Are all Group 24 batteries really the same size?

RA

radarcontact

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....was wondering about this the last few days. My wife and I live in Wyoming but bailed to the San Diego area the last 10 days for some warmth and So. Cal. beach camping (great time). While camped at Carlsbad for a couple days I managed to run my 2 Fiamm 80Ah deep cycle batteries low enough that I wondered if anything was wrong with them. I have a 100w solar panel on the roof with the ZAMP 30A controller, and a Dometic 110 liter frig which we keep set at about 4 (average cooling). I had a 24 hour period where I didn't start my truck, which means that all charging was coming from the panel. We've camped off the grid for days where I didn't start the truck, and the batteries have performed flawlessly. We must have put a load on them this time, because on the second day they drained down low enough that the compressor on the frig kept starting and stopping, and the red LED error light on the frig indicated an inadequate power supply. When we relocated to a new campsite the next day, driving the truck plus the solar panel seemed to top off the batteries fine. I did have the batteries checked at a truck repair shop, and they look ok for now. They're about 2.5 years old.

Anyway, I started looking online for type 24 batteries in case I needed to replace them, and found that there are slight differences in sizing....? Isn't the purpose of a group # to ensure that the battery will fit into the compartment/space? Four Wheel built a pretty tight space for my two batteries, and I'm not sure if any new batteries that might differ by a 1/4 inch or whatever in length or width would fit into that area.

Anyone else run into this?
 
Lots of size variance within the group 24 designation. Same thing is true for group 27 and 31 etc.
 
I’m of the opinion that a 100 watt panel isn’t sufficient in hot weather. That’s what we had with our first pop up, and it could not keep up with the demand when parked in truck/trailer parking at Lake Powell. I believe the batteries were Lifelines, they were group 24. About a year old at that time. Daytime temps were in the low 90s, nighttime temps in the high 60s. We were away from the camper for three days, coming back to warm beer.

Now to answer your question, I’m pretty sure there are slight differences between manufactures and types. Typically, that’s not going to be an issue unless things are really tight
 
Thanks, guys. It wasn't completely sunny while we were in San Diego, and I'm not sure if the panel was able to do a good charge on the batteries. I do recall that it never topped off the batteries - the green indicator light on my controller indicating a float charge never came on - so I probably ran into a situation where I was using too much power between the frig and lights and the batteries couldn't catch up.
 
My Eagle has a Dometic 65L fridge and I started out with a 100w panel but it wasn't near enough on warm sometimes hazy days. I ended up adding 2 more 100w panels and that's just about right for my needs. I have 2 75ah batteries, fwiw.
 
Thank you, Stalking. I may add another 100w panel next summer.

Here's an additional question for you guys....

Do any of you leave your camper batteries plugged in to shore power all winter, to keep them fully charged? I'm thinking it's a good idea, as I live where it gets pretty cold.

The FWC manual says to keep the silver kill switch OUT, or in the ON position if you want to continuously charge the batteries from shore power. What it doesn't say is what to do with the 120V circuit breakers. Do I need to leave the MAIN and CONVERTER breakers ON, so the 120V is converted to 12V? Or is that circuit panel only for the electrical stuff in my camper that runs on 12V?
 
I shut the power completely off. My camper is covered and once a month I plug in the portable solar panel. After a month I'm still at 12.6-12.7. I can't comment on having the power on to charge off shore power, but I'm pretty sure it isn't a good idea to stay completely plugged in. Many trickle charge to keep the batteries charged. jd
 
Thanks Longhorn. I checked w/Denny here at FWC in Jackson and he said the company recommends leaving the batteries hooked up to shore power if you can...supposedly the controller keeps the batteries from overcharging. Not sure if I buy into that, although I do notice that when I keep the batteries plugged into shore power for a few days the controller reads FUL, and the indicator light shows that the battery is maintaining a float charge. But whether it overcharges I can't say. I know it won't overcharge if just solar is charging the batteries, but not sure if the same reasoning applies if charging is from shore power.

Stalking, actually I mistyped earlier...I have a 160W panel on my roof now. I could add another 80 or 100W panel and wire them in series if I want. Seems as if 160W should be enough for my needs. This was the first time I ran the batteries down, so I'll have to keep an eye on it and see if it happens again.
 
FWIW 300w is probably higher than I would need if I lived in a low humidity area like you do where it cools down at night even in the summer, but I live in the high humidity SE and many summer nights it stays in the 80's. I tried with 100w, then 200w and finally 300w before I was comfortable I had enough solar.

When I'm out west 200w is enough. I do also run my Mac to edit photos and a cell booster to update my web site which all adds to my requirements, but based on my experiments and experience humidity is the biggest killer (next to the inefficiency of the Dometic fridge).
 
smlobx, what size charger are you using? They have different amperages on the Amazon site.

Also, I have two batteries, wired in parallel (I believe), so, digging back to my brief coursework in electricity from college, I think I can hook up a 12V charger to the positive and negative anodes on one of the batteries, and it will charge both. I think as long as the charger is below 10 amps it should charge evenly across both batteries....? Probably need to research that.
 
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