As most of you are aware I just received my Renogy 100w Suitcase Solar and have a question relating to the Viewstar VS1024BN controller.When setting proper battery size and type the controller has a rated value field for the Amp Hours which I cannot locate on either of my 12 volt Interstate group 24 (HD-24-DP) batteries.I called Renogy and they said to set it at 45AH which I have done but I cannot find any information on where the 45AH they recommended came from.I have looked everywhere and the only information I can find is 405CCA and 505MCA but cannot find the Amp Hours for these batteries even checked labeling on the batteries and no AH posted on them. I would guess that these batteries are not a true deep cycle battery is why no Amp Hours are posted but I may be wrong.Can anyone help me out on what the controller Amp Hour setting should be set at? (is 45AH correct?). I want to make sure that my solar controller is set up properly.

Group 24 battery is typically about 75 amp hours.If this will be hooked up to the RV and you have more than one battery, then you add up the sum, and set it for that.They might have suggested 45 amp hours so that it will allow charging at 5 amps or so. Should you have set it for say a 20 amp hour scooter battery size, it might limit charge rate to say 4 amp to keep from overheating the battery.Really 100 watts is nothing in a RV. Sure it will attempt to charge the battery, but your CO meter, propane detector and refrigerator will combined use about 35 amp hours daily, while the 100 watt solar panel can at best produce about 30 amp hours per day. It is better than nothing, but still after 3 days you will need to crank up a generator - even if using no lights or anything else on 12 VDC.I have a pair of 120 watt panels, pair of 45 watt panels and a 75W panel. That way I can watch as much TV as I want, and never need to run the generator just to recharge the battery.SunElec.com THey sell solar panels for about $1 - $2 per rated watt. Controllers are extra, but a low cost 20 amp PWM controller is good for about 300 rated watts, and only run about $20 these days. Select 12 volt 'nominal' panels, with a 20 - 22 volt 'open circuit' voltage rating. These will quickly charge the battery, no matter how large your battery bank ends up being.I have 4 golf cart batteries rated at 440 amp hours at 12 volts, and each is 67 pounds! That is to much weight for the typical RV, and a larger solar system can make up for a smaller and lighter weight battery, because you will be generating power all day long, and only need to store 1/2 as much for nighttime use only.If you can add water to the battery that you have now, I would say keep it until it dies. Deep cycle battery is one that you can add water to it. If it is sealed, then still keep it until it dies, perhaps next spring replace it with something better. It will not last more than 3 years, regardless. I have never had a 12 volt battery last 4 years, but my Trojan 6 volt battery lasted 13 years!Good luck,Fred.

Trojan 24TMX is rated 85 and probably 70 to 80 for Interstate that does not seem to like publishing the A/h rating.

4aSong wrote:I would guess that these batteries are not a true deep cycle battery is why no Amp Hours are posted but I may be wrong.Correct. You have Marine batteries, meaning they are a cross between deep cycle and starting. The battery specs online (a good source of information) say that it's about 45ah, so two of them are 90ah. I've never encountered a controller that asked for that kind of information. 45ah is not very much for a camping battery. When you get the urge to replace them, get some true deep cycles.

I am still running on similar batteries, with 300w of solar. I don't have to worry about them overcharging, since it will float at 13.2 volts if they get totally charged up, anyway. I've been looking at some AGM deep cycle batteries, since the 6v golf cart batteries I'm most familiar with won't fit the metal compartment under the step! So, I've seen some AGM's that will fit, and some that might have to go in sideways, in over to fit. I have another remote camp with true deep cycle batteries and there is a big difference in reliability and duration compared to marine batteries. I started solar with used forklift batteries that I could only move with a front end loader. You'll love having solar, and when you add more, you'll love it more. The people that have already answered have some consistently good advice about batteries and solar. To me, it's fascinating to make the whole rolling residence as self sufficient as possible.

Interstate's website lists them with reserve capacity at 25Amp for 100 minutes = 42 Amp Hours, That's sorta the 2 hr rating, at the more common 20 rate, its probably 50 to 55 AH.I'd set the controller for 100 AH for the pair.They're not the best for your application, but with a little bit of care will serve you well for years.Doug

Amp Hour question | Good Sam Community

15 Replies

loggenrock
Explorer
Apr 15, 2015
Don't "dish" 100W of solar! Those of us with smaller rigs likely have less power consumption than the "big guys". My 100W portable keeps me going for 5 to 6 days (usually moving again at that point...), since I, too, only have a single house battery. Sometimes "older is better" - NO 12V drain for my refer when on propane. And my CO meter is 9V battery powered. Only LP alarm off house battery. 4aSong - you should do real well with that set-up in AZ - works for me in the shady/cloudy northeast! ST
red31
Explorer
Apr 15, 2015
75 would be its reported 1 amp discharge rating as seen with their other marine batteries, not 20 hr
wa8yxm
Explorer III
Apr 15, 2015
red31 wrote:
Based on the 24 DP's RC of 100 and the 'regular' 24's RC of 140 I'm guessing the 24 DP comes in @ 56ah each.

Had good luck with general inquiries of the battery maker Johnson Controls

johnson controls general inquires

Based on the battery specifications given by Interstate and others it is, as I said 73.

All the figures I gave were researched,They are NOT estimates but actual numbers obtained from East Penn, Johnson Controls and US-battery.
red31
Explorer
Apr 14, 2015
Here ya go 69 ah based on this '04 spread sheet from JCI
MEXICOWANDERER
Explorer
Apr 14, 2015
BCI average amp hour capacity for a group 24 is 85. You learn from the amp hour meter readings what your batteries actual rating is.
red31
Explorer
Apr 14, 2015
Based on the 24 DP's RC of 100 and the 'regular' 24's RC of 140 I'm guessing the 24 DP comes in @ 56ah each.

Had good luck with general inquiries of the battery maker Johnson Controls

johnson controls general inquires
wa8yxm
Explorer III
Apr 14, 2015
4aSong wrote:
When setting proper battery size and type the controller has a rated value field for the Amp Hours which I cannot locate on either of my 12 volt Interstate group 24 (HD-24-DP) batteries

75 amp hours each 150 total (Well 73 and 146)

Group 24 about 75 (73)
Group 27 Just below 100 (95)
Group 29 Just above 100(105)
Group 31 About 130
Size 4D 230
Pair of GC-2 Wired in series to make one BIG 12 volt..210-230 (See 4D)

You can use the Round number but there is a slight difference between one brand and another (As you can see the difference is very small).

In addition: GC-2 (And you can get a 4D this way) are DEEP CYCLE
Most of the batteries identified as GROUP XX above are MARINE/deep cycle starting batteries.. What is the difference?

A MARIN/deep cycle should be kept around 3/4 full at the minimum, that is out of every 100 amp hours of capacity only 25, perhaps 30 are usable before serious long term damage sets in

A true DEEP CYCLE like the GC2 you can to to half full without doing serious damage.

Next we get Floooded Wet Cell,,, Maintenace free, AGM

The flooded wet you can add DISTILLED water as needed to replenish that which is "Boiled" off (Itis not really boiling it is electrolysis)

The others you can not SOME (myself included) think this is an advantage for Flooded wet.

AGM may well have a lower INTERNAL resistance They can also be mountd without regard to "THIS SIDE UP" You can find small (GROUP ##) AGM in DEEP CYCLE types.. THEY ARE EXPENSIVE.

GC-2 is best bang for your buck (Baring one heck of a sale on AGM)
doughere
Explorer
Apr 14, 2015
100 watts of solar is close to the edge of what will keep the battery charged over long periods camping.

BUT: it can certainly make enough if you can find a sunny spot. Total of 100 AH battery does not give a lot breathing room, but in good weather is probably enough.

I keep hearing the mantra of never go below 50%, that's a great idea in theory; but in the real world going to 20% or so sometimes is certainly not a killer. Just make sure the battery is brought up to 100% as soon as you can.

Doug
Harvey51
Explorer
Apr 14, 2015
My guess would be the 45 comes from estimating 90 amp hours for a good deep cycle battery but realizing you shouldn't discharge below 50% of that. You want your family to see zero energy remaining on the meter at that point and turn off the TV.

Really 100 watts is nothing in a RV. Sure it will attempt to charge the battery, but your CO meter, propane detector and refrigerator will combined use about 35 amp hours daily

If so, we wouldn't have been able to go four days on 2 batteries (50% discharge) without charging! Our fridge must use less power than that. Or it may be cooler where we camp. No light, no defrost feature, no fan. CO detector runs on a 9 volt battery. I made a few measurements and figure a 100 watt solar panel should let us go without other charging sources for twice as long - a full week. Of course we don't carry a TV and use propane to make coffee.
4aSong
Explorer
Apr 03, 2015
Thanks to everyone for your inputs on the AH rating for my batteries.
Just to be sure I have contacted Interstate today and explained to them that I needed the Amp Hour rating on their HD-24-DP and still waiting for a response. In the interim I have set the controller to 100AH.
Will update this posting once I receive back from Interstate.