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Topic: Battery troubleshooting - am I on the right track? Boost Solonoid replacements? (Read 560 times) previous topic - next topic

Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

A few ago, my battery voltage was much lower than expected after a few days of good sun, and I realized that when my batteries were reaching about 12.7V (at rest, after removing the charging source), my chargers were recognizing them as fully charged and going into float charge mode. 

1) At first I thought this was a charger issue, but a quick test of both the solar and generator charging modes revealed that both these independent charging sources were behaving the exact same way.

2) Then I thought it was a battery issue.  I have six L16 AGMs that are only 9 months old. Yesterday I spent a few hours:
- Hooking up the batteries in 6 different pairs to get a charge and de-charge test on each individual battery in two different pairs, with voltage readings at each stage.
- Took temperature readings
- Visually inspected all

All the batteries passed the test - (or at least all the batteries behaved the same way).  Nothing I saw led me to believe I had a single bad battery dragging down the bunch.

AND THEN when I was hooking everything back up, I connected the positive cable while the negative cable was still disconnected, and boom the wire sparked and the fridge/systems came on inside!  With the negative cable disconnected!

The only logical conclusion is that the chassis batteries are connected to the house batteries, even though the boost switch is off, right??  The different battery type and lower full rating of the chassis batteries would explain the pre-mature "full charge" on the entire system.  I also noted afterwards that the Magnum display said when the generator was charging, the inverter was passing through 125-ish Amps of charge, but the actual monitor leads on the house batteries only read at 67-ish Amps of charge.

I ran out of time, so I will go back out today to test.  I have the boost solonoid, plus an independent battery charging system that could be the possible causes of combining the battery.  Probably the boost solonoid, because the cabling from the independent system isn't thick enough to handle that much of an energy diversion.  But before I left I did test the boost solonoid, which did audibly click on both on and off.  Is it possible that the boost solonoid clicks as if it was working correctly, but still be stuck in the on position?  Tried some quick percussive adjustment, but didn't seem to make a difference.

Any other suggestions, anything else obvious that I'm missing?

I looked in the archives and found a few links for replacement boost solonoids,  but the ones I saw were not visually similar to mine.  Several suggested this was OK, but a confirmation on that would be appreciated? Any have a specific part to suggest?
James
w/ DW Erin, sons Gideon and Tobias, cats Oscar & Oliver
Fulltime 1999 U270 34' #5508

Re: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #1 –
James,

Easy to test the boost solenoid.

With boost switch off AND, assuming you don't have some other connection between the batteries such as a battery combiner to keep the chassis battery charged check voltage at each lug of the boost switch.  There should be a difference, based on voltage at the two separate battery banks.

With boost switch on, voltage should read exactly the same as the contactor in the boost solenoid "combines" the two banks.

The "AND" part may take some digging, as most owners HAVE added some means of maintaining chassis battery charge while in storage.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #2 –
Quote
AND THEN when I was hooking everything back up, I connected the positive cable while the negative cable was still disconnected, and boom the wire sparked and the fridge/systems came on inside!  With the negative cable disconnected!
Edited after more careful reading of the post!
The boost solenoid only makes and breaks the connection between the house positive and chassis positive cabling, and is 3-0 cable on our coach. This robust enough to start our coach just with the house batteries through the heavy duty boost switch (Blue Sea magnetic latching relay) I installed. I learned this by accident when I inadvertently started the coach while the chassis battery disconnect switch (heavy duty Blue Sea unit I installed) was off.
As to the behavior of your charging set up, has this changed since you installed your system? Running the batteries down to say less than 70% or so should tell you what the bulk charge current is doing. The bulk phase will of course take longer the lower the state of charge is.
Don
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Don & Tys
1999 U270 3602 WTFE #5402
Xtreme Stage 1 w/Headlight, Step Conversion, etc.
2009 Honda Fit Sport with Navi
Freedom is NOT "just another word for nothing left to lose"... with apologies to Kris Kristofferson

Re: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #3 –
The charging behavior is very unusual.  Charging/capacity has been similar since installing the system in January until a week or so ago.  Bulk charge via solar is usually 40-60 A depending on sun, and it has been 25-30A.  Bulk charging via generator is usually 100-120 Amps, and now it is 60-70 Amps.

Most important to me (as a full time boondocker) is the charging/battery capacity.  I think I'll start the generator, look at the charge rate, shut down, disconnect the chassis batteries completely, and then restart the generator.  If the rate is normal after disconnecting, I'll know my problem centers around the battery combiner system.  Then I can test/replace the boost solenoid at my own convenience.
James
w/ DW Erin, sons Gideon and Tobias, cats Oscar & Oliver
Fulltime 1999 U270 34' #5508

Re: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #4 –
Didn't work...  even after unhooking the chassis battery.

Weird thing is that the inverter still says it's passing through 130 Amps of charge, but the battery monitor itself says only 70 Amps are going into the batteries.  Batteries are mostly discharged - normally would be getting 100+Amps into the batteries if I turned on the generator.  Solar charging behaving similarly, so it doesn't feel like a charger hardware issue.

Maybe a bad negative cable? And the because of the grounding item that Don mentioned, I could be losing a ton of charging amps due to the resulting uneven cabling lengths/gauges?

Picture one is the inverter charger/passthrough reading.  Picture two is the reading directly from the battery.

Any ideas?  Not sure what to check next?
James
w/ DW Erin, sons Gideon and Tobias, cats Oscar & Oliver
Fulltime 1999 U270 34' #5508

Re: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #5 –
Since you just resently had this system installed by John, I would check with him first.  Since your combiner was also installed by John I would check with him for a test procedure also.  I installed ground cutoffs for just the same sparking issue you mentioned, so I know both systems have no ground.
97 U295 40, Build #5040, 6C8.3 325 HP
Oregon Continuous Traveler
Samsung Residential #RF20HFENBSR,
Xantrex SW2012, (3)AGM8D Hse, (2)AGM Grp24 Eng, Victron BMV-712, 1800w Solar 4 LG & 2 Sunpower
Extreme Full Body Pt w/hdlmps, new furn/floor, 4 down Lexus 2004 GX470 AWD curb weight 4,740 lbs
Prev: 1990 Barth, 10L 300 2 yrs; 91&92 Monaco Signature, 10 yrs, 10L C 300 &  6C8.3 300; 1997 ForeT 6C8.3 325 since May 2017.  Employed by Guaranty RV 14+ yrs.  Former VW New Car Dlr/Service Dlr, Sales Mgr, Rv Sales, and Service Adviser from 1968-2017
"Don't criticize what you can't understand" Bob Dylan

Re: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #6 –
In the two photos above does the second one show the "net" condition of battery bank?  I.e. What is going in minus what is going out.  Did you have any big loads turned on when photo was taken?
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: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #7 –
1st photo is supposedly the power running through the inverter.
2nd photo is the net at the battery bank.

No big loads.  Generator was on, and would have covered even the biggest of loads, even if that were the case.
James
w/ DW Erin, sons Gideon and Tobias, cats Oscar & Oliver
Fulltime 1999 U270 34' #5508

Re: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #8 –
Suggest using a clip-on DC current meter to measure actual current flowing in each positive and negative lead from the various sources and batteries when charging. By process of elimination you should be able to see where the issue is.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #9 –
Couldn't you just disconnect one side of the boost solenoid and try repeating what you did?
If it still arcs and sparks then you have the two battery systems tied together at some other point.
At least you would have eliminated the boost solenoid as the problem.

OR... as Peter stated, get a DC amprobe and a multimeter and dig in deeper.. ;D
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #10 –
Funny as my magnum inverter remote panel shows a percentage of the chargers output actually arriving at the batteries according to the fuel gauge wired  in the system.

Your loss seems much higher percentage wise.

How many house batteries?

Quick read of the posts is you are may all seeing the same differences.

My guru buddy mentioned when I asked him about this same output from the inverter difference from our old heart interface freedom heart interface 2500 said "the batteries will only accept so much input power."

Now that I think about this and read the lifeline AGM website they mention the double quick recharge time.

Hmmmm.  So while the gels MAY be superior that seem to not accept  the 1/5 C charging rate maximum normal.

Maybe why Lifeline switched  from Gels to AGM'S? maybe customers noticed the charge rate difference?

Maybe I need a fourth 8gd gel to absorb the charge rate closer to the max available rate.

More solar would maybe  help overcome the lower power absorption rate it seems the gels have.

The gels longer life may be offset in a lower charge acceptance rate.

The tradeoffs are the longer charge times I and you seem to have noticed.

More solar. More gen run time. 1/2 service life from AGM'S? 

My guru's  mk 8g8d's typically last 12 years or so.

The higher capacity(225vs250) amp hours and quicker recharge rate of lifeline agm's is maybe offset by a much shorter service life and, if abused, may require equalizing and a specific lifeline mode that is not offered in some inverter models  plus the higher voltage bulk and absorbtion rates their design allows.

Seems that magnum and lifeline units are designed to work together

Depends on how short term you think and exactly what equipment you have.

I seem to remember DaveM posts as the gen man about installing a 4th 8d after a House refer install.

I may see why.

I changed the inverter out basically to allow a higher recharge rate.

Maybe the gels cannot accept the 1/5 C that the alternator and inverter/charger can put out?

Anyone's agm's Bulk charge to the battery at 120 amps.

Long use to get here but my guru mentioned that the lifeline AGM'S were the best AGMS

In general non abusive damaging mode the trade off to the lifeline might be worth considering.

Pedestal to pedestal or gen on people may not notice or care about this but dry campers and gen rechargers and House refers users may consider this.

Things change. You learn more things,

"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4
 

Re: Battery troubleshooting - am I on the right track? Boost Solonoid replacements?

Reply #11 –
Quote from: Caflashbob –
Funny as my magnum inverter remote panel shows a percentage of the chargers output actually arriving at the batteries according to the fuel gauge wired  in the system.

Your loss seems much higher percentage wise.

In an electrical circuit DC current is not lost or reduced. If a charger is producing say 100 amps, but another gauge is showing less current, the difference is going somewhere else in the circuit or the other gauge is not reading accurately.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B