Finally bought a battery hydrometer, need help with results

[RDMueller]

I have read repeatedly here how you need a hydrometer if you want to really know the SOC of a battery. This was clearly confirmed with the results I got...

Battery is a new, never used Interstate group 24 12v marine battery. I've had it for several months now and it's just been sitting in my garage on the Battery Tender. The date code shows it to be almost a year old though, so I'm sure it was somewhat discharged before I got it.

Anyway, I disconnected it from the tender and waited about 24 hours before testing. All 6 cells were pretty close to each other, but the SG was only 1.225 to 1.250. If I understand correctly, fully charged they should read 1.275. I don't understand why the battery wouldn't be fully charged since I had it connected to the tender. I can't imagine it would be sulfated since it's never been used, but what explains the low SG?

Hydrometer is a EZ Red 101.

[MEXICOWANDERER]

Anything from 13.4 - 13.7 finishing voltage is fine for a flooded battery up to around 100F. After that figure is broached reduce finishing voltage by .3 Oooooo lookie just the exact mount that a 5-amp Schottky diode provides.

[westend]

All right, another outlaw charger gets branded.:B

FWIW, I actually took notes on my charging procedures with the wall wart as charger. I don't believe they were saved. IIRC, the 500ma wall transformer took about three days to charge one of the car jars to 14V from 12.3. I'd guess them to be about 80AH capacity.

[RDMueller]

So I was looking at the wall warts I have laying around when I realized that my portable jump starter came with one to charge it up. I checked the voltage without it connected to anything and it was about 18 even though the label says it should be 13.5V. So then I thought I'd plug it into the jump starter, let it fully charge and see where it stabilizes (still plugged in). Turned out to be 14.9V which I think is just about perfect. So, rather than ripping the plug off of a wart, I'll just try connecting the jump starter to the Interstate. Should yield about the same results.

I calculate the SOC of the Interstate to be about 75% currently so I need to add about 20AH to get to 100%. At 300mA we're looking at at least 66 hours. I'm going to continue to check the voltage and SG each day and see how well this works.

[MEXICOWANDERER]

Depends on the depth of the discharge. A trolling battery discharged 30% will do fine with a 14.4 volt potential left on it for 12-15 hours.

Cycled batteries need more voltage. There is a world of difference between a battery with a 30% discharge and another with 50% discharge.

An AUTOMOBILE, or pickup truck charging system starts out at 14.4 volts. And that is to replenish a battery that has 97% state of charge remaining.

"How fast ya going?"
"Dunno. I think it's a pain keep looking at the speedometer so I don't"
"That's silly"
"I kin guess good enough and if it's good enough for me, it's good enough for everybody".
"What's those red and blue lights I see out the side mirror"
"Dunno, but they got to be stupid if they think I'm doing anything wrong"

[RDMueller]

That's what I was thinking too, but in my case it didn't work out that way. Unless... It is of course possible that my Tender is defective, or I could have a defective battery. But I tend to think, based on what I've read here that 14.4 won't do it, 14.8 seems to be the magic number if there is one. That's what Trojan recommends anyway.

[RJsfishin]

A battery tender is a 14.4 charger. It will fully charge any 12v battery from 50% discharge.
Mine does it every time I go fishing, and that is quite often anymore.

[MEXICOWANDERER]

"Ummmmm hmmmmmm"

[RDMueller]

I have several wall warts sitting around so I'll definitely give that a try and report back.

[westend]

RDMueller wrote:
I don't know, all I can say is that my brand new battery was on the Battery Tender for a few months in the garage, properly watered, and 24 hours after removing it from the tender the SG was only 1.225 or so. The voltage was about 12.3v. My guess is that even though the battery is new, it was was somewhat discharged when I got it and the tender is just not an adequate way to fully charge it. Might work fine to maintain a fully charged battery, but don't expect it to ever bring a somewhat discharged battery up to 100%, no matter how long it is connected.

If you have a tossed-off 12V transformer and a meter make up a trickle charger like I mentioned. If the wall wart wiring terminates in a small jack, cut and strip wire, the (+) phase is usually the center of the jack. Plug in and check unloaded voltage. Connect to battery and monitor voltage to your own cut-off point. I chose 14V because at 500 ma and a duration of a few days, I can be pretty well assured that they are charged 100%. Since these batteries are sealed car jars, I haven't bothered with SG. Occasional monitoring shows the batteries are operating as normal.

[RDMueller]

I don't know, all I can say is that my brand new battery was on the Battery Tender for a few months in the garage, properly watered, and 24 hours after removing it from the tender the SG was only 1.225 or so. The voltage was about 12.3v. My guess is that even though the battery is new, it was was somewhat discharged when I got it and the tender is just not an adequate way to fully charge it. Might work fine to maintain a fully charged battery, but don't expect it to ever bring a somewhat discharged battery up to 100%, no matter how long it is connected.

[RJsfishin]

Ok, guess I was wrong about the 15v on the PD. But everything else is gospel !!

[NinerBikes]

pianotuna wrote:
Hi RJ,

Funny my PD only does 14.4 for 15 minutes during the 'desulphate' mode. They call it equalization and it is on a timer. ISTR every 20 hours?

I'm no battery expert, but I think some of RJ's posts need desulphating. This might be one of them.

I've never seen my PD do 15V either, which was why I sold it and I bought a MegaWatt instead, because it would do 15V+ to top charge my T-1275's when they were getting weary.

[pianotuna]

Hi RJ,

Funny my PD only does 14.4 for 15 minutes during the 'desulphate' mode. They call it equalization and it is on a timer. ISTR every 20 hours?

[RJsfishin]

Quote:
Ahhh, that makes sense. I guess they are fairly low amp, but because the voltage is up to about 16, they have the ability to get the battery fully charged. I'm going to guess that the problem with my Battery Tender is it just never gets the voltage high enough for the battery to achieve a full charge
----------------------------------------------------------------------
I don't know where this info comes from.
My battery tender always holds 14.6 for 4 hrs, and does fully charge the batts.
2 of my shumacher maintainers holds voltage at 15,2 volts for 4 hrs, and does fully charge the batts.
My larger shumacher has finish voltage of over 16, before floating.
My PD does 14.4 for 4-5 hrs, then does 15+ during desulfate mode.
You don't need anymore than todays smart chargers to do 15 volts, that will makes batteries last 10 yrs.

[ol_Bombero-JC]

Chum lee wrote:
Bob: As others have said, get a good hydrometer and if your battery is on the following list, charge it according to Interstates charge recommendations. You may need a more substantial charger than your battery tender (float charger) to do that.

See: www.batteries-faq.com/activekb/questions.php

Chum lee

Chumming for a clickable link - Is the one intended?

BTW - the "goggles" icon (7th from *right*) does links.

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