Bad Alternator or Bad Batteries?

[ereadingrv]

Originally Posted by twinboat

Get it started and check battery voltage. If it goes up to 13 volts or more, drive it to an auto parts store or Battery Plus, with a big parking lot, and have them test the batteries.

Thanks for the advice. Question: is there a different process for checking the battery than just the voltage? In other words, is there some kind of indicator or other factor, besides voltage, that would point to whether the battery is bad versus just discharged?

[ereadingrv]

Originally Posted by vsheetz

A quick check if charging from the alternator is occurring is to check battery voltage with engine/charging off - then start engine/charging - about 1 volt or more increase should be seen. No change = no charging.

Was not aware of this technique. Thank you! We will try this. Much appreciated.

[ereadingrv]

Originally Posted by Unplanned

Do you have a multimeter? Do the voltage checks. How long g were you boondocked?

We're usually parked for a week or so before we move the coach to our next location. Sometimes up to two weeks or so. We're going to do the voltage check during startup, as someone suggested. We weren't aware of that as a technique for checking charging from the alternator, so I'm hoping that will give us some initial insight. Thanks!

[ereadingrv]

Originally Posted by nodine

Unless an aftermarket device had been added to your coach, the Diplomats did not charge the chassis batteries from the generator or shore power. Suggest you do as twinboat says and have the batteries checked. Boondocking for only a few days should not be a problem unless the batteries are marginal. You might want to consider one of these:

https://www.rvupgradestore.com/Ultra...ik-l-start.htm

Ultra TRIK-L-START Starting Battery Charger/Maintainer

Bob

Thanks, Bob. Those are incredibly useful links. Good to know that the original Diplomats did not charge the chassis batteries.

It seems likely, then, that sans a bad alternator, that the chassis batteries need to be replaced. Jumping them from the house batteries, and getting a reduced charge, would then seem to make sense, unless we're missing something.

Very helpful, and very appreciated. Thanks, Bob.

[ereadingrv]

Originally Posted by distaff

I'm with TeJay, your original post contains some non-sequiturs.

The main one is if you were boon-docking and running the generator, and you saw 10 V on your chassis batteries, why would you assume your alternator was the culprit? Have you, in addition to running the generator, been starting and running the engine periodically? If not, how would your alternator have provided charge?

When I wrote the original post, I accidentally omitted the fact that the coach is run and moved every one to two weeks. That was my error; but the sarcasm by TeJay, rather than simply asking if we moved the coach (as you did) was uncalled for. Thank you for asking; and I have clarified that yes, as I said, we do move the coach and travel in it. Thank you.

[ereadingrv]

Originally Posted by slickest1

On my last coach, an Imperial I had a phantom draw somewhere that would drain my batteries in a couple days. I replaced the batteries and it still did that. My solution was when parked I would turn off the disconnect switch for the starting batteries and they would still be charged when I switched them back on.

That sounds like a real pain to track down! Just curious, although you found a workaround, did you ever figure out what the draw was? Thanks!

[Monacoach]

personally I think you answered your own question when you stated your batteries are old. just toss them and get new batteries. if the batteries have removable caps you can check the gravity of each cell to confirm that they are toast but I say save your time and go with new batteries. .... how old are they?

[ereadingrv]

Originally Posted by Monacoach

personally I think you answered your own question when you stated your batteries are old. just toss them and get new batteries. if the batteries have removable caps you can check the gravity of each cell to confirm that they are toast but I say save your time and go with new batteries. .... how old are they?

Great name, BTW Yes, I am more and more inclined to think you're right. Thanks for the tip on removable caps; didn't know about that. We're looking into the new batteries today and will probably pick them up this evening or tomorrow. We have a new Atwood water heater going in on Tuesday, too, so an expensive week coming up!

[nothermark]

Originally Posted by Soppy

Your best bet is to fire up the coach engine and then measure the chassis battery voltage. It should be above 13 volts and gradually increasing to 14 volts as the batteries charge. If the voltage does not increase , you have a charging problem . Could be as simple as as loose alternator belt . On some coaches , some items are run off the chassis batteries like the radio & steps. Over a period of time the loads will discharge your chassis batteries. Most coaches charge the chassis batteries when on Genny or shore power . Some do not . With batteries that low , you are not charging them from shore /genny power. You'll have to do some investigating to find out why no charging. I would not run out and buy new batteries just yet.

The alternator voltage will be higher than the battery voltage. If it is too much higher it will put out more current than the alternator can support. Same thing with a charger. Either way the source has to limit the voltage differential or shut down or fry itself. These days most electronics will pick one of the ways to protect themselves. That makes picking an absolute voltage a chancy answer. All one really wants to see is a voltage increase.

[nothermark]

Originally Posted by ereadingrv

Great name, BTW Yes, I am more and more inclined to think you're right. Thanks for the tip on removable caps; didn't know about that. We're looking into the new batteries today and will probably pick them up this evening or tomorrow. We have a new Atwood water heater going in on Tuesday, too, so an expensive week coming up!

I'd go the trik l start route before I tossed my batteries. That way they get charged and you will get years more life out of them.

There is no secret to the idea that modern chassis have draws for things that you may not want to leave without power. Your radio loses station programming and the engine computer can lose some of it's programming for two examples.

[ereadingrv]

Originally Posted by nothermark

I'd go the trik l start route before I tossed my batteries. That way they get charged and you will get years more life out of them.

There is no secret to the idea that modern chassis have draws for things that you may not want to leave without power. Your radio loses station programming and the engine computer can lose some of it's programming for two examples.

Very true on chassis draw. In the case of our Diplomat, it's never been an issue before, hence our concern and confusion, to an extent.

Perhaps I missed it, and if so, I apologize...but what is the "trik l start route" you refer to? Is that an add-on device, which someone else mentioned? Thanks again!

[ereadingrv]

Originally Posted by nothermark

I'd go the trik l start route before I tossed my batteries. That way they get charged and you will get years more life out of them.

There is no secret to the idea that modern chassis have draws for things that you may not want to leave without power. Your radio loses station programming and the engine computer can lose some of it's programming for two examples.

Third read-over was the charm! That was one of the links that we saved. Duh! Okay, thanks, nothermark (and to the recommending poster). We're going to check that out. It seems like a wholly-justifiable and valuable addition to our coach restoration! Thanks again!

[twinboat]

Originally Posted by ereadingrv

Thanks for the advice. Question: is there a different process for checking the battery than just the voltage? In other words, is there some kind of indicator or other factor, besides voltage, that would point to whether the battery is bad versus just discharged?

The auto parts or battery sales place will have a load tester that they connect to the battery. It will display the condition of the battery.

Most places will test them for free.

[Applefarmer]

When i had the same problem with my 04 Diplomat I added the Trick-L-Start. It took 3 days to bring chassis battery back to full charge