RV.Net Open Roads Forum: Tech Issues: Battle Born Charging

RV Blog

  |  

RV Sales

  |  

Campgrounds

  |  

RV Parks

  |  

RV Club

  |  

RV Buyers Guide

  |  

Roadside Assistance

  |  

Extended Service Plan

  |  

RV Travel Assistance

  |  

RV Credit Card

  |  

RV Loans

Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Tech Issues

Open Roads Forum  >  Tech Issues

 > Battle Born Charging

Reply to Topic  |  Subscribe  |  Print Page  |  Post New Topic  | 
Page of 22  
Prev  |  Next
Sponsored By:
landyacht318

Near a large body of salty water

Senior Member

Joined: 07/11/2007

View Profile



Posted: 02/18/20 10:36pm Link  |  Quote  |  Print  |  Notify Moderator

I ire was not directed at you Bfl. Apologies.

Seeking info about a subject or posting a good source about it, is not the same as lecturing someone on it, while having no personal experience with it, a methodology rife on many forums, which grinds my gears.

I bought another Northstar AGM, but a group 31, when my group 27 Northstar lost the CCA ability to start my engine last December with about 1300 deep cycles on it. It is now my workshop battery and cycling lightly nightly powering lights and fans and 12v experiments.

The 27 had a higher full charge resting voltage and retained higher voltage under the same overnight loads than the 31, upto about 45 amp hours from full.

Not sure I'll be as impressed long term with the 31 as I was with the 27 at least Voltage retention wise for the first ~45AH removed
I had an alternator failure at night ~120 miles from my destination a month and a half ago. It was nice to know I had enough battery to make it without stopping. It was still retaining 12.24v when I arrived, under a 20 amp load for those 120 miles. Lifepo4 would certainly have retained more, unless I started at a lower state of charge and the Battery protector kicked in and left me stranded.

Itinerant1

Itinerant

Senior Member

Joined: 05/23/2017

View Profile



Posted: 02/19/20 05:25am Link  |  Quote  |  Print  |  Notify Moderator

bob_nestor wrote:

BFL13 wrote:

" Are you sure about the float? Seems like it should be 13.6v or HIGHER, not lower."

You didn't read the BB replies in the link. [emoticon]

Also note how they distinguish a float from a storage trickle, and how the float should be with working the battery and not while on shore-power and no cycling of the battery if the float is above 13.6

Lots of good info in those BB replies on all sorts of topics raised.


Actually I did a lot of research on the BB batteries before I installed them over a year ago and at that time the setup in my RV was fine with them. They recommended using an AGM profile on my solar controller since mine didn't have a Lithium setting. I've since replaced with a newer model that has a Lithium profile and it uses a float voltage of 14 for Lithium and 13.7 for all other battery types.

So if the float is to be 13.6 or lower and my batteries bulk charge up to 14+, then I can maintain my charge level with a 6v supply? After all, 6v is less than 13.6v.

If you're charging to 14.4v then floating at 14v you could be stressing your cells holding them there even if using them during that time period. If I'm understanding correctly what you're saying.




BFL13

Victoria, BC

Senior Member

Joined: 02/15/2006

View Profile



Posted: 02/19/20 08:33am Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1 wrote:

Those setting are basically for all lfp batteries not just BB. Depends on the voltage needed for balancing cells.

I've been using Bulk 14.1v, 14.2v absorb (10 minutes), float 13.6v for almost 4 years now with everyday use.


You have posted that the Absorption Stage for Li does not start till at a high SOC compared with Wets and AGMs.

The BB advice keeps referring to a full charge, but there is also talk of only operating at 80% and under. So when saying they want a charge rate of half AH capacity (which is a lot) or less, and an Absorption time of 20-30 minutes to get to full, does that compute?

IE will that "extra" half hour at 14.4 once amps start to taper get you to full?

Your 10 minutes would then get you from whatever SOC Bulk ends at (95%?) to part way closer to full, but this is still way over 80%?

It is hard to figure out what the "rules of thumb" really are for

1.when camping and
2. for getting to true full and
3. when you should go to full and not stay in the operating zone of SOCs.
---
"Here are our (BB's) charging parameters for our batteries:

Bulk/absorb 14.2 – 14.6 Volts(14.4 is great)
float 13.6 Volts or lower
No equalization(or set it to 14.4v), no temperature compensation and absorption time is 20-30 minutes per battery(if its an option)."


1991 Oakland 28DB Class C
on Ford E350-460-7.5 Gas EFI
See Profile for House electronics set-up.

Itinerant1

Itinerant

Senior Member

Joined: 05/23/2017

View Profile



Posted: 02/19/20 12:24pm Link  |  Quote  |  Print  |  Notify Moderator

I'm at my 99% SOC when it hits absorb.

BFL13

Victoria, BC

Senior Member

Joined: 02/15/2006

View Profile



Posted: 02/19/20 12:39pm Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1 wrote:

I'm at my 99% SOC when it hits absorb.


I presume you know when that is by observing that amps start to taper.
Why do 10 minutes more? 99 is way over 80.
What is the truth about operating under 80%?
Can you do the 20-30 min BB wants past that 99% without overcharging?

What is the "marker" for true full with Li? ( With Wets it is the full SG. With AGMs it is when amps taper to 0.5a/100AH at 14.4v during Absorb.)

Itinerant1

Itinerant

Senior Member

Joined: 05/23/2017

View Profile



Posted: 02/19/20 01:17pm Link  |  Quote  |  Print  |  Notify Moderator

I can tell by looking at my displays.

I'll be honest with you I see that 80%-20% or 90%- 10% mentioned on different forums and even on this one. I even ask awhile ago on this forum to someone that said that, what would the voltage be at those points and they didn't know.

With drop in batteries and depending on the bms for balancing cells that will be the deciding factor.

I know with my prismatic cell batteries and the bms 14.1 is good enough to balance my cells and reset the SoC capacity. No reason to go high or longer. 13.6v float while the sun is out keeps the batteries ready for evening time and solar carries my daytime loads.

BFL13

Victoria, BC

Senior Member

Joined: 02/15/2006

View Profile



Posted: 02/20/20 09:50am Link  |  Quote  |  Print  |  Notify Moderator

You might wish to modify your routine based on this advice. It could be that your 99% is not correct. Your displays might not be showing the true picture based on the graphs etc here. You might be overcharging somewhat?

At last some graphs and a way to tell when your Li batt is full!

" Full charge is reached when the current decreases to between 3 and 5 percent of the Ah rating"

https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

Itinerant1

Itinerant

Senior Member

Joined: 05/23/2017

View Profile



Posted: 02/20/20 10:49am Link  |  Quote  |  Print  |  Notify Moderator

BFL13 wrote:

You might wish to modify your routine based on this advice. It could be that your 99% is not correct. Your displays might not be showing the true picture based on the graphs etc here. You might be overcharging somewhat?

At last some graphs and a way to tell when your Li batt is full!

" Full charge is reached when the current decreases to between 3 and 5 percent of the Ah rating"

https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries


I'm sure you mean well but I'll stick to my routine/ settings.

Stick to what you know best. [emoticon]

BFL13

Victoria, BC

Senior Member

Joined: 02/15/2006

View Profile



Posted: 02/20/20 11:05am Link  |  Quote  |  Print  |  Notify Moderator

Itinerant1 wrote:

BFL13 wrote:

You might wish to modify your routine based on this advice. It could be that your 99% is not correct. Your displays might not be showing the true picture based on the graphs etc here. You might be overcharging somewhat?

At last some graphs and a way to tell when your Li batt is full!

" Full charge is reached when the current decreases to between 3 and 5 percent of the Ah rating"

https://batteryuniversity.com/learn/article/charging_lithium_ion_batteries


I'm sure you mean well but I'll stick to my routine/ settings.

Stick to what you know best. [emoticon]


Not trying to tell you how to suck eggs. Just want to know more, as do others I suspect.

If you have the time and patience, it would help to understand all this if you explained more how your routine does not contradict the advice in the link.

Also how exactly your displays tell you where you are at wrt the graphs in the battuni link. ( I know you have posted photos of the displayed info before, but it is hard to relate the readings to where things are at on the recharge graphs in that link)

Itinerant1

Itinerant

Senior Member

Joined: 05/23/2017

View Profile



Posted: 02/20/20 09:59pm Link  |  Quote  |  Print  |  Notify Moderator

About the link you posted the gragh is not showing LiFePO4 chemistry.

I have an Elite Power Solutions system which consite of 20 GBS cells and uses a per cell sense boards for voltage and temperature, top balancing per cell shunts, a system shunt for current monitoring and coulomb counting (EMS) and 2 high current protective 400a relays.

[image]

[image]

The EMS CPU is programmed with these alarms and warnings are displayed at the bottom of the display screen after the word “Pack:”. There are seven alarms:
- Over voltage (highest cell is over 3.8V after a 3 second delay).
- Under voltage (lowest cell is below 2.8V after a 30 second delay).
- Over current (current exceeds 10C for 10 seconds).
- Over temperature (highest cell exceeds 150°F or 65°C).
- Under temperature (lowest cell is below 32°F or 0°C, charging is not allowed).
- Ground fault (There is a high voltage leakage greater than 2mA to the chassis pin).
- Unmanaged cells (The programmed number of cells does not equal the number of cells read).

SOC:
The EMS system has a minimum recorded resolution of +/- 0.5A so any current below that level is not accounted for. The system could be setup for a finer resolution, but the shunt value would have to be reduced which reduces the systems maximum current capability. 

The system will reset the capacity to 100% whenever the pack voltage reaches 3.49 to 3.52 vpc on average, the pack current must be negative (charging) and typically under 35A and then it will set the capacity to 100%. These are all firmware variables.

With these things in place I don't really worry about the batteries. It's been almost 4 years now with everyday use and solar being the main source for charging 99% of the time using the settings I mentioned. Daily sundown to sunup usage 175-225ah.
If I didn't fulltime I would break the cells down for a capacity test after 4 years now but not possible seeing they are my power source and I boondock all the time but some day maybe if I come off the road.

* This post was edited 02/20/20 10:32pm by Itinerant1 *

Reply to Topic  |  Subscribe  |  Print Page  |  Post New Topic  | 
Page of 22  
Prev  |  Next

Open Roads Forum  >  Tech Issues

 > Battle Born Charging
Search:   Advanced Search

Search only in Tech Issues


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:




© 2020 CWI, Inc. © 2020 Good Sam Enterprises, LLC. All Rights Reserved.