Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 06-02-2013, 12:00 PM   #1
Senior Member
 
MN_Traveler's Avatar
 
Join Date: Apr 2012
Location: Minneapolis, MN
Posts: 375
Charging Rates for AGM Batteries

As a follow-on to my earlier question re. uneven charge/discharge character on my house batteries, and concern that it is being caused by corrosion-induced degradation of the battery connections - I have been looking over past discussions on AGM batteries. A lot of good discussion, lots of pros-and cons. In the interest of NOT initiating another long discussion on "which is better", I am asking for feedback on the following question (that is still unanswered for me), and ask that the discussion be limited to only that question .... :-)

QUESTION: some "informational" data on the web indicates that AGM's are NOT able to take as fast a charge-rate as flooded cells. Other information indicates that AGM's actually CAN take a faster charge-rate than flooded cells. My manual for my Magnum Energy charger/inverter indicates that the Bulk charge setting for AGM's is 14.5 VDC, versus 14.6 VDC for flooded cells (which implies only a slightly slower charge rate for AGM's. What is the experience of the AGM users out there: do AGM's take a much longer time to charge than wet cells (from an equavalent state of discharge), or is the the difference small in practice?????

Thank you, as always, for sharing your experience !!!
__________________

__________________
- 2012 Fleetwood Expedition 36M -
MN_Traveler is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 06-02-2013, 12:44 PM   #2
Senior Member
 
GaryKD's Avatar
 
Newmar Owners Club
Join Date: Jul 2006
Location: Wellington, Florida
Posts: 12,325
Hi MN_Traveler,
As best I can tell think of this as the other way around. A charging system will present X amount of charge capability to a battery. The amount of charge received depends on the battery. A battery needing quite a bit of charge will accept more than a battery almost at 100% of full charge. The important thing to remember is have a charger capable of presenting more than enough charge capability to the battery(s).

AGM fully charged 12 VDC battery is 12.8 VDC. A fully charge flooded deep cycle battery is 12.6 VDC. This might not seem like much difference. However, depending on the charger, one would not want the charger to "turn off" at 12.6 VDC if one has AGM batteries.

For me the most important thing to remember is for the charging source to stay charging until 12.8 VDC is reached (I have AGM batteries). Next is to have a charger that provides more than enough charging voltage for the battery to accept whatever amount of charge it needs.
__________________

__________________
Gary
2005 Newmar KSDP 3910 + GMC ENVOY XUV 37K lbs Moving Down The Road
The Avatar Is Many Times Around The USA
Nobody Knows Your Coach Like Somebody Who Owns One Just Like Yours
GaryKD is offline   Reply With Quote
Old 06-02-2013, 01:07 PM   #3
Senior Member
 
Join Date: Nov 2012
Location: bis. nd
Posts: 687
remember also that volts going in is not always how many amps the charger is pushing which would be like you describe about being able to charge faster...

chargers have limits on haw many amps they push for charging and the volts do not always coincide with that...say your battery is mostly dead and the volts going in will coincide with that but the amps the charger is pushing for bulk will be the max it can deliver..until it goes to absorbstion then amps go down edct...jeff
__________________
London Aire..350hp Sparton chassis... with all the good stuff from the time.
2007 Alfa Gold!! model 1008. 400hp Freightliner, now in use!!
beenthere is offline   Reply With Quote
Old 06-02-2013, 02:00 PM   #4
Senior Member
 
MN_Traveler's Avatar
 
Join Date: Apr 2012
Location: Minneapolis, MN
Posts: 375
Ummm - I probably simplified things too far for my question. When I asked about Rate ... I meant RATE (not total time). All else being equal (depth of battery discharge, same internal resistance for the battery bank (which may not be accurate for wet cell versus AGM), and the same charger delivering my 14.5 versus 14.6 VDC bulk charge (my charger does FLOAT at 13.5 VDC for AGM and 13.4 VDC for flooded). sorry: I guess to get at this question I need to be either really specific, or very, very general (I am an engineer, so we can get specific if you folks want to). I suspect though that for now a really simplified approach would be more productive.

So lets try reducing the question to the following: for those of you who are using AGM's, do you notice a significant difference in time to recharge (or at lease finish the Bulk step) for AGM's versus wet cells, assuming the banks having started from a similar depth of discharge?
__________________
- 2012 Fleetwood Expedition 36M -
MN_Traveler is offline   Reply With Quote
Old 06-02-2013, 02:09 PM   #5
Senior Member
 
Join Date: Nov 2012
Location: bis. nd
Posts: 687
like i said it comes down to amps in not voltage...until the end for float
__________________
London Aire..350hp Sparton chassis... with all the good stuff from the time.
2007 Alfa Gold!! model 1008. 400hp Freightliner, now in use!!
beenthere is offline   Reply With Quote
Old 06-02-2013, 03:40 PM   #6
Senior Member
 
macnut's Avatar
 
Winnebago Owners Club
Ford Super Duty Owner
Join Date: Jun 2012
Location: Dublin, CA
Posts: 1,131
One of the major advantages to an AGM battery is that it can accept a faster charge rate than fooled cell batteries. Gel batteries are sometimes confused with AGM, and that may be why you are getting differing information. You should get consistent info from the battery makers....Lifetime, Trogan, etc.
__________________
macnut is offline   Reply With Quote
Old 06-02-2013, 04:22 PM   #7
Senior Member
 
Join Date: Feb 2010
Posts: 4,493
Amps is the flow of current to replace the charge in the Battery.

Voltage determine the amount of amps during charge.

The VRLA or AGM batteries FLOAT at 2.25 volts per cell, or 13.5 VDC.

The float current should never excede 0.1% of capacity, so a 100 AHR Battery should never be charged higher than 0.1 Amp after it is fully charged.

They have a lower internal resistance so they can be charged faster..
BUT AT A PRICE... they have a chamber to retain the gasses and allow them to recombine and stay inside the Battery.

If charge rate is high enough to cause excess gassing the relief valve will "gass off" or release the excess gass, and there is no way to replace it, so capacity is reduced.

Seek out the manufacturer data sheet for the specific Battery.

It will specify the charge currents, voltage for charge as well as the actual capacity based on the loading from the installation

The rating of the Battery is usually at the 8, 10, or 20 hour rate, it puts out a certian amout of amps for that time to get total.

Say it is listed as "100 AHr @10 HR.

That means it will do 10 amps for 10 hours.

Place a 50 amp load and it will NOT run 2 hours.

Plus pay attention to end voltage, 1.75, 1.80 or 1.85 VPC, sets the end of cycle.

Plenty more information if you search for it.
__________________
Tony & Lori
1989 Country Coach Savannah SE
TQ60 is offline   Reply With Quote
Old 06-02-2013, 06:00 PM   #8
Senior Member
 
GaryKD's Avatar
 
Newmar Owners Club
Join Date: Jul 2006
Location: Wellington, Florida
Posts: 12,325
Hi MN_Traveler,
Being a retired engineer, I'll answer your revised question as simply as possible. I notice no difference in the time to charge between flooded cell or AGM batteries.
__________________
Gary
2005 Newmar KSDP 3910 + GMC ENVOY XUV 37K lbs Moving Down The Road
The Avatar Is Many Times Around The USA
Nobody Knows Your Coach Like Somebody Who Owns One Just Like Yours
GaryKD is offline   Reply With Quote
Old 06-02-2013, 06:48 PM   #9
Senior Member
 
dons2346's Avatar
 
Country Coach Owners Club
Join Date: Dec 2010
Posts: 4,497
"So lets try reducing the question to the following: for those of you who are using AGM's, do you notice a significant difference in time to recharge (or at lease finish the Bulk step) for AGM's versus wet cells, assuming the banks having started from a similar depth of discharge? "


I see a significant reduction in charge time. I have never timed it down to the minute but it appears that charge time is reduced about 30%
__________________
dons2346 is offline   Reply With Quote
Old 06-02-2013, 06:57 PM   #10
Senior Member
 
macnut's Avatar
 
Winnebago Owners Club
Ford Super Duty Owner
Join Date: Jun 2012
Location: Dublin, CA
Posts: 1,131
Here's a link to the technical manual for lifeline batteries. Pages 10-12 provide a table comparing AGM to other battery types.

http://www.lifelinebatteries.com/manual.pdf

Hope this helps!
Al
__________________

__________________
macnut is offline   Reply With Quote
Reply

Tags
batteries, charging



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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


» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 01:20 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.