Engine batteries

Topic: Engine batteries (Read 1591 times) previous topic - next topic

Engine batteries

July 08, 2012, 12:11:26 am

How long should engine batteries stay charged with no load. My son-in-law went to start my 96 U320 while I was out of state and the engine batteries were dead. These batteries are about two months old and nothing was supposed to be on. Do I need to leave the boost switch on while my motor home is stored?

Re: Engine batteries

Reply #1 – July 08, 2012, 12:50:22 am

Boost switch will combine batteries so both house and start would both probably have been dead if turned on.

Disconnect start battery ground cable is one option to keep start bank from discharging.

Re: Engine batteries

Reply #2 – July 08, 2012, 12:53:24 am

There are always parasitic loads but I would think you'd need a bigger draw with good batteries in that short a time. Mine has heavy duty battery disconnects on each battery and if I store without charging I throw the switches and kill everything. They stay charged up for quite a while like that. Note that the floor switch inside the door to disconnect the batteries won't do the trick. I know the propane detector stays powered. I suspect the transmission brain (ECU) probably does too.

Re: Engine batteries

Reply #3 – July 08, 2012, 07:27:57 am

Agree on the parasitic load, a dome light will kill a car battery in less than a day, the coach has the opportunity to have quite a few little things on when you think everything is off. If you can not have a charging system connected, for sure disconnect battery.
Don't know about your son in law, but that sounds like a normal son in law happening.

Dave M

Re: Engine batteries

Reply #4 – July 08, 2012, 11:17:51 pm

Fully charged house or engine batteries will go all winter in freezing temps if disconnected. I had an extra solar system 12V battery that went a year on the shelf and still had 12.5 volts.

On the other hand, warm, humid summer weather can flatten even a disconnected battery in a month.

If stored inside, a newer charger/converter with a 13 volt maintenance voltage limit (not 13.6V) will keep batteries happy. Outside, a medium or small solar panel with a regulator that limits voltage to 13 volts will also prolong battery life. Point being that you don't need a big panel in outside storage to keep batteries maintained.

High storage voltage will ruin the batteries as well as low voltage discharged batteries that will freeze in winter. A lot of the new batteries also don't like the anti-sulfation feature some converters/chargers have. Can be easily switched off in programming.

Check the battery brand and model online for manufacture's recommendations.

Pierce

Re: Engine batteries

Reply #5 – July 09, 2012, 10:32:09 pm

Decided to check on my batteries today. I use the Trik-L-Charge and keep the unit plugged in. What I found surprised me. I'd forgotten which battery was the coach and which the house so I had 12V lights on inside and disconnect one batter at a time (with the shore power off) to see which was which. 12V lights stay on with either battery as does the ignition and dash gauges! I do notice that the boost switch will slightly alter the voltage on the gauge or AUDIT screen. Not sure what is happening. Perhaps when I had the alternator replaced they altered the wiring trying to figure why it wouldn't charge. Finally used a jumper wire between posts on the alternator to externally excite it and all was well. I am posting a photo of my isolator. Can someone tell me what to check to determine if it has failed? I suppose it could also be the boost solenoid stuck open.

Re: Engine batteries

Reply #6 – July 09, 2012, 10:35:09 pm

Dwayne,

Read the labels on the cables/wires on each terminal lug and compare to your electrical schematic. If you don't have an electrical schematic, post what is on each terminal and one of us can look it up.

Brett

Re: Engine batteries

Reply #7 – July 10, 2012, 12:01:10 am

Quote from: Dwayne – July 09, 2012, 10:32:09 pm

Decided to check on my batteries today. I use the Trik-L-Charge and keep the unit plugged in. What I found surprised me. I'd forgotten which battery was the coach and which the house so I had 12V lights on inside and disconnect one batter at a time (with the shore power off) to see which was which. 12V lights stay on with either battery as does the ignition and dash gauges! I do notice that the boost switch will slightly alter the voltage on the gauge or AUDIT screen. Not sure what is happening. Perhaps when I had the alternator replaced they altered the wiring trying to figure why it wouldn't charge. Finally used a jumper wire between posts on the alternator to externally excite it and all was well. I am posting a photo of my isolator. Can someone tell me what to check to determine if it has failed? I suppose it could also be the boost solenoid stuck open.

Let me know if you don't have the schematic and I will send it PDF. Ours is a '93 U300 but think the schematic for the isolator should be close. Our isolator had the cables installed incorrectly and the boost solenoid was stuck on when we bought ours so this IS a possibility. Can also send a photo of our isolator after I replaced the solenoid and switched cables. You may have trouble reading the factory labels but should be able to trace them out.

Pierce

Re: Engine batteries

Reply #8 – July 10, 2012, 09:11:47 am

I have no schematic. This coach came without a scrap of paperwork. Even though I know the boost ties the batteries together for start-up, I wasn't sure that merely having the boost stuck on would cross connect the batteries such that with one disconnected every item normally powered off of it would have power from the other. So, to clarify...the boost stuck open would completely cross connect my batteries together in every respect? I am reasonably certain that the shop that struggled with figuring out my alternator repair did not move any wiring at the isolator. I know they had to rig the wiring at the alternator with a jumper to externally excite it as they couldn't get it to charge. This was a huge Freightliner repair facility in Jackson, MS and they didn't have a clue (thanks Brett and Gary for bailing me out on that one two summers ago). I can't imagine that this would be the point at which the batteries are now wired together. My feeling is that the isolator has failed but of course I have to prove it. The isolator looks like something that should be difficult to fail. What typically goes wrong?

Re: Engine batteries

Reply #9 – July 10, 2012, 10:24:11 am

Yes, a boost solenoid stuck in the ON position would power all things in your coach from EITHER battery bank.

Easy to troubleshoot. At the solenoid:

With a voltmeter, check voltage between each of the large lugs and ground. If not the same, the solenoid is not making contact/ON.

Check voltage between the small terminal and ground or, if two small terminals between them (if a second one is present it is ground). With boost switch off, no voltage should be present.

If no voltage present and boost switch is ON, switch bad.

If voltage present and boost switch is off, you have a bad switch or wiring.

Brett

Re: Engine batteries

Reply #10 – July 10, 2012, 11:29:40 am

I'm guessing the boost solenoid is in the far right of this photo.

Re: Engine batteries

Reply #11 – July 10, 2012, 11:41:16 am

Quote from: Dwayne – July 10, 2012, 11:29:40 am

I'm guessing the boost solenoid is in the far right of this photo.

Correct, That is the boost switch.

Re: Engine batteries

Reply #12 – July 10, 2012, 12:06:21 pm

The 12V version of this is the part...correct?

BargainBoatParts.com - 200 Amp Continuous Duty Solenoids

Re: Engine batteries

Reply #13 – July 10, 2012, 12:12:26 pm

Quote from: Dwayne – July 10, 2012, 12:06:21 pm

The 12V version of this is the part...correct?

BargainBoatParts.com - 200 Amp Continuous Duty Solenoids

I just bought one at a better price at:
Cole Hersee 24143 - 12V Continuous Duty Solenoid 200 amp

Re: Engine batteries

Reply #14 – July 10, 2012, 12:26:26 pm

Dwayne,

OK, here are a couple of shots of the schematic I used to figure out my problem as well as a foto of my isolator panel. It needs to be cleaned up but think I will follow Brett's excellent idea and move the whole thing to under the bed.

You will notice the schematic has 4 connections at the isolator but the foto shows only 3. The middle terminal on the isolator is the alternator. The right side (passenger's side) is the engine battery connection and the left is the house battery connection.

The boost solenoid is the silver one on the right side of the foto. The black solenoid is the remote start solenoid from the button in the engine compartment.

The factory codes were too faded to read so I used a label machine to identify them. As you can see, my isolator was replaced. When the last owner or mechanic did it, he switched cables so nothing worked correctly. Bottom line is to label all cables BEFORE you take any off as they all look the same after you remove them. A photo before removal is also good.

You need the manuals for your coach. I would suggest that if you can locate one from another owner, use a fairly good digital camera (newer iPhone would work) and shoot all the pages that you can. You can download into an app like iPhoto, and then, with a laptop, you can view them.

The electrical schematics are the hardest to decipher especially if you use glasses. Bill Chaplin had large copies made at the print shop and gave a set to me when he visited. I am forever grateful. I keep them rolled up in a overhead compartment where I can get my hands on them quickly. When you are tired and it's dark, the large schematic is just what the doctor ordered. Only cost a couple of bucks each to have done.

Pierce

Re: Engine batteries

Reply #15 – July 10, 2012, 12:58:03 pm

A quick note to all, as I see everyone's electrical panel that has been posted is in the same condition mine was before cleaning and covering. Why not make a simple vinyl cover that is just fastened along the top and drapes down to completely cover this panel and then make some way you either tie it or hold it down. This stops a lot of road crap from getting at that area and believe me it works great. In the yr or so mine has been on it has kept the panel in the same condition (I still need to go back and do more cleaning that I did not finish). I hold my cover down with some of the plastic covered spring drapery wire and a screw head either side to attach the hooks to.
John h

Re: Engine batteries

Reply #16 – July 10, 2012, 06:40:48 pm

Excellent idea John. I just spent all afternoon working in that wheel well changing out the boost solenoid which I thought was bad after checking for continuity. After installing a new one...same problem. My batteries are permanently connected. I took the old one across the street from where I keep the coach to the auto electric shop and they tested it as ok. I guess I need some remedial training on the multimeter. I told the shop owner that my isolator checked ok too so I don't know what is up unless it has something to do with the alternator replacement I had to do while on the road in Jackson the summer before last. They replaced it with this:

Delco and Leece Neville High Output Alternators

After being unable to get it to charge they ran a jumper wire between two of the posts to externally excite it. The shop owner said he wanted to see the alternator so he came over and looked at the back with the wiring and told me that if I leave it like that the batteries will discharge (unless they are on a charger) and that I could drive it and it will charge but if parked I need to disconnect that jumper wire. He thinks this is my problem and told me to take the alternator off and bring it to him.
I find it hard to believe that the wiring arrangement at the alternator can be linking my two batteries. But since I can't even operate a multimeter, perhaps I should listen to him. The guy is a friend of my father-in-law and didn't even charge me for the solenoid when I went in to buy it so I don't think he's trying to BS me. This might explain why my new converter / charger didn't last too long what with being overworked.

Re: Engine batteries

Reply #17 – July 10, 2012, 10:05:55 pm

Dwayne,

I'm not all that familiar with the Delco alternators but here's the connection diagram for the 28si.

http://www.delcoremy.com/Documents/Alternator-Instruction-Sheets/28SI-installsion-instructions_10524210.aspx

It uses remote sense (it's the terminal marked S) but also has a terminal for a relay which you won't use. It's marked R which is for Relay, not Remote sense. Make sure the remote sense wire is hooked to the S terminal,not the R which I get the impression is a common mistake. There should be a wire from the S terminal running to the outside terminal on the isolator that your start battery is hooked to, that's the remote sense wire.

Then it has the standard heavy output terminal which goes to the middle of the isolator, this feeds juice to your batteries.

The ignition wire that goes hot when your key is turned on (it dies when the ignition is turned off, easy to check with one terminal on wire end, one to ground, have someone turn the key off and on and see if it goes hot with the key.) goes to the I terminal. There should be no need for jumpers on the terminals.

So, that's three wires total. One for remote sense, one for ignition turn on and one for alternator output. Any jumpers added will make your batteries discharge.

That's my interpertation of the instructions, you might look at them and possibly give Delco Remy a call for tech support, tell them you're trying to hook up as a Duvac.

Good luck, Chuck

Re: Engine batteries

Reply #18 – July 10, 2012, 10:45:06 pm

Thanks, this confirms what the auto electric guy said with one glance. I should have photographed it but I think there was a wire connected where battery is indicated and one connected where remote sense is indicated...then the jumper from this post to the next one over marked ignition on the diagram.

Re: Engine batteries

Reply #19 – July 11, 2012, 09:23:35 am

Looked it over this AM. Aside from the main connection to the isolator, there are two small wire connected at the next post over and a jumper over to the third post.

Re: Engine batteries

Reply #20 – July 11, 2012, 10:09:16 am

Can't see any labeling on your pictures. You should have a wire that is activated by the ignition switch on your coach. Use that to the I terminal and it will turn on the alternator when the key is on. Check to see that the other wires are connected to the right terminals on the alternator.

Re: Engine batteries

Reply #21 – July 11, 2012, 12:48:00 pm

Looks like they have two small wires at the remote sense position and a jumper from there over to the ignition position. It does charge driving down the road. Unfortunately it discharges the batteries unless plugged into shore power and it may be why my two batteries are always connected to each other regardless of the boost switch being off.

Re: Engine batteries

Reply #22 – July 11, 2012, 06:23:45 pm

Yep. Hooked up wrong.

Re: Engine batteries

Reply #23 – July 11, 2012, 07:32:08 pm

A more major issue with a small wire serving as the battery boost/combine switch is that if one battery bank is at a much lower state of charge, you could start a fire moving a lot of amps from the charged to discharged battery through a small wire (that is how a resistance heater works!

Brett

Re: Engine batteries

Reply #24 – July 12, 2012, 08:44:21 am

Oh...that's great. You'd think a Freightliner dealer with 30 repair bays could change out an alternator. I took the cover off the panel next to the battery and had someone throw the boost switch and a very loud click can easily be heard so I'm assuming that solenoid is ok and I know the one next to the isolator is ok. That points back to the alternator wiring I guess. I'll take it off (never done that before) and take it to the auto-electric guy and see what I end up with. I do feel confident that he took one look at the alternator and instantly said "that's wrong."

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