Chassis battery charging

Topic: Chassis battery charging (Read 1035 times) previous topic - next topic

Chassis battery charging

October 27, 2014, 05:17:01 pm

Normally whilst driving dash volt meter is 13.5 , digital on monitor is 13.2
Today i noticed both reading 12.6 , stopped at small town napa and stripped out battery's and they told me all fine but need charging ?
I am now looking for shop to test alternator enroute to san atonio tx .
Am I thinking this through or can you guys see another problem

Re: Chassis battery charging

Reply #1 – October 27, 2014, 05:26:10 pm

Seems low. I get better or higher voltages when testing at the isolator in the engine area.

Re: Chassis battery charging

Reply #2 – October 27, 2014, 05:39:52 pm

It IS low. Before thinking it is the alternator, spend 5 minutes with a digital voltmeter (CAREFULLY).

With engine running at high idle (around 1000 RPM) carefully raise bed and check voltage at the large center lug of the battery isolator. Should be 14.5-14.7. Check voltage at the outer large lugs of the battery isolator. Should be 13.8-14.2. Readings at the batteries should be the same as at the outer lugs.

If it is not, make sure the small "sense" wire from chassis battery lug of the isolator to alternator is clean and tight. Check other connections as well (all with the engine off).

That will help tell you if it is the alternator or wiring issue or isolator.

Re: Chassis battery charging

Reply #3 – October 27, 2014, 06:04:34 pm

Check the sense wire for sure. After taking the voltages that Brett suggested I would remove, clean and apply dielectric grease to all connections on the alternator, isolator, boost relay, aux start relay and start batteries.

Roland

Re: Chassis battery charging

Reply #4 – October 27, 2014, 07:56:09 pm

Thanks guys ,
Two questions , how to identify isolator switch ?
Will a small digital volt meter work , my larger quality meter went missing in Florida !
Thanks again

Re: Chassis battery charging

Reply #5 – October 27, 2014, 08:03:56 pm

Jimmy,

Looks like this:

Re: Chassis battery charging

Reply #6 – October 27, 2014, 08:40:29 pm

Just parked and hook up , it's dark and I feel pretty tired so will hit it in morning with fresh eyes and report back .
Thanks so much for everyone's time and advice , I would be lost without you

Re: Chassis battery charging

Reply #7 – October 27, 2014, 08:56:36 pm

Sounds like the voltage regulator in the alternator. Some are built in, and some are external. Any reasonable meter will tell you if it's good or bad. 12.6 is battery voltage with no charging voltage. Charging voltage should be around 14 volts, give or take a little. Check the voltage as close to the alternator as you can safely do with the engine at idle. Have a great day ---- Fritz

Re: Chassis battery charging

Reply #8 – October 28, 2014, 11:15:04 am

Ok guys , did the best I could with this meter ,
Engine at 1000rpm , center post 6.4v outer posts 9v
If this sounds way out , I can go buy a better quality meter .
Any thoughts ??

Re: Chassis battery charging

Reply #9 – October 28, 2014, 11:18:16 am

Brett
Thanks for the careful note , I really don't want to make this problem worse

Re: Chassis battery charging

Reply #10 – October 28, 2014, 11:32:57 am

Jimmy,
With that low of voltage on the center lug of your isolator your alternator isn't putting out voltage. Check your sense wire for good connections at both ends along with the wire itself to see if it is broken. You could have a bad voltage regulator or broken wire on the regulator. There are 3 wires under your regulator (usually black, red, and most likely blue of some sort). It is also possible that you have a stuck brush in the brush holder. The brushes are what connect the regulator to the rotor commutator rings. A good alternator shop will need to look it over for you if it is that deep inside.

The voltage on the outside lugs is real low at 9v and that will cause damage to batteries if they are truly that low.

Pamela & Mike

Re: Chassis battery charging

Reply #11 – October 28, 2014, 11:36:20 am

Find a way to charge batteries asap, is coach plugged in?

Re: Chassis battery charging

Reply #12 – October 28, 2014, 11:47:07 am

Coach plugged in and boost switch on
Engine cooled down so I could get good look at alternator , it's super hot to touch after only 5mins of test running , also notice burn mark pm " regulator " ? At back

Re: Chassis battery charging

Reply #13 – October 28, 2014, 11:54:56 am

The burn mark is not arcing , connection is tight .
If you guys think it's the alternator , then any advice on getting it out. , belts etc .
Exchange from napa is $450 , could ask around for a shop that could rebuild ?

Re: Chassis battery charging

Reply #14 – October 28, 2014, 12:03:04 pm

Jimmy,

That white box is your brush holder. The voltage regulator is mounted on top of it with 4 Philips head screws. If you take the 4 screws out it will get you to the brushes. The thing is after you remove the voltage regulator the springs on your brushes will go twang and it can be a challenge to get them back in without proper tools. In the pic it looks like it has been very hot. Your alternator shouldn't be that hot after a 5 min. run. It should be just warm after a all day run. From what I see in the pic you need to unhook your start batteries so there is no voltage on any of the 4 wires that hook to the back of your alternator so you can safely remove it and get it checked over. You have a Leece Neville duvac alternator, looks like a 2800JB but can't be for sure until you look at the nameplate.(there is no diode trio on your brush holder)

Pamela & Mike

Re: Chassis battery charging

Reply #15 – October 28, 2014, 12:09:52 pm

Jimmy,

If the stator & rotor are not burnt up the rest of the parts to rebuild that alternator is less that $100. It should take a good alternator shop about an hour to check, tear down, repair. I would have it repaired rather than exchange.

Where are you broke down at? There may be a member close by that has knowledge of a good shop.

Pamela & Mike

Re: Chassis battery charging

Reply #16 – October 28, 2014, 12:13:51 pm

What number Leece Nevill do you have?

Re: Chassis battery charging

Reply #17 – October 28, 2014, 12:37:41 pm

Just south 3miles south of San Antonio

Re: Chassis battery charging

Reply #18 – October 28, 2014, 12:39:00 pm

A0012824LC

Re: Chassis battery charging

Reply #19 – October 28, 2014, 12:50:33 pm

Jimmy,

Also you need your sales # it is located on the same tag.(if you are doing an exchange) The LC is the newer version of the JB. Both are repairable at a reasonable cost.

Pamela & Mike

Re: Chassis battery charging

Reply #20 – October 28, 2014, 01:00:21 pm

This may help

Texas Alternator & Starter is a Leece-Neville Distributor
5426 Interstate 10 E
San Antonio, Tx
877-839-2587
Texas Alternator Starter Service

Re: Chassis battery charging

Reply #21 – October 28, 2014, 01:07:37 pm

Quote from: Jimmyjnr – October 28, 2014, 12:39:00 pm

A0012824LC

Is it pad mount or does it have ears,The Delco Remy cross is a 28SI Truck Pro saud pad mount brand new no core charge 323.99 check Fleetpride with that part number abd mount style for a price quote.

Re: Chassis battery charging

Reply #22 – October 28, 2014, 01:09:18 pm

Charge the batteries by another means (shore power). THEN, recheck. A bad battery can also cause low readings-- alternator output is not sufficient to bring the batteries to "proper" voltage.

If the battery voltage before you start is 12.5 or better, a bad battery as the cause is ruled out.

Re: Chassis battery charging

Reply #23 – October 28, 2014, 01:50:36 pm

Thanks again
Just read Barry's page and it said a bar was needed to relieve tension on belt , so I am off to rent a car then Home Depot to buy a pry bar back to park remove alternator then to a rebuild shop .
Will keep you guys informed
Ps the none working tv has gone to bottom of list

Re: Chassis battery charging

Reply #24 – October 28, 2014, 01:51:39 pm

After checking battery's , as per Brett's instructions

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