New Odyssey battery high self discharge?

[Avery4]

Hello everyone, I just bought a new Odyssey Extreme group 65 AGM battery from Autozone and it seems to have more self discharge than I would have expected. It arrived at 12.7 volts which seemed maybe a tad low for an AGM battery, but not at all alarming. Charge it up and it'll be good to go, right?

At about 9:30 AM, I put it on my Ctek MXS 5.0 charger and when I left at 2:00 PM it was still in the absorption stage drawing about 0.6 amps at 14.7 volts and didn't seem to be dropping quickly. When I got home around 7:00 PM, the charger finished and was in float mode. But suspecting that it moved on because the 8 hour time limit in absorption stage expired, I disconnected and reconnected the charger to restart the charging cycle and it was still drawing around 0.3 amps, which is much higher than I'm used to considering how long it's been charging. 2 hours later, the charger was still in absorption phase with 0.3 amps current.

Anyways, not wanting to keep subjecting the possibly fully charged battery to full charging voltage when the current doesn't seem to be dropping, I put it on a 13.8 volt float charge, which is the ideal float voltage for the temperature of my house according to Odyssey's technical manual. At 13.8 volts, it is still drawing 0.2 amps. Again, this seems high to me for a brand new fully charged AGM battery on float charge. I'm going to leave it on float charge overnight and see what the current ends up at in the morning.

Does this seem right to you folks? I'm used to fully charged AGM batteries drawing not much over 0.1 amps at absorption voltage and barely anything on float charge, but this is my first Odyssey battery so maybe it's normal for these?

Thanks in advance for any input, it is greatly appreciated!

 

[aquariuscsm]

I was reading (maybe on Oddyforums) where someone said that a bad alternator can cause a discharge? First time I've ever heard of that possibility. I know how a bad alternator could drain the battery of a car while it's not running, but that's what the poster said was happening to his Odyssey.

 

[Avery4]

I was reading (maybe on Oddyforums) where someone said that a bad alternator can cause a discharge? First time I've ever heard of that possibility. I know how a bad alternator could drain the battery of a car while it's not running, but that's what the poster said was happening to his Odyssey.

It certainly can, but my battery is still sitting in my living room and isn't connected to anything but the charger.

 

[atikovi]

I was reading (maybe on Oddyforums) where someone said that a bad alternator can cause a discharge? First time I've ever heard of that possibility. I know how a bad alternator could drain the battery of a car while it's not running, but that's what the poster said was happening to his Odyssey.

The BATTERY is an Odyssey. I don't think he is talking about a HONDA Odyssey.

 

[SubLGT]

How accurate is your ammeter at low currents?
What is the battery open circuit voltage 24 hours after disconnecting the charger?
I see no evidence the battery has high self-discharge (loss of capacity over time).
Odyssey has lower internal resistance than most batteries, and can accept higher charge currents. Looks normal to me.

 

[aquariuscsm]

The BATTERY is an Odyssey. I don't think he is talking about a HONDA Odyssey.

Good catch atikovi! Haha I was half alive this morning when I responded to this thread

 

[Avery4]

How accurate is your ammeter at low currents?
What is the battery open circuit voltage 24 hours after disconnecting the charger?
I see no evidence the battery has high self-discharge (loss of capacity over time).
Odyssey has lower internal resistance than most batteries, and can accept higher charge currents. Looks normal to me.

I just got the Odyssey yesterday morning and it spent most of yesterday on the charger, so I don't know what it's open circuit voltage is yet now that it's charged. It was at 12.7 when I first got it, but I'm sure it will be higher now that it's charged. My Klein meter seems pretty accurate down to around 0.1 amps, at least it gives me an idea of what it's doing compared to other batteries.

It seems like it may have just needed a bit more time to charge, perhaps because it is brand new and has been sitting on the shelf for a while. After float charging overnight, it is now drawing less than 0.1 amps at 13.8V and somewhere around 0.15 amps at 14.7V. Although still slightly higher than my old Optima Yellowtop group 34, I'd say that's expected since it's a bigger battery. Now that it's fully charged, I'm going to install it in the car and see how it does. Seems like it will serve me very well for a long time, but I will report back after using it for a while.

 

[atikovi]

Any reason you felt the need to buy a nearly $400 battery? https://www.autozone.com/batteries-...y-65-pc1750t-group-size-65-950-cca/832143_0_0 I could understand if it had a 10 year warranty or something, but how much better can it be than a $100 battery?

 

[wrcsixeight]

Every new agm battery i have charged, behaves that way on the initial charge.

It will behave more in line with expectations after a discharge recharge cycle.
Down below 65% and then apply no less than 25 amps initial current, and amps will taper to near zero at absorption voltage. And ocv will be over 12.8 rested.

 

[Avery4]

Every new agm battery i have charged, behaves that way on the initial charge.

It will behave more in line with expectations after a discharge recharge cycle.
Down below 65% and then apply no less than 25 amps initial current, and amps will taper to near zero at absorption voltage. And ocv will be over 12.8 rested.

Good to know, thank you. If it doesn't resolve itself after some regular driving, I'll give that a try. I knew that lead acid batteries had to be cycled a few times before reaching their full capacity, but I wasn't able to find how the charging current is affected by the break in.

However, I did find in the Odyssey technical manual that 0.001 C(10) is the current at which the absorption phase of the charge is considered complete and float charging should begin, which would mean I should eventually see the charging current drop to somewhere around 0.065 amps. That would be more like what I'm used to seeing.

 

[wrcsixeight]

In general, when amps stop tapering, stop the charging.
If the amps start rising at a constant voltage, overcharging has begun.

Every new AGM I've gotten, and monitor closely on that initial charge, the amps do not taper to 0.005 at absoprtion, or less, until I cycle it deeply, then feed it 25+ amps from a well depleted state. They also would not hold the full charge open circuit rested voltage as they did after that deep cycle high amp recharge, and did not have that impressively fast engine starting gusto until they got deep cycled and high amp recharged until amps stop tapering at absorption voltage.

I don't know if they eventually would, only that Mine did not hold the full charge open circuit resting voltage that they did, until I cycled them.

The TPPL AGMS are thoroughbreds. They should not be compared with the budget AGMS all over the market now, and the god like status the 3 letters seem to impart upon them by the general public.

Assuming a true proper full recharge is immediately applied one can drain a TPPL AGM to 50% state of charge 900+ times, in a lab.
The budget starter AGMS perhaps would last 300 in the same exact usage, in a lab.

I'd not fret one deep cycle as negatively affecting overall life, assuming one is able to feed it properly, quickly, to true full.

 

[Avery4]

In general, when amps stop tapering, stop the charging.
If the amps start rising at a constant voltage, overcharging has begun.

Every new AGM I've gotten, and monitor closely on that initial charge, the amps do not taper to 0.005 at absoprtion, or less, until I cycle it deeply, then feed it 25+ amps from a well depleted state. They also would not hold the full charge open circuit rested voltage as they did after that deep cycle high amp recharge, and did not have that impressively fast engine starting gusto until they got deep cycled and high amp recharged until amps stop tapering at absorption voltage.

I don't know if they eventually would, only that Mine did not hold the full charge open circuit resting voltage that they did, until I cycled them.

The TPPL AGMS are thoroughbreds. They should not be compared with the budget AGMS all over the market now, and the god like status the 3 letters seem to impart upon them by the general public.

Assuming a true proper full recharge is immediately applied one can drain a TPPL AGM to 50% state of charge 900+ times, in a lab.
The budget starter AGMS perhaps would last 300 in the same exact usage, in a lab.

I'd not fret one deep cycle as negatively affecting overall life, assuming one is able to feed it properly, quickly, to true full.

Good to know, thanks for sharing! After a few days of normal driving it seems that the current during the absorption phase was still around 0.3 amps, so I ran the battery down at about 45 amps for 20 minutes or so (key on, high beams, blower on high, radiator fan on), which used up probably about 20Ah of its capacity. I then let the alternator charge it up since it's the only way I can charge it at 25+ amps.

And wow does this battery charge fast! Initially it maxed out my alternator and was charging at 100+ amps! Within probably about 30 minutes of running at a fast idle, the current was down to under 6 amps. And surely charging it at the recommended 14.7 volts would have gone much faster than the 14.1 or so my alternator was producing.

It's now finishing the charge on my Ctek MXS 5.0. I will report back with what the absorption and float current levels out at once its fully charged.

 

[SubLGT]

.....And wow does this battery charge fast! Initially it maxed out my alternator and was charging at 100+ amps!

I think wrcsixeight sees around 160A when he charges his deep cycled Northstar/Odyssey batteries with a dual alternator setup, plus he monitors the alternator temperature. Did you monitor your alternator temperature?

 

[wrcsixeight]

When newer, and depleted below 50%, my group31 northstar was able to to accept 134 amps.of plug in adjustble voltage power supplies in parallel, For several minutes before hitting absorption voltge.

I do have dual, individually regulated, 120 amp alternators, but have not combined their output into one battery.

 

[Avery4]

It seems like cycling the battery may have done something. During the absorption phase, the current now dropped to around 0.2 amps. Not as low as other batteries, but I guess alright for its size. I emailed Odyssey and asked what current I can expect to see once the battery is fully charged, but I have not gotten a response yet.

I didn't take any temp measurements of the alternator when recharging the battery at high current, but I did feel it several times to make sure it didn't get excessively hot and it never did. However, until the current dropped to around 40 amps, I held the engine at around 1500 RPM so the alternator's fan spun fast enough to provide adequate cooling. Running under a full load at idle RPM isn't ideal since alternators can get very hot when heavily loaded at idle.

 

[wrcsixeight]

The 0.2 amps.might not be going into battery, but is powering vehicle loads.
Perhaps body control senses charging voltages and does not put some loads to sleep.

Lots of ammeters become increaasingly innacurate/imprecise at low amperage.