40 plus amp discharge

[moisheh]

I am having charge problems with our 08 Dynasty. This unit has the Big Boy solenoid with an Intellitec B.I.R.D . The Intellitec is a computer board. All of this is in the rear run bay. Before we left for Mexico in the fall I replaced both the Chassis and the 8 House batteries. WE drove the 2500 miles with no problems. I have always had a long wait time when driving before the House batteries start to charge. I have been told this is normal. I can get to screen in the Alladin that shows the volts and amps for the house batteries and the volts and amps form the solar panel. Ab The unit sat in my shop in Mexico all winter. 3 weeks ago I took apart one of the battery compartments. Cleaned up all the rust, primed it and applied truck box liner to the inside. Reinstalled all the batteries and all was good. We left for Canada 2 weeks ago. I noticed that the screen would show me a 45 amp discharge for the house batteries and as much as 20 volts and 2 amps for the Solar. As I drove it would drop to 12 amps of discharge on the house batteries and under under 20 volts for the solar. I was in a hurry to get home and di not want to fool around on the road. The last night we were on a Wal Mart lot. Went to leave at 5 am and it would not start. Tried the battery boost but no luck. Generator also would not start. I checked with a voltmeter and all the batteries were very low. At first I thought maybe I had a battery with an internal short. But none of them were warm. My truck was still on the tow bar but I was able to get everything going with my booster cables. I ran the generator until we got home. It is now plugged in to 50 amps AC. Yesterday I checked all the battery connections. I took voltage readings on both sides of the Big Boy. All was good. I disconnected the house batteries and checked the specific gravity. All good. I then checked each battery with a voltmeter. All good. I could not read the Specific gravity of the 2 coach batteries as they are sealed. But voltage was fine. The 2 fuses on the Intellitec board are good and the green light is on. I shut off the AC power and started it up. Screen shows a small amount of charge for the house batteries. A it should be. I cannot figure out what is wrong. I know that the Big Boy can prevent the house batteries from charging I had that happen about 6 years ago and I installed a new one. But what could cause such a huge amp draw. It cannot be anything that is fused as there are no items with that a mount of draw. If a wire were shorted to ground by now it wold have melted. If that logic is correct it has to be a large battery cable. The ground is still frozen here and it is a little cold so I have not crawled to see if something is obvious. Where do the house battery cables go ? To the inverter? They do go to the rear run box. Anywhere else? I want to change the Big Boy setup to a Blue sea but don't want to make any changes until I find the problem. I was going to drop the ceiling in the large bay and see if the solar controller could be causing a problem. Any help appreciated. Thanks.

[twinboat]

What was your chassis battery voltages during the run ?

Pull shore power and start the engine. Check for at least 13.5 volts on the chassis battery.

If you have a residental fridge, 20 amps from the inverter is about right.

Did you have the block heater plugged in. Some run on inverter power.

If your alternator wasn't working, you would have ended up with dead batteries all around, which you did.

Once you started the generator, the inverter charger took over thru the big boy and BIRD and keep all of the batteries charged.

[moisheh]

Chassis batteries were at 13.7
Block htr. Was off. Could the BigBoy be the problem?

[twinboat]

If they were at 13.5 driving then the alternator is working, but then they were dead one morning. Odd.

If the Big Boy was stuck closed, it can draw all batteries down, if you have a large load on the house batteries.

Pull the shore plug, turn everything off and let it sit an hour or so.
Put a load on the house batteries and see if the chassis battery goes down with the house battery.

You still need to find what was drawing high amps while traveling. The Big Boy didn't do that.

[Reka]

Had a similar experience on the exodus from Arizona 10 days ago. All was good when parked the motor home at storage batteries were right up went back 2 days later all house batteries were dead not even a light would come on, chassis batteries were good so was able to start big motor and get enough juice to get gem running and lights back. Temps had dropped to -20 and snow was on solar panels so no joy going into batteries while looking around discovered heat pads were on for water tanks they are 12 volts and the cold temps activated the switch and drained them. Luckily I stopped and drained all the water before I hit the cold weather on the way home

[YC1]

Maybe the clue is "always a long wait time before the house batteries start charging"..

If you have a bad diode in your alternator it may not be putting out enough voltage to engage the big boy.

A bad diode can also draw 20 or more amps when shorted inside an alternator. I have only seen about two alternators draw huge amps but yours could be the third.

Measure the engine battery voltage as soon as you start the RV. Turn on your headlights and the dash AC or at least the fan. Get some loads on the thing.

If the voltage is struggling to get up you may have the culprit.

[K7JV]

The 45 amps discharge that you saw raises two questions. Why is it discharging and what would cause it to be 45 amps?

Addressing the second half first, if it is not charging, the house battery will be carrying the house 12 volt loads as well as the inverter 120 volt AC loads which easily could add up to 45 amps. I would expect a few amps of DC load on the battery from lighting, furnace control and fan, refrigerator (if not residential), etc. It would be easy to have a bunch more current draw to supply the inverter, however, and 40 amps or so would not be out of line.

When you look at AC loads on your inverter, a rough approximation would be to expect 10 times the magnitude of the AC current to be demanded on the DC side. So if your refrigerator is a residential and might be pulling 4 amps of 120 VAC that would equate to approximately 40 amps on the 12 VDC side of the inverter. So the high current you are observing would not be involved with your normal fuses and wired, but rather with the 4/0 cable that runs from the battery to the inverter. That would all be as it should be.

Quick thought on residential refrigerators. There are loads in addition to the compressor which only runs occasionally to keep the unit at temperature which include mullion heaters, door seal heaters, defrost cycle heaters and internal fans, some of which are continuous and some of which are active during defrost cycles. Those can add up, not to very big numbers, but when multiplied by ten on your inverter supply they can add up to significant battery loads. You might consider checking to see if your refrigerator allows you to turn off the frost-free mode, at least when you are dry camping or relying on your batteries and your inverter to power it for an extended period.

Addressing the first half, you are getting good input. I'll try to keep an eye on your thread to see what you find and to see if I can add to what you are hearing from others. I will share a bit of what I was told by "Monaco Tech", back when they still existed. Jason told me:

1) If it is not already energized, the Big Boy will NOT pick up until the coach battery is at least 13.4 volts.
2) If the Big Boy is ALREADY energized when the shore power is removed, it will stay energized until the combined battery voltages drop below approximately 12.6 volts.

The idea is that when shore power is connected, the generator is started or the engine is started, priority will be given to charging the chassis battery until it's charging voltage gets to 13.4 volts at the battery. At that point, the Big Boy is energized by the "BIRD" to begin charging the house battery bank as well. (I think you said you were observing 13.7 volts, so the Big Boy should have been energized and you should have seen nearly zero volts across the two large lugs on the Big Boy.) The Big Boy should then remain energized until the charging voltage is removed and/or the combination of the two battery banks eventually drops below 12.6 volts at which time it would open and wait until charging energy is again available and the chassis battery is again up to 13.4 volts.

By the way, the 20 volts that you were seeing on the solar was measured on the input side of the solar controller, and not the output charging side. The fact that it was at 20 volts just gives you a feel for how much the solar panels will be able to assist with charging the batteries. The number from your solar controller that really matters is the amps that it is delivering to your system.

Sorry for the long post, but hopefully you may find some helpful input. Batteries and charging systems on coaches like ours can be an ongoing challenge!! By the way, our coach is an '06 Dynasty, so yours and ours should be very similar.

[moisheh]

Thanks everyone. I did check the block heater outlet snd it does not run on the inverter. I do think the bigboy needs some work. My chassis battery voltage on the alladin will show around 13.7 so the alternator should be fine. Once the weather is warmer I will check all the cables after they head to the frame. My battery cables are still original but yesterday i noticed one of them had some green powder under the shrink tubing. I will check with an ohmeter. I do not have a load tester but I will turn on some of the stuff that runs on the chassis batteries and watch the voltage. Even if the fridge was pulling 40 amps the alternator should be able to handle that and easily charge the house batteries. I try to never leave after boondocking without running the genset for around 2 hours. We are sequestered for 8 more days so I cannot do a road test. I will update my post as I progress. Unless I slit my wrists in despair. Thanks again.

[pduggs]

Great info in this thread. Thanks guys.

OP please let us know what you find.

[moisheh]

No worries. I will report back. It might be awhile. We are getting 6 inches of snow tonight and another 2 0r 3 on Friday. What fun.

[Reka]

You are right the block htr does not run off the inverter, but the tank heaters do on my Monaco it is labeled system heat. Hope this helps

[YC1]

Originally Posted by Reka

You are right the block htr does not run off the inverter, but the tank heaters do on my Monaco it is labeled system heat. Hope this helps

Very interesting. Is your tank heater a small square type heater? Seems very inefficient to run any heat generating device from an inverter..

System heat on mine just activates a 12 volt source to the system heat system that is controlled by a snap thermistor.

Just curious because I like to log these types of things into my memory banks.

[Reka]

yes it runs the the 12v heater and a couple of heat pads on the water tanks
turn on the switch and the thermostat disk activates heaters when cold enough

[moisheh]

I do not think we have tank heaters in our Dynasty.
The bay with all the tanks is heated Even the AH heaters do not run on the inverter.