4 of 8 house batteries not charging

[Garry Donohue]

07 Dynasty I have three battery trays. One for Chassis and one below holding 4 house. Then behind that bay, I have a separate tray that holds the other 4 house batteries. When I charge..Only the tray of 4 house batteries below the chassis batteries take a charge as well as the chassis batteries. However the tray holding the other 4 house batteries in the rearmost tray do not charge and are at 5.7 volts. It seems they are just going along for the ride. Is there a fuse or relay or a connection between the front and rear trays that I can look at? 

[Tom Cherry]

6 hours ago, Garry Donohue said:

07 Dynasty I have three battery trays. One for Chassis and one below holding 4 house. Then behind that bay, I have a separate tray that holds the other 4 house batteries. When I charge..Only the tray of 4 house batteries below the chassis batteries take a charge as well as the chassis batteries. However the tray holding the other 4 house batteries in the rearmost tray do not charge and are at 5.7 volts. It seems they are just going along for the ride. Is there a fuse or relay or a connection between the front and rear trays that I can look at? 

First…..hope you have a VOM.  Time for some housekeeping.  First pull the jumpers between the sets of batteries or the short cable going from Positive to Negative.  Now all 8 batteries are “on their own.  Start checking voltage.  I don’t know how old or new, but my hunch is that you have at least two bad batteries.  You should see around 6.3 volts.  

Do the bank that seems to be charging.  Write down the voltages.  A fully charged 6 VDC battery should read 6.3/4 VDC….or 100% State of Charge (SOC).  
 

NOW….on to the problem bank.  If you “loose” or in reality, short out one of the 3 cells, your voltage will drop by 1/3.  No magic or major math.  If one cell in one set (the two in series with a jumper) is shorted out it acts like a big resistor and the charging current doesn’t get past or is extremely weak.  
 

The OTHER thing….  Are these sealed batteries (no twist off or screw off caps)?  If not sealed, open up each cell and use a flashlight to see the electrolyte level.  Should be halfway between the top of the plates and the bottom of the fill well.  Use Distilled Water and replenish.  Now…to give you some more info.  When I said “shorted out”….there is a “lead oxide” coating on the plates or fins of the battery.  If the liquid drops below, the coating dries out and starts to deteriorate and eventually starts to flake off.  Then as you drive, the vibration exacerbates that and the lead oxide drops to the bottom of that cell.  Once that residue gets thick enough and builds up….it then starts to touch the bottom of the plates.. BINGO…Dead short… No longer a Galvanic cell… No LONGER producing voltage…so, you have 2 cells….or 4.1/2 VDC….there is NOT any cure or repair….recycle it….  Sometimes a cell will also be contaminated and the Specific Gravity will be low. Same deal.  TOAST.  If all the batteries are “good”….but you said one “set” was 5.7…..not good.  IF all the batteries measured above 6 VDC, then start looking at connections.  If you follow the negative cables….Each terminates to a Ground Stud behind and under the battery boxes.  Loosen snd clean snd retighten.

That’s enough for now.  Download and read this.

let us know

 

[Garry Donohue]

Ok Tom I will return with my findings this week when my mechanic friend meets me to keep me from blowing things up, lol. Thank you so much. That battery 101 info was very helpful, 

[Tom Cherry]

2 hours ago, Garry Donohue said:

Ok Tom I will return with my findings this week when my mechanic friend meets me to keep me from blowing things up, lol. Thank you so much. That battery 101 info was very helpful, 

Good Luck.  Just do NOT go crazy.  Test each battery for Voltage.  Then the ones that show 6 volts or so....or maybe even 5.5 VDC or so.....check the electrolyte.  THEN if you have any BAD batteries....do NOT put the Jumper across them.  Take them OUT.  They are TOAST.  You can use two batteries, that do NOT have shorted cells, in the back bank.  I ran my 4 bank set on 2 batteries for quite a while....

Then Recharge them....and see what the voltage is.  After they are recharged (it takes 3 - 4 hours for 4 so....6 -8 for 8..  After they are charged....turn on some interior lights for a while....maybe 10 minutes.

THEN....turn OFF the Batteries at the HOUSE Switch.  THEN remove the Jumpers and retest the batteries.  That way you can compare to what they were before. 

Let us know...

[Garry Donohue]

Wanted to clarify, are there any fuses or relays that can be bad? 

[Tom Cherry]

3 hours ago, Garry Donohue said:

Wanted to clarify, are there any fuses or relays that can be bad? 

Back to basics.  If your front bank is being charged, as you indicated, then the back bank has either bum batteries (highly likely from your voltage comments) or there is a major problem with the cabling and/or the connections or grounding.  It is very possible that the back bank’s ground cable is corroded…but you have to do the trouble shooting to determine,  The only “relay” in your system is the “Big Boy”.  The House batteries are cabled directly….i can’t recall without digging into yhe prints for your year and Dynasty if the Inverter is cabled DIRECTLY to the two house banks via a 300/400 Amp (big sucker) inline fuse or THROUGH the House Switch then through the 300/400 Amp fuse.  Your Chassis is definitely wired direct.  But, you have BIRD (Bi-Directional) charging….ll the Big Boy is doing is connecting them….think a mechanical Jumper Cable.  So, if your Magnum charges OK….then it appears to be only charging bank ONE.  Bank TWO is in parallel with NO fancy stuff.

The issue is the condition of each battery and the cabling (clean connections) and proper grounding.  We have had maybe 10 or instances in over 14 years of reading snd then moderating this site of a “ABSOLUTELY NO CORROSION” on either end of a main battery (positive or negative’) cable being defective and having to cut off the terminal and reinstall.

You can NOT determine that until you do the tests and also verify the grounds. No magic bullet…

Let us know what you find out after following the methodology and then it should be obvious….but we will have enough info for the next step….if needed….

[Frank McElroy]

3 hours ago, Garry Donohue said:

Wanted to clarify, are there any fuses or relays that can be bad? 

Gary, there are no fuses or relays.  You need to trace cables to find the bad connection either ground or positive cable.  Could be inside the battery box or outside the box where connections are made to the other bank of house batteries.  All this assumes that the rear battery bank batteries are all connected properly.

[Garry Donohue]

Thank you Frank and Tom, I’m heading over Thurs or Fri to put the info to work. 

[Garry Donohue]

Frank had put me wise on the big boy research when I was leaving for Florida last March. At that time none of my house batteries were charging. He told me to flip on and off multiple times my disconnect switches to get the big boy to temporarily work. It worked. But he did say to put it on my to do list when I get home to clean the big boy. As you can see from the pics he was correct about the corrosion. After I get this cleaned up, I will then concentrate on the back tray of house batteries not charging. In two of the photos…I did find the cables that Tom mentioned and as you can see they are very corroded. Hopefully that is my charging problem. 

[Frank McElroy]

32 minutes ago, Garry Donohue said:

Frank had put me wise on the big boy research when I was leaving for Florida last March. At that time none of my house batteries were charging. He told me to flip on and off multiple times my disconnect switches to get the big boy to temporarily work. It worked. But he did say to put it on my to do list when I get home to clean the big boy. As you can see from the pics he was correct about the corrosion. After I get this cleaned up, I will then concentrate on the back tray of house batteries not charging. In two of the photos…I did find the cables that Tom mentioned and as you can see they are very corroded. Hopefully that is my charging problem. 

Judging from the amount of corrosion on just that single battery box passthrough connector, I suspect you have corrosion on most every positive and negative battery connection going to the rear battery box.  Many time folks just focus on the battery terminal connections.  There are a number of other connections both inside the battery box and passthrough connections on the outside of the battery box and the ground connections to the chassis frame.  They all need to be checked.  Also check for cable corrosion on feeds to the RRB (rear run bay)

[Tom Cherry]

2 minutes ago, Frank McElroy said:

Judging from the amount of corrosion on just that single battery box passthrough connector, I suspect you have corrosion on most every positive and negative battery connection going to the rear battery box.  Many time folks just focus on the battery terminal connections.  There are a number of other connections both inside the battery box and passthrough connections on the outside of the battery box and the ground connections to the chassis frame.  They all need to be checked.  Also check for cable corrosion on feeds to the RRB (rear run bay)

Agreed….you are way past the typical …..loosen the ground stud nut and twist or rotate about 90 deg in each direction.  You need some materials.  Lowes and probably others sell small parts cleaning brushes.  They come in brass as well as steel. You need one about the size that you would use on a grizzly bear or maybe 3 - 4 times a normal tooth brush.  Also need some medium steel wool pads.  A small bucket of water and some “Brillo” scouring pads.  Some cotton toweling or wash cloths.  You also probably need 2 small cans of battery terminal spray or protectant.  All the auto parts box stores (Autozone) carry that.  

you will have to develop or experiment with which brushes or steel wool or whatever works.  If you use the scouring pads which have an abrasive cleaner, rinse and dry.  I still would snug down and twist or rotate to let the cable terminals abrade each other. Then tighten…spray.  Start with 5he grounds and work to the bank.  Frank reminded me that you may have the pass through studs or terminals….so do EVERY connection….

The 5.7 VDC is. Bit of  mystery.  Clean all the teeminals.  Then take some distilled water and refill and recharge.  If the rear set has any life….measure….no sense in trying to charge a shorted battery (does not read close to 5.7 VDC….it will just be a big resistor and keep it’s mate from charging….

Good Luck…

 

[Frank McElroy]

Unfortunately, if corrosion entered the cable crimp connection, the only option is to replace the connector and if the cable is too short to replace the cable.  Hopefully corrosion didn't enter the crimp joint. 

If you need a new connector, be sure to crimp with a hydraulic crimper (or equivalent) and be sure to use a marine grade heat shrink seal.  Marine grade has an internal adhesive seal to prevent water intrusion and it will prevent internal cable corrosion at the cable end crimp joint.

[Garry Donohue]

Will do

[Garry Donohue]

Reporting back to Cherry+ McEllroy..

We separated the house batteries into separate groups of 2- 6 volts by removing the short cables that tied the 4 together as instructed. The good tray in the front, below the chassis batteries read 6.5 volts on each battery.  The tray in the back read 5.7 volts. 
 

we then cleaned all the connections including the pass through bolts. My mechanic friend then took a light tester and probed between each cable. Although the back of the two shut off switches had corrosion, power still passed through. We then started the Generator. His thought was to probe with a volt meter, each connection. Starting from the furthest connection away from the batteries, we got 13.5 volts. We continued moving toward the bad tray in the rear, we disconnected from the batteries, and probed the last positive and negative cables that would normally attach to the batteries. And read 13.5 volts with generator running. Now it appears that the coach is fine except for the batteries themselves. Although they read 5.7 volts equally with no difference between the 4 batteries in question. My friend is going to bring over a portable load tester to see if we can detect a dead cell somewhere in that rear tray. We did notice that two of the batteries in question seems to have a slight bulge on the top. That’s the only thing that looks out of normal. He even checked for ohms resistance to the cables that bridge between the batteries. ( no resistance showed on the meter). So I guess I’ll get back with the results of the load test this week unless you two have any other suggestions. 

[Frank McElroy]

1 hour ago, Garry Donohue said:

Reporting back to Cherry+ McEllroy..

We separated the house batteries into separate groups of 2- 6 volts by removing the short cables that tied the 4 together as instructed. The good tray in the front, below the chassis batteries read 6.5 volts on each battery.  The tray in the back read 5.7 volts. 
 

we then cleaned all the connections including the pass through bolts. My mechanic friend then took a light tester and probed between each cable. Although the back of the two shut off switches had corrosion, power still passed through. We then started the Generator. His thought was to probe with a volt meter, each connection. Starting from the furthest connection away from the batteries, we got 13.5 volts. We continued moving toward the bad tray in the rear, we disconnected from the batteries, and probed the last positive and negative cables that would normally attach to the batteries. And read 13.5 volts with generator running. Now it appears that the coach is fine except for the batteries themselves. Although they read 5.7 volts equally with no difference between the 4 batteries in question. My friend is going to bring over a portable load tester to see if we can detect a dead cell somewhere in that rear tray. We did notice that two of the batteries in question seems to have a slight bulge on the top. That’s the only thing that looks out of normal. He even checked for ohms resistance to the cables that bridge between the batteries. ( no resistance showed on the meter). So I guess I’ll get back with the results of the load test this week unless you two have any other suggestions. 

Yep, sure sounds like bad batteries.  A load test will confirm.

BTW - measuring cable resistance tells very little - you need to measure voltage drop under load.  Since the rear battery bank was seeing 13.5 volts at the batteries, the cables are fine.

[Garry Donohue]

Also, as there is corrosion on the backside of the shut off switches, is there a trick to get up there between the walls to clean them?

[Frank McElroy]

39 minutes ago, Garry Donohue said:

Also, as there is corrosion on the backside of the shut off switches, is there a trick to get up there between the walls to clean them?

There is an access plate on the side of the rear battery box.

[Garry Donohue]

Ok We didn’t see an access plate but we will remove the batteries from the back box to look further. 

[Tom Cherry]

I personally would be a big spender and replace the Blue Seas Switches.  They are easy (at least on mine).  You need this one....color is option.  It has TWO sets of wires.  Two LARGE (High Current) cables and two smaller ones.  That is a circuit that allows your Big Boy (maybe other stuff...Frank is the expert) to work.

https://www.bluesea.com/products/9004e/e-Series_On-Off_Battery_Switch

Verify the PN on the OEM one.  Amazon and others sells them.... You want the one that says (Amazon) On/Off W (with) AFD.  That SHOULD be what is there now.

Personally, the portable load tester, IMHO, is a waste.  You should check the Specific Gravity of the cells.  My BET is that they are TOAST.  The ONLY way, should you want to spend some time, is to pull the GOOD bank out and then put in the BAD 4 and let them charge. If they are at 5.7 VDC, then they are totally depleted.  The only way to really know.....charge them and then drain them....repeat 3 times.  Whatever the voltage is after the 3rd or 4th recharge....that is what they are good for.  Odds are....they are way less than 50%, if that good.  BUT, you never know.

A $8 hydrometer....with a SCALE is a cheap insurance policy.  I use this one from Amazon....

EZRED SP101 Battery Hydrometer, Factory

Amazon's rating are high.  The ONLY "not really clear" instruction....there is a LINE almost at the top.  It might be 1/2" down.  It is easier to see on the back.  If you BLOW up the picture of the package....you can easily see the line.  You MUST pump or mash the electrolyte and get the fluid LEVEL and on this line.  THEN the scale is about as accurate as you could ask for.  I have a second (curioisty) and it is a spectrometer.  It MUST have the entire little prism coated with fluid.  I actually like the bulb one better and I verified it with new Trojans. There is also a "WATER" mark.  If you fill it with distilled water (flush the bulb several times), then the Distilled water reads EXACTLY "1.000" or is on the WATER mark.  You can learn how to use it by tinkering with Distilled water and then test them. Specific Gravity and Load testing is the ONLY way to actually KNOW how good they are.  The Portable ones are flaky and are not exactly "100% accurate.  I would NOT make a decision off them.  BUT, if the batteries are TOAST....YES.  

NOW the Quandary.  Are your FRONT batteries actually GOOD or are they marginal. Again (read the Battery 101 file) if you cycle them up and down and then get them "exercised", you can read (SG and or Voltage) exactly HOW GOOD they are.  You do NOT want to take a bank of 4 that are in the 50% range and add in 4 brand new ones.  They older ones will eventually damage or kill or deplete the new ones.

SO, you need to know....WHAT is the condition.  

ONE OPTION...and I did this. Do NOT install new ones in the back (make sure you get the cables OK and working.  Actually, put TWO of the GOOD ones back there and the OTHER Two up front.  Then use the MH and run them down and then test and measure them.  I only have 4 anyway and I am fine.  I actually got along with only 2 when I had two fail.  BUT, now with a Res Refer, I need 4.  SO, don't be in a hurry.  If you put in NEW ones and then the ones you THOUGHT were OK start to kill them....by the time you realize it...you have already cut the life of the new one.

Knowledge is POWER (PUN) and you need to know what the real condition is before you spend.  Frank and I are old school guys.  Our cars have Buggy Whip holders.  LOL.  We like the Trojan T105 vs AGM.  Whatever you do...do NOT buy a Combo battery or a SEALED Deep Cycle battery.  If you want to get 7 or so years, as we do, then the Hydrometer and learning how to maintain batteries will save you grief and $$...

Keep us posted...

[Frank McElroy]

33 minutes ago, Garry Donohue said:

Ok We didn’t see an access plate but we will remove the batteries from the back box to look further. 

Yes, the batteries need to be removed to pull off the access plate.

[Frank McElroy]

4 hours ago, Garry Donohue said:

Ok We didn’t see an access plate but we will remove the batteries from the back box to look further. 

Attached are a few pictures.  One shows the access plate as viewed from the rear battery box.  The other shows a picture of the back side of the battery disconnect switches and to the right you can see the access panel on the side of the rear battery box.  It is held in place by 2 bolts (the nuts are welded to the side of the battery box).  You will need to remove the rear batteries to gain access to remove the access plate. 

On my coach, in order to make it easier to install a Magnum BMK option, I put all 8 house batteries in the large battery box and put the chassis batteries in the rear battery box.  So, in my setup, I can remove the access plate without removing the chassis batteries.

[Garry Donohue]

My EZRED SP101 arrived today. Dumb question..Do I have to charge the batteries to full in order to test with the Hydrometer?

[Frank McElroy]

You can use a hydrometer to test batteries at any state of charge.  But if you don't recharge the batteries first, you won't know if they can be fully recharged. 

So, recharge the batteries first then test with a hydrometer.  If necessary, use battery jumper cables or an external battery charger, or swap the rear to the front battery bank to recharge the rear battery bank. 

If all batteries are seeing a Magnum inverter bulk recharge voltage of about 14 volts overnight and then after disconnecting all batteries for an hour, I'd then measure specific gravity on each battery.  You will see those that pass and those that fail. 

[Tom Cherry]

9 hours ago, Frank McElroy said:

You can use a hydrometer to test batteries at any state of charge.  But if you don't recharge the batteries first, you won't know if they can be fully recharged. 

So, recharge the batteries first then test with a hydrometer.  If necessary, use battery jumper cables or an external battery charger, or swap the rear to the front battery bank to recharge the rear battery bank. 

If all batteries are seeing a Magnum inverter bulk recharge voltage of about 14 volts overnight and then after disconnecting all batteries for an hour, I'd then measure specific gravity on each battery.  You will see those that pass and those that fail. 

Frank is correct.  Since you are “new” to the hydrometer and such, I’d actually test each one and also record the voltage.  Just make sure you get the electrolyte up to the molded in line at the top.  Keep if level.  I did a complete evaluation of my set a few years ago.  This sounds like a physics lab exercise….and it is.  Here is what i did……

• first make up a notecard of a battery.  Two posts….one “+” & the other “-“.  Then the 3 cells.  Positive on the left….  Now the first cell on the left is A, then B, then C.  
• then number the batteries.  Front 1,2,3,4……back 5,6,7,8.  Now you need a chart so you can record the time on the left & then the voltage (for battery 1)….then the SG for cells 1,2,3…. Repeat so you have them all.  I’d do that as they sit now so you have a baseline.  Then follow Frank’s comments.  Throw two jumper cables between the two banks, just to make certain you get good charging.  
• make sure the electrolyte is half way between the plates and the bottom of the well….unless you have a “fill to” mark.  Your hydrometer can be used to remove any cell you get  heavy handed on.  Squirt the excess in a empty milk jug.  Glasses are recommended.  This is acid.  I have a pair of “holie” jeans i wear and they get holier every time.
• then pump or charge them up.  Unplug shore and then turn on some lights or maybe fire up a TV….leave it on for 5 minutes.  Turn off.  Turn off the hiuse disconnect switch and let them sit and pull the jumpers 
• record the data.  Then look at the voltage for each battery.  The ones that are the highest should have the least variation between those 3 cells.  So….the average (estimated) value of the SG and the voltage should tell you the State of Charge.  If younhave some duds that are really bad and didn’t change any from the start, take them out.  Leave the “might be OK” batteries in….of course they have to be in pairs of two (think Noah’s Ark”.  
• The next step is to repeat.  Put back on the Jumpers.  Hook up some AC loads.  You need one big halogen (500 watt) or equivalent load….run them down.  Measure the voltage on the front bank every 15 minutes.  STOP or pull the load when you get 11.9/12.0 on them,  refill or check the electrolyte …..recharge….remeasure after knocking off the surface charge (TV on).  It may take 3cycles .  But then you will know how much “real” capacity you have.

[Garry Donohue]

The top photo is what all the bad batteries showed, and the bottom was the 4 good batteries. But I have not charged them yet. This is my baseline 

Edited June 7, 2023 by Tom Cherry
Photos duplicated