Replacement batteries

[Mike.Way]

I need to replace 2 chassis batteries. My question is:

Are the 750 CCA RV Deep Cycle Interstates at Costco adequate? This will be the third pair of Interstates in 5 years, in longevity little better than car batteries.

Thanks,
Mike

[Joel Weiss]

I guess I'm puzzled why you are using Deep Cycle batteries for the chassis.  The primary job of a chassis battery, I believe, is starting the engine.  My understanding is that you would always use standard automotive batteries for that purpose.  My chassis batteries are Interstates with 5 years on them and I'm first beginning to consider replacing them.

[Keith Oliver]

Deep cycle batteries!  I wonder if they would be a better choice for the chassis batteries, as they get deeply discharged from the constant load of the ECM, drawing them down at more than 2 amps continuously.  Regular readers will know that in 20 months of ownership, I have replaced my chassis batteries (in month one) and have seen them discharged to a level far below what a start battery is designed for, on at least three occasions.  Those discharged are due to failures in the charging system, but those failures seem to occur despite best efforts to prevent them.  Deep cycle batteries would have at least a chance of surviving those deep discharges.  If Mike is replacing regular Start batteries, for the third time in 5 years, he is getting lousy longevity on the start batteries, likely due to being deeply discharged at some point in their short life.  I get 6 or 7 years out of all my car batteries, (no ECM draws there), so I think there is a message in that.
There is a combining button that brings the house batteries into the start circuit if you need it.  When my chassis batteries were flat, the house deep cycles worked just fine as starting batteries, so why wouldn't deeps work just as well in the place of the chassis batteries?

[Joel Weiss]

Keith--

You may not be aware of it, but modern cars also have substantial current drains on their batteries; it's not just the ECM we have.  My E450-based Class C with the Ford V-10 would kill a battery in a couple of months if a battery-tender wasn't connected to it.  I had had my dealer check the current draw and verified it was within normal limits.  He said it was always a problem at the dealership when customers would want to test drive vehicles that wouldn't start because their batteries had been drawn down.

From my experiences, the Echo Charger included in my MH prevents drawdown of the chassis battery while we are parked and plugged in.  I have 5-year-old chassis batteries and am just considering replacing them.  My house batteries are a little over two years old and appear fine (for our limited needs, anyway).

As for the use of deep cycle batteries in place of starting batteries there appears to be no particular concern that I can find, other than the fact that the battery should be oversized by ~20% to allow for the reduced cold cranking amps that a deep cycle battery produces per kg in comparison with a starting battery.  The use of solid plates reduces the effective plate surface area which reduces the maximum current.

Joel

[Joel Ashley]

Solving poor chassis battery longevity by replacing them with deep cycles is not an optimum solution.  My coach is over 6 years old and the factory batteries are still going strong.  A big diesel needs the cranking amps of a true chassis battery, and Mike, you would be best off sorting out what mechanical or procedural failure is ruining your batteries.  I'd start first with professional alternator and inverter charging checks.

Joel

[Gerald Farris]

Mike,
The batteries that you are referring to are undersized as far as the CCA (cold cranking amps) is concerned. The chassis batteries in your coach should be rated at about 950 CCA. While the 750 CCA batteries that you are considering are below specifications, they will probably serve your purpose when new but since they are marginal at best, you will not see the long life that you are looking for, because as their capacity drops a little with age, they will no longer start your coach, although they will still function quite well for their original manufacturer's intended purpose.

I would determine the failure reason for the chassis batteries, such as an inoperative Echo Charger, and replace the batteries with cranking batteries. If you do not allow your chassis batteries to discharge, they should last in the 4 to 7 year range, depending on the use and climate conditions.

Gerald  

[Keith Oliver]

Joel:

Interesting observation.  As my newest car is a 2005, I have been spared the parasitic load that you reference and have experienced long life out of my car batteries, even when unused over long periods.  EG, my 2005 XC90 was left unattended and unlicensed for 5 months last year and started on the first crank. Its battery is the original from 2005. It was again left unattended for 5 weeks ending 2 days ago and again started on the first crank.  My 2000 S70 has had its battery replaced twice, the last two or three years ago, so I expect it to last a while longer. It is presently unattended (not plugged in either) with the Beaver in SoCal while we are home for Christmas and I expect it to start on the first crank.  The Beav is plugged in with a dedicated charger on the start batteries.

Gerald:
My point is that you can't rely on being able to "If you do not allow your chassis batteries to discharge, " so as to get the rated life from your start batteries.  I have, in 20 months, had a bad echo charger and a bad dedicated smart charger, both allowing a total discharge of the chassis batteries.  I can't be the only one with that trouble.

[Mike.Way]

Been out all day, not sure I can marshall my thoughts to reply succinctly.

Thanks Gerald that was what I wanted to know.

Now in order:

Why RV deep cycle?  Because that is what I had used in 25 years of trailering and I wanted to know applicability.

Charging problems?  I doubt it, alternator rebuilt 2 years ago, new Magnum charger inverter about the same time.  Echo charger shows fine. Some sulfites on the poles though.

Battery problems?  I live in Florida.  Around here car batteries with bad cells are typically replaced at around 30 months. I usually buy mine at Costco and they carry Interstate here.  Never had one that lasted 5 or 6 years.   Heat and humidity kills them.

We have not been traveling a lot in the last year or 2.  I normally can not keep my coach plugged in when not on the road and the draw down can be severe.  It is not unusual to have severe lightning strikes in our area very, very near.  That is why I have a whole house surge as well as battery backups on house hold electronics.  Not sure what effect that might have.

So I will travel down to the Interstate shop and get some 950's.  Hopefully the move to Oregon and a planned MH garage will help the situation.

Thanks all,

Mike

[Edward Buker]

The chassis battery issue of a shortened life in these coaches is something I have experienced also. When i bought our coach the chassis batteries were 12 months old, but one failed in the next three months on the road so i bought heavy duty versions from NAPA and replaced them both. That set had a failure in 20 months so I replaced them once more. The alternator is well regulated and has never indicated any over voltage condition, the echo charger and inverter charger are on literally all the time in our coach, and the voltages and charge curves are as they should be. When the NAPA set failed I popped the covers to check electrolyte level even though these are maintenance free. I was thinking the electrolyte level from the constant charging may have boiled out and caused some plate exposure but they were fine. So that leaves the possibility of heat killing them, but that side of the engine compartment and battery location is not an overly warm environment. The other failure mode is from vibration. My guess is that these batteries fail due to plate or plate insulator failure from vibration. I say that because I get no signs of diminished capacity like from sulfation, they crank fine and then one day they do not, even though they are being charged and have been kept charged. This also happened while on the road as opposed to being home plugged in. The other indicator that this is so, is the 6 deep cycle 6V golf cart batteriies see the same vibration and heat and survive just fine but the plates are thick and the construction technique is much more rugged for this duty. I think getting a long life out of these starting batteries is luck of the draw regarding construction and defects. I have always replaced these batteries in pairs but Gerald wisely pointed out that he does not, just the defective one. That is what I will do if the alternate one is 4 years old or less from here on out given age and sulfation does not seem to be an issue. I'm sure there are many cases where deep discharge for one reason or another has shortened the life of a set of chassis batteries but that has not been my issue. I bring this up because there may be an argument for a stronger battery design having a longer life as a chassis battery. I'm not sure what configuration or brand that would be and still provide adequate CCA.Just food for thought especially if someone has had exceptional luck by brand or type.

Later Ed

[Joel Weiss]

Even though I have 5-yr-old chassis batteries and haven't experienced the problems you refer to, I do have an idea as to how the problem might be arising.  When I first bought my coach two years ago I was surprised that none of the batteries were tied in place in the battery tray.  I had always been taught that batteries had to be tied down securely to avoid vibration-caused failure.  I can understand how the thicker plates of the golf cart batteries may make this unnecessary for them, but I wonder about the chassis batteries with their far thinner plate assemblies.

Has anyone thought about this previously? I would think that a small ratchet strap (or two) across the two chassis batteries would keep them from moving vertically.  I may put one on mine just as a precaution.  

[Jim Nichols]

Still have the original 2005 (2) Cat batteries. When that time comes my choice will be Cat batteries as they are built to take the vibration and cold crank amps.

[Mike.Way]

Final resolution.  A pair of NAPA Commercial type 31. 925 CCA.  

$98 each; 18 months free replacement, 36 months prorated.

According to the NAPA guy Interstates are now built in Mexico, Delcos in Viet Nam and the Napa's are made in eastern Pennsylvania.

Mike

[Mike.Way]

Good news and a correction

Correction, the batteries were 109 each.

Good news, they are installed, the coach started.  We are now on a 14 day count down to out'a here.

Thanks again for your thoughts and help.

Mike

[Norm Green]

I have found this discussion very interesting.  If my coach is not plugged in, the chassis batteries seem to discharge to the point where they will not turn the engine over after only a few days and I have to use the battery boost switch.  I'm not sure of the year of the batteries and I have only had the coach for 6 months.  I normally keep the coach plugged in at home but there are times when that is not possible.  I am certainly considering replacing them but I'm not sure if there is not some significant draw on them while parked that is drawing them down or if they just do not hold a charge like they should.  I have considered installing a battery cut-off switch on the ground wire, maybe similar to the attached, which should remove the possibility of any drain and thus discharge when not plugged in.  Has anyone used this method or is it advisable?

http://www.amazon.com/BATTERY-CUTOFF-SWITCH-BOAT-RACECAR/dp/B001HSBW74/ref=sr_1_1?ie=UTF8&qid=1354719663&sr=8-1&keywords=battery+cutoff+switch+car+rv+boat+racecar+atv+cut+off

http://www.amazon.com/Wirthco-20108-Knife-Blade-Battery-Disconnect/dp/B002OWFLC4/ref=sr_1_16?ie=UTF8&qid=1354719745&sr=8-16&keywords=battery+cutoff+switch

[Edward Buker]

Norm,

If there is a current draw breaking the ground circuit would be a good method to use. The screw type disconnect I think is a better configuration than the knife switch. I do worry about the hand tighten connection coming loose with vibration while driving. As you pull the battery tray in and out there is cable pressureand flexing involved also. If you have a source I would recommend that you first get someone with a meter, either clamp on with a low DC scale, or one that you can put in series with the ground lead. With the coach disconnected from shore power and everything you can think of off in the coach measure the current draw. If it is 200 milliamps or less you probably do not need the modification. If it is a half amp or more and you go for extended periods not plugged in I would add a disconnect. These measurements are to help sort out the battery question and not necessary if you just want to go ahead and add a disconnect. My chassis batteries have a 1.7 amp load all the time as an example and I share the problem when not plugged in.

These starting batteries produce a lot of current and diesel starters pull a lot of current. My first choice would be a marine battery disconnect switch, something like this, that is rated for the current involved and built to marine environment standards. They are inexpensive and once mounted and set up should be trouble free. You would move the current battery lead to one side of this switch and have a suitable length cable made or purchsed of similar guage wire with the proper lugs to go from the switch to the battery connection allowing for tray movement. Hope this helps.

http://www.wholesalemarine.com/p/BSS-6006/

Later Ed