Battery power

I know this likely has been covered previously; but can't seem to locate the pertinent postings; so please bear with me as I post this.

Just purchased our 98 2720sl and looking forward to many a trip in it. In our part of the country, Nevada, 87% of the state is federal land (BLM, forests, etc) ... so naturally, we boondock a lot. Plus, our neighbor states, Utah-Calif-Idaho-Ariz-etc. also have lots of federal/forests/parks/etc available as well.

I have gleaned from reading a few postings I came across that one can extend the boondocking battery power aspect by adding additional batteries. Even see some discussion on even using 6v types; which is strange ... at least to me.

Would like to know more about the subject of adding additional battery power please.

Thanks
doon

[Denny_A]

Originally Posted by doonboggle

I know this likely has been covered previously; but can't seem to locate the pertinent postings; so please bear with me as I post this.

Just purchased our 98 2720sl and looking forward to many a trip in it. In our part of the country, Nevada, 87% of the state is federal land (BLM, forests, etc) ... so naturally, we boondock a lot. Plus, our neighbor states, Utah-Calif-Idaho-Ariz-etc. also have lots of federal/forests/parks/etc available as well.

I have gleaned from reading a few postings I came across that one can extend the boondocking battery power aspect by adding additional batteries. Even see some discussion on even using 6v types; which is strange ... at least to me.

Would like to know more about the subject of adding additional battery power please.

Thanks
doon

Here's a link to a long Solar Panel thread. Others will respond to the extra battery power question:

http://www.trailmanorowners.com/foru...ht=solar+panel

Denny_A

[Bill]

As you would expect, adding batteries will extend your total battery capacity, and therefore your camping time. If one battery lasts 3 days for you, then two identical batteries would last 6 days.

But there is a limit to how far you can go with this approach. Specifically, batteries are heavy, and the 2720SL is already quite close to its load limit. In addition, the batteries in a 2720SL are mounted in the back, and adding more weight in the back reduces the tongue weight, which in turn reduces the inherent towing stability (lack of sway). So although you can put two batteries in your 2720SL, and they can be a bit bigger than the OEM battery, I wouldn't install any more than two.

A simple upgrade is to replace the factory 12-volt Group 24 battery with a Group 27 battery (the term "Group" simply describes the physical size of the battery). It will drop right into the same spot. The OEM battery is an Interstate SRM-24 - Interstate also makes a somewhat larger SRM-27B. See http://www.ibsa.com/www_2001/content...uct_marine.asp

If you are willing to install a pair of batteries, a first approach might be to replace the factory 12-volt battery with TWO Group 27 batteries wired in parallel (+ to + and - to -).

An even better upgrade, and only slightly more expensive, is to replace the original 12-volt battery with a PAIR of 6-volt golf-cart-type batteries. Trojan T-105's are commonly used for this application, and the pair will give you perhaps 3 times the capacity of the OEM battery. The T-105's are taller, which is a problem with some TM models, but should be OK with the 2720SL. Six-volt batteries are wired in series to get 12 volts.

If you need to go even farther than this, then you need some way to recharge the batteries while you camp. You can use a generator (often frowned upon in fire-prone areas, or if you will have neighbors where you camp). In the west and southwest, an ideal solution is solar power. Denny has pointed you at a good thread, and several TM'ers have purchased solar systems for their rigs. Read the thread, plus several of the others right around it, and come back to us with additional questions.

As a final note, if you install multiple batteries, they should be of the same type/size, and approximately the same age. Don't mix old and new batteries, or big and small batteries, or (worst of all) conventional cranking batteries and deep cycle batteries.

Bill

[mjlaupp]

Originally Posted by doonboggle

Would like to know more about the subject of adding additional battery power please.

Here is a link on how to install 2 6v batteries in a 2720SL
http://www.trailmanorowners.com/foru...ead.php?t=1696

MJL

[B_and_D]

Earlier this summer we installed two Trojan T-105's (6v batteries). They were alot better than the group 24 battery that came with the TM, but they were starting to wind down after 3 nights of very frugal use (no heater, sparing lights at night). They were still working fine but dropping towards the 12.2V point per my voltage meter and I didn't want them to go much lower without recharging. We brought along the other 12v battery, and that only lasted one night before it dropped down.

The next step for us will be (probably) a solar panel to charge up with. One of those small Honda generators wouldn't be bad, either. One of the campers next to us last trip had one, and it was much quieter than most.

For the 2005 TM 2720 with swing-away hitch, the battery (only one) is mounted behind the propane tanks. The available space, without modifying the welded in battery rack, is H=10.75 W=8.375 L=35.

Without hiring a welder to reconstruct the tray the choices seem to be:

3 SRM-24 (the TM came with 1, 3x11<35)
2 SRM-27B (too long for 3, 3x12.75>35)
2 T105 (L=10.625, 3 fit but only 2 or 4 make sense, also too tall)

I'm inclined to use 2 or 3 SRM-24's because I don't have to hire a welder to construct a new tray and I don't have to lower the tray closer to the ground to gain some height for the taller batteries. Gotta clear the front shell as it goes up. I can just go to the store and buy two more batteries and two more battery boxes.

Here is another thought, thinking out loud. Instead of 3 SRM-24 batteries with a weight of 138 pounds. A single battery plus the Honda 3000 is 180 pounds. The Honda 3000 will even run the A/C.

I'd like to be able to camp in the Nevada desert in July/August (fool that I am) and also camp in northeast CA in October in the forest. Solar would work in Nevada, but I don't see how I could get enough power from solar in a dense forest in October. Sooner or later I will need a generator. Either dual Honda 2000's or a single Honda 3000 seems to make the most sense. With a generator, I don't see any reason to have more than one battery.

I probably won't be buying a generator this year. It doesn't sound like a single battery will last 4 nights for the first trip in 2 weeks. Especially with 5 adults staying up until midnight. My best bet seems to be to purchase a second SRM-24 and try to stretch the two batteries into 4 nights with conservation and recharging from TV. I might be able to borrow a generator from my neighbor's brother for my first trip.

[B_and_D]

I've thought about wiring up the truck to be able to take a spare battery with us on day trips (like to the store, even), keep it in the tool box, and charge it while we're driving. It wouldn't be that hard to hook up. You could switch it back and forth with the house battery and that way keep them both charged up. When we camp, we hardly go a day when we don't drive somewhere.

Most TV's have a great recharging source - the alternator; some are better than others. The one in our Chevy truck seems to be a very good charger. However, the way most TM's and 7-prong plugs are wired, the charging doesn't always get to the TM house battery that efficiently through the 7-prong plug. In our 2720, the converter is way in the back, and then the power has to be transferred way into the front of the TM where the batteries are mounted. The wire gage and the length the charge has to travel makes a great deal of difference in how efficiently your batteries will charge. Take a look at how your battery in your TV is charged...it is through very heavy gage wire and short cables. Compare that gage of wire with the wires that connect your TM house battery to the TM! I believe that we could also mount a spare battery in the engine compartment of our Chevy 1500 which could be plugged into the TM at night. You would need an isolator or a manual cutoff switch to keep the main TV battery from draining. From what I understand, you can order a special bracket from GM to hold the extra battery in the Chevy trucks. We had an auxiliary battery in our old GMC with a camper, we would hardly ever run out of power, but we didn't have much to run back then, just a couple of lights, the water pump, and the Thetford. No phantom drains!

I highly recommend this book: RV Electrical Systems: A Basic Guide to Troubleshooting, Repair and Improvement, by Bill and Jan Moeller. I got our copy from Amazon.com.

[RockyMtnRay]

Originally Posted by PopBeavers

3 SRM-24 (the TM came with 1, 3x11<35)

YIKES! That's only a Grp 24...about 80 amp hours total or about 50 to 60 usable amp hours at a 5 amp rate of drain before going below 30% charge. At a 10 amp rate (normal if you're using more than 3 or 4 lights), you've got maybe 4 hours of battery...barely enough to make it through one evening!

Here is another thought, thinking out loud. Instead of 3 SRM-24 batteries with a weight of 138 pounds. A single battery plus the Honda 3000 is 180 pounds. The Honda 3000 will even run the A/C.

You'll definitely need a WDH if you put a Honda 3000 on the tongue...those things are quite large and quite heavy. And reworking the battery tray will be simplicity compared to crafting a secure mount for the generator.

I'd like to be able to camp in the Nevada desert in July/August (fool that I am) and also camp in northeast CA in October in the forest. Solar would work in Nevada, but I don't see how I could get enough power from solar in a dense forest in October. Sooner or later I will need a generator. Either dual Honda 2000's or a single Honda 3000 seems to make the most sense. With a generator, I don't see any reason to have more than one battery.

I probably won't be buying a generator this year. It doesn't sound like a single battery will last 4 nights for the first trip in 2 weeks. Especially with 5 adults staying up until midnight. My best bet seems to be to purchase a second SRM-24 and try to stretch the two batteries into 4 nights with conservation and recharging from TV. I might be able to borrow a generator from my neighbor's brother for my first trip.

If the battery was the larger Grp 27 (total amp hours about 115), then maybe you'll be able to get by with just one battery for 1 or 2 nights. Even with a generator you've got problems...for one thing, most developed campgrounds have quiet hours (NO generator usage) from 10 pm to 6 am. And a lot of campgrounds are now restricting generator useage to afternoons and evenings before 8 pm. Furthermore, your charging current has to be under about 20 amps (deep cycle batteries should never be rapidly recharged). If your trailer came with the 7300 series converter, the converter can produce that level of current...but if it has the older 6300 series, the charging current is only about 8 amps. You will need to run the generator for 4 to 6 hours a day just to keep the batteries recharged...and that's a lot of time.

I've tried the recharging from TV while camped routine...it doesn't work worth a whoot. The current coming into the battery (even with the refer on propane) is only about 15 amps (battery nearly discharged) and tapers off to 5 amps (battery moderately charged). To get any effective recharging, you'd have to leave the TV continuously idling for 2 to 3 hours! An idling TV engine burns around 2 gallons an hour...which means you'd go through 6 gallons (about a quarter tank of gas) every day trying to recharge your batteries.

All of the above is why I installed 170 watts of solar panels on my TM's roof...they generate a steady 11 amps of current for nearly 10 hours a day in full summer sunshine. Even if I fairly severely deplete the house battery overnight, I'm just about guaranteed a full recharge by the next evening. No, they won't run the AC...but if you have lots of sunshine (like Nevada in the summer) solar is unbeatable for battery charging.

Solar even provides some charge in Autumn in a forest...when I camped in RMNP (far northern Colorado) in Sept 2003 in a quite shady (pine forest) campground I was able to get about 2 to 3 hours of recharge per day (around 25 amp hours). No, it wasn't enough to fully recharge the battery (only had a single, worn out Grp 27 back then)...but it was enough to get me through 3 days of camping. Because of that experience, I went to dual T105s in the Spring of '04 to have a few extra days of reserve capacity in the event of extended cloudy weather or a very shady campsite.

[Bill]

Pop -

Ray is kind of nibbling around the outside of your problem. Let me be more forthright. If you are going to dry-camp in the Nevada desert in July and August, you NEED an air conditioner, and that means you NEED a generator to run it. Your basic goal is air conditioning, not battery charging. But as long as you have to run a generator to cool your TM, then you might as well charge your batteries with it at the same time. But this is your particular requirement, and probably doesn't apply to very many other people. That's why the desert is a lonely place in July and August.

But what about the rest of the year, and what about those of us who don't camp in the desert in August? The answer may be a little different. If the basic goal is battery charging, a generator is not a great way to go. A Honda EU2000 can supply only 8 amps of battery charge, and the EU3000 only 12 amps. As Ray points out, if you use your generator to power a 7300-series converter, it is a bit better, and the Progressive Dynamics 9160 retrofit would be even better than that (in my opinion). But for battery charging, a solar panel installation would be the best of all, for the reasons Ray points out. When you are camped in a sunny area, they are a nearly ideal solution.

So what about the times when we are not expecting to camp in a sunny area? (I camp a lot in the sunny but forested northeast.) Well, you do without - or you buy a small generator for long stays. A Honda EU1000 won't run the air conditioner, but it is a lot cheaper than a 2000 or 3000, and will run the TM's converter to charge the batteries at whatever rate the converter will produce. The big advantage is that it is very light (only 29 pounds, as opposed to 134 pounds for the 3000) which means you just toss it in the back seat - you don't have to build a mount for it or expose it to the weather and grime on the road. Seems a reasonable compromise.

Just my thoughts.

Bill

So, it sounds to me like I will need a generator. Perhaps a single Honda 2000 now and add a second one later when I take the first trip where I need to run the A/C.

If I have Honda 2000 generator and I am somewhere that I can run it at least 4 hours per day, is there any reason to have more than a single 12-volt battery? If so, which of the following two choices is best?

3 SRM-24
2 SRM-27B (3 SRM-27Bs won't fit)

For my first trip out I just don't have time to modify the front of the 2720 so that I can put T105's in. Switching over to T105s will likely require either relocating the propane tanks further forward or lowering the battery tray to make room for the taller T105. The factory installed battery tray will not take any battery taller than 10.75 inches. The T105s are 11 &3/16.