Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rating: Thread Rating: 33 votes, 4.82 average. Display Modes
Old 20-03-2013, 07:10   #2416
Registered User
 
ebaugh's Avatar

Join Date: Dec 2011
Location: On the boat
Boat: DeFever 44
Posts: 525
Quote:
Originally Posted by T1 Terry View Post
There is no history of lithium ferrous cells suffering an internal dead short, even if a cell in the 3v, 6v, 9v or 12 parallel pack was to go dead short, with a fuse in between the 6v and 9v parallel packs would mean the highest voltage at the shorted cell would that of 2 parallel packs in series. The pack with the dead short would already be pulled to a low voltage so the total voltage would be less than 6v, but possibly at very high amps.

Maybe the fuses would minimise potential damage to the other cells in the pack, but it adds so many failure points that would create cell capacity imbalance if a fuse failed due to fatigue, but wasn't noticed, that it may actually cause more problems than it would prevent.
T1 Terry
I won't debate if this is necessary or not, because I don't know. But it won't hurt, and for the most part detectable. I attached a picture of what I am considering, if the parallel fuses can be made small enough, any cell issue will be detected immediately. An overload on the bank side might trip a serial fuse and go undetected for awhile, but it won't damage the cells.
Attached Thumbnails
Click image for larger version

Name:	image-519056503.jpg
Views:	89
Size:	113.0 KB
ID:	57450  
__________________

__________________
ebaugh is offline   Reply With Quote
Old 20-03-2013, 12:21   #2417
Zil
Registered User

Join Date: Mar 2013
Location: South Jersey
Posts: 186
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

ebaugh; I can't get my head around how you lose 6 volts (9 volts) if a parallel fuse fails.
__________________

__________________
Zil is offline   Reply With Quote
Old 20-03-2013, 13:54   #2418
Registered User
 
ebaugh's Avatar

Join Date: Dec 2011
Location: On the boat
Boat: DeFever 44
Posts: 525
Quote:
Originally Posted by Zil View Post
ebaugh; I can't get my head around how you lose 6 volts (9 volts) if a parallel fuse fails.
Zil,

I don't lose 12V, or for that matter 6 or 9V. But if you were measuring the second cell voltage (the second column is a 4 cells paralleled) with a voltmeter between the 3V bubble and 6V bubble, it should read about 3V. OK, normally 3.2V since this is a LFP pack. But should any of the six parallel fuses blow, the voltmeter will read 0V. Detecting the failure of one of the 6 fuses. I call that the 6V level since that represents the second cell on a system designed to monitor cell voltage.
__________________
ebaugh is offline   Reply With Quote
Old 20-03-2013, 15:36   #2419
Registered User
 
NahanniV's Avatar

Join Date: Mar 2011
Location: On the Boat
Boat: Finnsailer 38
Posts: 1,026
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

ebaugh:

I don't see how the voltage would go to zero either ?

Also, be aware that the Junsi monitor inputs are ground referenced; The controller calculates the differential, there is even a function that allows for the leads to be connected in any order and the controller will sort it out.
__________________
NahanniV is offline   Reply With Quote
Old 20-03-2013, 18:07   #2420
Registered User
 
ebaugh's Avatar

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

I don't see how the voltage would go to zero either ?

Also, be aware that the Junsi monitor inputs are ground referenced; The controller calculates the differential, there is even a function that allows for the leads to be connected in any order and the controller will sort it out.
Nathan and Zil,

You guys are right. I need to think more. It takes more than one fuse.... Hmmm.
__________________
ebaugh is offline   Reply With Quote
Old 20-03-2013, 19:26   #2421
Registered User
 
ebaugh's Avatar

Join Date: Dec 2011
Location: On the boat
Boat: DeFever 44
Posts: 525
OK. I thought I had it mostly solved. I was wrong. You need an ohm meter down the fuse line to detect an error. That would work. Not so easy to accomplish. I think the cell protection scheme works, but fuse failures are not easily detectable.

Or maybe I'm missing a different configuration? The voltmeter always had to be differential input, I don't have a Junsi, so it may or may not have that functionality. Differential means sensing voltage like a Fluke handheld DVM would, irrespective to ground, in this example for reading Cell 2,3,4 voltages.

We are leaving Panama tomorrow afternoon for San Andres Island arrival Sat morning. Maybe someone can figure it out? Starbucks gift certificate for anyone who can with one channel per cell differential voltmeter.

Bob
__________________
ebaugh is offline   Reply With Quote
Old 20-03-2013, 19:31   #2422

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 12,110
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

"fuse failures are not easily detectable."
You need fuses that blow more dramatically.<G>
Actually there are fuses with built-in idiot lights, just not in these types. What they do is put a cheap LED and dropping resistor in parallel with the fuse element, typically set to allow a 10-20mA current to light the LED when the fuse blows.
So, fuse blows? Red light next to it. Resistor still limits the current to 10-20mA which hopefully won't let anything else catch fire.
Bag of big cheap red LEDs, two cents each? And another nickel for the resistor?

Just saying, if you want a fast way to find blown fuses, there's an arguably reasonable way to do it.
__________________
hellosailor is offline   Reply With Quote
Old 20-03-2013, 19:44   #2423
Registered User
 
ebaugh's Avatar

Join Date: Dec 2011
Location: On the boat
Boat: DeFever 44
Posts: 525
Hellosailor...That's a good idea, but it won't let my battery manager detect the problem. I gotta go look in the battery box, I think? Bob
__________________
ebaugh is offline   Reply With Quote
Old 20-03-2013, 20:34   #2424

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 12,110
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Depending on what your BMS is capable of detecting on, and what you're willing to spend, well sure, there's a way to turn an LED into a signal to the BMS. Or do like Boeing, and use a different battery type that emits gobs of easily visible smoke?
__________________
hellosailor is offline   Reply With Quote
Old 21-03-2013, 19:35   #2425
Zil
Registered User

Join Date: Mar 2013
Location: South Jersey
Posts: 186
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

It would have to be an active short to light the LED. But the LED could be in a remote panel, wired from the bank. Also that is a possible signal to use for a trigger. Enjoy your voyage.
__________________
Zil is offline   Reply With Quote
Old 21-03-2013, 20:00   #2426

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 12,110
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

"It would have to be an active short to light the LED."
No, as long as the fuse has blown and there is ANY other connection being made, the LED will light. That could be an active short but it could also be any overcurrent condition. This is the crude but fairly effective commercial solution that's been on the market for a numbre of years now. There are better ways but nothing that can approach being as effective at such a low cost. Not perfect--just very cost effective.
__________________
hellosailor is offline   Reply With Quote
Old 22-03-2013, 07:21   #2427
Registered User

Join Date: Jan 2013
Posts: 5
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

Interesting article, primarily the last few paraggraphs, on the Boeing battery testing and that only the LiFePO4 technology passes the testing.

http://www.foxbusiness.com/news/2013...tcmp=obnetwork
__________________
Gbtillman is offline   Reply With Quote
Old 22-03-2013, 08:57   #2428
Registered User

Join Date: Oct 2011
Location: Winter Bahamas - Summer BC
Boat: Lagoon 450, Bavaria Vision 40
Posts: 599
I want to help fiend replace his LA batts on a cat with LiFePo. I want to keep it simple for him and I am considering the per-packaged Balqon 12 V 90Ah times 6 batteries for him. Does anyone know what is inside the box I terms of BMS , specifically HVC and LVC?

The other option would be 4 times 700Ah clearance cells. But this would require that I have to spend two weeks with him installing and testing everything and I live on the other side of the continent.

Thanks for the help.
__________________
roetter is offline   Reply With Quote
Old 22-03-2013, 10:02   #2429

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 12,110
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

roetter, Balqon are a wholly-owned subsidiary of Winston, who have been reported to be in bankruptcy. Which means orders may not be filled (Balqon has apparently been sporadic about that) and there may be no company to warranty the batteries if the bankruptcy goes through. Just a couple of things to look into and perhaps beware of, for that source.

Their web site store indicates they "provide battery management solutions" which says to me that there are none in the battery itself.
__________________
hellosailor is offline   Reply With Quote
Old 22-03-2013, 11:52   #2430
Zil
Registered User

Join Date: Mar 2013
Location: South Jersey
Posts: 186
Re: LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

HelloSailor; The fuses I referenced were the ones from positive to positive. I had to test using 9v and 1.5v dry cells. Yes the LED lights if the batteries are not balanced to volts.
__________________

__________________
Zil 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 07:15.


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.