Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rating: Thread Rating: 33 votes, 4.82 average. Display Modes
Old 01-03-2013, 06:17   #2146
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 2,901
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by diugo View Post
Genasun describes its lithium charge procedure simply as "CC/CV". I think most here assume that "CV" means "apply constant voltage until X."

Genasun sells a solar charge controller for LiCoO2; does it really subject a volatile cobalt-based lithium-ion battery to a constant 16.7V indefinitely??? I somehow doubt it.

Most lithium chargers employ a C/20 or similar cutoff scheme, but there are other methods. For example, a periodic topping charge: disconnecting the voltage source as soon as the CV voltage is attained, and then reconnecting it only whenever the battery voltage falls below a delta.

This is much different than floating, where the voltage source is always connected. Genasun clearly differentiates the two terms in its spec sheets, taking pains to use "float" only for its LA chargers and "CV" only for its lithium ones.

IMHO this suggests Genasun does not truly float its lithium batteries.

Genasun batteries can be supplied 14.2V CV and this is per the most recent manual dated Nov 2012....... They call for all charge sources to simply be set for CC/CV to a 14.2V limit with temp compensation disabled.

If chargers and sources can't be programed for a single stage, what they term a "forced float", at 14.2V, they suggest setting all stages of multi-stage charging to 14.2V and this includes bulk, absorption & float..


Genasun:
"However, the systems used to charge and monitor the battery must be set appropriately. All chargers should be set for a simple float voltage of 14.2V (28.4V for 24V nominal systems), with no temperature compensation. This type of charging is variously called Constant-Current/Constant-Voltage, CC/CV, and Forced Float, among others."


The manual further describes exactly how to program battery chargers and regulators for their batteries. If you want to drop to a further reduced "float" voltage after attaining 14.2V that is your choice but Genasun does not require it and they allow CV charging... They do not call for charge sources to "terminate" once at 14.2V...
__________________

__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 01-03-2013, 07:41   #2147
Commercial Member
 
CharlieJ's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: St. Petersburg, FL
Boat: Gulfstar Long Range Trawler; 53'; BearBoat
Posts: 815
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

daddle-
Thank you for taking the time to find and post this reference. Facts always trump opinion, especially on the bleeding edge!
__________________

__________________
Charlie Johnson
JTB Marine Corporation
"The Devil is in the details and so is salvation."
CharlieJ is offline   Reply With Quote
Old 01-03-2013, 07:48   #2148
Registered User
 
typhoon's Avatar

Join Date: Feb 2007
Location: Toronto Canada
Boat: Bristol 45.5
Posts: 900
Images: 1
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

This was Echo-tech's solution to charging LiFePO4 batteries. There tech emailed me this


""I added the sense lead and a potentiometer so you can adjust the set point to whatever you want. After you reinstall the regulator just Krazy-glue the potentiometer to the back of the black regulator back plate I included. See attachment.

"I changed the potentiometer so the range of adjustability for the set point is 0.94 volts. Itís currently adjustable from 13.44v to 14.40volts.

Malcolm""

Regards




Attached Thumbnails
Click image for larger version

Name:	sense lead.JPG
Views:	91
Size:	81.8 KB
ID:	55910  
__________________
typhoon is offline   Reply With Quote
Old 01-03-2013, 08:37   #2149
Registered User
 
ebaugh's Avatar

Join Date: Dec 2011
Location: On the boat
Boat: DeFever 44
Posts: 525
Just the other day we were discussing electrolytic capacitors to protect an alternator from a LFP management disconnect. I believe the consensus was this would not work. Probably would not absorb enough current to hold back the spike.

But what about a small SLA computer UPS battery on a say a 10A slow blow fuse always connected to the alternator output? Or even a series of AA NIMH or Nicads sized so they are not overcharged during normal operations?

Second, are any of the "alternator protection" devices really capable of multiple cycles? I assume most use a Zener diode that shorts to ground over a certain voltage. Can one be sized right to function indefinitely to protect from multiple disconnect events? Is there any easy way to sense a failure of the diode, other than when the alternator fails?
__________________
ebaugh is offline   Reply With Quote
Old 01-03-2013, 08:56   #2150

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 12,106
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

I'll hazard a guess:

"But what about a small SLA computer UPS battery"
OK, that's just a small AGM battery these days, has been for the last decade.
" on a say a 10A slow blow fuse always connected to the alternator output?"
Fuse won't matter, and a 10A fuse won't impress a 100A alternator, will it? That battery is probably going to die a fast death from being in the charging circuit during normal operation, so while it might protect the alternator from momentary disconnects, so would a more useful "spare" or conventionally sized battery.

"Or even a series of AA NIMH or Nicads sized so they are not overcharged during normal operations?" Same problem, wrong size, wrong charging, good risk of "BOOM" when they do go.

"Second, are any of the "alternator protection" devices really capable of multiple cycles?" Of course. Diodes can work repeatedly as long as you don't exceed their ratings. Alternators with internal protection exist--and they use these parts.

"to function indefinitely" For a long time, yes. Forever, no. One reason that alternators with internal spike protection aren't common, is because they use avalanche diodes which, oops, blew out and took out the alternator faster than unprotectred alternators in many cases. Delco had a big "reliability" problem with this.

"Is there any easy way to sense a failure of the diode, other than" Ergh, test light? Or more circuitry, more components, which can fail too?

Your best protection probably comes back to "don't touch that switch!". Find a way to ensure the alternator is shut down before it is disconnected. Whatever is going to disconnect the battery bank, should be able to get your attention, or do an engine shutdown, without needing to break the battery connection "now now now" faster.

Explosive fired guillotine cutter on the alternator belt, perhaps? <G>
__________________
hellosailor is offline   Reply With Quote
Old 01-03-2013, 09:39   #2151
Registered User
 
ebaugh's Avatar

Join Date: Dec 2011
Location: On the boat
Boat: DeFever 44
Posts: 525
Quote:
Originally Posted by hellosailor View Post
I'll hazard a guess:

"But what about a small SLA computer UPS battery"
OK, that's just a small AGM battery these days, has been for the last decade.
" on a say a 10A slow blow fuse always connected to the alternator output?"
Fuse won't matter, and a 10A fuse won't impress a 100A alternator, will it? That battery is probably going to die a fast death from being in the charging circuit during normal operation, so while it might protect the alternator from momentary disconnects, so would a more useful "spare" or conventionally sized battery.

"Or even a series of AA NIMH or Nicads sized so they are not overcharged during normal operations?" Same problem, wrong size, wrong charging, good risk of "BOOM" when they do go.

"Second, are any of the "alternator protection" devices really capable of multiple cycles?" Of course. Diodes can work repeatedly as long as you don't exceed their ratings. Alternators with internal protection exist--and they use these parts.

"to function indefinitely" For a long time, yes. Forever, no. One reason that alternators with internal spike protection aren't common, is because they use avalanche diodes which, oops, blew out and took out the alternator faster than unprotectred alternators in many cases. Delco had a big "reliability" problem with this.

"Is there any easy way to sense a failure of the diode, other than" Ergh, test light? Or more circuitry, more components, which can fail too?

Your best protection probably comes back to "don't touch that switch!". Find a way to ensure the alternator is shut down before it is disconnected. Whatever is going to disconnect the battery bank, should be able to get your attention, or do an engine shutdown, without needing to break the battery connection "now now now" faster.

Explosive fired guillotine cutter on the alternator belt, perhaps? <G>
I like the C4 idea, except the belt also runs the water circulation pump....

The 10A slow blow fuse should not normally blow on a 100A alternator since all you are doing is giving the regulator a chance to do it's job and adjust the output voltage. SLA/AGM is very happy 12.5 to 14.4V which is a larger range than the normal Li operating range. The disconnect is going to happen at the upper end of that range if a cell is out of balance. But you're right, there could be problem if the disconnect happened at 13.4V instead of 14V and the alternator controller was trying for 14.2V, it might take too long. Hmmm.

The SLA normally just stays fully charged, a LFP charge profile would not kill it, and in any case you don't really care about it's capacity loss much.

I do agree shutting down the alternator is the best solution, but do do this right, there is a timing issue with simple controllers since it really needs to happen first, before the solenoid pulls the LFP, say in the case of using a Junsi logger.
__________________
ebaugh is offline   Reply With Quote
Old 01-03-2013, 09:45   #2152
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 2,901
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by ebaugh View Post
Just the other day we were discussing electrolytic capacitors to protect an alternator from a LFP management disconnect. I believe the consensus was this would not work. Probably would not absorb enough current to hold back the spike.

But what about a small SLA computer UPS battery on a say a 10A slow blow fuse always connected to the alternator output? Or even a series of AA NIMH or Nicads sized so they are not overcharged during normal operations?

Second, are any of the "alternator protection" devices really capable of multiple cycles? I assume most use a Zener diode that shorts to ground over a certain voltage. Can one be sized right to function indefinitely to protect from multiple disconnect events? Is there any easy way to sense a failure of the diode, other than when the alternator fails?
I have seen alternators with ZapStop type devices sill blown because the owner apparently disconnected the "load" one to many times. I have also seen alts with quenching or avalanche diodes with those diodes blown and the main diodes. Most of the alts with this type of protection are automotive designed. Not many heavy duty HO alts use quenching diodes that I know of.

I currently have three alts in my shop that are there because the owners disconnected the load and blew them. They simply chose to replace the alts with new and did not want the old ones. One is a Delco and two are Hitachi.

The easiest way to solve the problem is to simply cut the wire to the field/brush and extend it out to the HVC relay. This not only saves the expense of buying an expensive relay like the Tyco EV200 it saves all sorts of expense trying to figure out a way that may or may not work to prevent blown diodes from a load disconnect.

Any good alternator shop can tap into the field/brush assembly for you for very short money....
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 01-03-2013, 10:15   #2153
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 2,901
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

This is what CV charging looks like on my pack at 13.8V when the battery has reached 13.8V.. 0.0A



I've been in the shop now for two hours and not seen the charger need to kick in to supply any current.... These cells hold voltages tremendously well. It does happen when the voltage falls off of 13.8V but the current only kicks back in for a couple of minutes at best. Once back to 13.8V there is no need of any more current because the bank is "at voltage" so the current delivery stops until the voltage drops again....

This behavior is likely why Genasun says 14.2V CV is suitable for their packs...

Contrast that to the many LA batteries I have in the shop. They will keep taking current indefinitely and never shut the charger down...
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 01-03-2013, 10:24   #2154

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 12,106
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Maine, the first time I met a zapstop we couldn't figure out why it didn't do anything. Turned out the PO had installed it "in space" with electrical tape over the whole thing, and BOTH wires had sheared off under the tape. Well, yeah, that's gonna protect the diode alright.<G>

eb-
Those UPS batteries typically are "throw away at four years" in normal float-charging use, derated 25% per year AND something like 25% per 10F temperature rise over nominal room temperature. So...very much consumable and likely to be forgotten and consumed somewhere along the way. I've also seen more than one with the internal invisible fuse blown and the case bulging out in a most uninspiring manner. Better to have your high voltage sense connected to a klaxon that will bring a human intervention, I think.
__________________
hellosailor is offline   Reply With Quote
Old 01-03-2013, 10:56   #2155
Registered User
 
ebaugh's Avatar

Join Date: Dec 2011
Location: On the boat
Boat: DeFever 44
Posts: 525
Quote:
Originally Posted by Maine Sail View Post
This is what CV charging looks like on my pack at 13.8V when the battery has reached 13.8V.. 0.0A

This behavior is likely why Genasun says 14.2V CV is suitable for their packs...

Contrast that to the many LA batteries I have in the shop. They will keep taking current indefinitely and never shut the charger down...
The question is for the 14.2V Genasun spec, is letting them float at 3.55 per cell causing any harm. Like when on shore power, potentially for long periods of time?

What little research we have seen makes me like your 3.45 Vpc or even my 3.35Vpc until we have more definitive data.
__________________
ebaugh is offline   Reply With Quote
Old 01-03-2013, 11:05   #2156
Registered User
 
ebaugh's Avatar

Join Date: Dec 2011
Location: On the boat
Boat: DeFever 44
Posts: 525
Quote:
Originally Posted by Maine Sail View Post
The easiest way to solve the problem is to simply cut the wire to the field/brush and extend it out to the HVC relay. This not only saves the expense of buying an expensive relay like the Tyco EV200 it saves all sorts of expense trying to figure out a way that may or may not work to prevent blown diodes from a load disconnect.

Any good alternator shop can tap into the field/brush assembly for you for very short money....
Thanks for the information. It's kind of what I expected, but had not seen firsthand on the alternator protection devices.

I've been trying to answer someone else's installation questions. The field disconnect is the way to go, but does it have to be timed if the desire is to both disconnect the pack and turn off the alternator? With a solenoid for one and a relay for the other, which one really disconnects first? I assume it only takes a fraction of a second to cause problems.

Simple devices like the Junsi only have one alarm, and the high voltage could be solar and not the alternator, so you have to disconnect for any alarm.
__________________
ebaugh is offline   Reply With Quote
Old 01-03-2013, 11:55   #2157
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 2,901
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by ebaugh View Post
Thanks for the information. It's kind of what I expected, but had not seen firsthand on the alternator protection devices.

I've been trying to answer someone else's installation questions. The field disconnect is the way to go, but does it have to be timed if the desire is to both disconnect the pack and turn off the alternator? With a solenoid for one and a relay for the other, which one really disconnects first? I assume it only takes a fraction of a second to cause problems.

Simple devices like the Junsi only have one alarm, and the high voltage could be solar and not the alternator, so you have to disconnect for any alarm.
In a well thought out design the HVC relay/relays and the load or LVC relay are separate buses. The battery does not get disconnected in a high cell voltage event, only the charge sources via relays do. You don't need big relays just enough to handle cutting an alts field or B+ wire (Balmar says cut B+ to regulator only) or solar or wind. I have two HVC relays one for solar, and one for the alt regulator. I will also have a solid state relay for the shore charger to cut the AC charger feed.

My LVC relay will only cut the "loads" but not the charging and my HVC relays will only cut the charging but not the loads... No sense in disconnecting the bank if a cell has gone out of range as that means you're likely at full charge or close to it...
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 01-03-2013, 12:03   #2158
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 2,901
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by ebaugh View Post
The question is for the 14.2V Genasun spec, is letting them float at 3.55 per cell causing any harm. Like when on shore power, potentially for long periods of time?

What little research we have seen makes me like your 3.45 Vpc or even my 3.35Vpc until we have more definitive data.
Genasun has had tremendous success with their design but they also have many thousands of dollars in equipment to closely match cells in a pack. Alex is also an MIT guy and really quite brilliant.

Their BMS design is also very top shelf. They have the longest track record, so far, in the marine Li business so I can't argue with their success.

Still, for me, having done my own experiments in my own shop, closely monitored, I feel that 13.8V for our bank is a very safe choice. I have tried it at 14.2V and 14.0V and feel 13.8V just works for me...

Even at just 13.8V the battery will take everything my equipment can throw at it right up until about the last 10 -15 minutes. I over sized the bank because I knew I wanted to leave the top end (upper knee) out of my day to day charging range. As near as I can tell, based on my battery monitor, charging to 13.8V leaves about 10+/- Ah's on the table and I can live with that to stay out of upper knee range....
__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Old 01-03-2013, 12:38   #2159
Registered User
 
ebaugh's Avatar

Join Date: Dec 2011
Location: On the boat
Boat: DeFever 44
Posts: 525
Quote:
Originally Posted by Maine Sail View Post

In a well thought out design the HVC relay/relays and the load or LVC relay are separate buses. The battery does not get disconnected in a high cell voltage event, only the charge sources via relays do. You don't need big relays just enough to handle cutting an alts field or B+ wire (Balmar says cut B+ to regulator only) or solar or wind. I have two HVC relays one for solar, and one for the alt regulator. I will also have a solid state relay for the shore charger to cut the AC charger feed.

My LVC relay will only cut the "loads" but not the charging and my HVC relays will only cut the charging but not the loads... No sense in disconnecting the bank if a cell has gone out of range as that means you're likely at full charge or close to it...
I agree, but if you have combination inverter/chargers in the system, what then? Am I missing an easy solution?
__________________
ebaugh is offline   Reply With Quote
Old 01-03-2013, 13:02   #2160
Marine Service Provider
 
Maine Sail's Avatar

Join Date: Jan 2007
Location: Maine
Boat: CS-36T - Cupecoy
Posts: 2,901
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Quote:
Originally Posted by ebaugh View Post
I agree, but if you have combination inverter/chargers in the system, what then? Am I missing an easy solution?

Unless an I/C is your primary charge source I usually consider it a load bus item. If it was to be your primary source of charging then it could go on the charge bus. The AC input can still be interrupted by an HVC relay to cut charging, despite it being on a load bus. Many ways to wire them in..
__________________

__________________
Marine How To Articles
Maine Sail is offline   Reply With Quote
Reply

Tags
battery, lifepo4, LiFePO4 Batteries, sailing

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
LiFePO4 Batteries - Okay Tear Me Apart ;-) jallum Electrical: Batteries, Generators & Solar 395 03-12-2015 13:19
Voltage drop under load, amps read 99% ?? VVD Electrical: Batteries, Generators & Solar 25 28-06-2011 16:25


Our Communities

Our communities encompass many different hobbies and interests, but each one is built on friendly, intelligent membership.

» More about our Communities

Automotive Communities

Our Automotive communities encompass many different makes and models. From U.S. domestics to European Saloons.

» More about our Automotive Communities

Marine Communities

Our Marine websites focus on Cruising and Sailing Vessels, including forums and the largest cruising Wiki project on the web today.

» More about our Marine Communities


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 23:51.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2016, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.