Community Forums

eflester · 05-19-2013, 12:44 PM

I'd be grateful for a little input. Short version of story: I think my house batteries are due for replacement. Latest test procedure: took them to an auto parts store and had them load tested. Tech there said the batteries were fine, and that they were fully charged. Being skeptical, I stopped at a second vendor, who also--after load testing--said the batteries were fully charged, and in good condition. I took the batteries home and connected them to the MH. I turned on 3 interior lights and the FM radio and let the MH sit for about 7 hours. After that time, I found that the batteries were absolutely dead. Measured less than 7 volts across them.

We recently tried some dry camping with these batteries (2- "Diehard" deep cycle, size 24, rated at 135 minutes RC) and they seemed to run down very fast. After recharging with our onboard generator (4KW Onan) for about 2 hours, they ran down in about an hour and a half.

I'm leaving out many (boring) steps I've taken in this troubleshooting process, but the only question I have left is, how likely is it that the batteries are NOT the problem? I was somewhat concerned that the onboard converter may not be allowing a good charge, but having the batteries charged "outside," and then finding the above level of performance, which I think is unacceptable, I'm more or less concluding that the batteries need to be changed out. They have a mfr. date of March 2008.

We have a 2004 Winnebago Minnie (class C) 29B, which we have owned for nearly 3 years. These batteries were in the MH when we bought it. I don't know if they are the originals (OEM) or replacements. We haven't done a lot of dry camping, but I seem to recall better performance from the batteries on occasions in the past.

This may be educational for others: apparently, if my conclusion is correct, the testing procedures available from automotive businesses aren't really useful for those of use using deep-cycle batteries for our homes-away-from-home lighting and appliances.

Sorry for the long post, I guess I like typing.

CHCam42 · 05-19-2013, 01:22 PM

Elflester diehard deep cycle sounds like a 135 ah battery. Not designed for your application. Most MH come with deep cycle 235 ah batteries two or more. The time you used them adds up to the total available hours. Trojan T-105 are 6 volt 235 amp hr batteries and are designed to be recharged many times. They don't last long if you run them below 50%. There are many mfg of deep cycle batteries you can choose from. You do not want a battery that is rated in cca cold cranking amps.

eflester · 05-19-2013, 01:32 PM

Hmm. Well, actually, if I convert RC to AH, these batteries are about 56AH. That's a far cry from even 135AH. Perhaps I'm simply trying to do too much with too little? I don't know. As I said in my post, I have used these in the past (they are the only batteries that have ever been in the MH as long as we've owned it) with better results, it seems. But your point is well taken. We may need to shop for something with a lot more capacity. Thanks very much for your post.

RickO · 05-19-2013, 01:37 PM

Hi and welcome to the forum.

The batteries may well be the wrong size for your application... but if they were in the coach when you bought it three years ago I'm betting it's time for a change. I'd do some research on the best batteries for your application and plan on getting a couple.

Rick

Coaster1 · 05-19-2013, 01:44 PM

Just replaced 2 group 24s wet cell with glass mat group 24 (fitment). The seem to recover faster.

TQ60 · 05-19-2013, 02:26 PM

Search the Forums for Battery testing, engineering, troubleshooting and repair.

There is extensive information already here to assist you in determining exactly what you have in capacity and determining your run time

GaryKD · 05-19-2013, 06:05 PM

Hi eflester,
A load test on fully charged batteries will tell you if there is a bad cell, or the batteries are completely dead. It may not tell you if they are just worn or wearing out. One can put a clamp on AMP meter and test for draw. Because you got the batteries when purchasing the coach, you do not know their history. Gut feel says it is time to replace the batteries.

An easy test is to charge the batteries turn everything in the coach off. This includes any master switches. There may still be a bit of a parasite draw but this should make no difference if the batteries are good. Let the batteries sit for a couple of days (no charging). The batteries should remain at full charge. If the measurement shows more than a 1/10 volt drop, the batteries a just worn out.

eflester · 05-19-2013, 07:12 PM

Thanks to everyone for your helpful remarks. I did do the test that GaryKD recommended about a week ago, and there was a drop of about 0.4V, as I recall. I'm getting the feeling that these batteries are a little worn out, but I'm wondering about the replacement. I see that many people use 6V batteries in series. 6V batteries have a higher current rating, but will produce less power (P=IE), so I wonder if there is any real advantage to using 6V batteries, or if it's a case of folks seeing the higher AH rating and deciding it must be a better battery. I'll be doing more research and picking the brains of anyone I can get to listen, and I'll let you all know how it turns out.

Anyone else?

Dmiles · 05-19-2013, 08:55 PM

LOVE my Glass Mats!

tompen · 05-20-2013, 06:47 AM

Just something to consider. Charging the batteries for 2 hours from dead will not recharge them. It may put a surface charge on, but that's all. Charging with the generator is the same as on shore power. Available charging amperage is cut in half with two batteries. They may still be under size for what you want, but the 1 1/2 hours is probably because they were not charged up.

DAN L · 05-20-2013, 11:59 PM

Quote:

Originally Posted by eflester

I'd be grateful for a little input. Short version of story: I think my house batteries are due for replacement. Latest test procedure: took them to an auto parts store and had them load tested. Tech there said the batteries were fine, and that they were fully charged. Being skeptical, I stopped at a second vendor, who also--after load testing--said the batteries were fully charged, and in good condition. I took the batteries home and connected them to the MH. I turned on 3 interior lights and the FM radio and let the MH sit for about 7 hours. After that time, I found that the batteries were absolutely dead. Measured less than 7 volts across them.

We recently tried some dry camping with these batteries (2- "Diehard" deep cycle, size 24, rated at 135 minutes RC) and they seemed to run down very fast. After recharging with our onboard generator (4KW Onan) for about 2 hours, they ran down in about an hour and a half.

I'm leaving out many (boring) steps I've taken in this troubleshooting process, but the only question I have left is, how likely is it that the batteries are NOT the problem? I was somewhat concerned that the onboard converter may not be allowing a good charge, but having the batteries charged "outside," and then finding the above level of performance, which I think is unacceptable, I'm more or less concluding that the batteries need to be changed out. They have a mfr. date of March 2008.

We have a 2004 Winnebago Minnie (class C) 29B, which we have owned for nearly 3 years. These batteries were in the MH when we bought it. I don't know if they are the originals (OEM) or replacements. We haven't done a lot of dry camping, but I seem to recall better performance from the batteries on occasions in the past.

This may be educational for others: apparently, if my conclusion is correct, the testing procedures available from automotive businesses aren't really useful for those of use using deep-cycle batteries for our homes-away-from-home lighting and appliances.

Sorry for the long post, I guess I like typing.

i really like my 6 year old lifeline agm batteries.

Lifeline GPL-6CT Battery

The 12volt Side of Life (Part 1)

BatteryStuff Articles | Guide to Understanding Flooded, AGM, and Gel Batteries

UFO Pilot · 05-21-2013, 12:29 AM

Quote:

Originally Posted by DAN L

i really like my 6 year old lifeline agm batteries.

Lifeline GPL-6CT Battery

I have had mine for 4 plus years and am very satisfied. I accidentally drained them recently and they bounced right back. They are pricy but they work and are maintenance free.

eflester · 05-21-2013, 07:57 AM

Again, thanks for the helpful replies. This is exactly what I was looking for, the result of your experience. In the course of this project, I've read a lot of great technical articles (The 12V Side of Life is terrific, and so is the Deep Cycle Battery FAQ. For information about the AC wiring in most RVs, this is a very good site) but your personal stories are particularly valuable. Getting the "feel" of how these things should behave is the reason I'm here.

Experience is the best teacher, but she's tough.

I have decided to replace the existing batteries with the largest ones that I can fit into my battery box. I found some series 31 12V batteries at Les Schwab yesterday, and they are about all I have room for.

After I get them installed I'll test them over the next few days. I am still thinking about replacing the converter with a Progressive Dynamics 9200 series device, as they seem to have a good design for charging, and a good reputation.