How long to charge 48v LED batteries

[Rockten]

I recently bought six (off the shelf) 8V rechargeble led batteries from 2019 at a discount from a local shop who did not have newer batteries. I even got a 3 month guarantee from the shop. These 6 batteries are manufactured by DEKA and 8148EX (GC8V) batteries and the manufacturer informed me via mail that each 8V battery is fully charged when it reaches 9.6V per 8v battery which equals 57.8V for all 6 batteries.

I also bought a new Lester Series II OBC bypass charger on the internet to charge these batteries. However I have been charging the batteries for more than 12 hours and is still not fully charged. Is this normal? Or is this a sign that these 2019 batteries are damaged?

When I plugged the charger yeaterday, the charger read 47V and reported 0% charge and more than 1200 charging minutes remaining. This represents 20+ hours of charging. I attached a picture of the bluetooth connection of the Lester charger when it reached 3% (maybe an hour later) that showed something similar. Is this normal?

I decided to leave the batteries charging the whole night and this morning the charger is reporting a 86% charge at 58 volts but still 300+ charging minutes (5 hours) remaining. I also attached a screenshot of this report. Is this normal?

I need to know if this is normal or if I should return the 2019 batteries.

Thanks in advance for your replies.

[Fairtax4me]

In the app make sure you change the battery profile to match the batteries.
Deka is manufactured by East Penn, so they are the same as Duracell and a few others.
The proper battery profile will make a difference in the charge time, and will make sure the batteries do not get over or undercharged.
Batteries that have been in storage, especially used batteries, may take quite a bit of time to come up to a full charge.

When that charger is brand new or you get new batteries, it does not have any stored info from previous charges of those batteries, so any calculation of charge time or battery charge % will not be correct until it has done a few charge cycles.
Lastly, full battery charge voltage is based on the design of the battery and will vary slightly by manufacturer. The proper charge profile will charge them to the correct voltage.

[Roxyflash]

Did you check the voltage before charging bad thing is batteries will discharge them self from sitting being 2 years old how low were they?Wonder if they got charged before they were sold sitting on the rack?Might want to ask them how were they maintained.

[Rockten]

Thanks to Fairtax4me and Roxyflash for your valuable reactions.

@Fairflash: When I bought the batteries they measured 7.6 volts each. They took them out of carton boxes as if they were not charged by the seller but I am not 100% sure because the boxes were not sealed.

[ThreeCW]

Originally Posted by Rockten

When I bought the batteries they measured 7.6 volts each.

As per the attached state of charge chart, at 7.6 volts each those batteries are essentially totally dead. The problem with a totally dead lead acid battery that has been stored for a long time (in your case over a year), sulfation occurs which can form permanent damage. That permanent damage may not show up right away (or it might) but it will at a minimum shorten (or dramatically shorten) the life span of the battery.

If you would normally get 4 years out of a new, well maintained battery pack ... a damaged pack might give you 1, 2 or 3 years ... at likely reduced performance as well.

So those batteries that you bought at a discount might actually turn out to be a very expensive battery pack on a dollars per year basis ... depending on the life you get out of them.

I suggest the following to access the condition of this "old / new" battery pack. :
When you are done charging, disconnect the charger and let the battery voltage stabilize for 24 hours or so and then measure the voltage of the pack and of each individual battery.
Then take your cart for a short run (10 to 15 minutes), then park it for 1 hour and measure the individual and pack voltages again to get the stabilized, at rest voltage.
Then take your cart for a longer run (say 30 to 45 minute more), park it again for an hour and take the voltages again.
Then fully recharge the battery pack, disconnect the battery charger and let the voltage stabilize for 24 hours or so and again measure the voltages.
Note - measure all voltage to 2 decimal place.
The above voltage readings may help to access the condition of the battery pack.

Note that several back to back charges may help to remove some of the sulfation damage in the cells but given the total discharge and length of storage, I suspect that considerable permanent damage is possible .

[ThreeCW]

Here is an interesting article that discusses your situation in detail:

Discharging too deeply and leaving the battery ‘flat’

The worst treatment a battery can experience (apart from receiving a dangerously high charge voltage) is to be drained of all charge, and then stored without re-charge.

What happens that when a battery is deeply discharged – particularly below 20% SOC – the plate is mechanically damaged by the extensive formation of sulphur crystals which undermines the material’s cohesion. Some of the material loosens, and begins to fall away. This degrading process will happen anyway, as the battery ages, but deeply discharging a battery greatly accelerates that ageing process.

So much for discharging too deeply: If the battery is then left in a discharged condition the tiny crystals of sulphate which have formed begin to grow. The sulphate on the surface of the plates begins to harden – eventually forming themselves into an impenetrably hard white coating around the lead plate, which plugs the porosity of the material – and greatly impedes the diffusion of ions which drive the chemical process. By this stage the battery’s capacity, and its ability to accept or release energy will be so slow that it will be unable to do the work for which it has been chosen.

This kind of battery damage occurs when, for example, a vehicle’s headlights have been left on, and the vehicle remains unused for a period of days or weeks …or a battery has been left on a shelf in a workshop for a period of months, and it has self-discharged until it is flat. Almost undoubtedly, in both cases the battery will have to be recycled.

If any of the damage is reversible, it can be reversed by recharging the battery in the normal way (it may be slow if it will recharge), and then applying an equalisation charge until the battery voltage reaches 16V or 17V (for a 12V battery) for a period of, say, three hours. This will force the sulphated areas of the plate to release the sulphate back into the electrolyte. Success is not guaranteed, and in nearly all cases there will be some permanent capacity loss.

Be very careful to monitor the battery closely at these high charge voltages, as this will also be causing the electrolyte to separate into gas.

Source: https://www.victronenergy.com/live/d...battery_part_i

[Rockten]

Originally Posted by ThreeCW

As per the attached state of charge chart, at 7.6 volts each those batteries are essentially totally dead. The problem with a totally dead lead acid battery that has been stored for a long time (in your case over a year), sulfation occurs which can form permanent damage. That permanent damage may not show up right away (or it might) but it will at a minimum shorten (or dramatically shorten) the life span of the battery. .

MANY THANKS to you all. Today I went back to the shop and got all my money back!!!

Will consider buying lithium batteries now instead of lead batteries.

Happy Easter!