Battery Health & Charging Options

SirDrake · 07-25-2016, 03:14 PM

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 · 07-25-2016, 03:54 PM

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 · 07-25-2016, 05:11 PM

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

BrucePerens · 07-25-2016, 06:26 PM

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** · 08-01-2016, 12:25 PM

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 · 08-01-2016, 02:59 PM

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.

**Bill** · 09-19-2022, 12:45 PM

Quote:

I have a battery tender Jr installed with the plug accessable from outside the battery box. When parked at home I just connect directly to the plug and let it do its thing. Keep the tender running all the time while at home.

I also have a Battery Tender Jr hanging on my garage wall, for when my 2720QB is parked at home. In my case, I leave it connected full-time into the Bargman connector, where the 12-volt line is (of course) connected directly to the battery. Easy to connect or disconnect, no need to remember to connect or disconnect, no need to open the TM. I don't like plugging the TM's power cord into a wall socket. The TM's converter is not well-controlled enough for long-term maintenance.

Bill