Slightly OT: New PC925 battery not getting to full charge Options

[Literati914]

Couple days ago I picked up two new Odyssey PC925 batteries from a marketplace seller who was supposedly selling them for his dad. The story was that his dad bought them for a couple of electric bike builds and they were too heavy. Dad chose something else after only opening and trying one of them (one was unboxed and one had never been opened when I purchased). So they sat for 4-5 months, his dad said 'get whatever you can for them'. The seller had them at $200 a piece, before dropping them to $100 each - which is what I bought them for.

The one that was already opened was only showing like 7V so I put it on a little charger I already had (not necessarily the recommended type, that I'll need to purchase I guess). I kept a watch on it so it did not over charge.. but I finally took it off the charger when it reached 12.25V or so (took a long time tbh). I installed it in a 2.5L Volvo wagon (will be going in 914s eventually), it showed 14.3-4v, so I did a 20+ mile loop on the freeway to finish topping it off. I did not check it as soon as I returned but about and hour after the drive, it's still only showing like 12.15V. Is this just a bad battery or need more (proper) charging?

[Artfrombama]

Couple days ago I picked up two new Odyssey PC925 batteries from a marketplace seller who was supposedly selling them for his dad. The story was that his dad bought them for a couple of electric bike builds and they were too heavy. Dad chose something else after only opening and trying one of them (one was unboxed and one had never been opened when I purchased). So they sat for 4-5 months, his dad said 'get whatever you can for them'. The seller had them at $200 a piece, before dropping them to $100 each - which is what I bought them for.

The one that was already opened was only showing like 7V so I put it on a little charger I already had (not necessarily the recommended type, that I'll need to purchase I guess). I kept a watch on it so it did not over charge.. but I finally took it off the charger when it reached 12.25V or so (took a long time tbh). I installed it in a 2.5L Volvo wagon (will be going in 914s eventually), it showed 14.3-4v, so I did a 20+ mile loop on the freeway to finish topping it off. I did not check it as soon as I returned but about and hour after the drive, it's still only showing like 12.15V. Is this just a bad battery or need more (proper) charging?

In my experience, when any battery discharges and isn't recharged immediately a strong chance it won't, especially if it's two or three years old.
I've used the Odyssey battery for years and keep them on float chargers (Battery Tender, NOCO) when not regularly used.

Once they fail, they're gone. YRMV

[Superhawk996]

AGM batteries want to charge at higher voltage - 14.7v even up to 15v isn’t unheard of. The Volvo isn’t delivering enough voltage - guessing it is designed to handle Lead acid conventional battery.

Put on a charger that is AGM capable. Should be 12.7v at 90% state of charge. 12.1 is more like 60%.

[fiacra]

I've had a different experience than Artfrombama with my Odyssey 925. My previous 914 sometimes sat for months between drives and I did not keep it on a maintainer since I had to park it in the driveway. I let it go dead multiple times, at least four times, and would pull it and put it on a charger overnight and it always came back to life. When I sold the car the battery was still going strong at 9 years old.

I would say that the jury is still out on your batteries. You need to put a full charge on them and see if they can hold it. I don't think it is fair to task your alternator to fully charge a dead or depleted battery, especially a big battery like this one. Get the right AGM battery charger, give them a good charge, and then test them. Hopefully they are fine. They are the only battery I use now, and nowadays I do keep them on a maintainer.

[flipb]

Optima makes their own charger/maintainer that seems to be optimized for their AGM batteries. It's kept the red top in my 914 working for many years including months without driving during the winter.
https://www.amazon.com/dp/B00DHGPVKI?ref_=p...itle_5&th=1

[burton73]

My buddy Mark Sonners had a Red top in his 914 with a 2270 that would not take a full charge. He bought a battery conditioner, different than a TENDER and after a couple of days it came back 100% His Red Top was only 2 years old and sat for around 3 months.
Before the problem was the starter would not spin up.

Good luck.

Bob B

[rick 918-S]

I bought a battery tender from Harbor Freight last month for my optima red top. I had something draw it down to 5v. I had to keep starting the charger. It would bring it up a little at a time then shut down. When I got it upto 7.8v I put my big charger on it. The system i guess is to put the charger on one battery and use jumper cables on the second battery.

[Root_Werks]

Run a PC925 in my Bug and PC1200 in my 914-6 for 5+ years. Really like the batteries. Don't know if you'll be able to pull the one back from 7 volts though.

[Jack Standz]

Optima makes their own charger/maintainer that seems to be optimized for their AGM batteries. It's kept the red top in my 914 working for many years including months without driving during the winter.
https://www.amazon.com/dp/B00DHGPVKI?ref_=p...itle_5&th=1

Also really like Optima products. Have used this exact same charger for years and it always does the job.

It is a little unusual how you select the type of battery, but the charger starts with testing the battery (state of charge and type) then adjusts volts and amps throughout the charging process.

[rjames]

The Odyssey PC925 needs a compatible charger to maintain it or it will die an early death. Ask me how I know. Get the right charger and it should last a long time. I've been very happy with mine.

All the links I can find for compatible chargers aren't working anymore. I'm using a Battery Minder 128CEC1, which was one the approved models.

[Artfrombama]

The Odyssey PC925 needs a compatible charger to maintain it or it will die an early death. Ask me how I know. Get the right charger and it should last a long time. I've been very happy with mine.

All the links I can find for compatible chargers aren't working anymore. I'm using a Battery Minder 128CEC1, which was one the approved models.

My NOCO as well as the Battery Tender maintainers have settings for AGM, flooded and lithium batteries

[Literati914]

There's a couple Noco Genius-10 chargers close to me, I'm gonna pick one up and see what happens, fingers crossed. It btw, besides providing 14.7-14.8 volts, it also has a desulfation mode too. So in theory, that could bring back a half charging battery I guess (?).

BTW, when I cut the box open on the other battery and checked voltage, it was sitting at 12.54v .. already more than I've been able to make on the open box one that I got with the deal.

Thanks for the feedback guys, I feel good about getting these charged now - but I'll report back once I find out.

[burton73]

This is what Mark used to get his low batt to work
From Mark:

This is the charger that renewed the optima agm battery . It’s particularly suited to an agm type. Bout $32 from Amazon

Best Bob B

[rjames]

The Odyssey PC925 needs a compatible charger to maintain it or it will die an early death. Ask me how I know. Get the right charger and it should last a long time. I've been very happy with mine.

All the links I can find for compatible chargers aren't working anymore. I'm using a Battery Minder 128CEC1, which was one the approved models.

My NOCO as well as the Battery Tender maintainers have settings for AGM, flooded and lithium batteries

On my first PC925 I used a NOCO (can't remember the model, but it was their cheapest AGM model at the time and didn't charge past 14.4 volts, IIRC). The battery lasted a little over a year. After researching, I found the NOCO I had wasn't on the 'approved' list, likely because of the voltage rating. The Battery Minder 128CEC1 was, and I've had no problems since. Key info copied from another site:

Higher Voltage: ODYSSEY AGM batteries need a higher charging voltage, around 14.7 volts, for a complete charge. In contrast, standard chargers that only reach 14.4 volts will leave your battery undercharged. Over time, this leads to sulfation and a shorter lifespan.

Fully Automatic Charging: Furthermore, an ideal charger features a multi-step, fully automatic charging cycle. This process ensures the battery charges efficiently without overcharging. For example, ODYSSEY’s own chargers use an intelligent 8-step cycle.

Temperature Compensation: Finally, ODYSSEY chargers have built-in temperature controls. This is critical because charging voltage requirements change with temperature. A smart charger, therefore, adjusts its output to protect your battery from both undercharging in cold weather and overcharging in hot weather.

Edited- here's the most recent list I could find from 2020:
 ODYSSEY_approved_12V_chargers__1_.pdf ( 52.61k ) Number of downloads: 4

[porschetub]

AGM batteries want to charge at higher voltage - 14.7v even up to 15v isn’t unheard of. The Volvo isn’t delivering enough voltage - guessing it is designed to handle Lead acid conventional battery.

Put on a charger that is AGM capable. Should be 12.7v at 90% state of charge. 12.1 is more like 60%.

(IMG:style_emoticons/default/agree.gif) handy info ,I learnt when I first charged my new AGM ,my newish 'smart charger" wouldn't lift the charge on it so went back to my electronic base model charger and although slow it did the trick and lift it into a range were the "smart charge " would top it off to around 13.8volts if required.
Lasted 4.5yrs until I accidently shorted it out and it was toast but was running strong until then .
Replacement is still going strong after 3 +yrs using the same charging method ,not really worried as they are golf cart type battery ,common and cheap, my wholesale price was less the $100nzd on the last one ,cheers.

[L-Jet914]

On the Optima yellow top I have in my 914, I recently purchased new maintainers for the 914 and my motorcycle. I use the CTEK MXS 5.0's to keep both batteries charged when I am not using either vehicle. Before that I used the Schumacher $30-$40 maintainer/trickle chargers for years before they quit. One of the two Schumacher units kept my first Optima that I put in the 914 alive for about 11yrs.