Community Forums

ischua · 05-22-2011, 05:32 PM

My cheap house battery has given up. My question is as there is only room for one battery whats my best bet for a 12v deep cycle that won't die in 24hrs only things running will be the fridge (on propane) and a few led lights for more than that I can run the generator. I just want to know I can still start the generator in a couple of days

pwf16129 · 05-22-2011, 09:05 PM

i'm in the same boat with room for one battery i installed an agm that is as big as will fit and have been very happy with it i had lit the fridge two days before we left on vacation an the day before she loaded the fridge left a couple of lights on none led and walked off. went out the morning of the trip to leave lights still bright fridge running charged right back up
happy rving frank,cricket and harley

BryanL · 05-23-2011, 10:34 AM

No matter what battery you get as a replacement, it isn't going to solve this problem. AGM, 'true deep cycle', super brand name, whatever ... you get about 12 watt hours per pound of battery. Lead acid batteries are commodities and the differences are minor. Buy from a retailer who sells a lot to folks who use them like you do and will stand behind what he sells.

Where I suggest you start is in your battery charging and maintenance equipment - your RV converter. It needs to implement intelligent multiple stage battery charging plus an effective battery maintenance mode that keeps up a full charge and also does something to inhibit sulfation. This last, a good battery maintenance mode, is often the most overlooked part but most critical to keeping a battery healthy.

The refrigerator and alarms and other residual minor loads generally total less than 20 watts. At 12 watt hours per pound and a typical 60 pound battery, that means that a battery in good condition will handle the load 720 watt hours / 20 watts for 36 hours. Most folks have lower residual loads so the battery will last perhaps twice as long or more.

Also keep in mind that is takes longer than 8 hours to fully and completely charge a lead acid battery. Prompt and vigorous recharging coupled with an effective maintenance regime when the battery is not in use are keys to a long service life.

The most common ways to kill a battery include keeping it in a hot locale, letting it sit without proper charge maintenance and sulfation inhibition, and discharging too deep. Batteries don't usually fail dramatically, they just loose their ability to store the energy they did when young. If you use and maintain them properly, you should be able to get 5 years of so from them before the capacity drops much more than 20%.

ischua · 05-23-2011, 03:08 PM

Thanks for all the help
I picked up a AGM battery today to replace the WM special I had
My next question is I have no idea what my RV converter is or what its doing.(besides output voltage)
But as its 25 years old I doubt that its a multi stage anything..... So can I put an automatic charger/maintainer on the battery
while plugged in to shore power without doing damage? Most of the time nothing is on except the fridge

RJay · 05-23-2011, 03:25 PM

Hi Mike,
I would go with the charger/maintainer. A long slow charge is the best thing you can do for a battery, especially a new one. Batteries don't like a 60 amp charge over 4 hours, the battery doesn't properly charge and it takes the life out of the battery. So set your charger on its lowest setting an let it charge for 2 or 3 days and your battery will be fully charged ready to go. What size battery did you get?

BryanL · 05-23-2011, 04:07 PM

A modern converter such as the Progressive Dynamics ChargeWizard or WFCO can do a lot to provide good battery life. These can be installed and then the only thing you need to worry about is keeping everything plugged in so they can do their thing to charge and maintain your RV battery bank.

I disagree about the 'long slow' because that does not stir up the electrolyte and help prevent sulfation. Both of the converters I mentioned will charge a bit more rapidly at the start and this is not only good for the battery but also helps get the most from those times when you only have a genset to charge with for a few hours. The voltage you get from an RV converter isn't high enough to really pump charging current into a battery for any length of time.

Those converters also have a maintenance mode that will keep a top charge on the battery and inhibit sulfation buildup. The maintenance mode is often neglected, especially the sulfation inhibiting technique.

wa8yxm · 05-23-2011, 04:13 PM

The problem is any battery of the SAME SIZE is most likely going to be the SAME Capacity.

So... Here is what I advise.

Flooded wet cells. (If you can find 'em in 12 volt) are the least expensive but.. Take much more care and feeding, Must be mounted THIS SIDE UP.

Maintenance free.. Less care must be mounted THIS SIDE UP.

AGM: Also less care, like M-F, need not be mounted this side up.

NOTE: There is new technogoly in the piple More usable amp hours.. No this side up, BIG BUCKS however.. search on LiOn.

In any given type of battery. (Save Optima, avoid Optima, I will explain)

For the same size factor the amp hours will be right close, be it a starting, marine, marine/deep cycle, or deep cycle.

The difference is the usable amp hours. and the ability to recover from an "OH !!!!! I ran it dead"

Deep cycle can be taken to 50 percent with out major damage, other types like to be keept fuller,, Deep cycle are also the most likely to recover from an OH !!!!, (But that does not mean the will.. just they are more likely to than the other kinds)

That's about all I can say.

OH, I promised to explain why you should avoid optima.

Optima is only 3/4 battery, 1/4 air, and 4/3 price.. So you pay more and get less for it,, That's way, less amp hours.

ischua · 05-25-2011, 05:31 PM

First I want to thank everyone
When I removed the old battery I found that it was hot to the touch and the converter running merrily away. This one is cook I think. I was able to fit one Trojan Group Size 27(620cca) into the compartment . I then placed the charger/maintainer on the battery and plugged everything back in at day two the converter is off and the C/M is in maintenance mode and all is good. I will put it to the test this weekend.

mrblanche · 05-28-2011, 06:23 PM

Quote:

Originally Posted by ischua

My cheap house battery has given up. My question is as there is only room for one battery whats my best bet for a 12v deep cycle that won't die in 24hrs only things running will be the fridge (on propane) and a few led lights for more than that I can run the generator. I just want to know I can still start the generator in a couple of days

Exactly how large is the space you have?

A diesel truck battery would be my first choice, if it will fit. You might check with a Volvo truck dealer...they were selling a starting battery that also could deep cycle. Pretty reasonably priced, too.

brewster03rk · 06-04-2011, 07:50 AM

I needed a new batt for my 85 chevy/midas freeport, so having access to some used 12v 35ah deep cycle batteries (all still pulling 12.5 or better on the load tester), I wired 4 of them together in parallel with #4 battery cable, copper eye connectors, under the dinette seat, for what I figure is a combined 140 amp hours. I don't expect I'll be running out of juice on an overnight draw. :-)

wa8yxm · 06-04-2011, 09:04 AM

Re-reading this thread I see you commented on the quarter century old converter.

Yes, odds are good it is a single stage like a Magnetek 6300 (6345 was very popular) These are well known battery killers as they either never fully charge, or seriously over charge.. AGM's won't like that.

(I still am anti-AGM by the way)

Back to converter: I'd seriously consider an Upgrade.. Progressive Intellapower 9200 line or IOTA with IQ4 technology or Xantrex True Charge, all good converters (Not by any means the only good ones)

BestConverter - Converters, Inverters, Electrical Supplies, Electronics

Has links (Extra INfo frame) to "how to upgrade" has upgrade kits and all the top rated converters you could every salivate over.

ischua · 06-05-2011, 08:50 AM

wa8yxm thanks for the link.
Another question on using a charger/maintainer. Does the charger/maintainer have to be
at the battery itself or can I attach it at the converter? There is no room in the compartment for anything other than the battery and I would like to find an inside option for mounting. Thanks

RJay · 06-05-2011, 09:00 AM

Having the charger/maintainer(CM) at the converter is probably OK since the CM doesn't have the output of the converter so voltage drop isn't a problem. If you can take voltage measurements at the battery once the CM is connected and working. It should be in the range of 13.2 to 13.8 volts DC.

Conquest102 · 06-05-2011, 09:04 AM

I replaced my 6345 with one from best converter it was a fast and easy switch buy the kit w/new fuse block. It was complete with new screws and a new lock for the door even. Took me about 30 mins now reads 13.5-13.6 ALL the time. The web site even had step by step pictures to follow. I hate doing electric so this made me very at ease doing it. You might want to look into some solar panels as well they won't do it all but they will help put some power back into the battery.