New 6 volt batteries, problem?

[ryanPSD]

Hey everyone,

Hoping for some input on the new battery situation. We have a 2015 class C, about one year old next month. I’ve replaced the converter in my WFCO 8955 with a Progressive Dynamics 9270 already.

In the last week I purchased two new 6 volt US Battery 2200’s to replace the factory 12v’s house batteries that came with it. Date stamp on the new batteries was Feb (IIRC) 2016. When I installed them, voltage on each was around 6.2, and 12.4 when wired up. I figured no problem, and left the RV connected to shore power for about 3 days before our trip this weekend.

Upon unplugging and driving to our campsite today (less than 20 miles), my volt meter shows still 12.4 on the batteries. Any idea what gives? Shouldn’t I be seeing 12.7+ on a full charge still with two 6v batts in series?

I did notice the other day that the electrolyte level on the new batteries was not close to the bottom of the fill neck, but about halfway down to the plates. I estimate 1/2” above the plates, and 1/2” below the fill neck. I did not get a chance to top them off, but assumed they would be fine for the moment. I assume this should be the typical 1/8” or so just below the fill neck on these as well? The RV was level while charging, and is level at the campsite.

I did not check voltage after unplugging from shore power, before leaving. I only did prior to unplugging and the PD9270 was in storage mode at the time, it was around 13.2v if I recall, but I know it charged these batteries in all stages. The converter had no issues charging the previous 12v batteries.

Had to run back to work for the rest of the day but will be back this evening to see how they are doing, with the family using them. I don’t have a hydrometer but I think that may be next on my list.

Thank you for any input!

[ljr869]

11.8V in the morning? They're done, replace them.

[Canadian_Rainbi]

ryanPSD wrote:
I saw 13.2 at the batteries while the engine is running. This is, all, however immediate after being plugged in for 3 days into the PD 9270.

Bought a hydrometer on the way here. One battery shows 1250-1255. The other is a healthy 1270-1275. The low one also shows .06v lower than the other.

Possible bad battery?

Is every cell in the one battery 1.250-1.255, or just one cell? This is too low. Battery or cell is not charged. You need to charge this battery at 7.5-8.0 Volts until the specific gravity stops rising. If you don't have a "6" volt charger that will do this use the "12" volt charger. You may have to put it in equalise mode to get this. When SG stops rising that cell or cells is charged. If not up to 1.265 or better and is not rising with 15-16 volts (7.5-8 using one battery) then that cell has had it. Get the replacements offered by your dealer. Best to do this charging with ALL LOADS off the battery. Also, watch the cells for electrolyte level.

When charging or equalising, there should be enough electolyte to cover the plates and keep them covered. DO NOT over fill--the fast gassing can cause the electrolyte to spill over. Once the batteries are fully charged then top up the electrolyte with distilled water to just below the notch.

If the weak cell(s) come up to an acceptable level and stay within the range of the other cells after that then the battery is likely OK, though you should keep an eye on its SG. If it always falls much lower than the others, replace it.

[wa8yxm]

You drove about half an hour. You ASSUME there is no load on the batteries during that time... There is.. Several devices in the RV never fully turn off.

Second. Have you calibrated the meter? It's been a long time since I calibrated a voltmeter but all it takes is a FRESH Carbon Zinc Dry cell battery.. (you measure the voltage) for a basic calibration.. lab level calibration is a bit more complex but I know how to do that as well.

[MEXICOWANDERER]

Find out WHY none of your chargers will allow the batteries to charge correctly.

If you are getting an alternator voltage reading of say 14.0 and a simultaneous battery voltage of say 12.5, the answer should be obvious.

BOTH alternator AND converter low charge rates are indicative of bad charging pathways common to both chargers. A 130 amp engine alternator sucked down to 13 volts at the alternator stud is providing 100+ amps. Energy translation means a bad battery would champagne the cell caps and play the part of Old Faithful.

This is the price a person pays when trying to manage a complex system by single point voltage measurement. Start with voltage CHARGING sources and NOT the destination. Check converter fuse and alternator output stud voltage. Suggestions as to specific causes and components is utter guesswork. You need to test with your own fingers and your own hand held multimeter.

And don't omit the connection where the house batteries negatives connect to the chassis frame.

[ryanPSD]

Unfortunately, I don’t think I have access to a 6v charger, to try and bring up the one batt.

RJsfishin wrote:
Quote:

I saw 13.2 at the batteries while the engine is running. This is, all, however immediate after being plugged in for 3 days into the PD 9270.

------------------------------------------------------------

You should have seen the 13.2 w/o the engine running, if you checked it immediately after disconnecting the PD power. And w/ the engine running, you should have seen 14.2.

Your PD seems fine, but your alternator charging has a problem, as does at least one battery

True, I only fired up the engine for a moment (<30 seconds) and looked at the volt meter and afterwards thought it maybe should have been higher. The voltage was checked at the battery. I know it’s got to be near a 20’ run, maybe more, from the alternator to the battery, so I just chalked it up to voltage drop there.

Update after first night, still seeing a more voltage drop than previously experienced on light 5-6 amp loads, dropping to <11.8 now under these loads this morning. Looking forward to replacing them, as I can tell already they will have more capacity than what they replaced. I really wish I had room for 4 batteries, if I get two more, will have to locate the second pair 15’ away in a compartment and deal with venting as well. Still thinking about it, but will probably be happy enough with two for now.

I think we will make it through the weekend fine, and I will likely be exchanging these. The place I got them from received a newer shipment since I purchased these, and will be examining the replacements closely before taking them home. Maybe an upgrade to the 125's would be nice.

[RJsfishin]

Quote:
I saw 13.2 at the batteries while the engine is running. This is, all, however immediate after being plugged in for 3 days into the PD 9270.
------------------------------------------------------------
You should have seen the 13.2 w/o the engine running, if you checked it immediately after disconnecting the PD power. And w/ the engine running, you should have seen 14.2.
Your PD seems fine, but your alternator charging has a problem, as does at least one battery

[MrWizard]

it sure looks like the lower battery is weak
do you have access to a six volt charger to throw on the weak battery and see if it will come up ?

might need to take those back and have them load tested
and maybe replaced

[westend]

ryanPSD wrote:

westend wrote:
You have some sort of DIY shunt/cable connection on the negative post of your bank. What I'd suggest is to remove the cables and remove the shunt holder from the battery terminal and see how much resistance is through that connection. With two 4 AWG in 5' of run, you shouldn't see hardly any voltage drop.

Another thing you might try is to push some decent voltage through the single, lower 6V battery. Goose it hard and see if it responds.

Yeah, that is two pieces of flattened 1/2" copper pipe I needed to move and lower the shunt so it would clear the step the batteries are under. If you mean move the shunt overall, I don't think that's the issue, been good with it before the batteries. If not, you're right, the copper is the only thing new other than the batteries. I can try that tomorrow a beers in already...

Gotcha. I was thinking to test that connection combination, only, not advocating to scrap your design.

[ryanPSD]

westend wrote:
You have some sort of DIY shunt/cable connection on the negative post of your bank. What I'd suggest is to remove the cables and remove the shunt holder from the battery terminal and see how much resistance is through that connection. With two 4 AWG in 5' of run, you shouldn't see hardly any voltage drop.

Another thing you might try is to push some decent voltage through the single, lower 6V battery. Goose it hard and see if it responds.

Yeah, that is two pieces of flattened 1/2" copper pipe I needed to move and lower the shunt so it would clear the step the batteries are under. If you mean move the shunt overall, I don't think that's the issue, been good with it before the batteries. If not, you're right, the copper is the only thing new other than the batteries. I can try that tomorrow a beers in already...

[korbe]

.

[westend]

You have some sort of DIY shunt/cable connection on the negative post of your bank. What I'd suggest is to remove the cables and remove the shunt holder from the battery terminal and see how much resistance is through that connection. With two 4 AWG in 5' of run, you shouldn't see hardly any voltage drop.

Another thing you might try is to push some decent voltage through the single, lower 6V battery. Goose it hard and see if it responds.

[ryanPSD]

DrewE wrote:
That's a rather larger voltage drop than I would expect for those modest currents. I would check that your connections are all clean and tight and your wires and terminals are all solid and good. It would also not hurt to check the voltage output at the converter when charging (with a non-trivial charge current) and at the battery terminals. I'd also check for the off chance that there's a bad cell in one of the batteries.

Assuming the voltage dip is due to an ohmic resistance, you might see a voltage of somewhere around 8V when attempting to crank the built-in generator (if you have one), which could well be insufficient for the task...and, if it's a bad connection, it would be getting pretty hot pretty quickly.

Thaks, all connections are good. Converter to battery is a direct #4 awg run of <5 feet one way. I checked it once but forget what the drop was, very low though.

See my last response, also.

[ryanPSD]

I saw 13.2 at the batteries while the engine is running. This is, all, however immediate after being plugged in for 3 days into the PD 9270.

Bought a hydrometer on the way here. One battery shows 1250-1255. The other is a healthy 1270-1275. The low one also shows .06v lower than the other.

Possible bad battery?

[MrWizard]

what do you mean confirmed charge from alternator

voltage at battery should be 13+ to 14+ with engine running
or plugged into shore power or generator

a bank taking only a few amps at 13+ that immediately drops to 12.4x after removing the charging source has a problem
one oe more cells may be weak

or there is a bad interconnect cable creating a high resistance