Batteries

[James Walker]

Hi all, I need to replace my 6 volt coach batteries and I was wondering, in your opinion, which were the best to buy.  My coach is a 1995 Beaver Patriot, 37 ft.

[Jim Nichols]

We have always used 6v wet cells from Costco . We get 5 years on average and use the watering system from camping world.

[Joel Ashley]

My 4 Interstate Workhorses are nearly 11 years old, although likely about at their end.  The 2 starting ones still crank with enthusiasm.  This year I'll probably remove and take at least the house ones to Costco in exchange for their golf cart Interstates, as they seem to be the best value. 

There has been controversy about their hour rating, mostly due to confusion from whether one measures the hours a battery lasts at 20 or 25 amps, or 75.  The difference is substantial, and we need to take care about comparing apples to apples.  Costco's rating version is lacking, and part of the confusion.  The batteries nevertheless are just fine at ~232 amp hours for our purposes - the reserve capacity of the battery will theoretically push 1 amp for 232 hours;  around 120 mins. at 75 amps, 470 mins. at 25.

The Costco Interstates do as good as any, especially for the price.  But some here would rather spend more and do away with water level maintenance, buy AGM's, and some would spend more for the Trojan brand.  What you don't want to do is buy 12v deep cycles, because though tempting by the voltage, they have no where near the staying power (hour rating) of the lead content in 6v ones.

Joel

[Gerald Farris]

James,
I agree with the above post. I am using the Interstate 6 volt golf cart batteries from Costco. As a fulltimer my batteries are heavily used at times and they give good service at a low price which makes them the best value.

Gerald

[Paul Meehan]

I've had my coach for about a year.  All batteries are wet cells.  From the beginning I have felt I do not have the correct chassis batteries (2 each) as they are 12 Volt deep cycle and rarely start the engine after it has sat in storage for a week or two.  I engage the battery boost and all is fine.  Am I correct in saying I need a starting battery with as high CCA as possible?  House batteries are 6 Volt wet cell and perform well.

[Jim Edwards]

Hi. I might check current draw on the chassis batteries with all shut off. Might be batteries are fine but unexpected power draw. I was pinching one of the power cables in the back of the battery tray and as was having similar drainage issues. Started in short tern, needed boost occasionally, ran well but drained the battery. See attached Photos.   

[Gerald Farris]

Paul,
There are several issues that could be contributing to the starting difficulties that you are experiencing after a week or two of storage. The first and most common is caused by the parasitic drain by the ECM (engine control module). The keep alive memory draw by the ECM is between 1 and 2 amp for most computerized Cat engines, and since Beaver wired the ECM directly to the chassis batteries in your era of coach, bypassing the battery disconnect switches, that drain can discharge the batteries in one or two weeks enough to make starting impossible with using the boost switch unless a charging source is supplied to the chassis batteries. Also any other parasitic drain that is not removed would have the same effect.

Lastly we come to your chassis battery type. A true deep cycle battery has solid lead plates, and therefore it can withstand many discharge and recharge cycles with limited degradation to service life expectancy, but the solid plates give a very limited surface area that limits the peak amperage output for starting purposes. However, a starting (chassis) has lead plates that resemble a lead sponge, and therefore they have a much higher surface area that can deliver a much higher amperage for starting purposes. The down side to the sponge type plates is that discharging and recharging will very rapidly degrade the battery plates, and therefore make the battery useless in as little as 3 or 4 deep discharge and recharge cycles. That is why we use a high CCA cranking batteries for the chassis and true deep cycle batteries for house batteries.

There is a third type of battery that is commonly called a dual purpose deep cycle battery that tries to bridge the gap between the cranking battery and a true deep cycle battery technologies, and that is what almost all 12 volt deep cycle batteries are. The end result to this type battery is that it does not do either job as well as the battery that was designed for the intended purpose.

Gerald

[Paul Meehan]

Thanks Jim!  I will pull the battery tray out and check the cable conditions.  It is congested and I am sure cables are bent. 

[Paul Meehan]

Sorry to get away from James' original question!

Gerald,
I guess the roof mounted solar panel charges the house batteries and not the chassis batteries?  Thanks for your response.

[Jim Edwards]

To my experience it is true that the general intent of the solar panels are for charging the house batteries. BUT if equipped with bird and Big BOY relays the voltages can be such that the solar will be charging both house and chassis. See attached sheet . As voltages change, House and chassis are connected or disconnected. The up shot of this is just because you shut off the chassis batteries, doesn't necessarily mean house Batt. are NOT supplying power to chassis.  (at least on my coach as I unexpectantly discovered)
A way to think of it is the boost switch forces the house and chassis battery connection but BIRD relay is connecting them and disconnecting them in the background dependent on voltages of each.

[Paul Meehan]

Could the BIRD be a factor if after being connected to 50A shore power for two weeks the chassis batteries acted as if they were fully discharged?  The chassis batteries were supposedly new when we took delivery of the coach this time last year.  I have maintained the water levels.

Does the coach monitor panel (CMP-20) display any information related to the chassis batteries or is it just house batteries?

[Joel Ashley]

It has happened, Paul.  Some have discovered loose connections on the Bidirectional Isolator Relay Delay module.  I have to be sure to hand-guide its wires back into the compartment when closing the access door that the module is attached to;  otherwise they can get pinched.  I suppose your issue could also be the Big Boy solenoid that the BIRD controls.  But neither is a common malady. 

When on the highway, the BIRD lets the alternator charge the chassis set to 13.3v first, then lets the Big Boy switch charging over to the house batteries.  When plugged into city power, the BIRD moves inverter charger amps in just the reverse pattern - charging the house set to 13.3v first, then switching the Big Boy to allow amps going into the chassis set.  The solar system factors in when off the grid to charge the house set, then the chassis.

At least that's how I understand it;  others more familiar with details may argue differently or amend my take on it.  If your house batteries are fully charging okay, as per your remote screen panel in the coach, then it's probably not your inverter's charger aspect that's faulty (I don't have that particular system, but it should only be revealing house battery state of charge).

Usually the chassis set are maintenance free, so I'm not sure that maybe you were adding water to just the 6v house set?

Joel

[Jim Edwards]

Hi If you have Bird/big boy, and it was operating properly, and if inverter/charger set up correctly and connected to shore power for 2 weeks, The chassis and house batteries should have charged. I don't want to insult anyone but I have to ask. I know on my inverter there is a on/off for the charger. Is the charger on? (Again something I got to learn when I got started with my coach. Had connected to 30 Amp shore, shut the charger off to reduce a/c demand and I forgot about it. I figured it out the hard way a few weeks later.)

[Paul Meehan]

Good points Joel, thanks will check it out.. 
Jim, excellent point on turning the charger on.  After our trip we dropped the coach off for a few repairs when it dawned on me, did I turn on the charger?!  Will ensure it is on the next time out.

Thanks to all for your input.

[Gerald Farris]

Paul,
Your 2001 SMC era coach did not come with a "Bird" system. The "Bird" system was installed only on latter model Monaco built Beavers. However, your coach should have an Echo Charger to charge the chassis batteries when the house batteries are being charged. To verify proper operation, check the chassis battery voltage while the house batteries are being charged. The chassis battery voltage should be within a few 10ths of a volt of the house batteries, and if they are not, you need to trouble shoot your Echo Charger system. Call me if you need help with trouble shooting the Echo Charger.

Gerald