I have a “new” battery that was installed in the last year or so in a car that has been sitting but I think might have a slight draw. I put a trickle charger on it and after a day or two it shows a green light. When I open the car door the interior lights are dim, turn key & no go, everything just goes dead, won’t take any load. Is there hope? Does anyone have a cure?

92 year old Mom’s car, not being used regularly any more. FWIW - 90 Camry with 80k, Odyssey battery.

 

Take it to an auto parts store and have it tested. You don't say how long it was sitting, but if it was fully discharged, it may not be possible to recharge it. In the future, if the car is going to sit, disconnect the battery. There are small current draws, like radio clock and presets and so forth. They're not a problem if a car sits for a few days or ever a few weeks, but if it's been six months, that might be long enough to cause a problem.

 

If you have another battery, you may try to connect them together with jumper cables and charge both at the same time. You can also try charging at a higher amp rate but not on boost. If you do charge it at 40 amps, I would recommend taking it out of the car and cover it with a towel and do not leave it unattended. Don't charge it very long at the high rate and make sure it does not overheat. If you can get it up to 10 volts after charging a high rate, lower the amps and continue charging. At this point the trickle charger may work but it may take a few days. If it sat connected for a year or so I suspect the specific gravity is low and the plates are sulfated and hard. It will need some chemical action to break down the sulfation and I don't think the trickle charger alone will do it. Ideal thing to do would be just replace it.

 

I think that you got a bad one. If it's less than a year old, it should still be under warranty. Take it back and do an exchange.

 

PUT A VOLTMETER on the thing. Find out the open-circuit voltage (OCV) and the voltage when the key is turned to "crank". OCV better be 12.6--12.7 after the battery charger has been disconnected for an hour.

Easy enough for the battery to be fully charged, and none of the lil' electrons can get through the lead oxide covering the battery terminals where the cables attach.

AS ALWAYS, remove, inspect; and clean the battery connections as needed. Silver is a good color. Black, and fuzzy green are not. After the terminals are clean, and you're sure the cables are OK, connect the + cable, then connect an ammeter between - post of battery and - battery cable, to find out about your parasitic draw.

 

bccan, did you get your problem resolved?

 

Just so I don’t seem to have disappeared. Haven’t got to it yet, maybe tomorrow. I will poke it with a stick in a few places & report findings so you smart people might find a way for me to save this thing, they’re pricey but I won’t die if I have to replace it. Thx for checking up.

Some Clarifications-
Probably 3-6 months sitting (can’t recall), I think it is probably no load 12v+ as the trickle charger deems it charged but it won’t take a load. Terminals are near sterile. These are very high quality batteries & it worked well prior to extended sitting, doesn’t mean it couldn’t be bad but I’m betting against it. Don’t want to get involved in warranty as I mail order these from Battery Mart although I have a friend that works for parts store that now carries them so maybe I could put it through the process with him & see what happens but I hate to be a PITA.

 

Is this a restoration agm battery?

 

Not a resto style battery, Odyssey Extreme Series AGM.

 

Use the 2 battery charging method.

 

That's a good idea, because AGM batteries are not compatible with all chargers. Some of them dont recognize there is a battery there at all when it's AGM, and very low.

 

X2, you need to google how to charge an agm battery.

 

Please help dispel my ignorance: What is the principle behind the two-battery method of charging mentioned above?

 

AGM batteries have different open circuit voltages. A discharged old school battery has a higher open circuit voltage than AGM at the same discharge percentage. Hopefully this video explains it far better than I can.

 

See post 11. You are trying to get the low battery up to around 10 volts and then you can finish charging it without the second battery. If it doesn't come up using 2 batteries it is probably a bad battery. If using a flooded battery as the second battery, it should be disconnected and then the AGM battery should be charged alone even if the battery charger showed full charge when both batteries were connected. The AGM type have a higher voltage than the flooded batteries do. If you don't finish charging it to full it may never reach full potential even in a car with a good charging system. This brings up another topic for older cars with generators alternators and regulators. Modern batteries even flooded ones, require a higher voltage setting than they did 50 years ago. The voltage set point back then will never allow an AGM battery to reach full potential in my opinion.

 

Nice video. I wish I saw it before I finished typing my last post.

 

Thanks for the info. I'm still learning!

 

Yes, I found out the same thing. I have a pure-lead AGM in my Vista Cruiser and after a 150 mile trip the charger took a while to bring the battery to full voltage.

After that experience, I always connect my charger after using the car.

 

I finally got around around to attending this battery. I am happy to report it appears that the 2 battery method worked to revive it. I was pretty sure it shouldn’t be bad and appreciate the observations & advice provided. It is now a week or so later and I’ll recheck it. It now hibernates with the negative terminal disconnected.

 

Glad it worked out. Periodically check the voltage and recharge as required.