Need advice on replacing lead battery to AGM or Lithium? - Fiberglass RV


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 07-10-2019, 10:36 AM   #1
Member
 
Name: Brian
Trailer: 1990 13 ft Casita DLX #6
Colorado
Posts: 53
Question Need advice on replacing lead battery to AGM or Lithium?

Here is my current setup. 13 ft Casitas


1. I have a standard multi stage charger and a solar panel wire to battery
2. Lead acid battery
3. NO converter. Everything is wire from the battery directly to fuse box then to lights and (a rarely used water pump).
4. Basically battery powers only the LED lights 95% of the time.

What is cost effective? AGM or Lithium?
Do I need another type of charger for either of the above?
Do I need anything else to make the change to AGM or Lithium?
Losthwy is offline   Reply With Quote
Old 07-10-2019, 10:53 AM   #2
member
 
Name: J
Isle of Wight
Posts: 536
Quote:
Originally Posted by Losthwy View Post
Here is my current setup. 13 ft Casitas


1. I have a standard multi stage charger and a solar panel wire to battery
2. Lead acid battery
3. NO converter. Everything is wire from the battery directly to fuse box then to lights and (a rarely used water pump).
4. Basically battery powers only the LED lights 95% of the time.

What is cost effective? AGM or Lithium?
Do I need another type of charger for either of the above?
Do I need anything else to make the change to AGM or Lithium?
You havent said WHY you are changing.
Why not stick with lead?
WizWid is offline   Reply With Quote
Old 07-10-2019, 11:30 AM   #3
Senior Member
 
Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
North Carolina
Posts: 4,346
AGM batteries will work fine with 99 percent of chargers designed for regular lead acid batteries. I got a Vmax Tank AGM and made no changes, using a CTEK charger, Progressive Dynamics converter and Bogart Engineering Solar Charger.

Lithium batteries are expensive and will likely require replacing all chargers.

SEE: http://www.fiberglassrv.com/forums/f...ium-89150.html

To me its simple. AGM.
gordon2 is offline   Reply With Quote
Old 07-10-2019, 07:36 PM   #4
Senior Member
 
Name: Douglas
Trailer: Lil Snoozy
MD
Posts: 153
Registry
I did a conversion to a lithium battery in a Lil Snoozy (you can search for the thread detailing the conversion). For your needs as described, I would stick with lead acid. To convert to Li, you would almost certainly need to change out your charger and maybe some wiring. It is hard to say about your solar without knowing more. I spent about $1500 on my conversion and am guessing you could do a lights-only system for $500 or so. But I would just stick with what you have or go to a modest AGM (like 70 amp hour).

AGM is lead acid, by the way, you just don't have to worry about adding water or venting problems.
Air Doug is offline   Reply With Quote
Old 07-11-2019, 10:12 AM   #5
Member
 
Name: Brian
Trailer: 1990 13 ft Casita DLX #6
Colorado
Posts: 53
Thanks for replies. It does seem lithium is a bit pricey.
Reason for possible change is old battery not holding power like it use to.
Losthwy is offline   Reply With Quote
Old 07-11-2019, 10:48 AM   #6
Senior Member
 
Name: J Ronald
Trailer: Currently shopping
North Carolina
Posts: 236
Batteries

For heavy battery use Lithium is most cost effective when all factors are considered. Li can be discharged 100%, lead acid only 50% max. much less physical battery required because Li are physically smaller and fewer are required and they charge faster and last longer. But in your case of limited use and the initial expense of upgrading charger for such a small battery bank the lower initial outlay or lead acid is my choice. AGM are more expensive than other deep discharge batteries and less AH for size. Unless you need the ability to store the battery on it's side or installing it in your living space or just want to never have to need to check electrolite a good deep discharge battery of adequate AH rating would be my choice. Not a battery just labeled marine or marine starting.
J Ron is offline   Reply With Quote
Old 07-11-2019, 04:56 PM   #7
Senior Member
 
Radar1's Avatar
 
Name: Dave (and/or John)
Trailer: Scamp 16 (sold), Escape 19
Georgia
Posts: 1,036
Registry
I would think the most cost effective is sticking with your leaded battery since you have such low power demands. You mentioned you have a solar panel connected to your battery, but is there a solar charge controller in the circuit so that you don't end up overcharging the battery, which can kill it just as dead as undercharging.
Sounds like your DC needs are light so the standard (and cheaper) lead acid battery (look for deep cycle) should work well as long as voltage is not allowed to get too low or overcharged.
__________________
John-Dave and Marilyn
Sharpsburg, GA
04 Dodge Dakota V-8, 17 Dodge Durango V-6, 19 Ford Ranger 2.3 Ecoboost
radar1-scamping.blogspot.com
Radar1 is offline   Reply With Quote
Old 07-17-2019, 11:33 AM   #8
Member
 
Name: Michael
Trailer: Former Scamp 13, Former Airstream 16
Connecticut
Posts: 64
J Ron and Air Doug:

AGM batteries still require venting to the outside.

Electrical Myths, Part 4: AGM Batteries Don't Need Venting - RV Nerds

Mike
pedalmike is offline   Reply With Quote
Old 07-17-2019, 12:43 PM   #9
Senior Member
 
Name: J Ronald
Trailer: Currently shopping
North Carolina
Posts: 236
Venting AGM.

Thank you, I stand corrected. AGMS have a valve that allows venting under a fault condition. Thanks for preventing me continuing the myth that AGMS don't require venting, that will create an unsafe condition.
J Ron is offline   Reply With Quote
Old 07-17-2019, 01:01 PM   #10
Junior Member
 
Name: Scott
Trailer: Scamp 19
Texas
Posts: 9
Exclamation Lithium Facts vs. Lore

Most "drop-in replacement" lithium batteries use a battery management system, or BMS, that works perfectly well with a standard multi-stage charger.

Before listening to folks who aren't up-to-date on current technology, go to information sources that specialize in that technology. Will Prowse, a young YouTuber, has a good section on all types of batteries on his website ( https://www.mobile-solarpower.com/li...batteries.html ).

As for pricing, be aware that because of Lithium iron phosphate (LiFePO4) chemistry you get nearly double the usable power of a Lead-Acid battery (including SLA and AGM) so essentially you need only half the battery (capacity). You should be able to get a 40ah LiFEPO4 drop-in (equivalent to an 80ah Lead-Acid battery) for around $400 BUT it will have a 4000-5000 duty cycle life (vs. 1000-1500 duty cycles with Lead-Acid) and charges from solar 40% faster as it absorbs a charge far more efficiently than Lead-Acid (as it doesn't require staged charging). Faster solar charging means less panels necessary.

It amazes me the amount of bad information out there on Lithium batteries and, BTW, deep cycle Lithiums batteries aren't the same chemistry as mobile phone batteries so they won't explode or burst into flames!

Quote:
Originally Posted by gordon2 View Post
AGM batteries will work fine with 99 percent of chargers designed for regular lead acid batteries. I got a Vmax Tank AGM and made no changes, using a CTEK charger, Progressive Dynamics converter and Bogart Engineering Solar Charger.

Lithium batteries are expensive and will likely require replacing all chargers.

SEE: http://www.fiberglassrv.com/forums/f...ium-89150.html

To me its simple. AGM.
Techscott is offline   Reply With Quote
Old 07-17-2019, 08:15 PM   #11
Member
 
Nevada
Posts: 44
Registry
If your charger is a ďmultiĒ stage charger consisting of at least 3 stages, you should be good to go. I just upgraded to an AGM battery in my Casita but I had to replace the controller panel as it only had a 2 stage charger. AGMís are essentially lead-acid technology, for which we have 100+ years experience. Lithium cells have a much greater power density as well as other advantages, but, as you found out they are much more expensive an have a couple of very nasty failure modes if not properly designed, installed or maintained (they can catch on fire!). Iím sure someone will disagree, but they donít allow them to be shipped on an airplane for a reason.
egfasdsdsz is offline   Reply With Quote
Old 07-17-2019, 09:10 PM   #12
Senior Member
 
Byron Kinnaman's Avatar
 
Name: Byron
Trailer: 2006 Scamp 13' towed with a 2005 Dodge Dakota 4.7l Magnum W/full tow package (over kill)
Oregon
Posts: 7,048
Registry
Quote:
Originally Posted by Losthwy View Post
Thanks for replies. It does seem lithium is a bit pricey.
Reason for possible change is old battery not holding power like it use to.
Replacing a standard Lead Acid battery with a new one is whole lot cheaper than replacing with something else and it works just as well.
__________________
Byron & Anne enjoying the everyday Saturday thing.
Byron Kinnaman is offline   Reply With Quote
Old 07-18-2019, 07:06 AM   #13
Senior Member
 
Name: Gordon
Trailer: 2015 Scamp (16 Std Layout 4) with '15 Toyota Sienna LE Tug
North Carolina
Posts: 4,346
Quote:
Originally Posted by Techscott View Post
Most "drop-in replacement" lithium batteries use a battery management system, or BMS, that works perfectly well with a standard multi-stage charger.

Before listening to folks who aren't up-to-date on current technology, go to information sources that specialize in that technology. Will Prowse, a young YouTuber, has a good section on all types of batteries on his website ( https://www.mobile-solarpower.com/li...batteries.html )....
Will Prowse might be an expert for all I know, but I dont see any references to his training or education on his web site. I do this this:
William Prowse IV (www.mobile-solarpower.com) is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.

and I noticed that the page you linked to is mostly a list of these referral links helping him get paid. And you can buy his book too. Nothing wrong with a little capitalism of course.

But back to the statement that "lithium batteries [which] use a battery management system, or BMS, ... works perfectly well with a standard multi-stage charger."

My understanding (as a self-admitted amateur in this field) is that using a lithium battery with a standard RV converter or lead acid charger (multi stage included) will give you the advantage of the greater depth of discharge available with the lithium battery but you sacrifice the higher capacity of the lithium battery because for a full charge it requires higher voltage that the lead acid chargers will usually provide. So yes, it will work. But will it work "perfectly well" is subjective.

But since I am not an expert in the field, I will quote the manufacturer of what has to be the most common brand of converter / charger in RVs... Progressive Dynamics:

Can I Use My Present Progressive Dynamics PD9200, PD4000 or PD4500 Series Lead/Acid Units With the Charge Wizard to Charge My Lithium Battery?

Yes, if you are willing to live with an expensive battery that is only partially charged. The Normal Output voltage of the PD9200, PD4000 and PD4500 Series voltage provides only 13.6-volts and a full charge voltage for Lithium needs to be 14.4 Ė 14.6 Volts. The PD9200, PD4000 & PD4500 Series Charge Wizard will initially jump to 14.4-volts in the Boost Mode when first connected to 120 VAC power and will remain there until the battery voltage reaches 13.8-Volts, then automatically drops down to the Normal Mode of 13.6-Volts. The faster charge rate of Lithium means that in the Boost Mode it will reach this 13.8-Volt point after only a few minutes of recharging and then the charging current will drop to ZERO AMPS and will not add any additional charge to your Lithium Battery. This lower charge state will not damage your battery, but will eliminate most of the advantages you paid for.


Then there is the issue of the BMS design - some are very basic and some are quite advanced.

So for me, the bottom line is that it is not logical to use a lithium battery unless you also pair it to a charger specifically designed for it.
gordon2 is offline   Reply With Quote
Old 07-18-2019, 10:23 AM   #14
Moderator
 
Name: RogerDat
Trailer: 77 Scamp 13
Michigan
Posts: 3,504
I'm another vote for simply purchase a new lead acid battery. They are a lot of Amp hours per dollar and not a lot of dollars per year of use given good maintenance.

Maybe buy a battery minder to provide a maintenance charge during the off season. That can help the battery have a longer life span. Not to mention you have a charged battery to use during a power outage.

A good quality battery charger can make a difference, also don't forget many battery maintenance chargers can't charge a low battery, only maintain the charge of an already charged battery. The cheap maintenance chargers from Harbor Freight are a good example. They will probably die if hooked to a low or dead battery. Higher end devices will cover both charging and maintaining.

Keep the cells topped off to the bottom of the tube with distilled water, never tap or even bottled. Distilled only. Low water will reduce charge available and eventually deterioration of plates if the water gets low enough. That deterioration will permanently reduce the capacity if not provide a self draining short.

I too have only a couple of LED lights to run. I do have an inverter to power 110 volt items if needed but it isn't normally on so not much of a factor. If needed it can be turned on to charge camera battery, or laptop or maybe run a blow dryer "briefly" so dear wife can spruce up before going back out in civilization. Most power hungry thing I run normally is a small fan. I want to replace that with a 12 volt model to run directly from the battery instead of running the inverter because that is more efficient.
RogerDat is offline   Reply With Quote
Old 07-18-2019, 01:18 PM   #15
Senior Member
 
Raspy's Avatar
 
Name: John
Trailer: Black Series HQ19
Smith Valley, Nevada
Posts: 2,207
Quote:
Originally Posted by Techscott View Post
Faster solar charging means less panels necessary.
I'm afraid I don't understand this. How can you do faster charging with fewer panels?
__________________
I only exaggerate enough to compensate for being taken with a grain of salt.
Raspy is offline   Reply With Quote
Old 07-18-2019, 01:50 PM   #16
Senior Member
 
Jon Vermilye's Avatar
 
Name: Jon
Trailer: 2017 Escape 21
Oswego, NY
Posts: 2,074
Registry
Quote:
Originally Posted by Raspy View Post
I'm afraid I don't understand this. How can you do faster charging with fewer panels?
Because lithium batteries charge at the full output of the solar controller until almost full. Lead acid battery controllers must switch to an absorption stage, limiting charging current when they reach 80% of full.

In other words, you can use panels with less output because all of the output goes to charging the battery until full. With lead acid you need higher currents during the bulk stage to end up putting the same # of amp hours back in the battery.
Jon Vermilye is offline   Reply With Quote
Old 07-18-2019, 03:50 PM   #17
Senior Member
 
Raspy's Avatar
 
Name: John
Trailer: Black Series HQ19
Smith Valley, Nevada
Posts: 2,207
Jon, I get that. But how does that relate to fewer panels? Having a longer bulk phase, at a lower peak, with fewer panels, doesn't seem like it would always reduce the overall charging time. Maybe, in some cases, but not as a general rule.

Often, the full power of the solar array is far below what the batteries are designed to accept. And rooftop solar systems only produce about 40% of their rated output if laid flat.

The absorption phase is not a step function that drops the amps to a predetermined lower value, it is a gradual tapering off. So even though it might be the last 20%, it could be nearly the same amperage as bulk for a large percentage of that phase, especially if the solar array is small.

I just don't get how one can claim, as a general rule, that faster charging means less panels are necessary. Aren't there too many variables to generalize in that way?

It's not fair to assume that all charging will be done from nearly dead to fully charged. That is not the real world, and especially if the system is a rooftop system that is always ready to go whenever there is sun. If power use is small overnight, and every day is sunny, the lead batteries will be in absorption most of the time, but a smaller array on lithium could equal the average amps of the absorption phase. If you had more collectors, you might only need half the day to recharge the lithiums.

I'm just trying to understand how a smaller system can always charge faster.
__________________
I only exaggerate enough to compensate for being taken with a grain of salt.
Raspy is offline   Reply With Quote
Old 07-18-2019, 04:19 PM   #18
Senior Member
 
Jon Vermilye's Avatar
 
Name: Jon
Trailer: 2017 Escape 21
Oswego, NY
Posts: 2,074
Registry
Quote:
Originally Posted by Raspy View Post
Jon, I get that. But how does that relate to fewer panels? Having a longer bulk phase, at a lower peak, with fewer panels, doesn't seem like it would always reduce the overall charging time. Maybe, in some cases, but not as a general rule.

Often, the full power of the solar array is far below what the batteries are designed to accept. And rooftop solar systems only produce about 40% of their rated output if laid flat.

The absorption phase is not a step function that drops the amps to a predetermined lower value, it is a gradual tapering off. So even though it might be the last 20%, it could be nearly the same amperage as bulk for a large percentage of that phase, especially if the solar array is small.

I just don't get how one can claim, as a general rule, that faster charging means less panels are necessary. Aren't there too many variables to generalize in that way?

It's not fair to assume that all charging will be done from nearly dead to fully charged. That is not the real world, and especially if the system is a rooftop system that is always ready to go whenever there is sun. If power use is small overnight, and every day is sunny, the lead batteries will be in absorption most of the time, but a smaller array on lithium could equal the average amps of the absorption phase. If you had more collectors, you might only need half the day to recharge the lithiums.

I'm just trying to understand how a smaller system can always charge faster.
One example - With my lead acid batteries at 85%, even with 480 watts of solar, the controller limits the current to a couple of amps (example is with a pair of 6V Interstate 232 amp hour batteries & a GoPower PWM controller). I'm using a very small percent of the available solar panel output.

A single 100 watt panel with a controller designed for lithium would produce 5-6 amps until the lithium batteries are full.

After switching to a pair of 100 amp hour lithium 12V batteries, with 320 watts of solar flat on the roof, I was getting 16 amps into a pair of lithium batteries that were at 80% this afternoon. It took about 2 hours to bring them to 100%.

I'm not suggesting that one switch to lithium for just the recharging capabilities, but is is certainly one of the advantages. Now if they only cost a bit less!
Jon Vermilye is offline   Reply With Quote
Old 07-18-2019, 05:03 PM   #19
Senior Member
 
Raspy's Avatar
 
Name: John
Trailer: Black Series HQ19
Smith Valley, Nevada
Posts: 2,207
Thanks Jon,

I'm surprised that your controller limited the absorption amps, at 85% charged, to only 2 amps. That is a very aggressive reduction during absorption.
The smart charger I had some experience with, regulated the current to maintain a battery voltage of 14.1 (during absorption) until the amps fell to 5, and then it went to float. It was a gradual taper from full amps, down to 5.

If your flat array was producing 16 amps at 14 volts, you were getting about 70% of it's rated output of 320 watts. That seems like very good performance for panels sitting flat. Of course we are near summer solstice.

So, I can see from your example that in your particular conditions, with your particular controller, quicker charging could occur with lithium. But don't cut down the collector array too much or the "quicker charging with fewer panels" theory will not hold. Do all solar controllers fall off on their absorption amps to that degree? If so, they are wasting power and lengthening charge times. The amps delivered should be driven by the voltage of the batteries and be a continuous curve.

My theory is that, for the most part, usage will rise to meet supply. The practical result of this is that most systems will spend most of their time in the bulk phase. If usage is small, the system will spend a lot of time in absorption, but if usage rises to near capacity, then the bulk phase will be mostly where the charging occurs. It's easy to get to this condition because the available real estate on the roof is limited and the collectors are flat. Plus, the convenience of having power means it can get used a lot.

We seem to be fairly heavy users of power, especially in the winter with the heater getting used. But on average, three to four days gets us to 50%, and that is with (4) T105, 6 volt, flooded batteries. Most of my solar charging has been done on other rigs I've had. I also lived on a 42' Ketch for many years and had to manage those batteries while charging with a dedicated alternator for that purpose. I had two 8D deep cycle house batteries there. Solar is much harder to arrange on a sailboat, and the power usage can be much higher with navigation lights, radar, autopilot and depth sounder always on, as well as the other loads similar to what trailers experience.
__________________
I only exaggerate enough to compensate for being taken with a grain of salt.
Raspy is offline   Reply With Quote
Old 07-18-2019, 05:11 PM   #20
Senior Member
 
Name: Steve
Trailer: 2018- 21FT- FORD
NW Wisconsin
Posts: 4,205
Quote:
Originally Posted by Byron Kinnaman View Post
Replacing a standard Lead Acid battery with a new one is whole lot cheaper than replacing with something else and it works just as well.
I am 100% with Byron , lead acid batteries are cost effective , work well and provide my trailer with 12VDC .
steve dunham is offline   Reply With Quote
Reply

Tags
battery


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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lithium battery in Lil Snoozy Air Doug Electrical | Charging, Systems, Solar and Generators 64 12-23-2019 08:30 PM
Casita Battery Charger mods for adding a AGM battery? doctoruv Electrical | Charging, Systems, Solar and Generators 2 02-14-2019 01:51 PM
Lithium vs Lead Acid Batteries neparker Electrical | Charging, Systems, Solar and Generators 21 08-03-2018 09:48 AM
RV Lithium Battery honda03842 General Chat 20 07-16-2015 03:47 PM
Flooded Lead Acid vs Valve Regulated Lead Acid (AGM & Gel) The Minimalist Modifications, Alterations and Updates 6 08-24-2014 09:30 PM

» Upcoming Events
No events scheduled in
the next 465 days.
» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 05:17 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.