Main battery, 2nd interstate 31P-AGM in 18 months seems to be dead-ish (1 Viewer)

[Mike6158]

My Interstate battery, second one, seems to be toast. I have it isolated and on the charger now. On the charger I see 14.8V. No surprise there. I disconnect and immediately put the meter on the disconnected battery and the voltage has dropped 1V and falls about 10mV a second. No load. Before I put the charger on it the battery was at 12.6V. That should start the LC if it's got any CCA left and it doesn't. There's got to be a better Group 31 battery out there (no I haven't searched yet. I'm in testing mode).

Speaking of testing. I checked the parasitic current draw from... well... nothing other than the clock as far as I know. 270mA. 1/4A-ish. 17 days to use up 100Ah. I don't recall the rating of the battery but if the LC is going to sit for a while I'm going to assume that I need some sort of charger. Is there something I could permanently install that can live under the hood?

 

[saucebox]

NOCO and a bunch of others make chargers that can be permanently installed under the hood. I ordered a dual-bank charger over the weekend, still waiting on them to ship it. I got this one because I have two AGM batteries to feed: NOCO - 2-Bank 8A On-Board Battery Charger - GENM2

I'm dealing with the same thing now. I replaced the battery Friday (same battery as yours) after about 9 months. In searching across Mud, I'm figuring out that the charging voltage needs to be higher for AGM batteries...higher than what an alternator puts out (and even with the diode trick). From what I gather, plugging in the charger once a week or so should keep everything in top shape.

More info in one of the other sub-forums: Power Systems

Past that, it seems like folks are having good luck with the H8 AGM size. It's something like 92aH instead of 100, but the upside is that they seem to be in stock at every Autozone and the warranty is similar enough. That's probably the direction I'll go when this Interstate goes again. Waiting a week on a special order warranty replacement is a no-go. Not again anyway...it's my only ride.

 

[SlowBuild]

Yikes. My Slee main tray is on its way and I’m just looking to order this same battery. I already ordered the HBK MK3 mini blade 7.5A (electronic fuse version) voltage booster as recommended on this forum and installing the Sequoia 150A alternator hoping it might help a little.

Do you think the above setup will be enough to keep the group 31 happy or will I need a plug in charger as well? I hope not.

 

[jerryb]

this is what bugs me to death, and why I have stuck with regular lead batteries from walmart that last 2.5 years for me. this current one, 30 months) is lasting longer only because of plugging it in MORE than once a week (deltran) even with the diode. Being in the south doesn't make it easier either.

we need a better regulator. I have transpo and denso and they act the same, although not bench tested. I'd have to go digging into boxes to find something to get higher than 14.2v on the bench too test them both back to back at the same temp no load.




the sequoia cut point is also 14.2v for either alt. faik, or at least the transpos are both set at 14.2v for both sequoia versions.
Don't assume anyone posting that they are getting above 14v is legit. It's very difficult to believe anyone is getting anything close to the set point while the engine is running and with a ????? 20-30amp load, maybe less?

I'd switch alternator brands if I spent more time searching for X brand that had replacement VRs with different set points. 14.7 please.

if someone did this it would be a significant upgrade and a serious amount of battery threads would go away.

 

[abuck99]

If youre running an AGM battery you need higher charging voltage for normal driving conditions and model years equipped with the ALT-S fuse is the limiter. Its also a good idea to float charge every few weeks to top off/ excercise the battery.

Replace the ALT-S fuse with the HBK voltage booster (or the home brew diode hack) and you’ll see over 14V out of the 130A alternator (depending on your state of charge of course). If its been sitting for days, output is between 14.4 & 14.8v, then it drops down to 14.2~14.3v when battery is fully charged. Will running a consistently higher voltage reduce alternator service life- probably.

As far as AGM battery options Batteries plus X2 27F fits in the stock battery tray and is 92aH. Yes a little pricey but well made. It comes with a 5 year full replacement warranty. A budget friendly option as just a starting battery, the AGM “Champion” brand from Pep Boys is a solid option in stock configuration with decent warranty. But keep in mind any AGM needs more charging voltage for long service life.

 

[jerryb]

agree with the diode and if everything was perfect.
maybe I should have also said, without the diode, or whatever your ceiling is, you won't get above that. Or within .2

I still want a better VR

 

[Mike6158]

Is there a voltage and current that will kick the AGM's back into working (desulfate)?

This: Testing for Battery Sulfation/How to Desulfate a Battery | BatteryMINDers

Looks like the answer is yes BUT it's conditional and my batteries don't pass some of the conditions. The main one being the main doesn't hold a charge or have any capacity...

 

[gungriffin]

Just get the HKB voltage booster or make your own. I don't bother with plugging up since I got the booster. I went with the MK4 from HKB because it is adjustable. It was spendy, but so are batteries. I presently have the MK4 set for a 0.4v boost. At about 70 degrees at startup, I see 14.7v for charging and that will settle to about 13.9 for the float. My Odyssey group 34 and 31 both show a resting voltage of 12.95 now. That is right at 100% on their chart.

 

[abuck99]

Just get the HKB voltage booster or make your own. I don't bother with plugging up since I got the booster. I went with the MK4 from HKB because it is adjustable. It was spendy, but so are batteries. I presently have the MK4 set for a 0.4v boost. At about 70 degrees at startup, I see 14.7v for charging and that will settle to about 13.9 for the float. My Odyssey group 34 and 31 both show a resting voltage of 12.95 now. That is right at 100% on their chart.

13.9v reading on your scanguage /obd reader or tested at the terminals engine running? Asking since my Scanguage reads .4~.5 lower than actual output tested at the terminals. So the float reading on my SG is also 13.9v but actually 14.3~14.4 at the terminals.

 

[gungriffin]

13.9v reading on your scanguage /obd reader or tested at the terminals engine running? Asking since my Scanguage reads .4~.5 lower than actual output tested at the terminals. So the float reading on my SG is also 13.9v but actually 14.3~14.4 at the terminals.

I measured the voltage drop from my battery to my scanguage and I am only measuring somewhere around 0.1 drop.

 

[95Fantasma80]

My Duracell size H8 AGM from sams club lasted 2 years and 8 months! right at the 3 year warranty cut off, they didn't have any in stock so gave me my $200 bucks back.

I just installed an Interstate AGM from costco h8 as well and will see how long this one lasts.

I am running an HKB volt booster since first upgraded to AGM and didn't do much topping off with home charger so not too bad!

I mainly use for my fridge and can run for 1-2 days and never had any issues with running out of power.

The last two months my car did seem like it wanted to cut off a few times like 2-3 times, the lights on dash would briefly blink and was thinking the worst like fuel pump but never left me stranded until yesterday near my home which a quick AAA call had me back on road in 5-10 mins.

Now im set for another 2-3 years depending if this interstate is just as good as the Duracell.

Thinking of adding a small solar panel on roof racks to extend life and give me a lot of time fridge can run with peace of mind that i will be able to start car whenever.