NextStep2 regulator bulk charge issue

[belizesailor]

So, did disconnecting the temp sensor change anything?

[jackt]

Originally Posted by belizesailor

So, did disconnecting the temp sensor change anything?

Haven't yet returned to boat to execute experiment.

[jackt]

Q. What is appropriate FLOAT CURRENT?

I have done various checks since last posting.
I have still noticed that it tends to switch early from BULK to ABSORPTION phase at around 14.15 or 14.2V which is .1V - .15V less than set point of 14.3V - even with a temp sensor OFF.
I would expect with temp sens off that it would get closer to set point rather than be reduced - as expected by the temp compensation logic: to avoid boiling batts with increased voltage acceptance of chemicals as temp of batts increases, switch earlier. But temp sens wire was disconnected. Ambient temp is around 20 deg C.

Also puzzling is the float stage - float voltage is also higher by .1 or .15 V above set point of 13.4V - with temp sens OFF...or ON.
Float amps seem to me to be high - around 18 A in one test (T1) and 12 A in another (T2), instead of dropping well below 10 amps (to say 4 or 5 amps or less) as with my old Nextstep1 regulator. That's after a bulk charge from -60 Ah in T2, and -25 Ah in T1.
Absorption time set to 1 hour (at 14.4V, amps decreasing from around 65A down to whatever they are after 1 hour, say 20A).

With such high float amps (eg, 20 A) my batt monitor (Heart LINK 10) will never signal it's full because of its default "charged" setting - it needs float current to be "less than 2% of batt capacity for 5 minutes" (2% of 440 Ah batts = 8.8 A) to be considered full. I will have to change the setting from 2% to 5% = 22A float current. (p22, 23):
http://www.xantrex.com/documents/Dis...-01_rev-A).pdf

But is this too high a float current at 13.4 V??? The bat monitor shows positive amp hours while motor continues (eg, motorsailing) - amp hours keep going in...+5...+10...+15 Ahrs! Is this damaging?


Can I damage my wet cell batts with such high float amps? Is 15-20 A float too high?

Will call rep again but want to get my Q's clear first.

[jackt]

Originally Posted by belizesailor

So, did disconnecting the temp sensor change anything?

Yes. Very confusing. See my other post today. Seems when disconnected (T OFF) switch from Bulk to Abs is .1 V or .15 V early - not later as would be expected if T OFF. And Float volt set point is also increased by about .1 V too (13. 5 not 13.4).

[jackt]

Just read this in manual for Link20 (model similar to my Link10):

"For example, a 100 Ah battery at Float voltage will normally have about 0.1 amp flowing into it..." and I have 10 - 20 amps now!?!


"OVERCHARGE AMP HOURS
If the batteries are 100% charged and the
Link 20
is in sync, overcharge amp hours
are displayed as a positive amp-hour number. Some accumulation of overcharge amp hours
is normal with systems continuously connected to a charger. For example, a 100 Ah battery
at Float voltage will normally have about 0.1 amp flowing into it. This means you would
expect about 2.4 amp hours of overcharge to accumulate each 24 hours. If your battery
system is larger, proportionately more current flows and amp hours accumulate.
With a constant voltage charging system set at 14.2 volts, as much as 1 amp of current
may be flowing all the time
even after
the battery has reached the charged parameters. This
causes a small overcharge amp-hour reading to appear in the Ah display. When discharging
begins, these overcharge amp hours are erased and the
Link 20
resets to zero and begins
to report amp hours consumed.
Prolonged high voltage applied to a fully charged battery will probably cause gassing.
So, if you see a large amp-hour overcharge occuring daily, consider it a warning to check
your system. It could indicate that you are destroying your battery by overcharging"
http://www.xantrex.com/documents/Dis...196-01-01).pdf

[jackt]

Originally Posted by Persistent

Where are you taking the voltage readings from. All voltage readings should be from the regulator to start your troubleshooting. It can only regulate the voltage it sees. The operation seems normal it should run in CC (constant current) "bulk mode"max the batts will take/alt will put out until the set point is reached. Once the voltage set point is reached it switches to CV (constant voltage) "absorption" and depending on regulator type will run on time/amperage cutout until float starts. It seems your voltage is off by .3 volt which is easily accounted for in bad connections

Please see my recent post about float CURRENT...

[Maine Sail]

Originally Posted by jackt

Q. What is appropriate FLOAT CURRENT?

If you had a incomplete absorption period, and 1 hour is not enough absorption, then your float current will be high. Float current is not important it is the float voltage that is important. If you are seeing high float current you have had too short an absorption period, it's as simple as that. Set your absorption to 3-4 hours and now your float current will be lower at the transition...

[jackt]

Originally Posted by Maine Sail

If you had a incomplete absorption period, and 1 hour is not enough absorption, then your float current will be high. Float current is not important it is the float voltage that is important. If you are seeing high float current you have had too short an absorption period, it's as simple as that. Set your absorption to 3-4 hours and now your float current will be lower at the transition...

Thanks for checking back on this.
Why could 1 hour absorption not be enough? Why is that so definite? Could it not be possible to re-charge after 1 hour??? Example:
My OLD Nextstep1 (not the new NS2) did everything as expected and the abs time was set to 1 hr. At anchor this was an acceptable daily endurance. In that time, the bat monitor counted back the negative amp hours (eg, from a daily usage of -40 ah to 0) after running engine for about 1 hour with alternator putting out about 50-60 A during bulk, switching to abs after say 15 mins, and then to float - it kept float current low at about 2-4 A or less (if I recall) and float V was 14.3 V.

The new NS2 is set also by me to 1 hr. I have run about 6 test cycles writing down all the values to try to not get confused(!).

After charging, or what I assumed was charged since bat monitor had counted back to 0 ah, I restart engine. It quickly gets to abs set point 14.3V (1-2 mins), goes into abs, and goes into float after the pre-set time. I have also changed the abs time to make my tests quicker...from 1 hour down to 10 mins. Now you will say that's not enough time in abs, but that's from a fully charged (I thought!!) batt. anyway, after 10 mins it shows float at 18 amps which I am alarmed at but you say expected? Because not fully charged? But when I had abs time at 1 hr, the float current was still high - 17 A.

Also, see that quote I posted yesterday from the bat monitor manual:
"For example, a 100 Ah battery
at Float voltage will normally have about 0.1 amp flowing into it. This means you would
expect about 2.4 amp hours of overcharge to accumulate each 24 hours. "

Please tell me (convince!) can I damage batts with high current? I know high voltage is to be avoided, but does current matter???

I suppose I should go and put the batts on my external smart charger and make sure they are charged, then do the tests again.

[Neptune's Gear]

The battery wont accept the current at a given voltage if its fully charged. Simple - your batts were not full. As Maine Sail said, it's the VOLTAGE that's important at float stage.
Think of volts like pressure in a water pipe, going to a tank. Amps is like volume. Once the tank is full (the battery) it wont accept any more, unless the pressure (voltage) is increased.... and even then not much without distorting or destroying the tank!

[Maine Sail]

Do you actually know the current Ah capacity of the battery bank based on a 20 hour capacity test? If the answer to this is no, then please stop relying on your Ah counter to tell you anything meaningful. Your high float current is telling you the absorption time was not long enough.

You still seem to have a volt sense issue which can also lead to an inadequate absorption cycle..

At absorption voltage, 14.6V to 14.8V for flooded deep cycle batteries, you should ideally not transition to float until the batteries are taking less than 1% of Ah capacity in accepted current. They won't really be "full" until they are accepting about 0.5% of Ah capacity or less at absorption voltage but full enough to drop to float. Dropping to float before this will result in high float current because the battery is still charging and should still be in absorption.

[jackt]

Originally Posted by Neptune's Gear

The battery wont accept the current at a given voltage if its fully charged. Simple - your batts were not full. As Maine Sail said, it's the VOLTAGE that's important at float stage.
Think of volts like pressure in a water pipe, going to a tank. Amps is like volume. Once the tank is full (the battery) it wont accept any more, unless the pressure (voltage) is increased.... and even then not much without distorting or destroying the tank!

Thanks. So given that I am still seeing 20 amps (going in) at float stage - the battery is still accepting amps - and therefore it must not be full. Okay. I need to try running longer in abs...or put them on the external charger and get them fullfull.
Should I increase absorption set point from 14.3 to 14.5 or 14.6? I have those common in New Zealand 225 ah red/white ones (x4). What can they take? I thought (was told by tech?) they were spec'd at 14.45V absorption ...?? What is a wise voltage to set absorption for them at?
Thanks.

[jackt]

Originally Posted by Maine Sail

Do you actually know the current Ah capacity of the battery bank based on a 20 hour capacity test? If the answer to this is no, then please stop relying on your Ah counter to tell you anything meaningful. Your high float current is telling you the absorption time was not long enough.

You still seem to have a volt sense issue which can also lead to an inadequate absorption cycle..

At absorption voltage, 14.6V to 14.8V for flooded deep cycle batteries, you should ideally not transition to float until the batteries are taking less than 1% of Ah capacity in accepted current. They won't really be "full" until they are accepting about 0.5% of Ah capacity or less at absorption voltage but full enough to drop to float. Dropping to float before this will result in high float current because the battery is still charging and should still be in absorption.

No, I have not drained them with an actual 20 hr test (at 5 amps constant draw, right? Now where did I read about that only yesterday??).
Yes, the bat monitor default for full is 2% of bat size (450 ah = 9 A). And as you say they won't really be full til <5A is going in, more like 2A. This is what I had assumed and saw with my old NS1. This new NS2 is driving me nuts. Thanks.

[Neptune's Gear]

Get the make and model from the batteries, and then the spec sheet from the manufacturer. Use the voltages they specify. Don't take anyone's word for it, look it up.
The load for a 20 hour test to check battery capacity depends on bank size. That should be in the battery spec sheet as well.

[belizesailor]

Think Maine Sail nailed it. You are basing all this on an assumed accurate AH meter...its probably not. Very good article on his site about meters...be a good read for you.

Bottom line, if your batteries are in good condition, but still accepting higher current after end of absorbtion time...then they aren't fully charged.

[jackt]

Originally Posted by belizesailor

Think Maine Sail nailed it. You are basing all this on an assumed accurate AH meter...its probably not. Very good article on his site about meters...be a good read for you.

Bottom line, if your batteries are in good condition, but still accepting higher current after end of absorbtion time...then they aren't fully charged.

Thanks. I think it's sinking in. Have you a link to that post?