Do I Need New House Batteries

[QuiGonJohn]

My RV has (2) Deka SeaMate batteries Part #: 8A24M for the coach/house batteries.

I had the RV in the shop for some body work, (it was there for about 6 weeks). Now that I have it back, the batteries do not seem to be taking a charge. I had the RV plugged in overnight and battery level still only shows 2 of the 4 lights on the Test Levels Panel. I disconnected the batteries and checked the voltages, which were 9.57 and 10.97. Initially I thought maybe they weren't getting a charge, as in a problem with my charger, (which is a Parallax Power Center with charger). But, both batteries are quite warm, almost hot, and that makes me think they were getting a charge, just not accepting the charge.

Anyone have any suggestions? Or any other way to be sure if it is just the batteries and they need to be replaced?

If so, any suggestions for a relatively cheap option on replacing them? I would like to stay with AGM's.

Thanks!

[hermanmullins]

Sorry but that is an oxymoron, Cheap & AGM's. They are great batteries and are worth the price. Did you check the voltage with the charger connected?

Check the connections. If they are corroded they may be only making partial contact and can not take the charge.

Herman

[QuiGonJohn]

The connections are OK. I will check the voltage the charger is putting out.

As to cheap AGM's I guess I meant is their one brand or reseller that would give a better price than most of the others.

[desertdeals69]

You need to check different sources and compare prices for the different models and then determine which is best for you.

[QuiGonJohn]

OK, voltage at the charger is 13.89. When I have all the connections made and the battery disconnect on, (power to/from battery), I get 13.69. If I flip the disconnect and leave it all connected I get 11.39. (while it was unhooked today, I put a separate 12v charger on the batteries and got them up a little more).

Now, if I unhook the battery leads coming from the coach, I seem to only get mv's at the lead terminals which I would attach to the battery. Not sure why this is, could be some issue with the disconnect not staying connected if the batteries are not in the circuit.

Does any of this help troubleshoot?

[dickandlois]

QuiGonJohn, With 13.89 volt reading at the batteries when the disconnect is ON (powering the coach if I'm reading correctly).

When you flip the Disconnect relay your reading is 11.39 and no power to the coach. Correct?

When you disconnect the cables that feed power to the Coach you read very low voltage. This is normal. You do need to determine what cables come from the charger and the ones the feed the 12 volt fuse box.

With a reading of 13.89 the highest reading and a float voltage being 14.5 volts is most cases. That would lead me to believe that one of the 6 volt Coach batteries has a bad cell.

If you disconnect the jumpers that connects each set of 6 volt batteries from being in series, then you should read 6.5 to 7 volts across each battery. the one that reads around 4.5 volts is the bad one in the set of 4 coach batteries.

Rich.

[QuiGonJohn]

Rich, mostly right, except, I have (2) 12v batteries in parallel, (my first post I listed the voltage from each, unhooked from each other). After that time, I began a charge using a separate battery charger that I have. After a couple hours on that charger, that is when the later set of readings was taken. I plan to leave the (2) batteries on that charger overnight and see if I can get them up to full charge. If so, then I will connect everything back as it should be, and see what happens.

[dickandlois]

OK, Then after charging,read the voltage difference across each battery. 12.5 to 12.25 is good. 11.25 to 12.0 is not good. after running a charger on them for 12 hrs. or longer.

Rich.

[QuiGonJohn]

So after a day and half, with the house batteries unhooked from the coach and connected to a 12v charger I have, I still have 11.09 on one and 9.79 on the other. I'm pretty sure the batteries are bad.

But, I also have concerns about my Parallax Power Center/Charger. It is outputting 13.89v at the charger and that drops to 13.69 at the batteries, so I think that is fine. Also, in almost every other respect it seems fine. Except, I have not heard it's cooling fan coming on, something I used to hear quite often. Is there any way I can test the cooling fan?

[wolfe10]

Step one is replace the batteries-- you know they are shot.

Step two will be to check charger performance and fan operation with the new batteries in place.

[QuiGonJohn]

Well I hooked everything back up together and went out to the RV later in the afternoon and the fan for the Parallax Power Center was running. So it looks like that is OK. Just need to pickup 2 new batteries, (I hope).

BTW, I don't know for sure how old these batteries are. I bought the coach in April 2012 and they were already in there. The date tags on these have each month and the numbers 1 through 9 and 0.

What is punched off (removed) from one of the 2 batteries is MAR and the number 1. What would that indicate as to when they were purchased?

[QuiGonJohn]

I was wondering about the pros and cons of switching from my current arrangement of (2) 12V batteries in parallel to (2) 6 volt batteries in series. I have been reading about Deep Cycle Battery Care and it is mentioned that many RVers switch to the latter configuration. Assuming both would fit in my battery well, which I believe they would, what would be the benefits and what would be the drawbacks? Also, if I switch, what type of 6v battery should I look at?

[wolfe10]

The debate over two 6 VDC batteries in series vs two 12 VDC batteries in parallel has been going on a LONG time.

Basically, for the same quality, chemistry (wet, vs AGM vs Gel) and total amp hour ratings, there is no clear answer.

The reason 6 VDC batteries are popular is that golf cart batteries are deep cycle and much cheaper (because of the production/marketing volume) than 12 VDC batteries of comparable quality and ratings. This is especially true of wet cell batteries-- much less so for higher-end batteries like AGM. So this sentence is meaningful: "Golf cart batteries are the least expensive deep cycle battery". NOT the best battery, but least expensive good battery.

First choice is what battery technology: wet cell are the least expensive deep cycle batteries (golf cart batteries). AGM's are more expensive but offer real advantages-- they are maintenance free, don't out-gas unless severely overcharged (they are even legal to ship by air freight in the U.S.), and, can accept a much higher recharge rate (important if dry camping and running the generator to recharge).

[QuiGonJohn]

So I started reading about using 6v vs.12v. And now I am more confused than ever. If the 6v's really last longer, as many claim, that may be a big plus to switching, especially if they are cheaper than the 12v, which is also what many claim. But to stay with AGM and a pair of 6v's it seems the good ones cost as much as the 12v ones. But again, if they hold up better, may be worthwhile.

[wolfe10]

Actually, you have a good handle on it.

Because wet cell golf cart batteries are sold in such huge volume, they are the least expensive deep cycle battery.

But, cost of production is not that much different between 6 and 12 volt. As I mentioned above, no significant difference in price when you get to AGM's of the same quality and capacity.

So, repeating, your first decision is whether you want/need AGM's. If not, golf cart batteries make a viable choice is sticking with wet cells.

[QuiGonJohn]

Well I was back at my RV Shop today and he was telling me that for my coach, it seems to have been setup for AGM. He thinks the converter was optimized for AGM and because the battery well is accessed from the floor in the coach, I need to stay with AGM's vs. flooded cell. He also said that the currents if I switched to 6v's in series might be different and again, that my converter was probably configured for (2) 12v vs. (2) 6v. So it looks like I will just replace with (2) 12v AGM's in parallel.

[wolfe10]

Well I was back at my RV Shop today and he was telling me that for my coach, it seems to have been setup for AGM. He thinks the converter was optimized for AGM and because the battery well is accessed from the floor in the coach, I need to stay with AGM's vs. flooded cell. He also said that the currents if I switched to 6v's in series might be different and again, that my converter was probably configured for (2) 12v vs. (2) 6v. So it looks like I will just replace with (2) 12v AGM's in parallel.

Some good observations, and some "hoodo".

While a smart charger or smart converter or smart inverter/charger can optimize charging perimeters for different battery technologies, they could care less if that 220 amp hour @12 VDC "battery" was made up of two 110 amp hour 12 volt batteries in parallel or two 220 amp hour 6 volt batteries wired in series.

I would agree that either interior installation and/or difficulty accessing them WILL favor AGM batteries, as they are maintenance free AND don't out-gas unless severely overcharged.

[QuiGonJohn]

Well in my case, it is interior installation. Removing the battery well cover in the floor is prettty easy. But out-gas into the living space would be the issue. Although the cover is supposed to be sealed pretty good.