Battery charge

Topic: Battery charge (Read 1146 times) previous topic - next topic

Battery charge

January 23, 2020, 04:38:35 pm

I have a 2003 u320 it has 3 interstate 8d agm batteries about 1 year old. They are deep cycle 250 amp hour batteries. If they have have been hooked up to shore power and are reading 13.4 volts at a 5 amps charging when the shore power is disconnected and the inverter turned on but no loads applied within less than 8 hours the batteries are reading 12.2. I have checked at the batteries with an amp clamp which showed 7.5 amps. I am looking for which direction to go. I took the batteries to O'Riellys and the batteries tested good according to their meter.

Re: Battery charge

Reply #1 – January 23, 2020, 04:43:46 pm

When voltages for charged/discharged batteries are stated, it is for batteries AT REST-- no charging and no discharge for at least a couple of hours.

Inverter's take power to be on and in standby mode, even if nothing is running on them.

A 7.5 amp draw when getting the 12.2 VAC reading does not necessarily mean the batteries are close to discharged. Turn off ALL loads including the inverter and check a couple of hours later. Better, disconnect the battery ground connection.

Another point-- were the batteries separated and checked individually by the dealer? If there is a problem, it could be with one battery and that would not necessarily show up if all three were checked together.

Re: Battery charge

Reply #2 – January 23, 2020, 05:52:55 pm

As Brett says, at least 2 hours after the charge is complete and there is no load on the batteries, the voltage should match the voltage chart below.

P

Re: Battery charge

Reply #3 – January 23, 2020, 05:55:28 pm

Sounds like one is bad

Re: Battery charge

Reply #4 – January 23, 2020, 06:38:12 pm

I've used these numbers since 2011 to keep track of my battery's state of charge. I'm suspicious by nature and just as those drug store tube testers were designed to sell vacuum tubes, some of the battery salesman's numbers are suspect. The company behind Battery University makes battery charging systems, and not batteries.

Measuring State-of-charge - Battery University

Re: Battery charge

Reply #5 – January 23, 2020, 06:50:56 pm

Red tractor, I see alot of good advice already in this thread and in the following thread, 24 hr battery test, however it is long, having 47 replies. It has alot of accurate information, I've especially found forum member Roger's information most accurate on this subject.

I also recommend when you reinstall your batteries putting in a cutoff switch to them. It was the only way for me to easily and totally take my 3 AGM8Ds out of the system and to get an accurate at rest voltage.

We can easily improve what we accurately measure, and so I highly value my Victron BMV-712 with it's Android or iPhone app to do this easily on my phone.

24hr Battery Drawdown Test

https://youtu.be/tV055vmZgvY

Re: Battery charge

Reply #6 – January 23, 2020, 08:12:23 pm

The batteries were separated before I took it in. The batteries had been hooked up with positive and negative coming off of one battery but I have since changed that so that the positive of the bank is on one end of the bank and the negative on the other end. I will be doing the 24 hour test. I have a feeling that maybe one battery is bad.

Re: Battery charge

Reply #7 – January 23, 2020, 11:11:44 pm

A desulphanator seems to work on agm's to keep the plates in better condition. As they cannot be equalized other than Lifelines the other device would seem to help?

Re: Battery charge

Reply #8 – January 24, 2020, 03:41:11 pm

I have more information. The batteries were charged and had voltage of 13.1 this morning after being unplugged for 7 hours had a voltage of 12.9. I ran the front slide out and the voltage very quickly went to 11.5 I plugged the coach into a 50 amp plug and it showed voltage 14.1 at 88 amps for about a minute then dropped to 41 amps still 14.1 volts. The inverter panel is showing that it is in bulk charge. Makes me think bad batteries What do you think.

Re: Battery charge

Reply #9 – January 24, 2020, 03:42:45 pm

This coach has the original prosine 2500 watt inverter

Re: Battery charge

Reply #10 – January 24, 2020, 04:04:35 pm

Yup, if the 11.5 was after the load was taken off the batteries, you have no battery capacity left.

Re: Battery charge

Reply #11 – January 24, 2020, 08:36:51 pm

Just checked now and battery voltage 14.1 and 3 amps input. Definitely not right.

Re: Battery charge

Reply #12 – January 24, 2020, 10:38:07 pm

Those readings suggest it is fully charged and, if a smart charger or smart inverter/charger it should be going into float mode at lower voltage.

That does NOT give an indication of battery capacity.

Related story-- my brother is on the sailboat right now. The boat was on the hard with shore power since last April. Batteries read 13.3 VDC. Launched, motored (120 amp alternator with 3 stage smart regulator) from Ft Pearce down to W Palm and anchored out for the night. Two fully charged 4D AGM batteries. Light overnight loads--same loads we had run for years on the same battery size. Next morning dead.

Long story short, pulled into a marina and went and bought 2 new batteries. Would have been crazy to take off for the Bahamas with batteries that looked good when charged, but had no capacity.

Re: Battery charge

Reply #13 – January 25, 2020, 09:04:43 am

Quote from: red tractor – January 24, 2020, 08:36:51 pm

Just checked now and battery voltage 14.1 and 3 amps input. Definitely not right.

14.1 volts is a bulk charge voltage, and 3 amperes current draw tells me the batteries cannot accept current at that voltage and should be boiling furiously. Not good for flooded cell batteries, bad for gel or AGM battery construction. The charger should be stepped down to 13.6 V for the absorption phase of the charging process, to bring them from 80% to 100% state of charge over many hours.

After placing a heavy load on a lead acid battery, you need to wait a minimum of 1 hour, preferably 3 hours before measuring the resting voltage, a lead acid battery needs this time to "spring back."

Re: Battery charge

Reply #14 – January 26, 2020, 07:25:21 pm

Well I think that I have the answer to this problem. The coach has been unplugged for 36 hours. Last night the voltage was 12.8 this morning was 12.6. This afternoon it was 11.7 plugged in and went to 14.3 at 65 amps in bulk charge within 5 minutes it was in absorb 14.3 volts at 33 amps. So pretty sure bad batteries.

Re: Battery charge

Reply #15 – January 27, 2020, 09:26:12 am

Quote from: red tractor – January 26, 2020, 07:25:21 pm

Well I think that I have the answer to this problem. The coach has been unplugged for 36 hours. Last night the voltage was 12.8 this morning was 12.6. This afternoon it was 11.7 plugged in and went to 14.3 at 65 amps in bulk charge within 5 minutes it was in absorb 14.3 volts at 33 amps. So pretty sure bad batteries.

And I'm pretty sure this is what has happened. Enough plate material has settled in the bottom of the case to rise to the level of the bottom of the plates, thereby shorting the plates together.

Re: Battery charge

Reply #16 – January 27, 2020, 10:38:13 am

Quote from: Old Toolmaker – January 27, 2020, 09:26:12 am

And I'm pretty sure this is what has happened. Enough plate material has settled in the bottom of the case to rise to the level of the bottom of the plates, thereby shorting the plates together.

Not only to the bottom of the case but plate separators fail allowing shorts. HD/Commercial batteries have a greater distance between the plates and the bottom of the case plus more reliable plate separators.

Pierce

Re: Battery charge

Reply #17 – January 29, 2020, 09:36:04 pm

I will be replacing the batteries and will install a Victron 712 battery monitor so that the state of charge and amp hours can be monitored. Thanks for all the help with this.

Re: Battery charge

Reply #18 – February 06, 2020, 10:56:31 pm

One more indicator of a bad battery is one that is significantly higher temperature than the others during charging. Use your IR gun to check. If one is bad and the others are more than a couple of years old I'd replace all.

see ya
ken

Re: Battery charge

Reply #19 – February 08, 2020, 08:08:15 pm

I have replaced all 3 batteries with agm from O'Reilly. They were heavier than the agn interstate batteries that were in there. I also installed a Victron 712 battery monitor so that the condition can be watched.

Re: Battery charge

Reply #20 – February 10, 2020, 07:59:08 pm

What is your cold cranking amps. On new battery's. 550 or 750. And are they Deep Cycle.

Re: Battery charge

Reply #21 – February 10, 2020, 09:04:15 pm

I am not sure but they stood up great during the test that I put them through. I feel confident that the problem is taken care of.

Re: Battery charge

Reply #22 – February 10, 2020, 09:15:00 pm

Quote from: Richard11 – February 10, 2020, 07:59:08 pm

What is your cold cranking amps. On new battery's. 550 or 750. And are they Deep Cycle.

Hello red tractor, I am glad your issues are resolved.

and for Richard11 and others:

They are rated at 1450 cca each for a total of 4,350 cca. The are rated at 250 ah each, so 750 ah total.

East Penn makes these batteries and labels them for Oriellys. The East Penn agm battery can be used for either a starting battery or a deep charge battery. One of their markets is the marine industry. They have a tremendous resistance to vibration by design, which is so often the end of life for batteries. They weigh 163 lbs each, which I've used when comparing to other agm 8D batteries. So they also have a mac (marine cranking amps of 1800 mca) rating for a total of 5,400 mca.

They also have a reserve capacity of 480 minutes, for a total of 1440 minutes at a 25 amp discharge rate.

This is from the East Penn web site for the agm batteries they private label for the marine industry, such as West Marine.

"Learn more about East Penn's battery selection for marine and the difference between flooded, AGM, and Gel technology. ... The Intimidator AGM battery series won't have any trouble meeting marine needs, from starting performance to a boatload of trolling and accessory power.
"East Penn's Intimidator brand will now be available for automotive, marine, commercial, power sports, golf car, electric vehicles, marine house power, portable power, and other premium AGM battery needs.

The Intimidator's advanced power offering is not only becoming more imperative for cars and trucks, but for many other vehicles and applications that require optimized accessory and starting power.

The complete line of Intimidator products will serve as a single source of Intimidator branded, innovative AGM power solutions.

The AGM technology of the Intimidator line has the perfect combination of starting, dual purpose, and deep cycle power. Intimidator batteries have 2x the cycle life of conventional flooded designs so they provide more accessory power longer. They are also 20x more resistant to vibration, and are built with an enhanced durability that withstands multiple recharging or heavy deep discharges. Their premium leakproof, maintenance-free design has pioneered a new era in battery convenience, safety, and power that no vehicle or equipment owner should be without.

The Intimidator's flat plate design optimizes efficiency by making full use of the available battery space. Its complete use of internal space ensures a better fit, with less retrofit,while providing maximum power and true maintenance-free performance."

Cold Cranking Amps (CCA) is a test conducted at 0 F (-18 C) for 30 seconds without falling below 7.2v at the battery's CCA rating.

Marine Cranking Amps (MCA) is a test conducted at 32 F (0 C) for 30 seconds without falling below 7.2v at the battery's MCA rating.

https://www.oreillyauto.com/detail/b/fleet---heavy-duty-5000/marine---boat-30733/deep-cycle---marine-batteries-17354/409e0a64fe51/super-start-fleet-heavy-duty-group-size-8d-top-post-battery/agm8d/4742645

Re: Battery charge

Reply #23 – February 10, 2020, 10:23:13 pm

If I were installing any AGM's I would absolutely add desulfurization devices as most cannot be equalized.

Re: Battery charge

Reply #24 – February 11, 2020, 08:43:20 am

Quote from: red tractor – February 10, 2020, 09:04:15 pm

I am not sure but they stood up great during the test that I put them through. I feel confident that the problem is taken care of.

Congratulations on a successful end to your trials and tribulations.

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