Replacing house batteries

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Replacing house batteries

April 02, 2011, 09:40:12 am

I would like to thank all the members of this forum for the insight and assistance they have provided advising me as to my battery issues. It truly is a wealth of knowledge. As I mentioned in a previous post, Ruby has 6 house batteries, 3 batteries for each inverter. These are Northstar AGM batteries with over twice the capacity of what is normally used. One group of 3 is definately bad, as they will not come up to voltage and remain hot. These batteries are 5 years old and I am questioning the wisdom of replacing just 3. Also, does anyone have any insight or ideas on how I might more effectively vent the battery compartment to avoid future issues, as I have been told excessive heat is a battery killer. The compartment is currently vented by only 2 approximate 2 inch holes through the floor. I was thinking maybe some additional vents and a power blower to facilitate air exchange. Thank you so much for your help. I hope we have the opportunity to meet in person.

Gregory & Judy
2003 Designer.

Re: Replacing house batteries

Reply #1 – April 02, 2011, 10:11:11 am

You don't need a lot of air movement. A pair of computer case fans (I have tons of them laying around) work very well, draw little power and are 12V. Add a cheap thermostat if you want. I'll send you some if you can't source some locally. 5-10 cubic feet per minute is a lot of air movement in an enclosed space!
Total cost of two case fans and a simple thermostat is likely under 25 bucks and an hours work.
Since they are already divided into 2 banks, I wouldn't have a problem replacing the 'known bad' 3. At 5 years they may be getting long in the tooth anyway.
Are you planning on a lot of boondocking (and not running the gennie)? If not I would just replace the bad ones for now as you don't need a whole lot of capacity. Your alternator and/or generator will run everything on the road. You are keeping it plugged in in storage...

Dave Head

Re: Replacing house batteries

Reply #2 – April 02, 2011, 10:54:35 am

Greg
My batteries are in that sealed compartment also. In the summer months it gets over 90 - 100 in there. I have always had an issue with how long it takes to charge the batteries with the generator. Sometimes 10 - 12 hours because of temperature compensation charging. I have 3100 hours on my gen already. The only way I can charge faster is unplugging temp sensor which is not good. I went under coach and found PVC vent to compartment and put a marine inline blower. I tried it both ways blowing and sucking with no help to inside temp. I am dry camping today and charging right now and it is working great because temp is lower. I have not come up with an answer on how to cool that compartment when batteries are that hot inside. I am now getting ready to replace them with agm's in the hope that they can handle the heat better. I have talked to James T in the past with no real solutions because of the sealed compartment. Barry L and I have discussed how could we get an a/ c duct down there : ( out of desperation. If there is a solution I have been unable to solve it

Barry
Barry and Darlene Brideau's Personal Website

Re: Replacing house batteries

Reply #3 – April 02, 2011, 11:21:46 am

Maybe there's a lot more air movement needed than is current thought. We all know that multiple openings are needed to vent fresh cooler air into the compartment and expell the hot air out. My thought may not go over too well for the purists. That is, add a drier vent to the compartment door with a fan attached to the inside of the vent which forces air out of the compartment...FWIW.

If the drier vent is not visually appealing, then perhaps a body shop can add "slits" to the door...but that may allow water into the compartment. A small "hood" over the slitted area may be needed...again, perhaps not visually appealing.

Re: Replacing house batteries

Reply #4 – April 02, 2011, 11:46:04 am

I like that idea. Thanks Peter
Barry
Barry and Darlene Brideau's Personal Website

Re: Replacing house batteries

Reply #5 – April 02, 2011, 12:11:42 pm

We don't do a lot of dry camping, actually, hardly any, and I do leave it plugged in when in storage. I am the type of guy who likes things 100%. As far as cooling the batteries, can anyone tell me what the construction in the floor consists of. I was thinking of adding extra insulation to shield the aquahot, which is directly behind the battery department, and opening 4 - 2 in diameter holes on the floor at the extreme bottom rear, ducting a blower to remove heat from the ceiling of the compartment and blow it out the bottom near the door. I know these batteries are expensive, but you get what you pay for.

Re: Replacing house batteries

Reply #6 – April 02, 2011, 12:34:11 pm

In that case I would replace them all.

After you make your openings, run a PVE pipe from one to a few inches from the top of your compt and mount your fan on top of it to 'push out'. Mount another fan at the other opening to 'pull in' at the bottom. If you want to be way neat about it mount dryer outlets underside pointing to the back so you have no worries about water splashing, etc. Buy a simple thermostat and wire the negative to the control. Power it directly off one of the batteries. Set the thermostat to about 80 degrees and you will be fine.

Re: Replacing house batteries

Reply #7 – April 03, 2011, 11:12:13 am

my recent experience on replacing only 1 out of 3 type 8D house batteries (instead of all 3 even though 2 where still ok) turned out to have cost me over $1200.00. The new one soon affected the original 2. As I was throwing a bunch of money away I figured while I was at it I would change to Lifeline AGM type. The old batteries were put in 2005, so it was close to time up for them.
John

Re: Replacing house batteries

Reply #8 – April 03, 2011, 11:19:59 am

John,
Thank you for being willing to share your experience. Hopefully, others will learn from this.

Re: Replacing house batteries

Reply #9 – April 03, 2011, 11:40:05 am

Does anyone recall the "downdraft" tubes on the old cars that was used to draw out the fumes from the engine crankcase? It was a passive system with no moving parts, just the tube projecting below the frame/engine. Would something like that work?

Re: Replacing house batteries

Reply #10 – April 03, 2011, 01:00:47 pm

Those best worked from a venturi effect - the coach has to be in motion. Since heat rises - if the coach is parked it wouldn't be very effective.

Re: Replacing house batteries

Reply #11 – April 03, 2011, 01:30:51 pm

Dave, you are correct, but I was thinking in conjunction with fans, louvers, and intakes. One is effective while moving, one plus whatever would be effective while stationary. A grill such as is used for the outside access/cooling on the side of the coach for the refrigerator? Probably the least expensive and simplest remedy for ventilation. (I tend to think "K.I.S.S." method a lot)

Re: Replacing house batteries

Reply #12 – April 04, 2011, 12:05:26 am

Quote from: nitehawk – April 03, 2011, 01:30:51 pm

Dave, you are correct, but I was thinking in conjunction with fans, louvers, and intakes. One is effective while moving, one plus whatever would be effective while stationary. A grill such as is used for the outside access/cooling on the side of the coach for the refrigerator? Probably the least expensive and simplest remedy for ventilation. (I tend to think "K.I.S.S." method a lot)

Here is what I tried to exhaust the heat to no avail. It was so loud that I was glad it did not work. The 1st photo was the pvc vent I found under the coach coming from the battery compartment.

Re: Replacing house batteries

Reply #13 – April 04, 2011, 11:27:08 pm

Barry,
Is there any reason that battery compartment needs to be so closed off? Mine is accessible through a panel (about 18"x18") from the joey bed bay. If yours is same, would it help to replace that solid panel with a wire panel of some kind? In my layout, that would effectively open the battery compartment to the large storage compartment, which also is open to the inverter compartment.
Mike Spitz
2003 U295

Re: Replacing house batteries

Reply #14 – April 05, 2011, 08:37:03 am

Mike,

I would certainly isolate the batteries from storage mechanical or electronics areas. The out-gassing when charging all but AGM batteries is not good for other materials (sulfuric acid vapor) and one of the byproducts (hydrogen) is explosive. That is why the battery compartment is vented overboard. More air flow that exhausts overboard is great.

Brett

Re: Replacing house batteries

Reply #15 – April 05, 2011, 10:43:08 am

With non-sealed lead acid batteries, hydrogen is produced when they are charging. A spark from a fan in an enclosure could result in a bang. This is one of the big reasons to connect the ground cable on a set of jumpers to a bumper or engine block instead of the battery terminal (connect last, remove first). I have seen one blow and spray acid everywhere when the cables were removed after a charge.

Pierce & Gaylie
93' U300/36

Re: Replacing house batteries

Reply #16 – April 05, 2011, 05:19:39 pm

Hydro-caps are the answer for non-sealed lead acid batteries (golf cart). The catalyst changes the gas back to water so you don't have to service them and there is no gas to explode or cause corrosion.

Re: Replacing house batteries

Reply #17 – April 06, 2011, 09:24:21 am

Quote from: michaelespitz – April 04, 2011, 11:27:08 pm

Barry,
Is there any reason that battery compartment needs to be so closed off? Mine is accessible through a panel (about 18"x18") from the joey bed bay. If yours is same, would it help to replace that solid panel with a wire panel of some kind? In my layout, that would effectively open the battery compartment to the large storage compartment, which also is open to the inverter compartment.
Mike Spitz
2003 U295

I think the 18" X 18" cover is to prevent anything flying into the batteries.
I am thinking of doing the mesh cover to allow a little more air circulation or drill a bunch of holes in the cover & put the mesh behind it. We have the same arrangement as you.

Re: Replacing house batteries

Reply #18 – April 06, 2011, 11:11:17 am

Metal mesh cover? corrosion from battery acid fumes possible?

Re: Replacing house batteries

Reply #19 – April 06, 2011, 11:43:51 am

Quote from: nitehawk – April 06, 2011, 11:11:17 am

Metal mesh cover? corrosion from battery acid fumes possible?

Thinking more of a plastic mesh on a wood frame

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