Ultimate Battery Thread


Senior Member
Jan 31, 2008
Solvang, CA
I see there are ultimate threads on a number of topics but not batteries. I had to do a lot of reading to understand the various types of batteries and then ultimately determine what I wanted to use for my house batteries.

Since I see lots of other folks posting questions about batteries I thought it would be useful to collect some useful threads and web links in one place.

I will start with some good web sites on batteries that I have found. Below that are links to manufaacturer info and at the bottom links to battery related threads on WTW.

If I've missed a thread or you know of something we should add, just post and I'll add it to the first post.

There are three basic types of batteries used in vehicles, Campers and RVs:
  • Starting
  • Deep Cycle
  • Dual Purpose (starting/psudo-deep cycle hybrid)
The construction of these types of batteries are usually one of the following:
  • Flooded Lead Acid (FLA)
  • Absorbed Gas Mat (AGM)
  • Gel Cell
  • Lithium Ferrous Phosphate (LiFePO4)
Each of these has various pros and cons which make careful selection important. Follow the links in the next post to learn more.

There are various ratings for batteries that include cold cranking amps (CCA), Cranking amps (CA), reserve capacity (RC) and amp hours (AH). These ratings depend on time and battery temperature so it is important to understand the differences (read the info at the links).

In general, for our camper house batteries we are interested in the 20 hour AH rating.


Web links to Battery info:

Battery Basics - https://www.batterys...ery-basics.html

Battery University - http://batteryuniversity.com/learn/

Deep Cycle Battery FAQ - https://www.solar-el...attery-faq.html

What to look for when choosing a battery - http://jgdarden.com/...faq/carfaq7.htm

Extensive treatise on Lithium batteries -

Deep Cycle Marine Battery Test

Deep Cycle Battery FAQ

Lead Acid Battery - Lifetime Study
http://www.power-thr...White Paper.pdf

Should I not let my AGM battery discharge below 70% or 50%?

Battery Life (and Death) - Electropedia

BU-808: How to Prolong Lithium-based Batteries

Lead-Acid Battery Manufacturers and Brand Names List 2017 with some manufacturer links


More battery manufacturer links:

Trojan - http://www.trojanbat...ASAAEgJGZvD_BwE

Rolls - http://raysolar.ca/p...ASAAEgJm3vD_BwE

Lifeline - http://lifelinebatte...teries/gpl-4ct/

East Penn (Deka) - http://www.eastpennm...ional-vehicles/

WTW Forum links to Battery info:

Adding a Second Battery

AGM Battery Recommendation -

Battery choice - http://www.wanderthe...battery-choice/

AGM deep cycle vs. AGM solar battery -

LiFe Blue Battery - http://www.wanderthe...y/?hl=batteries

Using camper battery bank/solar to recharge other battery banks (such as boat batteries) - http://www.wanderthe...s/?hl=batteries

Batteries (new battery advice) - http://www.wanderthe...s/?hl=batteries

Low cost DIY Lithium camper batteries -

6 volt Dual Battery Set up - http://www.wanderthe...battery-set-up/

Lithium update - http://www.wanderthe...lithium-update/

Second Battery Setup - http://www.wanderthe...ons/?hl=lithium

House Battery as Helper to Truck Battery - http://www.wanderthe...ium#entry149600

How to Run a 75 AH and 100 AH Battery at the Same Time:

Second Battery Question

Ordering Tomorrow! Second Battery Option?

batteries - (effect of dead truck battery on camper battery(s)

Frozen Battery

Battery Planning
http://www.wanderthe...tomatic charge

Under-the-hood dual battery setup and FWC shell

Adding a Lithium Ion Battery to FWC
http://www.wanderthe...utomatic charge

12V LiFePo4 (Lithium Ion) Battery Project Photos
http://www.wanderthe...ifepo4 +battery

12V LiFePo4 batteries - possible choices

2x6=12 and 2x12=12 but which way to go?

AGM Charging Profile Graph

Camper Batteries

Battery relocation good idea or bad?

Camper batteries drop when truck is running

Lithium LiFePo4 comparison video - Very Informative - Pre-Built vs DIY

Converting to 6v Batteries? Can i keep the 12s too?

What battery are you using with your solar system?

New Battery

Adding a dual battery system for camper

Charging Choice

WTW Forum links to Info on Battery Charge and Monitoring Electronics:

CTEX CTX Battery Sense: http://www.wanderthe...-battery-sense/

Are all Group 24 Batteries the Same Size?: http://www.wanderthe...ger#entry183395

FWC Battery Care: http://www.wanderthe...ger#entry174850

Battery Charge/Maintenance:

Automatic Charge Relay - How to Improve your battery Isolator

How do you keep your batteries charged when......

Sure Power 1314 versus 1315 Battery Separator

Victron 702 Install - Tips Appreciated

Who's Installed and Inverter?

Reasons to add Charger - Maintainer for Shell Models

Power Interters

Battery Isolator - Noob question

Monitor Battery, Solar & Truck Charging - Find Truck Wires in Fleet?
http://www.wanderthe...tomatic +charge

Favorite Battery Monitor System?
http://www.wanderthe...tomatic charge

When Do You Recharge? (charge separator questions)

House Battery as Helper to Truck Battery

Battery separator question
http://www.wanderthe...tomatic charge

Automatic Charge Relay - How to Improve Your Battery Isolatior
http://www.wanderthe...tomatic +charge

Auxillary Battery wiring help needed

Battery Age affects charging (trickle or solar)

Camper Charging Issues
http://www.wanderthe...tomatic charge

Truck Mounted Camper Batteries
http://www.wanderthe...tomatic +charge

Truck to Camper Electrical (wiring for charging batteries)

Battery Wiring / Shutoff

Camper Battery Won't Charge

Sure Power 1314 Recall - FYI
http://www.wanderthe...tomatic charge

Charging House Battery

DC to DC - 12 volt battery charger
http://www.wanderthe...tomatic charge

Battery Separator -

SurePower 1314/1315 vs. "Battery Switch"

Improved battery charging is available cheap
http://www.wanderthe...tomatic +charge

Convertor Questions

State of Charge Monitor (Blue Sea?)

Charging Vehicle and House Batteries that are Different Types (e.g. FLA and AGM)

House battery and started battery with solar confusion

Alternator vs Solar Charging

Charge controller won't stay in float

Low cost Wifi Battery Monitor

Automatic charge controller or battery isolator voltage measurement

Can The FWC Smart Controller/Q4 Charge The Truck Battery?

Wiring question. Battery grounding

Where to Put Victron Solar Stuff?

Shunt and Battery Monitor

My Idea of the Perfect Truck Camper Electrical System

Power connection help

LiFePo4 charging

Blue Sea ACR question

Upgrading Wiring to Charge Camper Batteries From Truck?

MPPT + DC-DC = (cheap) B2B
Why you might want to consider adding a battery monitor to your house battery bank even if you do not have solar panels.

[SIZE=12pt]The FWC water and battery panel shows three lights to indicate battery condition and one light to indicate charge state.[/SIZE]

[SIZE=12pt]Charge (green on, not green off) [/SIZE]

[SIZE=12pt]Those lights don’t actually give you much useful information about the battery and the state of charge and if the batteries are getting to the end of their usable life. There is no way to tell if the particular battery in your camper is fully charged, close to fully charged, at 40 % charge at 30% charge or whatever. [/SIZE]

[SIZE=12pt]A person may or may not care and just let the charging and discharging do what it will do, but some of us want to maximize the life of our batteries as well as know when there is something wrong (diagnose issues) or when they are getting near the end of their usable life. That is why we instrument our batteries with battery monitors. [/SIZE]

[SIZE=12pt]With a good battery monitor, one that can be programmed for the max voltage for your battery, you can see the state of charge of the battery (volts and percent capacity) and you can use it, among other things, to determine what various electrical items draw when in use, which is useful for some of us to know. [/SIZE]

[SIZE=12pt]So this is one of those pick your poison kinds of decisions. Some of us want and use the information and others may not care one way or another.[/SIZE]

[SIZE=12pt]For a real good tutorial on lead acid batteries here is a link:[/SIZE]


[SIZE=12pt]See also:[/SIZE]




[SIZE=12pt]I like the Victron SmartSolar products for the quality/price as well as the bluetooth connectivity to the Victron app on my iphone that allows me to check on what is going on when I am within about 50 feet of the camper. However, [/SIZE]some folks like other products so you may want to shop around and compare.

Here are Some Simple Guidelines for Charging Lead Acid Batteries
  • [SIZE=12pt]Charge in a well-ventilated area. Hydrogen gas generated during charging is explosive. (See BU-703: Health Concerns with Batteries[/SIZE])
  • [SIZE=12pt]Choose the appropriate charge program for flooded, gel and AGM batteries. Check manufacturer’s specifications on recommended voltage thresholds.[/SIZE]
  • [SIZE=12pt]Recharge lead acid batteries after each use to prevent sulfation[/SIZE]. Do not store on low charge.
  • [SIZE=12pt]The plates of flooded batteries must always be fully submerged in electrolyte. Fill the battery with distilled or de-ionized water to cover the plates if low. Never add electrolyte.[/SIZE]
  • [SIZE=12pt]Fill water level to designated level after [/SIZE]charging. Overfilling when the battery is on low charge can cause acid spillage during charging.
  • [SIZE=12pt]The formation of gas bubbles in a flooded lead acid indicates that the battery is reaching full state-of-charge. (Hydrogen appears on negative plate and oxygen on positive plate).[/SIZE]
  • [SIZE=12pt]Lower the float charge voltage if the ambient temperature is higher than 29°C (85°F).[/SIZE]
  • [SIZE=12pt]Do not allow a lead acid to freeze. An empty battery freezes sooner than one that is fully charged. Never charge a frozen battery.[/SIZE]
  • [SIZE=12pt]Avoid charging at temperatures above 49°C (120°F).[/SIZE]
ckent323 said:
[SIZE=12pt]The FWC water and battery panel shows three lights to indicate battery condition and one light to indicate charge state.[/SIZE]

[SIZE=12pt]Charge (green on, not green off) [/SIZE]
So does the monitor panel that shows water tank level and battery level mean this:

C light: on if charging
G light: Good (any idea what level of charge this is?)
F light: Fair (again, any idea? Should we not use the battery?)
L light: Low (don't use the battery?)
A couple of years ago that panel in a 2016 Fleet was identified as a KIB Electronics M1106.

I called KIB at the time and the parts guy told me the voltages are:

Charge = 12.5 and up
Good = 11.7 to 12.5 v
Fair = 11.2 to 11.7v
Low = under 11.2v

I don't have one so can't verify that info.

Please note, however, that this thread says the voltages for M-series panels are:

Charge 12.7V+
Good 12.1V+
Fair 11.6V+
Low 6V+

So I called again today--- just a few minutes ago--- and talked to 'Walt' in Tech Support.

He told me the levels are:

C (Charge) is 12.5 to 13v
G (Good) is 11.7 to 12.5v
F (Fair) is 11.2 to 11.7v
L (Low) is 10.0 to 11.2v

He also said voltages are within 5% and please remember that these are voltages at the panel not at the battery (meaning you have losses between the battery and panel to account for)

I also asked if these were specifically for the M1106 or M-Series or what. He said those are M-Series voltages.

Nice guy. When I thanked him for the info he said to call anytime, that's what they're there for.

Note that I'm not sure the M1106 is still used in current FWC models.
Those are terrible numbers to have lights for. Most AGM batteries are at 50% at 12.2V, which I treat as "dead" - time to recharge NOW. I know rando will say you can go lower, and it is true, at the cost of battery longevity.
Yea those panels are black magic numbers that are reference to give you notice. Only if you have those equivalent numbers pasted next to the light how can one remember. Never used those panels and thinking to take mine out, just need to rewire a switch for the water pump. Even the water tank level I get a better reality by just looking at the tank for its level ( I can see my tank easily).
On our recent trip to Yellowstone our batteries seemed to be drained daily despite having solar and driving each day. Our 12v fridge was on but only pulls about 12 ah a day. We only ran the heater first thing in the morning, not overnight. All lights are LED. We have 150 ah and should not have had a problem. This has me thinking... If I put new batteries in a flashlight and turn it on it is nice and bright. An hour later it is still nice and bright. But if I have old batteries in a flashlight and turn it on it is nice and bright but within a couple of minutes it has faded.

Do 12v AGM batteries work in a similar manner? I had the batteries tested today and they are both showing a full charge. But they are the original ones from FWC in our 4 and 1/2 year old camper. So does everything look fine when we first start using them but they run down in a much shorter period than newer batteries would?
Sounds plausible, but you also need to think over those 4 1/2 years how the batteries were treated and were they fully charged properly. Charged up to full after every trip, meaning a proper bulk, adsorb and then on float voltage with the proper voltage levels?

While on this last trip you said "...our batteries seemed to be drained daily despite having solar and driving each day."...

You do own a Toyota and might not expect to get the alternator to give you a full proper charge, might just be the way it is. What version of battery separator do you have?

But you did have the system for 4 1/2 years and I don't remember you complaining before. Could just be that time to replace. Here lately getting batteries up to fully charged during or after the trip? Do you have a battery monitor I can't remember.

Going for fall colors this year?
they do deteriorate over time, even just sitting around on a trickle charger. 3% a year or so. 5 years old means 15% less AH capacity than when new.

That doesn't explain why your system wasn't getting back up to snuff by the end of the day though. Have you been following Hoyden's adventures with charging/batteries? Lots of good info there.
I suspect it is because the fridge is still running while the charging is happening. So during times of driving and solar, I may gain some charge. During times of solar but not driving, I stay even at best. and overnight the battery gets drained more. So a net drop over a few days finally gets me to where I am.

I have followed Hoyden laments and considered the replies here. I did a test yesterday - batteries were at 13 v. Turned on the fridge at 3 pm. This morning the batteries were at 12.2. Not dead but not great. We have two weekend trips coming up that should not be a problem. But we will replace the batteries before our next longer trip. And Patrick, yes, upgraded wiring and alternator would likely help also, but not so easily done on a finished package. We are considering an additional remote solar panel that could be plugged in as an easier charging boost.
True deep cycle batteries? What charge controller? Does your battery monitor show S.O.C:? (state of charge).
Just want to bring up and option that I'm pursuing that I don't see discussed in the forums (apologies if I missed it).
I'm going with a packaged Li-ion system -- Goal Zero or Inergy Kodiak.

There are 3 disclosures that really make this work for me:

1) I can get a very good discount on Goal Zero products -- as in cheaper than it would cost me to cobble something together.
2) I am starting from scratch so I am not retrofitting or changing technologies.
3) I am an energy sipper. A 1 KWhr supplemented with solar and onboard DC charging will allow me to meet all my expected energy needs and keep the discharge to 50% or less for optimal life and cell health.

Both Kodiak and the GZ Li 1000 are NMC batteries that come with a PWM controllers. The GZ has a MPPT available that I consider necessary. They are also coming out with a DC vehicle charger in a couple weeks (Kodiak already has that, I think) and a better 300W wall charger (absolutely necessary, IMO). Kodiak has a better charging profile.

Let's see... other differences
The larger GZ systems have WIFI but that makes little sense to me for camping. However, they are coming out with bluetooth capability, so that's nice.

A big plus for Kodiak is the claimed wt. - 20 lb. The GZ is 40 lb. which is ridiculously heavy for Li-ion batteries. The difference is all packaging. Regardless of the exact NMC technologies used, there is not that big of a difference in the specific energies to account for a 100% wt. penalty. I'll be bringing the battery indoors to store and charge on cold days (even while on the road, maybe), so that could be an issue as I age and weaken. Kodiak also has more outlets and battery chaining with Pb acid (ugh), if you want to expand capacity on the cheap.

Even though there is a huge marketing discrepancy w/ regard to battery life, they are about the same (they just use a different DOD benchmark).

Anybody use either of these - or a similar Li-ion/BMS package? It seems LiFePO4 batteries are favored in the forum discussions but I think that is just b/c of one popular supplier.

Also, do the campers usually come with 12G wiring. I can't imagine ever needing more ampacity than 12G can handle (I'll have to check the NEC but I think it's like 20A continuous). However, I know some of you have pretty big solar systems.

The reason that LiFePO4 batteries are favored is because of their backwards compatibility with 12v lead acid systems and safety. The Goal zero (and similar) NMC batteries are actually 11.1V batteries, which can cause issues when trying to interface with a vehicle and accessories. You can't charge NMC batteries from an alternator (directly) and you can have issues running 12v appliances with low voltgae cut off's etc. LiFePO4 has a 12.8V nominal voltage (13.2V when fully charged) which plays nicely with alternators and other systems that were designed to work with lead acid vehicle batteries.

LiFePO4 are also more tolerant to poor handling the NMC.

Unless there is some other motivating factor (in the case is seems like a steep discount), they are likely not the way to go for a vehicle installation.
Thanks Rando. Just got my truck yesterday, so my attention is a little scattered. Forgot about the NMC low voltage. The GZ spec gives a nominal voltage of 10.95. I assume that would wreak havoc with a Dometic fridge. Can you adjust the voltage cutoff on the fridge and, if so, how much does it help? What other appliances would be problematic?

I just chatted online w/ GZ and the said they are coming out with a voltage regulator to regulate the battery DC output ports. That's their solution and it should be out "by the end of the year".

I'm not sure this is a show-stopper b/c I could just run the fridge off the inverter (2 outlets). The efficiency penalty is not a factor b/c it's small and I am over-specing my battery capacity.

On the other hand, I see my big discount eroding fast with these add ons -- voltage regulator, MPPT controller, forthcoming DC charger (for alternator charging). However, I do like the portability (although I could probably package a home brew system for easy camper removal).

The LiFePO4 compatibility benefit might go away with the new voltage regulator. I don't know. Would like to hear your thoughts. Also, you mention that "LiFePO4 are also more tolerant to poor handling...". Do you mean temperature limits for charging/discharging or are you talking about the robustness of the cells with regard to vibrations and stuff.

Thanks for the feedback. I welcome any other advice.

Obviously just my opinion here - but this seems like a lot of kludges to get a a round peg into a square hole.

You need a DC-DC converter to charge the battery off the alternator (which may or may not be available "soon"). This is both an extra device and extra expense, but also limits the charging current to whatever the DC-DC converter is spec'd for. With a direct connection the the alternator (either lead acid or LiFePO4) the only limit to charge is the size of you alternator and wires.

You will need to convert the DC output to AC to run the fridge (figure 10 - 20% efficiency loss right there) then the fridge will have to internally convert that AC back to DC to run the compressor (maybe another 10 - 20% efficiency loss). Also the inverter has to run all the time, regardless if the fridge compressor is running or not, so you also have the inverter quiescent current being drawn 24/7.

As to the robustness issue - the LiFePO4 chemistry is inherently more tolerant of abuse (over charging, over discharge, mechanical damage) than the NMC chemistry without posing a fire risk. Not that the NMC battery will represent a fire risk inside the GZ, but you are relying on the protection circuits to avoid this.

So yeah, you can probably get it all to work, but at this point is the extra complexity and loss of efficiency really worth what ever savings you may have?

In the context of this being the 'ultimate battery thread', I think it is important to point out that for most people this is not a great battery solution.
I added some links to recent posts on batteries and battery chargers as well as to East Penn (Deka) company battery info - on page 1 post #2
I looked through all the faq's can't find my answer.

I have a interstate deep cycle, topped off yesterday @ 15.75dcv
Using a Sears 1.5 amp charger
Battery at rest of rest+/- 13.6

I have a Napa DP coach battery that I keep topped off using the inverter in the camper and it tops at 13.7 dcv, at rest the DP is +/- 12.5 dcv. Why the 2dcv difference in the floating voltage?
Voltage of about 13.5-13.7 is the battery charger float voltage rather than the battery resting voltage. The charger will keep the voltage there to ensure the battery remains fully charged in storage.

Your voltage of 12.5 volts is the battery resting voltage. If fully charged on a newish AGM battery, expect about 12.7-12.9 volts. That more closely represents the battery resting state of charge. To me 12.5 represents an older battery and possibly a Flooded Lead Acid (FLA) battery. I assume the DP means Dual Purpose but it could be either AGM or FLA.

If you see 13v plus, the battery is being charged or has just come off charge. That is why you need to wait several hours after charging stops to see what its full charge resting voltage is.

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