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Intro and a couple of questions
Hi everyone! My wife and I just bought a 1999 Prevost Marathon- our first RV. We have been busy getting up to speed on the systems, cleaning and fixing things as we go along. Not surprisingly I have a couple of questions.
Question 1: Our house bank does not hold a charge well and charging current drops off quickly. Can a Marathon house bank be equalized? Lifeline recommends equalization if there are frequent 50% discharges. How does one protect the house systems from the 31V during equalization? If I turn every DC consumer off, am I good to go?
Question 2: When connected to shore power, the chassis batteries do not seem to get charged. Is this normal for a Marathon conversion? Should I install an echo charger http://www.xantrex.com/power-products/power-accessories/auxiliary-battery-charger.aspx or use the engine bay outlet to hook up a normal 24 volt charger?
Thanks for your advice,
Gerald & Pam
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18 Replies
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I am not familiar with Marathon conversions, but in general I would get to know the coach and because of your post the first thing I would do is isolate each house battery and test it after they have been charged and the inverters go into float. Just based on what you said I suspect they might have problems. Even if the issue is one failed battery they need to be replaced in sets.
Typically your chassis batteries will not be charged from shore or generator power, however some conversions do have chassis battery chargers installed by the converter. Generally speaking you do not have to charge chassis batteries, so if they are losing their charge over a short period of time you either have a battery issue or you have a phantom load. Again, checking the batteries seems called for.
In your new-to-you Marathon try to get to know it. Learn the systems, learn what capabilities the coach has such as chassis battery charger, or a way to connect the house and chassis batteries if needed for starting, etc. I think Sawdust refers to this knowledge as weapons in your war chest. Knowledge of your coach is very important and your best resource is your converter, manuals, your own knowledge, and advice from other owners of the same or similar vintage Marathons. Keep in mind these coaches seem overwhelmingly complex initially, but if you take the time to develop an understanding of your coach and its systems you are likely to find they were designed and built with a great deal of logic and reliability making them not so scary.
Ask questions here, expect answers here, and sometimes the answers will actually be right. (I’m kind of kidding. On a forum you have to learn how to separate the wheat from the chaff)
If you need batteries or need battery information Tom is the guru. Your question about equalization is best left to him to discuss.
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Oh, and welcome to Prevost Community. Great bunch of folks.
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I have nothing to offer, other than a welcome. Glad you are here!
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Welcome to the forum.
After you test your chassis batteries and determine if they need to be repalced, Install a Guest battery charger to maintain them. I have mine plugged into the recepticle that is just above the rear engine doors.
If you do a search for “charger” on this forum, you will find a lot of information on batteries and chargers. Some of that information might even be correct!
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Gerald,
Welcome to the site and participating in the forum is what it’s
all about. You have lots of company here to help you through the
learning process. If you have questions about your Lifelines, please
don’t hesitate to contact me.The best solution as Jon pointed out would be to load test. Assure
your house batteries are fully charged and your inverter/chargers are
in the float mode. You then have to remove the cables to load test.
Lifelines usually last 5 years or better, so maybe they are aged out.
The batteries have a date code branded into the top side of the case
and is a series of letters. If you can send or call me with that
code, I can tell you the age. You probably have 6 4D’s.Equalizing may help, it hasn’t done much for me when I’ve done it,
but if the batteries are good, it may buy you some more time. I had a
97 Marathon and don’t remember, but if you have a house disconnect
for your DC, you may be able to do that and then equalize providing
your remotes are still alive after the disconnect. That would give
you piece of mind with the high charging voltage, but I doubt it
would hurt anything anyways.As for the chassis batteries, I installed a Guest charger on my
Marathon using the 120 volt receptacle in the engine compartment used
for the block heater. I then controlled the charger using the the
block heater breaker at the AC panel. -
I know a lot of folks have dealt with frequent discharges of chassis batteries by installing or using battery chargers or maintainers. I would caution that before doing that it might be best to find out why chassis batteries are discharging.
When the engine is turned off there should be no loads on the chassis batteries and therefore the problem could be as simple as a bad battery affecting the set, or worse a load that should not be on the chassis batteries. Part of coach onwership is knowing the coach and if there is a load that is capable of discharging a set of batteries I would suggest determining what it is, verifying it is safe and needed, and considering if it should be on the chassis batteries or if the load belongs on the house batteries.
All of my coaches would go months without the need to charge the chassis batteries when the coach was stored.
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Thank you all for the feedback! I’ll give equalization a try and report back. The bus has battery disconnects for each inverter and for the direct DC loads. I’ll turn the latter off. For the chassis batteries I’ll either install an echo charger or a marine 24V charger supplied by the preheat outlet for the engine as many of you have done.
Regarding the draw on the chassis batteries when disconnected, I read somewhere that the DDECIII computer is always on and draws about one amp. This would mean about 10 days to discharge the chassis batteries to 50% which is pretty much what I’m seeing. Maybe the newer computers use Flash/Eprom memory and do not need much in terms of keep alive current.
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Gerald,
The DDEC amperage is very small, I can go two months without any
charge and still be good. Of course my batteries are fairly new and
that makes a difference. I had an Echo charger on two plastic CC’s
and I didn’t like them. That design was to use the house batteries
via a solenoid and when the Echo saw a certain voltage, it would
allow current to feed the chassis batteries. They are a constant
source of problems on the CC forum.The Guest is the best bet in my opinion and I have bought several
from Aircraft Spruce. -
Welcome to the club .. your bank account will never be the same again ..
With discharge issues, you either have one (of two) problems. Bad batteries that simply cannot maintain the charge anymore, or some kind of parasitic load. You can have the batteries tested easy enough by pulling them and taking them someplace that will test them out (call around)
For parasitic loads, you have to do quite a bit more detective work. if you have the right tools the easiest way is to put a shunt and an ammeter inline (DONT DO THIS WITH IT RUNNING or try to start it, or even power on the mains) and look at the load .. It should be nonminal . only a few milliamps when everything is off. If its not, start systematically pulling fuses and popping breakers until it drops. When it does, That circuit is the one where your parasite is. You’ll need to eventually track down the load within the circuit, but temporarily you can leave that open when not running the engine.
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Just for fun I measured the DC amp load for the Ddec and it is 1.2 amp.
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That is stunningly high for the DDEC with the ignition and main power in the “off” position. What exactly did you measure and where?
fwiw, The DDEC IV manual says power off consumption is ” I < 1ma " I can measure mine over the weekend when I have other things pulled apart to confirm that ..
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Here’s another option for maintaining the 24 volt chassis bank, http://www.amazon.com/Battery-Tender-022-0158-1-Waterproof-Charger/dp/B002DTV172/ref=sr_1_1?ie=UTF8&qid=1345260046&sr=8-1&keywords=24v+battery+tender
This is waterproof making it easy to mount near the battery. Mine is mounted above the battery bank and plugged into the outlet in the tool box bay.
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I tend to agree the current draw expressed for DDEC sounds high. Based solely on my experience with three DDEC coaches (I, III, V) with the chassis main disconnect switches “on” and no battery charger my buses could all sit for months at a time and would still start any time I turned the key. If the batteries are losing their charge quickly something is wrong and all a battery charger is going to do is mask the problem. Solve the problem first. Then install the charger.
For those who do turn off the coach battery master switches the DDEC battery connections come directly from the batteries, bypassing the master switch. If you look at the list of circuit breakers in the rear electric box you will find those for the DDEC (19, 20, 21?) are hot even with the master switches off.
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I measured the yellow lead coming off the batteries with my Fluke.
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I stand corrected boy’s, hat in hand and long face! I failed to zero out my meter when I did the measurement so I was wrong.
The reading this morning with the meter zeroed and the key off was 2 amp and with the key on 4.
Remember, I’m on SS!
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