Can a float current be too high?

[jackt]

Can a float current be too high?

My new Nextstep2 regulator is tripping to float after, say, 1 hour in absorption phase (time set by me). At that point, current is still quite high...over 10A and as much as 18A, under various tests from various discharge states. Float set point is 13.4V.

Can I damage the batteries with this high float current at 13.4V? Battery monitor is then showing positive ah, eg, 10, 15ah etc if engine runs for 15 or 30 mins beyond when it says they are full (at 0 ah). Is this damaging? My old Nextstep1 seemed fine with float current around 2-3 A or less (can't remember clearly; but it died - pot screw stopped responding).

Note: I posted today related issues on this NS2 regulator on a separate thread. This issue on float current was replied to by Main Sail but are there other answers? Thanks.

[senormechanico]

Do you have any loads when this happens ?
How big is your battery bank and what type ?
FLA, AGM, NiCd,, LiFePo4?
Age of batteries and condition of battery terminal cleanliness?
What voltage do you have when alternator says they're full?
Is that voltage measured at battery terminals or at the alternator or somewhere in between. It all matters.
We're here to help.

[jackt]

Originally Posted by senormechanico

Do you have any loads when this happens ?
How big is your battery bank and what type ?
FLA, AGM, NiCd,, LiFePo4?
Age of batteries and condition of battery terminal cleanliness?
What voltage do you have when alternator says they're full?
Is that voltage measured at battery terminals or at the alternator or somewhere in between. It all matters.
We're here to help.

Thanks. Please see my other thread where I listed the specs. Voltage is measured at batt by batt monitor. There are some helpful answers from today there also...it might be my batts are just not fully charged before absorption phase terminates at 60 mins and so current is still being accepted...
Thanks.
http://www.cruisersforum.com/forums/...ue-179406.html

[Adelie]

Yes it can be set too high, yours is not. The battery has not adequately charged if you are still at 10a in float, unless you have a 2000a-hr bank.

Check your battery manual, absorption time should be on the order of 3-4hr.

[jackt]

Originally Posted by Adelie

Yes it can be set too high, yours is not. The battery has not adequately charged if you are still at 10a in float, unless you have a 2000a-hr bank.

Check your battery manual, absorption time should be on the order of 3-4hr.

Thanks! Yes, everybody is telling me this and I am finally understanding it. Thank you!

ps. Batt specs below. I posted in my other thread regarding this.
http://usbattery.com/wp-content/uploads/2017/02/usb_2200_data_sheet_2017HR.pdf

http://www.cruisersforum.com/forums/f14/nextstep2-regulator-bulk-charge-issue-179406.html

[Bleemus]

Originally Posted by Adelie

Yes it can be set too high, yours is not. The battery has not adequately charged if you are still at 10a in float, unless you have a 2000a-hr bank.

Check your battery manual, absorption time should be on the order of 3-4hr.

Exactly.

[a64pilot]

You don't set current, only voltage.
Bank accepts whatever current it can, no more.
However your earlier comment about not being fully charged is almost certainly what is happening

[DMCantor]

We have a large bank, 1000+ amp-hours. If we go down 50%, that's 500 amp-hours. Our shore-power charger can deliver 100 amps, so it is AT LEAST 5 hours to get out of absorption mode. As others have said, if your battery is accepting 10 amps at 14.4 volts, let alone 13.4, it is far from full.

[senormechanico]

A64's post just above is what I was getting at.
If your boat has other loads at the time, the meter might be reflecting that.
If no other loads and you still have big current on float setting, the cells haven't been fully charged.

[sailorboy1]

Originally Posted by jackt

Can a float current be too high?

My new Nextstep2 regulator is tripping to float after, say, 1 hour in absorption phase (time set by me). At that point, current is still quite high...over 10A and as much as 18A, under various tests from various discharge states. Float set point is 13.4V.

Can I damage the batteries with this high float current at 13.4V? Battery monitor is then showing positive ah, eg, 10, 15ah etc if engine runs for 15 or 30 mins beyond when it says they are full (at 0 ah). Is this damaging? My old Nextstep1 seemed fine with float current around 2-3 A or less (can't remember clearly; but it died - pot screw stopped responding).

Note: I posted today related issues on this NS2 regulator on a separate thread. This issue on float current was replied to by Main Sail but are there other answers? Thanks.

there's no problem with the amps in float. But your problem is that you aren't staying in absorption long enough.

[john61ct]

A good charging system, properly configured, won't drop to float voltage level until **after** amps has dropped down to well below .03C, or 3A per 100AH bank size.

Use the configuration options to adjust things until that's what you see while monitoring.

If that is very difficult, consider getting more flexible gear.

[jackt]

Thanks everyone.

I posted the below Q also over on the other initial thread I have related to this. Clearly, I am not running in abs long enough (1 hr). However, I thought I was running long enough - on my OLD batt bank the bat monitor was saying it was full. See below. Thus, I thought 1 hr would be okay for the new batts too...

Please take a look here too:
http://www.cruisersforum.com/forums/...-179406-4.html

I also don't understand why on my previous batt bank of 440 Ah, I would recharge each 24hrs from around -50 Ah. Alternator is a Bosch 90 A. This involved say 20 mins of bulk at 60 A to 14.3V and then another 1 hour of absorption at 14.3 V. In that time, my Link10 battery monitor would count back the amp hrs dutifully:
-50...-40...-30...-20...-10...-9...-8...-5...-1...0.
Also, the CURRENT would drop during absorption as expected:
60A...50...40...30...20...10...9...8...7...5...2.
at that point the monitor's algorithm indicated batt was full (algorithm: over 10% total Ah must be drained (>44 Ah) and current must drop to < 2% of declared batt capacity (8.8 A) for 5 mins).
Now it may well be according to your comments I was not running abs for long enough (only 1 hr) and batts were in fact woefully undercharged even though batt monitor said Ah were replaced AND CURRENT WAS < 2%. So were they undercharged or not after 1 hour? Since current acceptance was low - it was < 9 A and went as low as 2 or 3 does it mean they were in fact charged...or instead that the batts were not fully charged and simply could not accept more current because they were damaged? Sulfation? So the amps dropped (due to the regulator algorithm or the batt chemistry??) because they could not be "pumped in"??

[jackt]

Originally Posted by sailorboy1

there's no problem with the amps in float. But your problem is that you aren't staying in absorption long enough.

Thanks. So high amps (20A) at float voltage (13.4V) won't damage anything? It's the high voltage that can damage, right?

[jackt]

Originally Posted by a64pilot

You don't set current, only voltage.
Bank accepts whatever current it can, no more.
However your earlier comment about not being fully charged is almost certainly what is happening

Thanks. Please see the Q I just posted which your comment speaks to and perhaps you can expand?

[jackt]

Originally Posted by DMCantor

We have a large bank, 1000+ amp-hours. If we go down 50%, that's 500 amp-hours. Our shore-power charger can deliver 100 amps, so it is AT LEAST 5 hours to get out of absorption mode. As others have said, if your battery is accepting 10 amps at 14.4 volts, let alone 13.4, it is far from full.

Yes, at the end of 60 mins abs time, before step to float (13.4V), it was accepting 20A at 14.3V.