

The scenario for the Link 20 gotcha is this: The charging current has tapered down to about 13A with 20Ah still to go with the charging voltage at 14.4V. Now one of the refrigeration units turns on drawing 5A. This causes the battery charge current to drop below the 2% threshold and after 6 minutes the Link 20 thinks the batteries are fully charged because the charge voltage is over 13.2V, the charge current is below 2% or 9.2A, and these conditions have been met for 6 minutes. Then to make matters worse, the recharge efficiency factor is recalculated to a higher value (ex. 0.97 vs 0.95) so the at the next charge cycle the Link 20 thinks that the batteries require fewer input AH for the used AH. This is not true of course, but it makes the under-charge condition worse.

The fix for this gotcha is to set the Link 20 parameters to 15v and 1%. These parameters are not ever going to be met, so that means that the Link 20 will never think the batteries are fully charged until the AH used are fully counted down to zero. Also set the recharge efficiency factor to manual of 0.94 instead of the automatic setting of 0.95. This will stop the automatic recalculation and fix the recharge efficiency to be 0.94.

 

The point is, I don't really understand all of this as much as I would like and would appreciate input from the experts out there.  Incidentally, I did run this past the Enerdrive folk locally but didn't get much joy except to say that the fellow I chatted to wasn't at all happy about pushing the charge voyage to 15V.  He recommended I max that at 13.5V which seemingly is the voltage at which my system floats (or so it seems).

 

Apologies for the tortuous post...

 

Cheers

Brian

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Have you actually measured either the voltage at the terminals (say an hour minimum after all charging and discharging has ceased , to allow the voltage reading to stabilise ) and also the specific gravity of the electrolyte . You may not be able to measure SG on some sealed batteries.

Results may assist.

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No, I did not measure the voltage at the terminals but rather thought that since the battery was on charge without any outgoings (amps) for several days, the charge as indicated at the monitor would represent faithfully that at the terminals.  Right?

 

And you are correct, I can't get at my electrolyte.  Sealed AGMs.

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Your reading at the terminals while the battery while being charged (if i understand correctly ) may not necessarily be the same value of stored energy in the batteries after the batteries have been dissconected and allowed to test and stabilise for at least one hour.

Thats my thoughts only.

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