Batteries dead, gauge show charging?

[blmyachtsales]

6 month old batteries ( 2 interstate 4D deep cycle) were fine all summer, started noticing slow turning when temps got colder so last time I ran it I Ran the truck all day thinking it would get a good charge, charge gauge was to the right of the green scale where it always is so I shut her down for the night. The next morning about 40 deg. she turned over about 6 times slow then just clicked. Batteries had 10 volts. Charged em from the shop charger enough to move the truck and it sat 6-7 weeks till today.

Again 10 volts, charged em all day to full charge, 32 deg, started no prob with the cold weather Assist. Noticed gauge to the right of green again. Checked batteries individually with a 12v load meter while running, both indicated a bad charging system about 12.5v each battery.

Sounds like a bad alt but why would the gauge be in the same spot indicating the same voltage the whole time. I used this truck all summer with lights and accessories on, even forgot lights on overnight and it still started and seemed to stay charged. Batteries seem to hold when charged from a shop charger.

What is the best way to check these alternators? Is their an adjustment or something that is suspect to break on the voltage reg? Thanks.

 

[Sephirothq]

are you aware you can adjust the power output of the alternator?

 

[emr]

You should read up on all the batt posts in search,there is a ton of info about what you are experiencing and possible causes, Any batt that sits for more than 4 days needs a maintainer according to all batt and charger manufacturers. They sulphate shortening the life, Most blame the batts when they die, but when a batt dies it is 100% human error almost every time. Batts like ours having more than one need to be rotated , and fully charged at least once a year individually, then replaced in new order, The last batt in series never gets fully charged and dies before the others, sulfating, again human error. The only way to check a batt is pull it clean it charge it and wait 24 hours for any surface charge to dissipate and then use a hydrometer, that will tell you if there is a bad cell, if there is its junk, if it is just lightly sulfated there are ways to desulfate, many desulfaters out there, they will prolong the life, every time you let it sit as long as you are and jump it and run it thinking it is fully charged from running the motor , you are shortening the life of the batts. the alt fully charges the first batt only , like filling a pool, the charging system will only let it over flow so long into the next batt before cutting it off, You alt says its working , I think its your batts.

 

[doghead]

Your batteries have a 6 month free replacement.

 

[emr]

Ok It takes me a third read to see sometimes, So I have more useless ideas from a keyboard diagnose. 2 batts ? Shouldn't there be 4 ? Allot of guys say 2 is enough, well maybe, But not really. especially when sitting for long periods,and temp on top of that is a recipe for a no start. Is there a slow drain anywhere ? doesn't sound like it, but hey maybe enough to have fried a cell, 2 batts are working harder than they should,and possibly fry a cell? maybe... and sitting can't be helping, and cold to top it off. Maintenance is the biggest problem I think, Like said above, bring em back if in warranty, They have more wear than a standard set up because of sitting and to much draw on them when needed. As for a maintainer/desulfater, one 12 volt unit bolted on board connected to each batt you have is the absolute best way,I spliced all the plugs to one on mine .( I have 4 ) Also You never have to disconnect anything to charge, ..also meaning you can put a 12 volt charger on each batt anytime, you can jump with 2 sets of cables from 2 cars also, Also your driving last summer may very well not have been fully charging the batts all the time, so they may not want a full charge anymore... also Deep cell batts are better used for there purpose also,

 

[73m819]

TWO 8Ds = 4, my 819 with 2 8Ds sat for TWO years, charged the batteries, started fine, STILL HOLDING a charge,

I-- CLEAN the terminels real good
2--Look for a draw or short,, the alt can cgarge all day and if there is a heavy draw like a direct short, the batteries will NEVER charge
3--load test the batteries, look for a INTERNAL short. FULLY charge each battery then do a DEEP load test

If the charge gage is ALL the way to the right, the alt is OVER CHARGING, this tells you to look for a short, do not REAJUST the alt,, it was charging fine before, so it would be a good guess the problem is somewhere else

 

[blmyachtsales]

Thanks for the tips everyone. I did read a lot of posts on this but felt compelled to ask advice on my particular situation. As I understand it our alts should be set to put out 28.5v. Which corresponds to the gauge being to the right of the green (per another informative post). Guess I should test output with a multi meter while running, where is the best test point? The starter? I will also disconnect the batts, charge and load test after a day. Thanks, will let you know

 

[o1951]

I understand it our alts should be set to put out 28.5v.

Ideal charge is in that range - 28 is ok for newer batteries, close to 29 for older ones that become harder to charge.
The best way to check for adaquate charging voltage is with a hydrometer. If batteries show full charge after a good run, you got enough - if still don't, need a tad more voltage. Too much, or overcharge boils electrolyte, and you have to add distilled water too often.

 

[blmyachtsales]

This has reminded me about another prblem I have come to ignore. Every time I turn the main power on nothing happens, takes several clicks to make contact (then gauges and buzzer come on). I have had a hunch this has to do with that black controll box on the fire wall which also has the wire for the alt going into it and the main 24v lead going into it. Seems awfully suspicious, what does that box actually do.

I will check the batteries with a hydrometer.

 

[blmyachtsales]

So I charged both batts for an hr at 60 amps then let them finish off on auto at 2 amps. After sitting for 4-5 hrs I tested both with a load test and hydrometer.

The batt I thought was not holding as well dropped to the "replace" range when load tested. 5 cells had a specific gravity of just over 1225 and the last didn't register.

The second battery load tested fine but all the specific gravity readings were bellow 1220 4 cells didn't register at all!

How can the " good" battery have such poor specific gravity readings? ( I do understand specific gravity is measuring the density of the electrolyte relative to pure water and that density is lost when batteries sulfate)

 

[rrrr]

The big NHC250 needs a lot of amps to crank in the cold. What works in the summer won't in the winter. I replaced all 4 of my batteries for this exact reason. Now it cranks very well even below 32. Before it wouldn't start if it was below 40. Go over the TM's for adjustment of your alternator. I have mine set at 27.2 for both my vehicles. I also keep them on a 24v charger. I would take your batteries back. I went to napa to get my 6TL's, it was expensive but they fit perfectly and turn over the truck very well. As a reference the 6TL's put out I believe 900 amps at 32F. That means your two batteries are putting out about 50% less cranking amps than the four 6TL batteries normally installed. I'm sure you also made sure the alternator belt is tight.

Your power on delay might be a result of the poor output of your batteries.

 

[blmyachtsales]

Been away for a while but finally had a chance to dig deeper. The alternator is putting out 28v at idle, this is confirmed. Wire 5 is sending 28 v to the controll box from the alt but wire 81 going from the controll box to the starter only has 24.4 v as do the batteries.

I took the controll box apart and the solenoid seems to work when i supply switching power manually. this is leading me to believe their is a problem with the ignition switch. Anyone have this symptom with a bad switch.

I am looking the tests up in the TM but would like some advice as well.

 

[Cycletek]

I had the same issue with my main power switch, I would have to switch it on and off several times if the truck sat for any period of time. I got it to work better with some contact cleaner, but put in a new one and relegated the original to back up status........no issues since.

 

[blmyachtsales]

I took the control box apart to figure out what it actually does. It consists of 2 solenoids and an electromagnetic switch. I noticed that the top solenoid was not always making contact even though it was clicking. I looked at replacing the solenoids but Erics surplus had the whole box for $140 so I got a new one. Still could be the switch itself but I suspect the box is the problem. Will post results for future reference.