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Topic: Battery Draining - AC Trying to Turn On (Read 572 times) previous topic - next topic

Battery Draining - AC Trying to Turn On

First time poster, but I've been lurking since I bought my 2005 Foretravel U320 from MOT in November 2021.

I have my coach stored about 30 miles from our house and it has a 110 outlet I am able to keep it plugged in  On Wednesday I went and picked up my coach and brought it to the house to load up for a month long trip up north to include Yellowstone.  Everything seemed to be working as well or better than it has since we bought our coach.  I was feeling good.

I got to our house, generator running to keep the AC running (90 ish degrees at 10:00 am).  I leveled the coach and then shut the engine down like I have numerous times.  After about 10 minutes I realized I did not put the rear closet slide out and needed better access.  I went to start the engine as there were problems retracting the seal since I did the walk through with MOT and have always done slides with the engine running.

I hit the boost button (as I have almost every time) to restart the engine.  The lights in the coach flashed unlike I had noticed before.  With the noise from the generator and AC I could not hear the engine trying to start but could tell by the gauges it was not starting properly.

I turned off the AC and generator and tried again.  Nothing but clicking.

I waited a few minutes and tried again still just clicking.  I turned the boost off and my driver information panel was completely dark (not showing either line of information or lighting up like it normally does).  At this point I assumed I had drained my batter trying to start it.  I turned the generator back on and turned on the boost to get some charge back to the batteries.  With the boost button the driver information panel lit up again and provided information.  I think the voltage showed upper 11 or low 12.

Thinking the voltage was too low I left the generator running and the boost on to try and charge the battery.  After an hour or so I tried again.  Same results.  Engine would not turn over even with boost on.  With boost off driver information panel would be on until I tried starting the engine then would go completely dark.

Talked to James at MOT and he said the charging of chassis batteries (which were purchased and installed when I picked up the coach in November 2021) via the boost is just a trickle charge and would take a while.  I decided to go purchase a battery charger and hooked that up as well.

I let the coach charge overnight.  Yesterday morning there seemed to be better battery power (the engine was turning a little but still just slightly more than clicking).

I called a battery service person out and he put the big boost device on the batteries.  There was no difference in trying to start with the device attached.

We then went under the coach and tested the CCA of each battery.  The three batteries were 980, 650 and 65 (on 950 CCA batteries).  We replaced the two bad batteries.  The coach started right up.

We shut the engine right back down (20-30 seconds) as the technician still needed to finish putting the battery compartment back together.  A few minutes later he was done and I started the coach back up no problem.

Went to extend the rear slide for the closet and the seal would not retract (not sure if this is relevant but it has not happened before and I had the slide out the day before prior to leaving storage).

After about 10-15 minutes I wanted to make sure the engine was starting properly so I shut the engine down, waited a few seconds and tried to restart.  Nothing but clicking and flashing lights like the previous day.  I did have the generator and AC on and it seemed to be working fine.  Went to the rear start button and tried and the engine was again acting like the battery was not strong enough.  Clicking, belts moving and inch or so with each click.

Called the battery technician back out and he rechecked all the battery connections and tried again.  Still no dice.

While he was under the coach he confirmed that the clicking was coming from the starter and he began to think it was a starter issue.  This had also been discussed with James at MOT.  The starter was clicking and the engine was trying to turn (belts were moving an inch or two with every click)

I found a starter in town and found another tech who could come out and install it.  He is scheduled to come this morning (Friday).

The sun was going down last evening and we were not going anywhere so I shut the AC units in the coach down (switched black switch on bottom of thermostat to OFF), waited a minute or two and shut the generator down.

I was sitting in the coach trying to decide why not just set it on fire (only partially kidding) and I heard what sounded like the front AC unit trying to cycle on.  Maybe 5-10 seconds.  I waited to see if it did it again.  10 minutes or so later it tried again.  I looked at the voltage screen for the coach (I had the coach plugged into a 110 outlet for the refrigerator) and it had dropped to 103 +/- volts.  The cycling stopped again and the voltage went back up to 117.  I went to the back of the coach and turned off the breakers for all 3 AC units. 

As I thought this through laying in bed this morning it dawned on me that the AC unit trying to cycle with the generator off is probably drawing too much power and draining (or frying) the chassis batteries (I had the boost on trying to recharge the batteries).

Does this seem likely?  What would be causing the front AC to attempt to cycle even with the thermostat off?

I have had the batter charger on the chassis batteries all night with the breakers to the AC units off.  I have not gone out to try and start the coach yet but will likely soon.  Just wanted to see if anyone may have any insight into what I'm seeing as I am a newbie and have seen a lot of great advice on here that I have used for other issues.  Thanks for any help in advance. 
2005 U320 42'
2007 Lexus GX470

Re: Battery Draining - AC Trying to Turn On

Reply #1 –
Your house AC should not be connected to your start issue.  I would look at the ground wire and reinstall it.  They used a star washer and you might get a better connection if you reinstall it.  Then you need to look at the starter if you have new batteries. You can also check the connection to the isolator and there is a splitter before that to get the power to the starter and you might look at that too.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Battery Draining - AC Trying to Turn On

Reply #2 –
Can you jump from the positive battery terminal to the starter to see if the starter will run?
Also as stated above check the battery negative to ground connections.
John Duld
1995 U320C SE 40'

Re: Battery Draining - AC Trying to Turn On

Reply #3 –
Thanks.

I've got a mechanic coming in about an hour so we'll try those ideas.
2005 U320 42'
2007 Lexus GX470

Re: Battery Draining - AC Trying to Turn On

Reply #4 –
Personally I would mentally separate each problem and work separately.
So batteries do go bad and cranking excessively will destroy starters.
          Install new batteries and include service on both ground and power leads.
            There is a improved starter that is gear reduction and I would recommend replacing with it
                    ISM starter
Slide.
Is the aux air compressor operating? Should be the primary air source for your slide. If your forward slide retracts the air bladder normally I would assume the rear should also. This happens when the slide control key is rotated. The pressure is vented and a vacuum  pump runs to produce the vacuum to collapse the  slide bladder

I have also had a boost solenoid fail.

No clue what is happening with your ac and if someone has changed something. Would be a hands on trouble troubleshooting

By the way congrats on your coach. Always nice to have more people participating and learning about there coaches
Scott

Re: Battery Draining - AC Trying to Turn On

Reply #5 –
Quote from: murbanski234 –
Talked to James at MOT and he said the charging of chassis batteries via the boost is just a trickle charge and would take a while.
I would disagree with that statement.  When you turn on the boost switch, your two battery banks are mechanically combined.  Any charging current applied to either battery bank is equally conducted to the other bank.  When you run the generator or plug into shore power with the boost switch ON, whatever your inverter/charger puts out in charging mode will be "seen" by both battery banks.

Our MS2812 inverter/charger can put out (up to) 125 amps in charging mode.  I would not call that a "trickle charge".

You said you tried several times to recharge your batteries using the generator with the boost switch on.  It sounds like that was not successful, which makes me wonder if your (inverter) battery charger is working.


1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Battery Draining - AC Trying to Turn On

Reply #6 –
Quote from: Chuck & Jeannie –
I would disagree with that statement.  When you turn on the boost switch, your two battery banks are mechanically combined.  Any charging current applied to either battery bank is equally conducted to the other bank.

CORRECT.  The boost switch/solenoid is a high amp connection between the battery banks.  Anything less would do virtually nothing to start the main engine if chassis batteries were deeply discharged but house bank had good voltage.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Battery Draining - AC Trying to Turn On

Reply #7 –
Thanks for all the suggestions. Here is what we went through today

The problem ended up being a grounding issue.

After changing the starter and still experiencing a problem we cleaned all the grounds at the battery and the junction right near the batteries. Didn't seem to help.

Ran jumper cables from the the battery directly to the starter. Positive and negative. The engine turned over.

Jumpered just the positive side and it didn't work.

Ran a new negative cable from the battery to the starter. The coach started right up.

If I could ask one more question, what is the star washer referenced regarding the ground. Is this the ground junction of four wires near the starter?

We have now started our summer vacation so wish us luck.

Thanks again.
2005 U320 42'
2007 Lexus GX470

Re: Battery Draining - AC Trying to Turn On

Reply #8 –
A problem solved is always a pleasure and a relief.  Sounds like you did good analytic work.  Have a wonderful vacation and safe travels. 

Richard
Jan & Richard Witt
1999 U-320  36ft WTFE
Build Number: 5478 Motorcade: 16599
2011 Jeep Wrangler Unlimited w/Air Force One
Jan: NO5U, Richard:KA5RIW
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Re: Battery Draining - AC Trying to Turn On

Reply #9 –
A star washer is a type of lock washer. It has sharp points on both sides of the washer that dig in on both sides when you tighten it up causing it to act as a lock walker and also creating a good electrical connection.
John Duld
1995 U320C SE 40'
 

Re: Battery Draining - AC Trying to Turn On

Reply #10 –
Glad you solved the problem, have a great trip!
1998 U295 36'
Build# 5358

SMILE!....it makes people wonder what you have been doing.