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Topic: Alternator charging...does it tell me anything else? (Read 527 times) previous topic - next topic

Alternator charging...does it tell me anything else?

I started the coach yesterday in a somewhat colder environment than usual, and I did not use the boost switch.  I used to use the boost switch all the time for starting, but then I realized it really wasn't starting faster...it has always started quickly. 

Anyway, this time my VMSpc showed a charge rate of 14.3, which is very unusual.  Actually, I have  yellow caution light set on the VMSpc display at the 14.3 level, which is what caught my eye.  It took it probably 10 minutes before it dropped down to the more normal 13.8-13.9 setting that I had the alternator folks set the regulator when they installed a new one. 

With that as background, I am wondering if I can take from this that the alternator was trying to tell me that the batteries dropped further than usual as it started, and the batteries themselves are getting near the end of their useful life.  Any thoughts?  I'd rather replace them at a time convenient to me, instead of being surprised. 

Mind you, these Optima Yellow-Tops are the original batteries as near as I can tell.  I *know* they have been in there for 9 years, and I suspect they probably hadn't been replaced...thus making them 12-13 years old.
The selected media item is not currently available.Brad & Christine Slaughter
Was:  1990 U280 36'
Was:  2002 U270 36' (With a bathroom door) Build #5981
Is:  2021 Leisure Travel Van Wonder 24RL
2015 Jeep JKU, 2003 S10 QC 4x4 or 2017 C-Max
Lake Havasu City, AZ (or Gillette, WY)

Re: Alternator charging...does it tell me anything else?

Reply #1 –
Brad, before you trash the Optima's load test each one.  May be one is bad.  Charge them first and let set for a few hours,Remove all cables before testing each individually and of course the old SAW, start at the beginning with all connections clean and tight.
Gary B

Re: Alternator charging...does it tell me anything else?

Reply #2 –
Quote from: Gary Bouland –
Brad, before you trash the Optima's load test each one.  May be one is bad.  Charge them first and let set for a few hours,Remove all cables before testing each individually and of course the old SAW, start at the beginning with all connections clean and tight.
Gary B
I am going to be parked for a month shortly.  I wonder if anything would be wrong with disconnecting the terminals for a long period as I charge each one? Does that cause any issues with the Cummins ECU or the Allison ECU? I would not be unhappy having gotten so much time out of them, but I really don't want to replace a battery that is still good.  I'm just trying to see whether the scenario I described was indicative that they were getting weak.  I would replace all 3 at once anyway if need be.  I believe there is a trustworthy local place that could test them for me if I took them out. 
The selected media item is not currently available.Brad & Christine Slaughter
Was:  1990 U280 36'
Was:  2002 U270 36' (With a bathroom door) Build #5981
Is:  2021 Leisure Travel Van Wonder 24RL
2015 Jeep JKU, 2003 S10 QC 4x4 or 2017 C-Max
Lake Havasu City, AZ (or Gillette, WY)

Re: Alternator charging...does it tell me anything else?

Reply #3 –
Brad, Disconnecting the chassis batteries will cause no problems other than resetting the clock.
Do TURN OFF the inverter if you disconnect the house batteries.
Gary B

Re: Alternator charging...does it tell me anything else?

Reply #4 –
Harbor Freight has a battery load tester for under $50. I bought one and it paid for itself last month by identifying which start battery (old red tops) was bad. Replaced just that one out of the pair and now my start battery voltage stays at 12.7vdc for a week before dropping to 12.6vdc. Plus I don' t have to worry about some guy at the local battery store telling me that one is bad when it's not.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Alternator charging...does it tell me anything else?

Reply #5 –
Thanks, Gary.  Does that high voltage make you think there may well be at least one weak battery in the bank?  I couldn't think of any other reason for the high voltage (other than the alternator not thinking it was charging high enough because of a broken sense wire...or the sense and "other" tiny wires on the alternator being reversed...been there, done that).

Craig:  Sounds like a good expenditure.  I am in Salem, OR and there is a Harbor Freight in the North part of town in this nice, tax-free state.

I made it up here on my 9 yr old Michelins and am getting new tires on this morning at Les Schwab.
The selected media item is not currently available.Brad & Christine Slaughter
Was:  1990 U280 36'
Was:  2002 U270 36' (With a bathroom door) Build #5981
Is:  2021 Leisure Travel Van Wonder 24RL
2015 Jeep JKU, 2003 S10 QC 4x4 or 2017 C-Max
Lake Havasu City, AZ (or Gillette, WY)

Re: Alternator charging...does it tell me anything else?

Reply #6 –
In our service, replacing just 1 battery in a multi battery set, you are now going to enjoy the musical battery game,  not recommended for dependability, but it is cheap if that fits.

Re: Alternator charging...does it tell me anything else?

Reply #7 –
Quote from: Dave M –
In our service, replacing just 1 battery in a multi battery set, you are now going to enjoy the musical battery game,  not recommended for dependability, but it is cheap if that fits.

I understand.. I bought a second new red-top and it's sitting in the shop waiting to go in. The DW will get the one that's in there now for her hot-dog cart. (Her summer hobby is selling hot-dogs at the Saturday morning farmer's market.)

It would have been a higher priority if the voltage didn't hold up for so long. I moved to other projects. Maybe that's a good one for this morning. :D

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Alternator charging...does it tell me anything else?

Reply #8 –
When my coach was 5 years old, one of the original Optima batteries developed a shorted cell, I needed to use the boost switch all the time. I replaced just that one battery with another I happened to have on hand. At the 11 year mark, I needed to use the boost switch again to avoid a starter hesitation on the second crank, so all three were replaced. Now all is good.
Tom Lang K6PG (originally  KC6UEC)
and Diane Lang
2003 38 U295 build 6209
2016 Jeep Grand Cherokee Summit Ecodiesel
still have tow-ready 2006 Acura MDX 
Temple City, California
Motorcade 16681 California Chapter President
SKP 16663 member of SKP Park of the Sierra, Coarsegold California
FMCA F071251
Retired electrical and electronic engineer
 

Re: Alternator charging...does it tell me anything else?

Reply #9 –
I was trying to learn whether the initial 14.3 charge voltage was an indicator that something was up.  Normally, flooded cell batteries last in our AZ cars for 2 to 3 years and the heat kills them.  If I find that only one of my Yellow-tops is weak or some other way defective, I'll replace all 3 but probably keep the other two to stick in place of whichever car battery craps out next.  I still don't need to use the boost switch to start quickly, but I hate the surprise of a dead battery more than I hate buying a replacement too early.  There seems to be no real consensus of experience as to how long these last (any more that there is a concensus of Yellow-Top vs Red-Top...LOL).
The selected media item is not currently available.Brad & Christine Slaughter
Was:  1990 U280 36'
Was:  2002 U270 36' (With a bathroom door) Build #5981
Is:  2021 Leisure Travel Van Wonder 24RL
2015 Jeep JKU, 2003 S10 QC 4x4 or 2017 C-Max
Lake Havasu City, AZ (or Gillette, WY)