NextStep2 regulator bulk charge issue

[jackt]

I recently replaced my 10-yr old NextStep smart regulator with their most recent (mid 2000s) model, NextStep2. (Potentiometer control on old one seemed to die). It does not stay in BULK charge until the set point (14.3 V) with constant amps as it is supposed to, if a fair load has drained the amps, eg, -40 ah used up. Instead alternator puts out about a constant 60 amps with volts increasing as expected, eg, 13.4...13.6...13.8...then when it gets to about 13.9-14.0 V the regulator trips EARLY into ABSORPTION PHASE which means amps decreasing: 60...55...50...But all the while volts are still increasing up to the set point of, eg, 14.3 V. When it gets there, after about 30-40 mins, it does stay there at 14.3 V, while amps continue to decrease for the set time (eg, 1 hour); then it trips to float (sometimes at about 18 amps still going in).
If less amps have been drained, eg, -10 amps, then it ramps up to 14.4 quickly (1-2 mins) and acts as it should, tripping to ABSORPTION (ie, it gets to the set point quickly with constant 60 amps).
BATTS: 4 x 225 ah 6 V deep cycle batts = 450 ah bank.
Alternator: Bosch 85 amp that puts out about 60-65 amps - I know it is under-rated and not the recommended 20-30% of batts size.
Q. Is it to be expected to trip out of BULK *before* the set-point because of my small alternator that can not put out "enough" amps?? So then it sort of fizzles out of puff and trips to ABSORPTION...early?? The manual/leaflet (see link) mentions something along these lines. Has this something to do with "what the batteries can accept" etc and what can be given to them? What does that mean?

https://www.amplepower.com/manuals/ns2/ns2.pdf

"The regulator will not stay in bulk charge mode long if the batteriesare full, or the alternator can produce more than the batteries will
accept.
The regulator cannot drive the battery voltage to any specific level
if the alternator is not capable of producing enough current to
satisfy battery acceptance capability, which varies with state–of–
charge.
Alternators don’t produce maximum output unless they are rotating
at 6000 to 7000 RPM, so don’t expect high current unless the alter-
nator is rotating fast. If the batteries won’t accept high current, the voltage will quickly rise to the absorption setpoint and hold atthat voltage. The regulator hasn’t skipped the bulk charge step, just
moved through it rapidly because the batteries don’t accept much
current."

[smac999]

Does your regulator have a voltage sense wire? Where is it sensing ? At alt? Your alt post might be 14.4v and your battery may only be 13.8. So it kicks out early. You should voltage sense at battery. (And have large alt cable direct to house bank)

As current drops, The voltage drop is lower. And battery voltage will continue to climb as you see it. While the alt post remains 14.4 the whole time

[jackt]

Originally Posted by smac999

Does your regulator have a voltage sense wire? Where is it sensing ? At alt? Your alt post might be 14.4v and your battery may only be 13.8. So it kicks out early. You should voltage sense at battery. (And have large alt cable direct to house bank)

As current drops, The voltage drop is lower. And battery voltage will continue to climb as you see it. While the alt post remains 14.4 the whole time

Not sure where it senses at. Will have to check...

[jackt]

Where is it supposed to sense from - what is "best practice", that is, what do most marine electricians wire it up to sense from? Could my guy (qualified/best-practice etc) 10 years ago have done it wrong??

[jackt]

Just looked at the link to PDF of my reg in my post...
Pin 4 is sense wire and (should) goes to battery in the circuit diagram. I will check mine...

[belizesailor]

Originally Posted by jackt

Just looked at the link to PDF of my reg in my post...
Pin 4 is sense wire and (should) goes to battery in the circuit diagram. I will check mine...

Yes, it should go to battery+ or at least to the positive bus.

Where are you getting your voltage readings? At the battery or from a display/battery monitor? (Could be just a slight voltage drop between battery and panel for example).

Is there a battery temp sensor installed with your NextStep? (Warm battery could cause it to switch stage before set point).

How do you know set point is at 14.3?

Whats the battery configuration...just charging house bank, house + start...?

[smac999]

it should go near the same battery as the alt pos wire goes. if the alt goes to the starter post or start battery, then it's harder to do right as you'll have to sense the start battery and not the house. another good reason to always run the alt direct to the house bank.

[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

[jackt]

Originally Posted by belizesailor

Yes, it should go to battery+ or at least to the positive bus.

Where are you getting your voltage readings? At the battery or from a display/battery monitor? (Could be just a slight voltage drop between battery and panel for example).

From a battery monitor (Heart Interface Link 10).

Is there a battery temp sensor installed with your NextStep? (Warm battery could cause it to switch stage before set point).

Yes.

>How do you know set point is at 14.3?

Set via potentiometer screw and read direct from reg using voltage meter (see PDF for details)

>Whats the battery configuration...just charging house bank, house + start...?

2 banks - starter and house (450 Ah) + VSR

Thanks.

[jackt]

Originally Posted by smac999

it should go near the same battery as the alt pos wire goes. if the alt goes to the starter post or start battery, then it's harder to do right as you'll have to sense the start battery and not the house. another good reason to always run the alt direct to the house bank.

Alt goes to house bank.

[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

From bat monitor. Will check and take from reg next time I'm at boat.

Yes, off by .3 V. Bad connections eh? Maybe due to using bat monitor...will look.

[belizesailor]

Originally Posted by jackt

From bat monitor. Will check and take from reg next time I'm at boat.

Yes, off by .3 V. Bad connections eh? Maybe due to using bat monitor...will look.

Check at battery terminals and compare to batt monitor. I suspect you have a small voltage drop from batts to monitor.

Also check at NS2 and compare to reading from terminals and monitor.

[jackt]

Originally Posted by belizesailor

Check at battery terminals and compare to batt monitor. I suspect you have a small voltage drop from batts to monitor.

Also check at NS2 and compare to reading from terminals and monitor.

I checked with a multimeter at batteries. It is a similar value to amp/voltage meter. The regulator voltage sense wire is from house batteries, not from alternator as you suspected. So, still, Nextstep is switching out of bulk charge early - at 14 V instead of 14.3 as set on regulator - and switching to absorbtion charge (amps decreasing) while volts is STILL increasing up to the set point of 14.3. At that time, when it gets to 14.3, the 1-hour of absorption charging starts (I have set it for 60 mins). After 1 hour, it switches to float, regardless of what amps are going in, maybe as many as 15-20 amps.

[Maine Sail]

Originally Posted by jackt

I checked with a multimeter at batteries. It is a similar value to amp/voltage meter. The regulator voltage sense wire is from house batteries, not from alternator as you suspected. So, still, Nextstep is switching out of bulk charge early - at 14 V instead of 14.3 as set on regulator - and switching to absorbtion charge (amps decreasing) while volts is STILL increasing up to the set point of 14.3. At that time, when it gets to 14.3, the 1-hour of absorption charging starts (I have set it for 60 mins). After 1 hour, it switches to float, regardless of what amps are going in, maybe as many as 15-20 amps.

Your symptoms still point to a voltage sensing & voltage drop issue. We can't forget that voltage sensing needs to be a complete circuit, not just a positive side sense wire. My suspicion is that your regulator B- is not wired to the house bank neg terminal (the Ample manual is incorrect on Reg B- placement as is Balmar's) and therefore can't compensate for the volt drop in the negative wire between the alt B- and house bank negative terminal. Also remember that the reg B- may be asked to carry 2-8A +/- so the reg B- should really be sized for little to no voltage drop at all.

The real question is why you are charging, what I gather from your OP, ppis a bank of 6V golf cart batteries at such a low absorption voltage and for such a short absorption duration?

[jackt]

Originally Posted by Maine Sail

Your symptoms still point to a voltage sensing & voltage drop issue. We can't forget that voltage sensing needs to be a complete circuit, not just a positive side sense wire. My suspicion is that your regulator B- is not wired to the house bank neg terminal (the Ample manual is incorrect on Reg B- placement as is Balmar's) and therefore can't compensate for the volt drop in the negative wire between the alt B- and house bank negative terminal. Also remember that the reg B- may be asked to carry 2-8A +/- so the reg B- should really be sized for little to no voltage drop at all.

The real question is why you are charging, what I gather from your OP, ppis a bank of 6V golf cart batteries at such a low absorption voltage and for such a short absorption duration?

This NS2 is a replacement for my old NextStep1 reg that used a 1 hour absorbtion setting and it worked fine, I thought. Why do you think 14.3 is such a low abs voltage?? The 6V 225 ah (x4) batts are rated for about 14.45 bulk and 13.25 float. Anything higher that 14.5 could boil them.

Your comment on B- is insightful. I just spoke to the distributer technician and he suggested to check the neg is also coming off batts with good cable.

However, his main query was the temp sensor. He suggested removing temp sensor and see if it climbs beyond 14 V and toward set point of 14.3 better. He wants that test done before I consider sending it back to be checked/replaced.