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CanonFan · 04-23-2019, 09:15 AM

Just bought two new Interstate batteries (SRM-24) for my 2017 FC19. The original factory installed batteries were a little less than 2 1/2 years old before dying. When I got the new batteries home, I checked the voltage with my multimeter – each read 12.6 volts. I then connected each (individually) to my battery charger/maintainer to see if they would take additional charge. They didn’t. I then let the batteries sit, without load, for about 15 – 16 hours. Rechecking the voltage yielded 12.68 volts in each battery. Next, I checked the specific gravity (SG) of the electrolyte. Every cell read 1.260. The temperature of the electrolyte is 65 F. After subtracting .004 for each 10 degrees below 80 F (in this case 15 degrees below), I get a temperature adjusted SG of 1.254 (I subtracted .006 for the 15 degrees below 80 F).

As I understand the SG charts, this represents only about 75% charge – on brand new batteries. I checked the manufacture code on the batteries and verified they are fresh – made this month. The manufacture code is D9RBD (first “D” represents April, “9” represents 2019, don’t know what “RBD” represents).

I am somewhat of a newbie as this is my first travel trailer (or RV of any type

), purchased new approximatley 2 1/2 years ago. I would appreciate comments/suggestions from those on the forum that have far more knowledge than I have on this issue.

Bill M. · 04-23-2019, 11:18 AM

I do not think you have a problem. Put the batteries in and use them for a while.

Perhaps your "charger" is not as sophisticated as the 4 stage converter in the trailer and you will get more charge from a few days in the trailer. And it takes a while to actually get a full charge, whatever that is.

I am certainly less knowledgable than you. But this whole battery voltage thing is a tough nut to crack. So I just gave it up. I look at the simplistic voltage monitor and recharge with the generator when I am getting low. I get a couple of years useful life from my flooded cell batteries. I generally manage to run the batteries down too far a few times. I am relatively unrepentant about that and know the way to tractor supply or walmart.

AirMiles · 04-23-2019, 12:20 PM

Good answer Bill M. I too believe you have a good set of batteries with equally balanced specific gravity in all cells. I also use Bill M.'s battery philosophy. I use them and abuse them like propane exchange tanks and just replace them when they run out of juice. My first set of batteries only lasted 100 days of camping over 10 months. I must of abused them a little too much. My second set of 6V wet cell golf cart batteries have lasted about 130 days of camping over 14 months so far. That's about $1.50 per day. If I have to buy new ones next week I'd feel that I got my money's worth out of them. But so far, they still test and perform as new. So I'll continue using and abusing them which will lower my daily cost even more. I hope your new set of batteries last as long as your first set. Just put them in and go camping.

uncle_bob · 04-23-2019, 02:16 PM

Hi

At lest on the charts I've seen, your SG numbers should put you in the > 90% charge range for your batteries. Unless you put them on a pretty good charger for overnight, that's about what you should expect. Just as with voltages, letting the batteries sit for > 2 hours after charge is best practice for SG as well.

One chart ( of many ...):

http://www.batteriesnorthwest.com/ba...hool.cfm?TID=5

Bob

CanonFan · 04-23-2019, 02:31 PM

Well, I have been in touch with Interstate Battery and they have confirmed that these batteries should have a a specific gravity of over 1.285 for a 100% charge. These are "brand new" batteries. Just picked them up yesterday. Won't accept any additional charge. I'm concerned that I am starting out with "damaged" batteries on day one. My latest message from Interstate Battery is that the battery is "green" and may take up to 25 - 40 cycles before I can expect full capacity. Does this make sense to anyone? Does anyone check the State of Charge (SOC) of their brand new flooded cell batteries before you install and start using them?

As I said before, I am somewhat of a newbie. This is the first set of Deep Cycle batteries I have ever bought, Just trying to understand how these things work and what I should expect of fresh new batteries.

AirMiles · 04-23-2019, 02:46 PM

New wet-cell batteries do have a break-in period. Here is what I found in a search: https://www.cartsunlimited.net/battery-break-in-.html

New batteries are initially about 75% of their full strength. The following procedure will insure they reach their full potential. The 1st 10 to 20 complete charge/discharge cycles are critical to insure they reach 100%. New batteries should be charged before use and thereafter as follows:
Plug the charger in and leave it alone until the charger shuts off by itself. Then drive to discharge the batteries to 75% of battery pack capacity (see chart for voltage readings or use 9 holes of golf as a reference point) Plug the cart back in and repeat the charge cycle.......It is very important you let it charge until it is completely done. Repeat this for the first 10 - 20 cycles......by the 12th cycle you will notice a difference in power, speed, and run-time.........I have never had a customer say they have not noticed the increase.

sheriff1 · 04-23-2019, 02:52 PM

I wonder if this applies to AGM as well?

CanonFan · 04-23-2019, 03:38 PM

[QUOTE=AirMiles;2234268]New wet-cell batteries do have a break-in period. Here is what I found in a search: https://www.cartsunlimited.net/battery-break-in-.html

Thank you AirMiles! This is good info! Today is the first I had heard there is a break-in period for a flooded lead acid battery - now I hear it from the battery manufacturer AND from you via the link you provided to Carts Unlimited. I will proceed as per those instructions to bring my new batteries up to full capacity.

Thank you very much!

Bill M. · 04-23-2019, 04:19 PM

There is also a hysteresis effect to consider when measuring battery voltage. The state of the charge at a given voltage depends upon the recent charge/discharge history,

uncle_bob · 04-24-2019, 06:24 AM

Hi

Simple answer is to spend the summer using the batteries normally and not re-charging them a whole lot.

Bob

AirMiles · 04-24-2019, 06:40 AM

Quote:

Originally Posted by uncle_bob

Hi

Simple answer is to spend the summer using the batteries normally and not re-charging them a whole lot.

Bob

Huh? Wet-cell batteries like to be at 100% SOC. I leave my solar charging in storage and they float charge every day. They still test and perform as new after 140 days of deep cycles and about 300 days of float charging.

uncle_bob · 04-24-2019, 06:51 AM

Quote:

Originally Posted by AirMiles

Huh? Wet-cell batteries like to be at 100% SOC. I leave my solar charging in storage and they float charge every day. They still test and perform as new after 140 days of deep cycles and about 300 days of float charging.

Hi

If he's going to do the "break in" as described, the SOC needs to come down to 75 % and then go back up. That pretty much means it's not at 100% SOC all the time. The idea is to do that with normal use rather than some sort of artificial process. If you condition them with an artificially high discharge / recharge you aren't going to get it right.

Bob

AirMiles · 04-24-2019, 07:20 AM

Quote:

Originally Posted by uncle_bob

Hi

If he's going to do the "break in" as described, the SOC needs to come down to 75 % and then go back up. That pretty much means it's not at 100% SOC all the time. The idea is to do that with normal use rather than some sort of artificial process. If you condition them with an artificially high discharge / recharge you aren't going to get it right.

Bob

OK, now I get what you are saying.

First, I wouldn't worry about conditioning the batteries. I'd just start using them and recharging them daily. This is pretty much what I did with my batteries. The first few cycles, I did do some testing to see how they held up with various amp loads and then recharged them immediately. Since I got my wet-cell golf cart batteries, I only use solar charging and not the shore power converter. This makes each cycle on my batteries deeper. If you always use shore power while camping, the batteries would always be charging and never get deep cycled.

If you want to condition them. I would "artificially" condition them over a week or two by putting a low amp draw on them, totaling 25 amps over a six-to-ten hour period, and then I would immediately recharge them afterwards. I would never leave my wet-cells in less than 100% SOC any longer than necessary.

gypsydad · 04-24-2019, 09:31 AM

Quote:

Originally Posted by AirMiles

OK, now I get what you are saying.

First, I wouldn't worry about conditioning the batteries. I'd just start using them and recharging them daily. This is pretty much what I did with my batteries. The first few cycles, I did do some testing to see how they held up with various amp loads and then recharged them immediately. Since I got my wet-cell golf cart batteries, I only use solar charging and not the shore power converter. This makes each cycle on my batteries deeper. If you always use shore power while camping, the batteries would always be charging and never get deep cycled.

If you want to condition them. I would "artificially" condition them over a week or two by putting a low amp draw on them, totaling 25 amps over a six-to-ten hour period, and then I would immediately recharge them afterwards. I would never leave my wet-cells in less than 100% SOC any longer than necessary.

Not sure that statement is correct??

If you have a newer 4 stage converter with the smart charge technology, like the Boondocker or Progressive Dynamics, you should be fine. It's the older single stage converters that come with the 2017 AS's and older that the converters have issues and don't properly charge/maintain your batteries since they are mostly on. You can easily boil out the water in the OEM batteries (likely Interstate wet cell) in just a few days in some cases if not careful.

I too have been thru a "few" rounds of batteries and discussions on this topic over the years...my new 6V Trojans hold charge and have been fine since installation last July, but I did replace my converter with a Boondocker 4 stage with the smart charge technology.

Spinonedad · 04-24-2019, 09:31 AM

Keep the voltage above 12.2 volt and check levels periodically, the batteries will last year 4-5 years , invest in a real battery monitor

Spinonedad · 04-24-2019, 09:39 AM

Victron BMV 712

AirMiles · 04-24-2019, 09:43 AM

Gypsy, you misunderstood my comment. I meant to say that the only way to deep cycle an Airstream battery is to not plug in the 110V power cord, turn on some load such as the fantastic fans, run it this way for about 6 hours, then turn off the load and plug in the Airstream's 110V power cord to recharge the batteries. If you have the Airstream's power cord plugged in while running load, the batteries would not get cycled as all the load would be provided by the converter.

gypsydad · 04-24-2019, 09:59 AM

Quote:

Originally Posted by AirMiles

Gypsy, you misunderstood my comment. I meant to say that the only way to deep cycle an Airstream battery is to not plug in the 110V power cord, turn on some load such as the fantastic fans, run it this way for about 6 hours, then turn off the load and plug in the Airstream's 110V power cord to recharge the batteries. If you have the Airstream's power cord plugged in while running load, the batteries would not get cycled as all the load would be provided by the converter.

Maybe; maybe not quite accurate, if you have the newer converters. Have you read up on how these 4 stage converters work while connected to your batteries? Not sure running the fan or any appliance factors in to the smart charge characteristics with one of the 4 stage converters I mentioned? Randy; you out there??

AirMiles · 04-24-2019, 10:04 AM

What would not be accurate? If the Airstream is plugged in to shore power, I don't believe you even need batteries connected as the converter would be supplying all the 12V needs. To use power from the batteries, you need to unplug the Airstream from shore power, or turn the breaker supplying 110V to the converter off. Or possibly, turn the store/use switch to "store". But who knows for sure what that store/use switch does? It seems to be the least logical switch ever on an Airstream.

glcmranger · 04-24-2019, 10:07 AM

GypsyDad: WELL SAID. I just didn't want to beat the dead horse again in that if you have a 2017 or older model, the converter is single stage, which means you're ALWAYS on the edge of frying those batteries due to overcharge....which means a lot of battery management is involved. Do yourself a favor, if you haven't already done so, replace that Parallax converter with the Boondocks or Progressive Dynamics 4655v.... otherwise, in about 6 months you'll be back in the same situation with the batteries.