| Author | Message | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 42 Registered: 1-2007 Posted From: 76.176.144.96 Rating: N/A |
I seem to need 25 watts continuous to keep the house and engine batteries charged. Is that a lot? Everything in the bus is off. There are 4 90 amp-hr AGM house batteries and 2 8D engine batteries. I read somewhere you could expect a battery to decay 1% per day but that would only amount to 4 watts in my case. | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1131 Registered: 8-2006 Posted From: 99.180.11.80 Rating: N/A |
Thats way much, so lets consider some possibilities. The first would be VCRs and TVs. They are "off," but have a radio or infrared receiver which stays on all the time so as to be able to turn on the TV when you push the remote power button. Next is the 12 Volt control system in a LP/120 Volt refrigerator. Dirt conducting electricity on top of your batteries. The electronic memory in stereos and radios uses some current, again not as much as you are losing. I'm puzzled by your comment about both the house and start batteries going dead. No isolator or solenoid? The new "smart" solenoids draw some current continuously, but nowhere near what your loss is. Next thought is a leaky diode in the alternator, again we need to know if there is a separator between the battery banks, because only the chassis banks will discharge thru the alternator with a solenoid separator, no discharge will occur thru a diode separator. Light on in a bay or closet? 25 Watts is 2 Amps at 12 Volts, which will draw a noticeable spark when the offending circuit is disconnected... | ||
| les marston (Les_marston)
Registered Member Username: Les_marston Post Number: 159 Registered: 1-2010 Posted From: 68.151.225.213 Rating: N/A |
Steve how did you discover that you need 25 watts to keep your batteries from discharging? As George said that is a lot more than just parasitic draw from TVs or VCRs that are turned off. Ah a flash! do you have a webasto that is drawing power all the time. Would be about the right draw for the igniter. but shouldn't effect house and chassis batteries if they are isolated... Maybe a dumb suggestion. good luck Les | ||
| thomas flocks (Taflocks)
Registered Member Username: Taflocks Post Number: 386 Registered: 9-2009 Posted From: 67.253.124.108 Rating: N/A |
who still has a vcr? | ||
| Jack Fids (Jack_fids)
Registered Member Username: Jack_fids Post Number: 212 Registered: 1-2009 Posted From: 69.171.161.110  Rating: N/A |
My BetaMax makes the Energizer Bunny look like a greenhorn, VCR...indeed Next you'll be taken a swipe at my 8-Track & Vibrasonic combo! | ||
| Patrick levenson (Zubzub)
Registered Member Username: Zubzub Post Number: 265 Registered: 5-2007 Posted From: 174.91.221.96  Rating: N/A |
the old mechanical relays can suck a lot of juice and still work like they are supposed to (other than draining your battery). | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 1351 Registered: 10-2006 Posted From: 66.82.9.99  Rating: N/A |
New batts will loose 1% per day internally, Old and run down (too deeply discharged and not refilled often enough) can loose 4% per day. 25W sounds like a lot. Disconnect the entire bus and start with just the batts , to find the draw. IF its JUST the batts , sounds like $$$$$ time! FF | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 43 Registered: 1-2007 Posted From: 12.4.26.248 Rating: N/A |
The way I know the continuous power draw is to measure how many watt-hours are needed to recharge it after I let it sit for 72 hr. I don't think parasitic appliances are the issue. It could be the batteries. They're 4 years old and haven't been as carefully maintained as possible. Probably been through 200 discharges to 60% (for the house). There is a house battery rotary disconnect switch. I believe that disconnects the battery from the engine and the house but still connected to the inverter. There is also a rotary disconnect switch in the engine bay to isolate the engine batteries, which is standard operating procedure when boondocking. Today I isolated the house batteries from the house but to the solar charger and the rate of charge of the house batteries went up significantly. So, its something on the other side of that. I still don't know how exactly the house batteries and engine batteries are connected... a part of the bus not yet explored. | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 44 Registered: 1-2007 Posted From: 12.4.26.248 Rating: N/A |
George, Lights. Good Question. There are many interior cabinet and closet lights. Its all 15 years old now and the switches and the door latches need some work. Sometimes I find one on. Sometimes I can't tell because I can't see inside after I've closed the door. | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 1067 Registered: 3-2007 Posted From: 71.55.1.12  Rating: N/A |
Steve; get inside and have someone close the door and then you can see if the lights go out. Make sure you trust the person first.LOL You may be there for a while. Better still just keep looking on your own. Gomer | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 1356 Registered: 10-2006 Posted From: 66.82.9.53 Rating: N/A |
"I believe that disconnects the battery from the engine and the house but still connected to the inverter." Old inverters on stand by can be a big drain , newer ones really take minor juice when connected buy not providing power. FF | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 45 Registered: 1-2007 Posted From: 76.176.144.96 Rating: N/A |
The inverter is off. Its a Heart 2000 watt inverter/charger, about 10 years old. Has taken a licking and keeps on ticking. With the inverter on and floating the batteries the continuous power consumption is 75 watts vs 25 watts if its just sitting, doing nothing. I'll let you know if its engine batteries. I'm just going to see how long it takes them to discharge and what it takes to bring them back. | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1136 Registered: 8-2006 Posted From: 99.180.11.80 Rating: N/A |
Steve, From what you've said, it sounds like the power consumption is in the house circuit itself. It also sounds like you can isolate both sets of batteries from their respective loads. I would get them charged, open all the switches, and wait a couple of days. Take a voltage reading before and after, and you will know whether it is the batts, (which I don't think it is,) or the house load. A 25 Watt load is 2 Amps at 12 Volts, so you could trace it quicker by taking off the hot wire to each load, scratching it against the terminal, and looking for a spark. If the 12V circuits are individually fused, pull one end of each fuse up, then touch it to the clip and pull it away while looking for the spark. | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 48 Registered: 1-2007 Posted From: 76.176.144.96 Rating: N/A |
The batteries seem OK disconnected. It seems to be in the house. Might be a chore to sort that out. There's alot of stuff it could be. Thanks for the tips. | ||
| les marston (Les_marston)
Registered Member Username: Les_marston Post Number: 172 Registered: 1-2010 Posted From: 68.151.225.213  Rating: N/A |
good luck with it Steve. Do you have a clamp on DC amp meter? I have one and it is worth its weight in gold for finding power draw. Canadian tire $69.00 Les | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 49 Registered: 1-2007 Posted From: 76.176.144.96 Rating: N/A |
The two 8D engine batteries after being disconnected for a week lost 0.15 volt. I figure that's about a 3 watt load, 1.5% per day. The house has 10 fuses at the main terminal block. I'll measure current across each next. Hopefully will find an amp or two across one of them. | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 50 Registered: 1-2007 Posted From: 76.176.144.96 Rating: |
Resolution: There were several wires connected to the negative terminal on the voltage regulator that had hard, cracked insulation, bare wire showing, etc. Cut out the bad stuff, spliced in new and seems to be OK. | ||
| les marston (Les_marston)
Registered Member Username: Les_marston Post Number: 175 Registered: 1-2010 Posted From: 68.151.225.213 Rating: N/A |
It is often the easy stuff that we miss. I am glad to hear that you found and solved the problem! Electrical can be miserable to trouble shoot. When you spliced did you solder and heat shrink? Les | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 1366 Registered: 10-2006 Posted From: 66.82.9.81 Rating: N/A |
after being disconnected for a week lost 0.15 volt Voltage sucks as a method of finding flaws in a battery. A good TEMPERATURE compensated Hydrometer is a better bet,esp for finding a weak cell. FF | ||
| Dallas Farnworth (Dallas)
Registered Member Username: Dallas Post Number: 146 Registered: 7-2004 Posted From: 75.91.207.168  Rating: N/A |
In my opinion, (and we all know that opinions are like belly buttons... everyone has one), don't ever bother with a hydrometer, temperature compensated or not. They are not accurate because of many factors, such as sulfation, impurities in the liquid, not being cleaned from the last time used, etc. Ever see one where no matter what you do the balls won't float, but the battery is still fully charged? It happens a lot. Bite the bullet and buy yourself a good refractometer built for the purpose. It's infinitely more accurate and isn't subject to crud sitting in a tube that you can't clean out. To use, wipe off the lens, put a drop of acid or antifreeze, (If it's calibrated for it), hold it up to the light and read the actual specific gravity of the liquid. I use an older Reichert Duo-Chek 7181 but there are newer models out there. Like this: http://www.reichertai.com/products.html?productID=29 | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 51 Registered: 1-2007 Posted From: 76.176.144.96 Rating: N/A |
Well the frayed wires I replaced didn't do it. I did find where the energy is going. With the bus off the voltage regulator is powered, 12V across the pos/neg terminals and 8V at the field terminal with about 2.3 amps flowing through it. Next to the voltage regulator is a relay labeled "generator sensing relay". It is closed and provides the+12V to the regulator. All four of the relay terminals are at +12V. If I disconnect the wire on the GND terminal and manually ground it, the relay opens and the regulator is unpowered. When I do that I have about 0.2 amps flowing through the ground wire. This is all in the electrical bay behind the passenger-side rear wheel. Not sure how much of this is original to the 4106. It looks pretty original. Any ideas? | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 52 Registered: 1-2007 Posted From: 76.176.144.96 Rating: N/A |
Looks like the way the bus has been since who knows when is that the generator sensing relay coil terminal is directly connected to +12VDC by a wire from the engine battery bus bar in the rear electrical bay. The generator sensing relay GND is connected to terminal 54 which seems to have no continuity to anything. That means no current through the coil and the regulator always putting out field current. According to the schematic "Engine Control and Wiring Diagram (Standard) MD-90625B, the GND on the generator sensing relay is always ground and a "starter control and generator relay" is supposed to remove the 12V to generator sensing relay, closing the contactor and energizing the regulator. When I move the generator sensing relay GND to an actual ground, the coil is energized, the contactor is opened and the regulator is not powered (fixes the energy loss at rest). But, when I start the bus, nothing removes the 12V to the generator sensing relay and the voltage regulator is not powered. If I remove the ground wire, the regulator is powered and everything is fine for going down the road. Still haven't found a starter control and generator relay. As I said, it looks like the generator sensing relay is hard-wired to +12V. | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1153 Registered: 8-2006 Posted From: 99.68.214.35 Rating: N/A |
Steve, I think the simple fix is to take the wire that "powers" the regulator thru the normally closed relay you are describing off the relay terminal, and connect it to a "hot" wire SWITCHED BY THE MASTER! The original setup may have had one terminal of the relay coil connected to the alternator winding somewhere short of the diodes, (via wire 54,) and the other terminal connected to a hot. This way, the relay is energized because the other end of the alternator windings are grounded, and no opposing voltage is present when the eng is not running. This circuit keeps the field open while the engine is not running, but does keep the draw of a little relay on while dead. Switching the field circuit thru the master seems simpler to me? Put a 5-10 Amp fuse in wherever you take power, (Skinner valve circuit?) to protect the wire and reg. HTH, G | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 53 Registered: 1-2007 Posted From: 76.176.144.96 Rating: N/A |
George, I was thinking the same thing. In the original setup, it appears that the relays were arranged so that when the starter is engaged, the generator is not powered thus not creating an additional load for the starter. I wonder if that matters with the alternator on there now. Obviously it works since the field current seems to have been there for the past 4+ years anyway. | ||
| Steve Krane (Steve_krane)
Registered Member Username: Steve_krane Post Number: 54 Registered: 1-2007 Posted From: 76.176.144.96 Rating: N/A |
Put in a normally open relay. The coil wire is hot when the master switch is on, closing the contactor and powering the regulator. Seems to work. | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 1155 Registered: 8-2006 Posted From: 99.68.214.35 Rating: N/A |
Steve, It will work well. If the bus was originally equipped with a generator, that explains it all, as the regulator was equipped with a reverse current relay, to prevent the generator from motoring with the engine off. There was also a voltage relay which closed when it saw output, between the two of them, they did the field switching. Alternators make it easy, as they don't allow reverse current. Thanks for telling us what you found! G |
