Battery Health & Charging Options

[SirDrake]

I'm looking for some advice on Battery Health and Charging.
I have read through numerous posts on this forum concerning the TM battery and charging and I have a couple ideas.
I guess what I am primarily looking for is the best way of charging the battery in my TM and keeping it in good health.
We don't do any boon docking, at least not yet, so we use the battery primarily for the refrigerator while traveling.
Most of our trips take 6 hours or less on the road, so running the fridge on battery is feasible.
Also, we camp at sites with full hookups and I like to keep the TM plugged into shore power when parked at home.
I usually pull the battery for winter and store it in the garage.

The TM came with a group 24 marine battery, which I upgraded to a Group 27 a few years ago.
I learned the hard way that the Converter/Charger in the TM, if left plugged into shore power, will cook the battery; I didn't realize that the on board charger was not intelligent.
Needless to say the Group 27 Lead/Acid battery is dead. So I decided to buy an Optima AGM Marine battery to replace the old lead/acid unit (no more fumes, liquid, etc).
I just bought a blue top Optima D34M and now I am trying to decide the best way to maintain it.
https://www.optimabatteries.com/en-u...-starting/d34m
I read through many, many threads concerning the TM battery. I like the idea of either upgrading the charger in the TM or adding a third party charger to the battery compartment.
The DC Charger that ShrimpBurrito installed sounds interesting too and I believe it was Bill (the moderator) who has a Guest charger in his battery compartment.

Here are my thoughts.
Option1:
I could upgrade the Parallax 7300 on board Converter with the new Ultra III kit.
Found a site that sells 45 and 55 amp kits ranging $198-$213.
http://www.bestconverter.com/Magnete...-Kit_c_64.html
This kit upgrades the charging unit to 3-stage charging capabilities.
Not sure if I need 45 or 55amp though, and would this work well with my Optima battery?
Can I leave the TM plugged into shore power and not toast the battery with this upgrade?
If I go this route, is there a monitoring device I can install to show the stats on the battery?
Anyone have any experience with this kit or similar on board converter/charger?

Option 2:
My other thought was to skip the on board upgrade and install a separate charger in the battery compartment.
Optima sells a portable performance charger, the Digital 400 for $110.
It is designed to work best with the Optima batteries, obviously, and seems to get 5 star reviews online.
https://www.optimabatteries.com/en-us/battery-charger
I was thinking that I could mount it in the battery compartment and run an extension cord to the power outlet behind the refrigerator to power it (when plugged into shore power).
In addition, I was going to install a Three-way Battery Switch in the compartment as well, so I could switch between:
1. Shore Power/TM Charger (for traveling purposes)
2. The Optima Charger (for when I have shore power)
3. Off (battery disconnect)
https://www.amazon.com/dp/B001V7TL10...84KLCX38&psc=1

If anyone has any input, thoughts, etc I would greatly appreciate it.
Thanks!

~ John

[tentcamper]

For years I have had very good luck with batteries.

I think the biggest issue is how you store the battery.

I have always stored my campers with the battery switched off from the converter or the battery disconnected. I have used two different approachs throughout the years. Both seem to work great and I have gotten battery life of 6 to 8 years.
- 1st: battery tender left on all the time.
- 2nd: battery storage method, let the battery discharge over time, but not to less then 12.4v and recharge for 24 hours with stand alone charger. Do a 24 hour charge to top off the battery before trips.

Most camper don't have a great charger. If I'm camping with shore power. I switch off the battery from the converter after 24 hours of charging at the camp site, and re-start it the night before we are heading out to top off the battery. There is no reason to keep charging a fully charged battery the entire time you are at a camp site with a not so good charger. But even if you leave it on for the 2-3 weeks of camping each year its no big deal. It's the 48 to 50 weeks of improper storage that does the most harm

[scrubjaysnest]

When we had ours carried a smart charger for those times on shore power.

[BrucePerens]

About the first thing I installed after I got the trailer was a battery cut-off switch. It's going to be very easy to run any battery flat without one. I ended up running a little bypass wire to keep the radio clock and memory set, but all other parasitic loads go off.

A charger, even a modern super-spiffy one, doesn't have to be as well-regulated as a modern converter and might put some hash on your 12V lines when you are on shore power. If you still have the original converter, it's not regulated and as you found, overcharges.

I was less than impressed with the Boondocker converter, the unit they ship is not the one advertised on their web site. But there are a number of good converters at good prices that fit in that space.

What you miss with three stage charging is the occasional equalization charge. You really should not have an equalization charge more than once every month or two, because it is intentional overcharging. Any small 4-stage charger should provide that, you don't really need a permanent device in the RV to do it.

[Bill]

John -

I have had two TMs over 15 years, and like you, I have had bad luck with batteries. In the process, I have learned a lot, I seem to be doing a bit better with batteries now. Perhaps some of it would be of help to you. What follows is my experience only, so take it for what it is worth.

The first thing I learned is that there is a mental hurdle. You need to distinguish between battery CHARGING and battery MAINTAINING. Charging means that you have pulled some energy out of the battery and need to replace it. Generally, you would like to replace it quickly and correctly. "Correctly" is defined by the chemical nature of batteries, and results in the stages of charging called bulk, absorption, and float. The problem is that the details of these stages are often defined by the charger manufacturer. No two "smart" chargers are the same.

Maintaining means that you start with a fully charged (or nearly fully charged) battery, one that you won't be using for a while, and you need to maintain its health during the down time.

These two operations are very different, and despite glowing words in the advertising, I am not aware of a unit that is good at both. Why? "Charging" is basically a brute force operation, though smart chargers handle it better than earlier units like the 6300 and 7300. But almost by definition, charging is expected to happen quickly, while "maintaining" is a finesse operation. It takes place over a long time.

I went through the 6300/7300 era, and bought a new battery every year. I upgraded to a Progressive Dynamics charger, and things improved. I could get 2 years out of a battery. I started disconnecting the PD when there was going to be a long down time, and connecting the Guest trolling-motor charger instead. Things improved a bit more.

My current approach, and one that seems to be working, is to charge the battery using the PD, and then maintain the battery using a small Battery Tenda. This was a hard pill for me to swallow, since I had spent years warning people against cheap trickle chargers. But someone gave me a B.T., and I finally discovered that it is not a cheap trickle charger. I'm an EE, so I figured out why and how it works, and I have been using it with good results for a few years now. It is not magic, and it will not charge your battery. But after several 3-to-6 month periods of down time using the B.T., my batteries appear to be unchanged, and that is good. No water loss, no increase or decrease in terminal voltage, no scum on the surface of the electrolyte, no corrosion on the posts, and so forth. Those are signs of improper maintenance, and I saw them all with earlier approaches. I'm happy that I haven't seen them lately.

As I said, this is my experience, and you should take it for what it is worth. And I am not connected with B.T. in any way.

Bill

[RottieMom]

And, if you want, you can wire up a Bargman TV connector to your Battery Tender and then just plug in your TM Bargman to it when in storage. Bill taught me how to do this, and it just tickles me to be able to plug in my TM Bargman to this to maintain my battery.

[inghamm]

I followed Bill's advice and got a Battery Tender for the long periods of storage. Happy with that. Someone else can probably speak to the whether your option 1 or option 2 would be as good for float charging, however, if you are taking the battery out and putting it in the garage, Option 1 won't work for that.

For recharging at the campsite with shore power or at home, I've been using this:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

scrujaynest posted on one of my topics when I was having battery problems about having enough power for charging according to the manufacture's website - too slow was bad, so I looked up on the manufacture's website and found the charger with the correct amps. (That did apply to GC-2's)

"As a general rule GC -2s prefer a minimum of 10%, also called c/10 where c = battery AH rating. You can go as low as 5% but won't get as long a life expectancy. For a typical GC-2, call it 225AH C/10 is 22.5 amps! So something that will do a higher bulk charge rate may be in order."

So I went with that advice and got the appropriate smart charger. So far happy with that.

Your battery specs say maximum 10amps, so my charger would be too much, but you might consider the 7.2 amp version:
https://www.amazon.com/NOCO-G7200-Ul...o+genius+g7200

I also use a battery cut-off switch. Pull into camp and after I connect the shore power I disconnect the battery and then charge it with the NOCO, so I rarely have the converter charging the battery.

FYI at the bottom of the full specs for the 34M it says:
"Model: 34M
These batteries are designed for engine starting applications. They are not recommended or warranted for use in deep cycle applications." I wonder if that was a mistake or on purpose.

[ShrimpBurrito]

My experience has been a bit different.

When we bought our TM in 2007, I installed 2 Trojan T-105s. That was 9 years ago. After testing both specific gravity just last week, levels were consistent across all 6 cells, with the possible exception of one being slightly low. Between those readings and several open circuit voltage measurements taken 24 and 48 hours after any charging or discharging, I determined that my batteries had a capacity of roughly half what they were when new. So just last week, I replaced them with 2 Trojan T-125s, which are the exact same size, but with slightly higher capacity (240 Ah) and weighing about 4 lbs more each. $325 including tax and delivery to my front door via the dealer's truck.

We nearly exclusively dry camp, so our TM is plugged into shore power for maybe 6 weeks/year. A few days prior to each trip, and then maybe two 2-week periods. Other than that, whenever the TM is at home, I have it on a battery tender type charger. It's made by a company called PulseTech, which claims to have some sort of special pulsing technology that desulfates the battery in some unique way. Who knows if it works as they claim, or if it's different than other desulfating chargers, but with a lifespan like the above, who cares?

Maximum charge current is 2 amps. I know that's far below the recommended charge rate, but again, my batteries lasted 9 years before losing half their capacity. And the charger fully recharges my batteries. It takes awhile (a few days), but for me, that's plenty of time before the next trip.

Dave

[SirDrake]

First I would like to thank all of you who replied.

Inghamm noted the following in his post:

FYI at the bottom of the full specs for the 34M it says:
"Model: 34M
These batteries are designed for engine starting applications. They are not recommended or warranted for use in deep cycle applications." I wonder if that was a mistake or on purpose.

Just FYI, I purchased the D34M model battery. This is the Deep Cycle version.

I followed Tentcampers advise on our last trip (first trip with the new battery).
I connected the TM to shore power 24 hours before trip and also started the fridge. Then switched the fridge to battery the morning of the trip.
We were on the road for about 5.5 hours and the battery still had a charge when we arrived at the campsite. I didn't measure it but it was strong enough to power the tongue jack.
Something I haven't experienced in a few years!
I pulled the fuse on the battery after a day or so so that the onboard charger would not continuously charge the battery the whole week we were camping.
Then I put the fuse back in the day before we left so that the battery would get some juice. We made the 5.5 hour trip back home and the battery held up.

After reading all of your advice and through numerous other posts, I think I am going to install a battery disconnect switch and invest in the Optima Charger.
This way I can disconnect the battery from the TM and connect the Optima charger to charge and maintain the battery.
I figure that Optima makes the charger to maintain their batteries, it should be the best option. And they get excellent reviews.
I'll let you know how I make out.

On another note, I think I have had it with Gas Absorption Refrigerators, aka the Norcold N300. By looking through the forum I see that others have had similar issues.
It has been a very hot summer here in the northeast with temps into the 90s and high humidity, so I understand why it has been struggling.
I have a thermometer in the fridge which I monitor. Most times that thermometer was in the 50's and as low as 60's one time. I kept the fridge setting on 5, ran the fan continuously, and even removed the outside compartment covers to help with air flow.
In the past, I would have to keep lowering the setting because of food freezing up!
Funny though, even with the temps down to 50-60F stuff was still cool/cold to the touch and the ice cream in the freezer was still frozen!
We also use a small electric cooler plugged into the DC outlet in the TM to store drinks. I moved some items like milk and halfnhalf into the electric cooler at one point because I was getting worried.
In any case, I will probably be able to get through the rest of the camping season with the Norcold, but I think come spring I see a Dometic compressor fridge getting installed.
Anyone interested in a Norcold boat anchor?

[Lesherp]

I bought two 6 V batteries when we got the TM about 6 years ago. We camp without shore power most of the time. Have solar and am charged to 100% by dusk 99% of the time. I store the TM in my garage with batteries in it. I am not sure how I decided to try this but I plug in once a month for a few of days. So far this has worked for me. Have somewhere around 200 camping days in the TM.