BAC Forum
General Boards => Technical Support => Topic started by: Randy Perry on October 25, 2011, 12:14:29 AM
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So I just installed (4) new 6-volt coach batteries and my question is, while I'm parked in my Beaver Barn, I have her plugged into shore power, do I hit my "Coach Power Disconnect" switch? The guy I bought the batteries from said not to have them charging (even tricking charging) while the coach is in storage mode! Do they charge when it's in Coach Disconnect mode? I will put a meter on them to check, but just wanted to know what ya'll were doing! I would to get the maximum life out of these guys!
Thanks fer yer input!
Randy
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Get a second opinion about charging at a float charge. Disconnect allows a float charge for a reason but to stop you turn off the inverter.
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I would leave them on a float charge when in storage. Check the voltage to see if they are around 13.5 in float charge mode. This should also keep your chassis batteries charged as well.
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Just a random thought. Can you put a skylight in your Beaver barn above the solar panel??? I find my solar panel keeps everything topped of nicely when the coach power is turned off.
Alternatively, if you're concerned about the constant trickle charging, just plug it into a timer and have it come on for an hour/day or therabouts.
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Even in the NW winters my solar panel does a good job keeping my batteries up, as long as the main switches are off to mitigate minor drainage sources. During extended periods of dark weather I do plug into our 30 amp RV outlet and let it float. I'm at 5 years on original batteries, and going strong.
Our old coach didn't have solar, but I learned to extend battery life on it by using a Battery Minder device that did a superb job of float charging, and added several years. Part of that was due to The device's equalizing charge feature; not all charge maintainers can do that. I now use the Battery Minder to keep my infrequently used pickup truck's battery top notch.
Joel
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Randy,
Your batteries will be better off if you leave the inverter charging circuit on. If the house batteries are on float charge when in storage, the Echo Charger will keep the chassis batteries fully charged. Otherwise the chassis batteries will be completely discharged by the engine computer (ECM). The ECM (engine control module) is powered up at all times, and will kill your chassis batteries in a week or so if they are not recharged in some way.
The only other option if the coach is stored inside is to be certain that the coach and chassis batteries are completely disconnected ( most factory installed battery disconnects do not do this) when in storage. The batteries will self-discharge and need to be recharged if the coach is stored more than a month or two, if you decide to use this method, because the batteries will self-discharge enough to possibly cause alternator failure if not recharged.
Gerald
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Gerald,
On my 09 Contessa there seems to be a fair load on the house bank even with The battery switch off. I know the Magnum charger/inverter remote panel is powered, so I assume the charger/inverter is not islolated by the cut off switch. I'm considering installing cut off devices on both he house and chasiss banks. Is there any risk to taking power away from the ECM? Any other risks?
Thanks,
Gil
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Gil,
The only risk that I know of is the self-discharge problem that you get with any battery that is stored without a float or maintenance charge.
If you have access to a power outlet, it is much simpler to just leave the batteries on float charge. This will keep all of the batteries in good shape, and remove the risk of starting the coach with discharged batteries and overheating the engine alternator.
Gerald
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Plugged in and battery disconnect switch open, I'm reading 14.4 volts. Is that a "Float" charge? If it sits plugged in for 2 or 3 months will it boil the water out?
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I have the same question. If we have our RV plugged into 110 v for a trickle charge, will the batteries charge even if the coach power button by the door has been used to turn off coach power?
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When charging, batteries there are three charging stages. The first stage is the constant current charge, and typically takes about half of the total time required to reach a fully charged state. A battery is typically charged to 70% of the fully charged state during the constant current charge. During this state, voltage is typically increasing while current remains constant. The second stage is the topping charge. The voltage is relatively constant, typically between 2.4V and 2.45V per cell. This is very likely the 14.4v you are seeing. During the topping charge, voltage peaks and current decreases. The battery remains in this state, until the remaining 30% of charging is completed. Frequently, this is referred to as saturation. Once the batteries reach saturation or full charge, the third stage of charging (float charging) is entered. During float charging, both voltage and current are reduced. Float voltages vary depending on the type of cell (Gel 13.05V, Flooded 13.4V and AGM 13.6V).
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All the Coach Power button does is turn off the loads. It doesn't affect the charging. that is controlled by the Inverter/charger, which ought to be connected directly to the + terminals, so ON all the time.
Charging with a "smart" charger will give you battery health. In the old days (I think 20 years have passed since the last "dumb" charger was used in this sort of application) a ferro-resonant charger was as good as it got. those would boil the batteries if not turned off when done. If you have an Inverter/charger, is is undoubtedly "smart" and will have 3 stages, so will keep your batteries in perfect health if connected and turned on at all times that you are near shore power.
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Randy,
Like Keith said above your inverter will drop the charge voltage down to float voltage of 13.4 to 13.6 volts as soon as the batteries are fully recharged (usually about a hour or so unless the batteries are badly discharged).
Float charge voltage will not boil the water in your batteries. The water level in your batteries will need to be checked and toped-off monthly to once every three months, depending on the temperature and humidity where the coach is stored. Battery quality and condition will also affect how often you need to water them. Also always use distilled water when watering your batteries.
Gerald
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Gerald
Am a little confused about all this battery charge chatter. I have my coach plugged into 50 amp power at home, with a battery minder on the chassis batteries, when plugged into shore power. I leave the inverter OFF. My question is: Am I to understand that I should also have the inverter turned ON, rather than OFF, to ensure proper battery charging of the house batteries??
The only issue I have faced with these Interstate batteries is corrosion in the tray (not on the cables etc). I cannot understand why this is, or where it is coming from, but it does keep building up, and I have to constantly keep cleaning it off. I don't detect that they are boiling over, perhaps a small leak somewhere in one of the cases??
Would once again appreciate your insight.
Leah
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Leah,
Why do you have a battery minder? My '08 Contessa has a Magnum charger/inverter, that charges both battery banks. The Magnum charger is also a smart charger, so it goes to float charging after the batteries are charged. So, if your coach is wired like mine, the inverter should be off and the charger on. I think Gerald was just saying the charger/inverter should be energized.
Gil
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Leah:
Off/On? Your Charger is the same unit as your inverter. The only On/Off switch you have is for the Inverter side, which only comes into play when you are NOT plugged in. When you are plugged in, your charger is operational without you doing anything. When you are plugged in, your inverter is NOT operational, regardless of the switch setting. You should keep your inverter switch Off, when not plugged in, unless you want to run AC loads without starting your generator. OK for small loads, for a short time, but generally, too much inverting will deplete your house batteries. If you are always either plugged in, or driving (where the alternator picks up the slack), you won't need to worry about it, as your batteries will keep up.
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Leah,
Gil is right, if you leave the inverter/charger turned on to charge the batteries with the inverter portion turned off, all of the batteries will stay charged. There is no reason to use a battery minder on your coach.
Your corrosion problem is probably from the gas that your lead/acid batteries give off when they are being charged. There is no way to prevent corrosion with your battery banks unless you go to an AGM (absorbed glass mat) battery bank. AGM batteries are sealed, so there is no out gassing to cause corrosion, and you never have to add water. They will also hold a charge a little better than lead/acid batteries, however they cost twice as much.
Gerald
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Ok guys,
I use the battery minder on the chassis batteries BECAUSE if I don't the batteries lose power and show "low battery" reading on the Aladdin screen on the dash. The parasite drain brings them down. I have not been in the habit of turning off the chassis switch in the engine compartment. On the Magnum panel (mid coach) there are two (2) buttons ,one labeled for charger, "on/off" one labeled "inverter "on/off". I always have the charger button "on" The inverter button is always "off" UNLESS I need power if "not" plugged in to 120v.
If there is a battery feed to the chassis batteries, either it is not working, OR I don't know how it is activated. On my previous 99 Thunder, it was activated by tuning the coach key position to the "left". That doesn't seem to be the case on my 08 Contessa however.
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.....If there is a battery feed to the chassis batteries, either it is not working, OR I don't know how it is activated. On my previous 99 Thunder, it was activated by tuning the coach key position to the "left". That doesn't seem to be the case on my 08 Contessa however.
If your 08 is like my 04, it uses two relays called the "Big Boy" and "BIRD" to make sure both sets of batteries are being charged whenever there power from any source. The relays are automatic. My owners manual has a pretty good description of how they are supposed to work. Both relays are made by Intellitec http://intellitec.com/. Manuals for the relays are at their website.
I have not looked at it recently, but would be happy to dig out the books and re-learn it if I can help with questions.
If you don't have those relays, it is very unlike Beaver or Monaco to create something where both sets of batteries are not automatically kept charged. On the odd chance yours does not work that way, there are some easy fixes that will make it automatic.
Good luck.
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Leah,
Your coach has a "Bird' relay module that should energize the "Big Boy" solenoid to tie all batteries together when one bank is charging so that all batteries are charged equally. The "Bird" module should then de-energize the "Big Boy" when neither of the battery banks is charging to prevent one battery bank from discharging the other.
The "Bird" system is automatic and requires no operator input. So if your inverter/charger does not keep your chassis batteries charged when you are plugged into shore power, and it is charging the house batteries, the "Bird" system is malfunctioning, and should be repaired.
Gerald
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OK.........I have no idea where these BIRDS and BIG BOYS are located, or what they might even look like, MUCH LESS how to check them. This is a little above my skill and knowledge level. I guess since it isn't an issue that is causing a problem right now, I'll put it on my list to have checked next trip it make to Bend Service Center. I am not sure I trust RV dealers here.
Appreciate all your help guys.
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OK.........I have no idea where these BIRDS and BIG BOYS are located, or what they might even look like, MUCH LESS how to check them. This is a little above my skill and knowledge level. I guess since it isn't an issue that is causing a problem right now, I'll put it on my list to have checked next trip it make to Bend Service Center. I am not sure I trust RV dealers here.
Appreciate all your help guys.
On mine they are in the box above the batteries where the red cutoff switches are. Click here http://intellitec.com/pdfs/BATTERY_web/5300366.000.pdf for a picture of what the BIRD (Bi Directional Relay) looks like and an explanation of how it works.
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On my '08 Contessa these relays and their control electronics are located in the panel with the main DC switches for the chassis and house battery banks. This is located, in my coach, in the furthest rear bay. As I've said before, if I ever have problems with this system, I 'm changing over to the proven and far simpler systems used in boats.
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How do they do it in boats?
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Totally self contained, high current load capability, emergency combining of banks, charging of both banks from a charging source on either bank, low voltage bank isolation. Check it out: http://bluesea.com/category/2/productline/388
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We lived aboard a 50' sailboat for almost 10 year and batteries were an essential part, perhaps the most important, system on the boat so utter reliability vital.
The system had two banks of 6 each Trojan T-105's house batteries and two 12V engine start batteries. These were charged by a Freedom 20 (2000W inverter/charger) and a high output Powerline alternator. The Alternator was controlled by a Balmar smart 3 stage regulator. Note that the regulator also monitored the alternator temp and would reduce output if necessary to prevent burnout.
Charging current from the alternator fed the start battery preferentially and the house batteries were connected with a voltage sensitive relay once the start battery was refilled. The inverter charged the house bank(s) preferentially and the start battery through another relay once the house batteries came up to a predetermined voltage.
in addition, we had a manual paralleling switch for the two house banks (used mainly for isolation in the event of failure) and a paralleling switch from the house banks to the start battery.
All functions were controlled and monitored with a Link 2000 monitor as well as the inverter remote panel.
A Westerbeke 5KW generator rounded out the electrical system but was seldom used unless anchored for a significant period. Most charging was done with the engine duing transits.
Very simple, very robust, and totally without problems.