Confusing battery information?

[ThePair]

Hello all!

I am a prospective TM owner (likely to purchase in the spring, so I don't have to worry about winter storage this year, but that's a whole other issue!). These boards are a big part of my purchase decision--the TM itself is a marvel of engineering, but no less important to me is the strong, cooperative and supportive community that is seen here.

I've been trying to do as much research as possible pre-purchase, and I have a battery question that confuses me. Everything that I've read indicates that a deep cycle battery is best used down to a maximum of 50% before recharging, in order to prevent damage and maximize the life of the battery. This would be ~ 11.9-12 V, according to "The 12 Volt Side of Life" and other sites.

However (here's the confusing part) I came across this: http://www.1st-optima-batteries.com/...e_battery.html which outright talks about bringing the charge down to 10.5 V. On other pages, they indicate that this is the voltage where a recharge is needed, and their AH ratings are based on this as well. But, according to other sites' info, this would be a complete 0% discharge, and would pretty much ruin a lead-acid battery. So, why is Optima suggesting that this is normal, routine use of their batteries? Is there something special about their batteries, or is this my misunderstanding of the information?

In addition, it seems that their battery ratings are ~1/2 of other manufacturers. At first I assumed that they were just cutting their number in 1/2 for the 50% discharge as noted above, but now I'm not so sure.

It's not that I can't understand this stuff (I do have a Chem degree, and a LOT of physics background), but this is simply contradictory information, and I was wondering if anyone could make sense of it all.

Of note, I'm looking at getting a new 2720SL (DW, twins now 2, and a Springer Spaniel.) TV is a Sienna, so I'm not sure anything larger makes sense, plus the extra floor space is desirable for the doggie. Winter storage will likely not be at my home, so a no-maintenance battery solution is very, very high on my priority list--I will not be able to check water levels or keep the thing plugged in all winter, most likely. I am also considering the two-battery approach, and AGM should lead to an easier installation in the 2720SL, as I understand it (no need for vent worries or access issues.)

I have about a billion other questions, but I figured I'd start here!

Thanks!

Marc

[Wavery]

Originally Posted by ThePair

Hello all!

I am a prospective TM owner (likely to purchase in the spring, so I don't have to worry about winter storage this year, but that's a whole other issue!). These boards are a big part of my purchase decision--the TM itself is a marvel of engineering, but no less important to me is the strong, cooperative and supportive community that is seen here.

I've been trying to do as much research as possible pre-purchase, and I have a battery question that confuses me. Everything that I've read indicates that a deep cycle battery is best used down to a maximum of 50% before recharging, in order to prevent damage and maximize the life of the battery. This would be ~ 11.9-12 V, according to "The 12 Volt Side of Life" and other sites.

However (here's the confusing part) I came across this: http://www.1st-optima-batteries.com/...e_battery.html which outright talks about bringing the charge down to 10.5 V. On other pages, they indicate that this is the voltage where a recharge is needed, and their AH ratings are based on this as well. But, according to other sites' info, this would be a complete 0% discharge, and would pretty much ruin a lead-acid battery. So, why is Optima suggesting that this is normal, routine use of their batteries? Is there something special about their batteries, or is this my misunderstanding of the information?

In addition, it seems that their battery ratings are ~1/2 of other manufacturers. At first I assumed that they were just cutting their number in 1/2 for the 50% discharge as noted above, but now I'm not so sure.

It's not that I can't understand this stuff (I do have a Chem degree, and a LOT of physics background), but this is simply contradictory information, and I was wondering if anyone could make sense of it all.

Of note, I'm looking at getting a new 2720SL (DW, twins now 2, and a Springer Spaniel.) TV is a Sienna, so I'm not sure anything larger makes sense, plus the extra floor space is desirable for the doggie. Winter storage will likely not be at my home, so a no-maintenance battery solution is very, very high on my priority list--I will not be able to check water levels or keep the thing plugged in all winter, most likely. I am also considering the two-battery approach, and AGM should lead to an easier installation in the 2720SL, as I understand it (no need for vent worries or access issues.)

I have about a billion other questions, but I figured I'd start here!

Thanks!

Marc

Basically, the answer lies in the stability of the electrolytes in the AGM battery..

You can completely discharge the AGM and maintain stability. When one allows the specific gravity get too low in a liquid battery, it destabilizes the electrolytes and it may not recover. This is not an issue in the AGM because of the unique blanket of gel electrolytes that are literally wrapped in thin blanket around the core then the blanket is wound in several layers.

The AGM also excepts a charge at a much faster rate (lower temperature) and it is less necessary to fully charge the battery. As you stated, there is no worry of losing electrolytes due to evaporation.

The other benefits are that the AGM battery can be mounted anywhere in any position (sideways, upside-down etc). The down side is they are expensive to purchase but when you figure the lower "lack-of-maintenance" failure costs, charging time required (if using a generator) and flexibility, they may actually be a more cost effective choice, over time.

If you are not storing this at home and storing it for several months as is implied in your post, I suggest removing the battery ( no matter what type) and storing it at home preferably on a battery tender. This will also prevent curious children from turning on the outside lights and draining the battery.

[ThePair]

So...AGM batteries don't suffer from deep discharge damage, meaning I wouldn't need to fret over the 40-50% guidelines that "flood" type batteries do? I'm sold! One less thing to have to worry about.

As to removing the battery, I appreciate what you're saying, and a sealed AGM would certainly be easier to manage than an acid-spewing box of toddler death. I still don't know what I'm going to do about storage, but that would be OT here. I'll make another post someplace else about it.

But...are there any users who leave their batteries untended all winter, outside (in the TM, naturally, but otherwise outside)? That AGM website seems to imply that the AGM batteries will withstand the cold just fine, with minimal loss of charge...and if they won't be damaged by a deep discharge, what would it matter? A cut-off switch would mean no worries about someone turning on the lights...just wondering. I have lots to still think about...which is so frustrating sometimes, 'cos I'd just like to get it and go!

Marc

I leave my wet cell batteries untended all winter. For me, winter means November through January. I just make sure they are fully charged.

I don't get severe cold. A normal overnight low is probably about 40, and the TM is in the garage. I have had below freezing temps on one occasion for a few days around 1991.

I have an external battery disconnect switch that I added. So there is no drain on the batteries in storage other than internal leakage. I don't think there is all that much leakage in three months of storage.

[ThePair]

Chicago area = hard freeze for me.

Still trying to figure out if the TM will fit in the small single part of the garage I have (3 car total, 2+1). Parking it in the 2-car portion isn't a real option. I think I'm going to have a width issue with the single (8 feet wide at the opening, but I need to remeasure it from the outside to be sure).

[wbmiller3]

I wouldn't want to try putting ours in the single door part of the garage. By my measurements it's theoretically possible but with pretty much no margin for error.

Originally Posted by ThePair

But...are there any users who leave their batteries untended all winter, outside (in the TM, naturally, but otherwise outside)? That AGM website seems to imply that the AGM batteries will withstand the cold just fine, with minimal loss of charge...and if they won't be damaged by a deep discharge, what would it matter? A cut-off switch would mean no worries about someone turning on the lights...just wondering. I have lots to still think about...which is so frustrating sometimes, 'cos I'd just like to get it and go!

Marc

Just throwing another idea out there: How about fulling charging the battery before storage, and then just removing the fuse. The battery should stay charged without any parasitic loads pulling it down, and a charged battery shouldn't freeze even in a Chicago winter.

Chap

[ThePair]

Originally Posted by wbmiller3

I wouldn't want to try putting ours in the single door part of the garage. By my measurements it's theoretically possible but with pretty much no margin for error.

That's my concern, in addition to the bend in the driveway on that side (goes from 3-car at the house to 2-car at the curb, most of the bend is on the single side.)

I was thinking one of those powered dollys might work, but for the fact that it'd need to go on the grass of the front lawn for a bit to get the trailer aligned straight into the garage.

I take it the 8 foot width (7 foot 7 inch + 5 for the awning) is more or less inclusive of everything hanging off? Meaning, is there a point that is truly 8 feet wide, side-to-side, or is it a 'wiggle' situation?

I should probably go with my plan B, which is to ask a nearby friend with lots of land to park it at her place. She'd likely say yes, but I hate to impose. I'd look into a cover under that circumstance, though. The only other option is to rent parking from a storage place, but that's $80-$120/mo, which will add up quickly.

Marc

Originally Posted by wbmiller3

I wouldn't want to try putting ours in the single door part of the garage. By my measurements it's theoretically possible but with pretty much no margin for error.

We sometimes put our Trailmanor in a single door garage bay, but we have close to a 9' opening.......and it was still close with not much margin of error. In backing in, and even pulling out, the problem was not with guiding the back part of the Trailmanor in, it was the part in front of the TM wheels. Because of the distance between the rear TV wheels and the trailer coupler, when you are trying to move the trailer 1 way, you are actually moving the front part the exact opposite....even though the back is going where you want.......if that make sense. I got that puppy catty-wompass in the garage a couple of times, and had to do a lot finagling to get it back out of the garage.

Chap