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Topic: Alternator not charging house batteries (Read 1545 times) previous topic - next topic

Re: Alternator not charging house batteries

Reply #20 –
Auto-combiners are fine as long as both battery banks have the same or similar nominal battery voltage.  AGM house & AGM chassis....great.  Wet Cell....great.  If you have, or ever think you might have, lithium house batteries the auto-combiner may not be so great.  The higher voltage of the lithium bank will not combine well with AGM or conventional chassis batteries.  Yes, you lose a volt going through the isolator.  So what.  That's what the sense wire is there to correct.  And there is something to be said for being able to choose when to boost.  Auto-combiners can mask a weak battery bank by combining without you being aware that the boost was needed.  The isolator and boost relay arrangement is a pretty reliable design that does not limit your battery options the way a combiner does.  Both have their place and, as is frequently the case, there is no single perfect solution for everyone, regardless of what the industry says.

Re: Alternator not charging house batteries

Reply #21 –
Good points.  I figured someone would post about lithium.

AGM to gels work fine in my personal experience. 

Foretravel uses AGM optima start batteries and mk gels and an auto combiner in their new coaches and probably a small solar panel for 100% reliable charging if under the sun and probably wired up the starter sense wire to prevent the auto combining of the banks masking the battery banks condition.

Re: Alternator not charging house batteries

Reply #22 –
Quote from: bdale –
The isolator and boost relay arrangement is a pretty reliable design that does not limit your battery options the way a combiner does.  Both have their place and, as is frequently the case, there is no single perfect solution for everyone, regardless of what the industry says.
I second your thoughts on this subject.  Each owner should look at the available technology, and decide what they want to use.

When I rebuilt our isolator panel, I elected to retain the original factory battery management concept, but upgraded to more modern components.  I was able to correct the deficiencies of 25 year old design, but I didn't toss the baby out with the bath water.

'93 U280 Isolator Panel Upgrade

Re: Alternator not charging house batteries

Reply #23 –
I started the engine and turned on the boost switch but there was no change in voltage to the house side of the solenoid.  Maybe the boost solenoid is bad also.

Right now all we're really needing is a simple but quality way to chare the house batteries with the alternator. 

Right now I'm leaning towards a new, properly rated isolator to replace the missing one, but that could change. I appreciate hearing everyones opinions.

Re: Alternator not charging house batteries

Reply #24 –
Quote from: The Soft Boulders –
I started the engine and turned on the boost switch but there was no change in voltage to the house side of the solenoid.  Maybe the boost solenoid is bad also.
With dash BOOST switch OFF, there should be no voltage at either of the small terminal posts on the BOOST solenoid.

With BOOST switch ON, you should see 12 volts at one (either one - doesn't matter) of the small terminal posts on the BOOST solenoid.

If you are getting 12 volts at the small solenoid post (with boost switch ON) try tapping lightly on the top of the solenoid to see if it frees up and closes (percussive persuasion).  If so, it is probably corroded inside (or weak coil) and needs to be replaced.

If tapping on it doesn't work, it is toast.

Re: Alternator not charging house batteries

Reply #25 –
The fins on a isolator shows it consumes a lot of power.  Makes the entire system work harder.  Longer gen run time.

Re: Alternator not charging house batteries

Reply #26 –
If the boost relay is toast, you can easily bypass it by connecting both large battery cables to the same terminal on the relay.  Either side is fine.  That will create a jumper around the relay and directly connect your 2 banks, which should restore charging until you get it fixed.  Note that as you drain your house bank, you will also be draining your chassis batteries.  Not good to leave it this way any longer than you have to.

Re: Alternator not charging house batteries

Reply #27 –
I'm looking over the drawings that we have and trying to get an understanding of what all is happening.  I don't really understand what each component does or how it does it. 

Re: Alternator not charging house batteries

Reply #28 –
Quote from: Chuck & Jeannie –
With dash BOOST switch OFF, there should be no voltage at either of the small terminal posts on the BOOST solenoid.

With BOOST switch ON, you should see 12 volts at one (either one - doesn't matter) of the small terminal posts on the BOOST solenoid.

If you are getting 12 volts at the small solenoid post (with boost switch ON) try tapping lightly on the top of the solenoid to see if it frees up and closes (percussive persuasion).  If so, it is probably corroded inside (or weak coil) and needs to be replaced.

If tapping on it doesn't work, it is toast.
We are getting 12v to one of the small posts on the solenoid but tapping on it didn't produce any results. 

On the drawings we have they show both the start and boost solenoids with only one small post instead of two.  Do both small posts have the same function?

And are these solenoids or relays?  Everything says solenoid but they seem similar to a relay to me.

Re: Alternator not charging house batteries

Reply #29 –
A solenoid is a type of relay.

If one small terminal, the solenoid grounds by its body being connected to chassis metal  If two, one small terminal is wired to ground.

Re: Alternator not charging house batteries

Reply #30 –
Quote from: Caflashbob –
Longer gen run time.

The isolator has nothing to do with the generator as it feeds the batteries from the main engine's alternator.

Tyler,
Think of the isolator as a swinging gate. If it sees one set of the batteries (whether it be coach or start) low it swings the gate open to feed  that side more juice.

Mike

Re: Alternator not charging house batteries

Reply #31 –
Quote from: Pamela & Mike –
The isolator has nothing to do with the generator as it feeds the batteries from the main engine's alternator.

I think he was referring to the power consumed by the isolator, which means the generator has to run longer to make up for any charging that the alternator can't complete.  A few seconds extra generator time on a typical charge cycle, I would imagine.  In reality, I think the small amount of  power wasted by the isolator just means a little (very little) extra work for the alternator.

Re: Alternator not charging house batteries

Reply #32 –
bdale,

What  I am saying is if the system is working properly the batteries should be fully charged or close to it after you have had the engine running down the road. The voltage regulator makes up the difference in the isolator.

All this discussion about mili amps really has nothing to do with helping out with the OP problem.

Mike

Re: Alternator not charging house batteries

Reply #33 –
Quote from: Pamela & Mike –
bdale,

 The voltage regulator makes up the difference in the isolator.

Mike

Let me state it a little differently.  The sense wire tells the alternator the voltage on the battery side of the battery isolator. So, if the "target voltage at the battery" is 14.0 VDC, the sense wire communicates that to the alternator.  The alternator must put out about 14.7 as about .7 VDC is lost to heat in the diode-based battery isolator.

Re: Alternator not charging house batteries

Reply #34 –
Just out of curiosity, if someone had a decent sized solar setup could an alternator be eliminated all together?
 

Re: Alternator not charging house batteries

Reply #35 –
Quote from: The Soft Boulders –
Just out of curiosity, if someone had a decent sized solar setup could an alternator be eliminated all together?

NO.  You would have to have a very large solar system to keep up with day time driving and ?? night driving???