Upgrading Batteries

[Road Geezer]

I want to increase the amp-hour capacity in our 2011 27FC. The installed grp24's simply don't have enough for our needs and require me to fire up our Yamaha 2kw generator too frequently.

I have checked dimensions of the battery box against a grp 27 I just bought and I'm sure that with a simple modification I can accommodate two grp 27's. The new ones will be wired in parallel just like the current batteries.

Question #1: Are any changes required to the electrical system required in order to accommodate the new grp 27's vs the grp 24's that came with our AS?

Question #2: Is there a meter I can install that will give me a reasonably accurate indication of the percentage capacity remaining in the batteries?

Thanks for your help,

Paul

[dznf0g]

#1 - No
#2 - TriMetric 2025RV (i think that's the model number)

Do you have the same front battery compartments as a Classic has. If you do, and you are going lead acid, Interstate make a group 29 which just BARELY fits, and I mean barely.

[dznf0g]

Look for the group 29 deep cycle on this page

Interstate Batteries

Here is the trimetric site

TriMetric Battery System | Bogart Engineering

Got mine at forum member www.bestconveter.com

[ROBERT CROSS]

The reasonably priced monitors I've been using since upgrading the batteries...
Bob

[dznf0g]

Originally Posted by ROBERT CROSS

The reasonably priced monitors I've been using since upgrading the batteries...
Bob

I guess it depends on what level of detail you want. TriMetric goes about as far in depth as you want with a lot of diagnostic aids. Well worth the money if you want that level of detail and accuracy.

[Gene]

Paul,

I replaced the Series 24 OEM wet batteries with Lifeline Series 27 AGM's and had to modify the battery box. The box is probably the same as on our '08 Safari FB.

I removed the cover—that was the easy part. There's a lip underneath the cover hinge and I cut it with a grinding wheel on a drill. The wheel was poor quality (Ace hardware brand) and it took forever. If I had to do it again I'd use a carbide tipped blade on a Sawzall.

The AGM's cost a lot more, but they last a lot longer and have no water issues since they are sealed.

If you want to go solar, the solar controller will have a meter that measures battery voltage, but that's a lot more expensive than a meter.

I am attaching a voltage chart that tells you percentage of capacity.

Gene

[bryanl]

State of charge is measured with either voltage or specific gravity. With a modern DVM, there is no need to delve into hazmat territory needed for specific gravity measurements.

The electron counters like the Trimetric need proper programming and can be deceptive. They calculate net energy flow and only infer current state of charge. The precision they indicate is way beyond any accuracy of the measure.

Voltage is really all you need. For best results, measure the voltage of a quiet battery - one that hasn't had any significant charging or discharging for at least a half hour. The chart is nice but all you really need to know is that you need to start thinking about a battery charge when the voltage gets down to 12.4, charging needs to be put on the priority list when it gets down to 12.2 and you should not let your batteries get below 12.0v.

You can also get a good idea of battery condition by watching how the voltage responds to loads like the water pump or furnace. A battery in good condition won't show much drop and will recover quickly. (note that battery condition and state of charge are two different things)

Factors like age, cycle to cycle variation, temperature, and use profile can each influence available battery capacity by more than ten percent. Measures more accurate than this are suspect and any changes on this order are not going to make much of a difference.

Battery energy capacity is a function of weight. Changes like from a group 24 to a group 27 or even to a T105 sized battery are within the nominal variations you can find in battery use so don't expect much.

The best thing you can do for better battery satisfaction is to upgrade your charging and maintenance equipment. Upgrade your OEM converter to one that does multiple stage charging and knows about battery storage maintenance like the ChargeWizard or Iota.

If you find you want a significantly bigger power budget, you need to think about a different RV. Those 24 ton class A's are big enough to carry a half ton or more of battery. A 4 ton Airstream TT isn't usually suitable for such a load so they keep it down to the 100 to 150 pound range for their battery bank.

[ROBERT CROSS]

All I really needed was an accurate reading of voltage, and a reliable source for AC status....KISS.

Bob

[RLS]

I also wanted to use the biggest battery that I could fit in. These are size 29. Had to use the Dremal and do some "custom alterations" to the bottom frame for them to fit. The bad part of doing this is getting them out! I had to make a shim that goes under the front battery lip at the bottom to catch on to and then pry it up and pull out at the same time.

[ROBERT CROSS]

Originally Posted by RLS

.... The bad part of doing this is getting them out! I had to make a shim that goes under the front battery lip at the bottom to catch on to and then pry it up and pull out at the same time.

Bob,

It's really hard to tell exactly where your mod's are from the pic. Did you have to notch the frame back a little?

I know the 27 Lifelines are a bear to get out in our 03 Classic....started using one of these plastic scrappers to slide it over the d@mn hinge...may be a little easier for me as they do have a handle on the end.

Bob

[Silver Goose]

I found this meter available for around $25. It comes with a lighter plug so you can simply plug it into the 12v socket on your tv antenna amplifier box if you have one. It doesn't take much to hard wire it to an unswitched 12v line if desired. It also has a user adjustable alarm if you want an alert when the voltage drops to a specific level.

Interstate publishes a spec chart found here:

https://www.interstatebatteries.com/...RVDeepCycle|3|

As you can see, there are some model differences within a given group size. Don't expect to see a spectacular difference in useful battery time going from a 24 to a 27. Airstream could do us a favor by providing battery boxes that could accommodate a pair of 6v golf cart batteries. A pair of them in series will provide noticeably more run time than a pair of Group 27s in parallel.

[dznf0g]

Originally Posted by RLS

I also wanted to use the biggest battery that I could fit in. These are size 29. Had to use the Dremal and do some "custom alterations" to the bottom frame for them to fit. The bad part of doing this is getting them out! I had to make a shim that goes under the front battery lip at the bottom to catch on to and then pry it up and pull out at the same time.

Me too, like I said they BARELY fit. I just slip a piece of a 2 liter coke bottle under each for a "slide". But they are 30 more amp/hours each bigger than the group 27s, so I think it's worth the hassle. I also installed a nylon strap around the batts so I can pull them out.

[Kamiak]

I agree, the 27’s are already a snug fit in the Classics, and taking on an additional ½” in height with the 29’s brings that positive terminal awfully close to the compartment frame on the way out. Any issues?

[Road Geezer]

Gene, the battery box mod you described is exactly what I'm planning to do. I already7 have a SawsAll, so I'll pop for a couple metal-cutting blades and have at it. The box is big enough for two grp 27s; as you already know, it's getting the battery in and out over the flange that's the problem. I think I only have to remove one flange.

Stay tuned, I'll post a pic of my results when I do the job in a couple weeks.

[RLS]

Originally Posted by ROBERT CROSS

Bob,

It's really hard to tell exactly where your mod's are from the pic. Did you have to notch the frame back a little?

I know the 27 Lifelines are a bear to get out in our 03 Classic....started using one of these plastic scrappers to slide it over the d@mn hinge...may be a little easier for me as they do have a handle on the end.

Bob

Yes, if you look at the second photo, the bottom of the battery does not have a shadow there, it is notched out. Since the battery is at an angle going in, the back top of the battery hits the wall and the battery will not fit till you notch out that bottom frame. I also use a thin nylon cutting sheet over the battery when sliding it in or out.

[ROBERT CROSS]

Originally Posted by Kamiak

I agree, the 27’s are already a snug fit in the Classics, and taking on an additional ½” in height with the 29’s brings that positive terminal awfully close to the compartment frame on the way out. Any issues?

I use a set of these on all the terminals.

Bob

[richinny]

Originally Posted by Kamiak

I agree, the 27’s are already a snug fit in the Classics, and taking on an additional ½” in height with the 29’s brings that positive terminal awfully close to the compartment frame on the way out. Any issues?

when i posted this same issue i was told to slide the battery in pos terminal first with the neg disconnected. when the pos post is safe then you can connect the neg post. it works :-)

for added safety i use a sheet of some of that indestructible anti-theft packaging.

[dznf0g]

Originally Posted by richinny

when i posted this same issue i was told to slide the battery in pos terminal first with the neg disconnected. when the pos post is safe then you can connect the neg post. it works :-)

for added safety i use a sheet of some of that indestructible anti-theft packaging.

Yes, it can be an issue if you're not careful. Never thought of turning them around. Will have to do that next spring.

[Gene]

I understand if you want to put series 29 in the battery box you will have to raise the cover. Basically, you shim it with some pieces of steel and paint them. I didn't think we needed more than an upgrade to series 27, so I didn't go that far.

The fit is so tight, you either need batteries with handles or use a one of those thingies that fits over the terminals and creates a handle. I expect getting them in is a lot easier than taking them out.

Gene

[Road Geezer]

To Everyone,

Thanks for your help and advice. I think I'm going to stick with upgrading to 27's rather than 29s. I already have one new 27 and the box will accommodate two with their handles without having to increase depth.

I'll also look at replacing the converter with a better quality version.

The other reason is that experience tells me that I'll get enough extra capacity using 27s. We're not long-term boondocking, just dry camping in campgrounds without hookups--like Yosemite. While our rig came with LED ceiling lights, I replaced them with 10w halogens because we simply found the LEDs too harsh--blue white--for our eyes. Thus, we're just looking for enough juice in the box to get us thru long winter's nights with the lights on. Next day, mid morning we can fire up the Yamaha without irritating neighbors.

And ... by keeping the grp oem 24s, I can have a bit of spare capacity to connect in through the umbilical if needed.

Paul