will gr27 batteries drop in to 27FB?

[Gringo]

After two years without batteries we're interested in some limited boondocking. By limited I mean only a few days at a time, but in a remote location with no hookups. I've just ordered the Zamp 200 watt portable solar charger and need to buy some batteries. I've read that people have upgraded from the group 24's that came with the trailer, to group 27s for slightly more storage.

I see there is a battery tray in the battery compartment of this 27FB. Will the gr 27 size batteries fit in that same tray, or does that need to be replaced to use larger batteries?

[Drathaar]

Hola Gringo,

The answer is yes, but there is a chance that you may have to modify the battery box. Let me see if I can find my photos of an installation.

Drat

Edit: I lied! These are Group 31s, in a 25' FC. The mod that was needed was to reposition the hinge for the box lid. The owner told me that the dealer in LA charged less than $100 to do the mod and install. They had the Lifeline batteries drop shipped to the dealer.

BTW, I hope you negotiated with the dealer who is installing your solar. My dealer wanted twice what other RV places in our area were asking, but did the job for the going rate in the region.

Edit: I just noticed you asked about the tray, not the box itself. My guess is that you will need to remove the tray. If they don't make one for larger batteries, a rubber mat below the batteries would probably be just as good. Block the batteries so they don't move.

[idroba]

I think others have said that the #27's will "shoehorn" into the original battery box but may be very difficult to get in and out. They are the same width, but longer than the original #24's AS supplied.

On mine, I removed the #24's and put two golf cart type 6 volt batteries in series in their place. The golf cart ones are the same size as the original #24's but about an inch and a half taller, so the top of the battery box must be raised, or the bottom lowered. I raised the top of mine with a metal C channel and it worked out well.

The original #24's had a capacity of about 75 amp hours each, 150 total for the two. Two golf cart batteries will have a capacity of about 220 amp hours. I am not sure about #27's but think they are around 95 to 100 amp hours each, or 190 to 200 total.

[Gringo]

We're either in the trailer, or it's in storage and we're thousands of miles away from it. There's no convenient time for it to undergo modifications. So I was looking for the most batt I could fit into the stock box without mods.

[SSquared]

Lewster installed a pair of group 27s in our 2013 25FB Flying Cloud. I was not there that day to see it happen, but he says that to put them in, he:

--Drilled out the pop rivets that attach the hinge to the box
--Cut away part of the lip on the hinge side
--Inserted the first battery, and slid it to the other side
--Inserted the second battery
--Re-installed the hinge & lid with new pop rivets.

[Gringo]

thanks. I'm inclined to give that a try. Do you know what he used to trim the sheet metal?

[Drathaar]

Originally Posted by Gringo

thanks. I'm inclined to give that a try. Do you know what he used to trim the sheet metal?

On the trailer that I referenced, I was told the dealer used a sawzall with metal cutting blade.

[SSquared]

Originally Posted by Gringo

thanks. I'm inclined to give that a try. Do you know what he used to trim the sheet metal?

I don't know. You can PM him here on the forums; I'm sure he'd be happy to tell you.

You might also feel under the edge where the hinge is on yours, to find out how wide the lip is, and measure the opening on yours. I don't know how precise Airstream is about forming these boxes.

[Gringo]

it looks like I need to trim it back 3/4" of an inch. I think I'm going to try a Dremel tool with the cutting disc wheels. I don't particularly want to buy a demolition saw for this one job, and I know what kind of job I would likely do with a hacksaw. A Dremel might be slower, but I'll do a neater job and can think of other uses for the Dremel. Besides, they're light and don't take up much room.

[idroba]

I doubt that a Dremel tool cutting disk will be heavy enough for cutting the metal on the battery box, at least the one I have would be hard pressed at it. But they are useful for other jobs.

[Drathaar]

Originally Posted by Gringo

it looks like I need to trim it back 3/4" of an inch. I think I'm going to try a Dremel tool with the cutting disc wheels. I don't particularly want to buy a demolition saw for this one job, and I know what kind of job I would likely do with a hacksaw. A Dremel might be slower, but I'll do a neater job and can think of other uses for the Dremel. Besides, they're light and don't take up much room.

Rent a sawzall, or take it to someone to do it for you. It will save you a lot(!!!) of frustration.

[Gringo]

Okay, it's done. I bought the cheapest Dremel tool WalMart had, thirty something bucks, and two little packs of the fiber reinforced cutting discs for it. Not the ones that come with the Dremel, those are brittle and not made for cutting. Anyhow along with a new pop rivet tool I have less than $ 45 into the whole project. I did just what was suggested, I drilled out the three pop rivets holding the hinge to the battery box, used the Dremel to cut the piece of lip out, and then installed the batteries. The Dremel had absolutely no problems cutting the sheet metal, I think that part of it took less than 10 minutes and used just two of the cutting discs. I pop riveted the hinge back in place. I figured a Dremel and a pop rivet tool would be pretty useful things to have around an Airstream anyhow, so I don't begrudge the costs of adding a couple tools.

The Zamp 200 watt portable solar arrived Friday, so we're looking forward to hooking all this up.

[KJRitchie]

Funny, my 2008 Classic 25fb battery box has 2 Grp 27 and there seems to be plenty of room for the two Interstates that came with our preowned trailer.

Please post your impressions of the Zamp 200 and maybe some photos. I'm looking at getting one of these systems. I had a 60 watt panel I used on my single grp 24 in my Casita and it kept that battery charged on summer trips to Glacier Natl Park. I figured a 200 watt portable would be able to handle 2 grp 27s. We are not heavy power users nor do we have an inverter system, just a portable unit to charge phones or run the LCD TV for a movie we play from an iPad via HDMI. I've converted the lights to LED. I didn't want to install a solar system on top of the roof.

Kelvin

[idroba]

Glad your Dremel worked out for you. Not sure what cutting disks you got, the ones I have would not cut metal like you said yours did. So, good news. I learned more today.

[Gringo]

I know the ones you mean, they pack them with new Dremels. Those are more like little grinding wheels than cutting wheels. They're good for sharpening stuff, but really brittle. They're good for cutting wire, like bicycle spoke kind of things.

The ones that work well cutting metal are these:
Dremel 426 Fiberglass Reinforced Cut-Off Wheels 1- 1/4" Dia., .045" Thick - Dremel Accessories Steel Cutting Wheel - Amazon.com

They're usually hanging in a five-pack with the Dremel accessories.

I think you could probably cut just about anything with these. They do a great job on hardened chain and locks, too.

[Drathaar]

Gringo, that surprises me. I would have bet money that it would be a genuine PITA getting the sheet metal cut with a Dremel. I am glad it worked out for you!!!

Post Script: I am glad it didn't bet money!

[rpmd]

Originally Posted by idroba

I think others have said that the #27's will "shoehorn" into the original battery box but may be very difficult to get in and out. They are the same width, but longer than the original #24's AS supplied.

On mine, I removed the #24's and put two golf cart type 6 volt batteries in series in their place. The golf cart ones are the same size as the original #24's but about an inch and a half taller, so the top of the battery box must be raised, or the bottom lowered. I raised the top of mine with a metal C channel and it worked out well.

The original #24's had a capacity of about 75 amp hours each, 150 total for the two. Two golf cart batteries will have a capacity of about 220 amp hours. I am not sure about #27's but think they are around 95 to 100 amp hours each, or 190 to 200 total.

Trying to do this exact replacement. Do you have pics of the metal c channel installed? Thinking this is the best way to increase the height of the battery box.

[idroba]

Here are photos of what I did. The aluminum C channel was something I had. I mitered the corners and put small L brackets inside the channel for stiffness, then attached it to the top of the battery box with sheet metal screws (or pop rivets) then attached the original top of the box to the new frame. I had some blue plastic matting which I simply put over the battery tops for slightly more protection.

The batteries are 6 volt golf cart type from Costco, about $90 each. They have the same footprint as the original type 24 that were in the trailer on delivery, but are about 1.5 inches higher.

At the top of the photo you can see the + cables, two large ones, one for the inverter, one for the main power. The orange wire goes to the electric jack. The blue wire and small white fuse is for the Tri Metric power monitor. The red and black jumper wires were the original ones used to parallel the original batteries.

The bottom of the photo shows the 100 amp shunt mounted on it's side with a short piece of twisted copper to connect to the negative side of the battery. The gray taped wires are part of the Tri Metric monitoring system. They carry virtually no current and are thus pretty small in size. I think I have a 1 amp fuse in the white fuse holder.


The two large black wires are the negatives for the main power and the inverter. One was a bit short, and that is why it runs across the battery at an angle. I would have liked 2" more cable, but it was not available and I didn't wish to extend the wire with a splice.

The battery hold down was extended with a piece of all thread.

When I disconnect the batteries for the winter, I simply remove the center red and black connecting wires, quick and simple. I don't have to mess with the shunt or positive cables that way. I leave the batteries in place all winter. They take very little charge in the spring when I return.

[KJRitchie]

I have two Grp 27 Interstates in my 2008 Classic 25fb. The are positioned sideways in the battery box. Most photos I've seen show two batteries running lengthwise or parallel to the centerline of the trailer. I was able to remove them easily enough but the center threaded hold down gets in the way a little of the rear battery. It might be a little more difficult to install the rear battery. They are 6 3/4" wide. Lifeline Grp 27 are 6.6" so they should fit the same way.

Kelvin