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Topic: UPDATE Engine batteries not charging while engine is on UPDATED (Read 841 times) previous topic - next topic

UPDATE Engine batteries not charging while engine is on UPDATED

Good evening everyone,
We've been running around the country and our volt meter has been indicating 13.8 to 14.
Today after stopping at Walmart and heading on our final leg I noticed that the voltage was down to 12 to 12.2 to 12.5. As we continue to drive voltage drop down to 11.8 but still would pop up to 12.4 on occasion.
Fortunately we were able to make it home and are now plugged into a 50 amp power.

Is there a specific way to check that the alternator is charging the batteries? I am also unsure on where The voltage regulator is and how to check it.

When I looked in the engine compartment I noticed a piece of aluminum up against this piece of equipment in the picture up on the wall under the bed, which I believe is the isolator. You can see some discoloration on the lug and wire

Thanks Frank
Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH

Re: Engine batteries not charging while engine is on

Reply #1 –
That is you battery isolator and I would start by checking the voltage there -- with and without the engine running.
1993 U225 Build #: 4285
500 Watts Solar
Honda CRV AWD
Former 1981 Foretravel Travco
Retired, Full Time Off Grid Snowbird

Re: Engine batteries not charging while engine is on

Reply #2 –
Frank,

The voltage regulator is located on the alternator (If you still have the OEM alternator) and is held on by 4 Phillips head screws. You could have a brush stuck rather than a voltage regulator problem. The brushes are hid under the regulator.

As hot as that isolator has been to melt the goodie around the diodes I would plan on changing it out whether it checks good or not.

Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Engine batteries not charging while engine is on

Reply #3 –
Quote from: Lt403 –

Is there a specific way to check that the alternator is charging the batteries? I am also unsure on where The voltage regulator is and how to check it.

Thanks Frank


Yes.  Take your DC voltmeter to the finned aluminum thingy aka battery isolator.  probe from the center terminal to ground and you should measure something on the order of 14.4 - 15.1 VDC with the engine running. If yes, the alternator is fine.  Then probe from the center terminal to each of the outer terminals.  You should measure 0.7V maximum.  Over 0.7V but less than alternator voltage, then clean the connections.  Alternator voltage?  Tie all of the cables onto one bolt. Then decide if you want to stay with a diode style isolator, which is what you have or a voltage sensitive relay disconnect which eliminates the 0.7v diode drop.  But isn't as magical.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Engine batteries not charging while engine is on

Reply #4 –
As stated above, the blue finned device is your battery isolator.  It has 3 big posts an it.  A bit hard to tell in the photos, but appears that the center post is where the charging cable from the alternator is connected.  If that is correct, then the other two posts are where the battery cables connect.  If you have a wiring diagram for your coach you can compare the cable numbers on the diagram with the number labels on the actual cables to determine which battery bank is connected to which stud.

To determine if the alternator is charging the batteries correctly, start the big engine and then using multimeter check the voltage at the following points:

1.  The "B" (POS) charging terminal on the alternator.

2.  The center post on the isolator.

3.  Both of the outside posts on the isolator.

4.  The POS post on both battery banks.

By doing this check you are following the battery charging current from the source (alternator) to the final destination (battery banks).  You are checking the condition of the alternator, and the isolator, and the cables, and the cable connections.

Report back to us with the voltage readings you get, and we can advise on what is the next logical step in trouble shooting.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Engine batteries not charging while engine is on

Reply #6 –
Thanks everyone,
Thought I had to just change the fan motor and start capacitor when I got here but now this takes priority
WILL LET YOU KNOW THE RESULTS IN THE MORNING.

THANKS AGAIN
Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH

Re: Engine batteries not charging while engine is on

Reply #7 –
Just ordered a Battery Isolator, mine wasn't charging house batteries while driving. From looking at your pictures, I see a crack and oozing near the center terminal. That is not normal and probably your issue. Mine was a Cole Hersee, 200amp, part #48160. Ordered off Amazon for $108.00.
Dave & Danette
2005 Foretravel U270, 3620 PBLW, Build #6331
2018 Jeep Grand Cherokee
2017 Can-Am Maverick X3 RR
2016 Polaris Turbo RZR
Motorcade #17839

Re: Engine batteries not charging while engine is on

Reply #8 –
Good morning everyone I just finished taking some readings at the alternator and isolator and this is what I found ( I had just started the engine and was not connected to shore power.

With the engine running
at the alternator be post I have 15.31 V

At the isolator center post I have 15.23 V
At the isolator left post facing it I have 13.96 V
At the isolator right post facing I have 13.93 V

The gauge on my dash is close to 14 and the scan gauge at 13.7

KEEP READING

It's been 32 minutes that I've been running the engine and here are my readings at the gauge
On my scan gauge I'm now reading 12.3 V

Alternator B post 1 V
Isolator center post 1V
Isolator left post facing 12.4
Isolator right post facing 12.3

Am I right to replace the alternator and isolator?
Is my alternator from 2002? The date is 200214.
It is 160 amps see pics

No markings on the isolator.

Should I upgrade the alternator and isolator or keep the same ratings?

Thanks everyone
Frank
Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH

Re: Engine batteries not charging while engine is on

Reply #9 –
The isolator is probably just fine but your alternator is failing once it warms up.  Happy new alternator. What you're reading on the outside posts are the battery voltage back-feeding from the batteries and being stopped at the isolator.  As it should.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.

Re: Engine batteries not charging while engine is on

Reply #10 –

Excellent job taking and recording the diagnostic readings plus providing good photos!

Your alternator is falling down on the job when it warms up.  It might be a voltage regulator problem, or it might be an internal problem.  You could try to get a alternator tech look at it and see if it can be repaired.  OR, you can just buy a new one and replace it.  Unless you have added a lot of exra load to your electrical system, I would not worry about upgrading to higher amp rating alternator.

That LN is probably the original unit that came with your coach from the factory.  It survived for almost 20 years.  It is a good alternator, and has sufficient capacity for your coach.  It is a DUVAC model, which means it works properly with the diode based isolator.  And the best news: it is still available brand new from several sources.  The easiest solution is just replace it with the exact same model.  Shop around for the best price.

Prestolite - Leece Neville

A0012824LC by LEECE NEVILLE - High Output Alternator

Meter readings say the isolator is still working and doing the job.  The only concerning thing is that crack in the casing with the potting material leaking out.  That might indicate that it has been overheated, possibly due to the alternator putting out low voltage.  You could probably get away with keeping it in service, but I think I would feel better replacing it.  Diode based isolators are available from many vendors.  Get one rated for 160 amps or better.  Search the Forum for recommendations on brand and model.

Dave said in Reply #7 (above):  "Just ordered a battery isolator...Cole Hersee, 200amp, part #48160. Ordered off Amazon for $108.00".

Amazon.com: Cole Hersee 48160 Battery Isolator: Automotive

That BEP Digital Voltage Sensitive Relay was probably added to keep your starting batteries charged by the inverter/charger when the coach is plugged into shore power.  You would need to trace the cables to see where they go, or better yet find the installation info in your paperwork file, to know for sure.  I believe the factory sells those, so it may have been installed by FOT.

Digital Voltage Sensing Relay (DVSR) 12/24V | BEP

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: UPDATE Engine batteries not charging while engine is on UPDATED

Reply #11 –
When I had this problem I simply took the brushes out of the alternator and reversed them.  Been good ever since.

Re: UPDATE Engine batteries not charging while engine is on UPDATED

Reply #12 –
Ordered a new alternator and isolator from find it parts. Will look at old alternator as a possible spare.
Will update when I install them.
Thanks to all who chimed in

Frank
Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH

Re: UPDATE Engine batteries not charging while engine is on UPDATED

Reply #13 –
anyone know if the alternator used above is the same as a 1998 U320 M11 450 HP?
Peter    Alberta Canada
'98 U320 40'  Build 5359 M11 450 HP, Aqua hot, Blu Ox

Re: UPDATE Engine batteries not charging while engine is on UPDATED

Reply #14 –
Quote from: dicksop –
anyone know if the alternator used above is the same as a 1998 U320 M11 450 HP?
Foretravel is notorious for using different components on different coaches at different times.  The only way to know for sure what alternator is mounted on your engine is to get a look at the manufacturer label and compare to Frank's photo.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"
 

Re: UPDATE Engine batteries not charging while engine is on UPDATED

Reply #15 –
Quote from: Chuck & Jeannie –
Foretravel is notorious for using different components on different coaches at different times.  The only way to know for sure what alternator is mounted on your engine is to get a look at the manufacturer label and compare to Frank's photo.

And if you can't deal with that stay away from late model Studebakers.  Studebaker closed their doors in South Bend, Indiana December 1963.  We own an early 1962.  Foretravel documentation for the win!

FWIW, my bet is on that errant piece of aluminum taking out Lt403's alternator.
1992 Foretravel Grand Villa
U225 SBID Build No. 4134
1986 Rockwood Driftwood
1968 S.I.A.T.A. Spring
1962 Studebaker Lark
1986 Honda VF700C
1983 Honda VF750C
Charlie, the Dog was broken out of jail 24 Oct 2023
N1RPN
AA1OH (H)e who must be obeyed.