New batteries yet low voltage

[Ponduke]

Hi all, I have an 04 Prescident and the batteries were 5 years old and showing their age so yesterday I installed 4 brand new US brand 155AH batteries. After a full charge overnight with my Powerdrive 2 charger i checked each battery and all 4 of them read 12.1 volt and the pack read 48.4 volt. So that seems concerning. I hooked up the charger again and the volt meter climbed to 56 to 57 volt during charge. It charger for a couple hours before the charger switched off. Not long after the volt meter showed 49 volt and a while later it was 48.7. What gives? I know it takes a while for the break in before full capacity is achieved with the batteries but all my reading appear significant too low and im wondering if i have a problem. Any guesses here whats going on?

[ThreeCW]

Try putting a new battery in your multimeter to eliminate that possibility.

Not sure of the US Battery numbers, but the finish charge of a 48 volt Trojan battery pack is 64.8 volts. You are substantially lower than that which could mean a problem with your charger.

Maybe someone familiar with Powerdrive chargers could advise you.

Your missing voltage should have nothing to do with your break in period ... new fully charged batteries should be at their full voltage even before being broken in.

What full charge voltage were you seeing with your old pack?

[Ponduke]

Thank you!! I thought it was possible my multimeter was faulty, but figured it unlikely. But, on your advice i ran to Autozone and bought a new one and lo and behold, the voltage was 51.3! I promptly threw the old tester in the trash and breathed a sigh of relief! Thanks again! Now ive read your post again but on the charts ive found online the fully charged voltage should be 50.9. Now im confused again lol

[Ponduke]

Like this one

[jakesnake27]

It's okay that they're at a little higher SOC than that chart, nothing to worry about.

[Ponduke]

Great! Thanks. Ive been reading and trying to educate myself on all this. Ive read after 12-24 hours after charging it should drop down to 50.9.

[jakesnake27]

Originally Posted by Ponduke

Great! Thanks. Ive been reading and trying to educate myself on all this. Ive read after 12-24 hours after charging it should drop down to 50.9.

Right

Also, if you haven't seen this yet, go ahead and read through it:

https://www.buggiesgonewild.com/atta...2&d=1289853436

[Ponduke]

Thanks. Just read it. Good advice that i intend on following.

[jakesnake27]

[ThreeCW]

Originally Posted by Ponduke

Now ive read your post again but on the charts ive found online the fully charged voltage should be 50.9. Now im confused again lol

Glad to hear that you have got your voltage situation sorted out . I have read a number of threads on BGW where meters are not reading correctly ... it is often just the battery in the meter ... but sometimes the meters are faulty too.

Yes, a fully charged battery that has "stabilized" for 24 hours should read 50.9 volts in theory. It depends on the make and model of battery ... for instance, my 48 volt Trojan T-125 battery pack stabilizes at 52.0 volts.

Sorry to confuse you but I was referring to the "finish charge" of a 48 volt Trojan battery pack is 64.8 volts during charging. The finish charge is a final charging stage of a 3 stage charge profile ... which finishes the charge with an elevated voltage of 64.8 volts for Trojans. After the charger shuts down and the battery voltages "stablizes" for about 24 hours, you end up with a "stabilized full charge voltage" of about 50.9 volts (in theory), 51.3 volts in your case and 52.0 volts in my case.

I like using the Carts Unlimited chart for determining the State of Charge as is has other useful information on it. I have attached a copy for your reference.

Also attached is the US Battery Charging Recommendations for your reference. I "believe" that your Powerdrive 2 charge follows a 2 stage charge profile with the final stage at 60 volts. The spec from US Battery Charging Recommendations is the second stage they call an Absorption Charge at a voltage of 2.45 +/- 0.05 volts per cell. Your 48 volts pack has 24 cells (6 per battery) so the US Battery Absorption Charge spec is 2.45 x 24 = 58.8 volts +/- 1.2 volts which is a range from 57.6 to 60.0 volts. If you are keen, you can check the Absorption Charge voltage with your new multi-meter.

I also like the Carts Unlimited battery break in recommendations here: https://www.cartsunlimited.net/battery-break-in-.html

I don't see it mentioned much in battery break in procedures, but it is also good practice to break them in slowly ... avoiding pedal to the metal driving and keeping the amperage draw to a reasonable level. This too will help to extend the life of your new battery pack.