DPI Accusense 48v

[scottyb]

Originally Posted by jbrzezinski14

Johnny B, you're correct, it seemed almost stuck at 61.7v and just under 5A for hours. You're the expert here and I'm still learning, so let me ask you a question: can a pack read 51.2v after charging and not be fully charged? Even according to US Battery, 51.2v is 100% SoC. Could two different battery packs (of identical batteries) read the same voltage but one pack is storing much more energy than the other in the form of amp-hours?

Update: The charger is now floating the batteries at 53.0v. I checked the water level and it seems unchanged so far, I'll check it again after the first few charge cycles with this beast. If you unplug this charger when the batteries are fully charged, then plug it back in a few minutes later, will it go through the whole cycle again lasting a few hours?

It would very much depend upon how soon after charging you got that reading. If the pack was not yet settled then that could be a falsely high reading.
Also Voltage and Amperage capacity are separate things. You can have a 51v reading after charge but little amperage capacity due to deteriorated plates.

[jbrzezinski14]

Originally Posted by scottyb

It would very much depend upon how soon after charging you got that reading. If the pack was not yet settled then that could be a falsely high reading.
Also Voltage and Amperage capacity are separate things. You can have a 51v reading after charge but little amperage capacity due to deteriorated plates.

With the Powerwise charger, I got a reading of 51.2 after about 8 hours off the charger, but its SoC would drop quicker than expected sometimes when driving.

[JohnnieB]

Technically, a Deep-Cycle Lead-Acid Wet-Cell battery is not fully charged until the SG (Specific Gravity) of the electrolyte ceases to rise while a charging current is flowing through it. Fortunately, the voltage tracks the SG, so it also ceases to rise, so the rate the battery voltage is changing over time (dV/dT) can be used to determine when the battery is "Fully" charged.

It takes a very complex analog circuit to monitor battery voltage vs time, but it is fairly easy to do with a microprocessor. Some, but not all, modern chargers use dV/dT technology, while few, if any, of the earlier chargers did.

The legacy chargers, charged the batteries to a fixed voltage (IE: about 60V for a 48V pack). The voltage pick was typically high enough to charge most batteries almost full, but not quite, so the weaker batteries in a pack wouldn't cause damage to the stronger ones in the pack.

All batteries are a little different and the Voltage vs SoC charts are average voltages for mature batteries. Newer batteries will read a bit above the charts and older batteries will read a bit lower. Different brands of batteries have different voltages at 100% SoC, Trojan being the lowest and US Battery being the highest.

You say your batteries are fairly new and you were getting about 51.2 using the QE, so I suspect the At-Rest voltage for your pack will be a bit higher after a few charges with the DPI. I'm guessing, but I think it will go over 52V.

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As for how long it takes the DPI charger to go through a charge cycle on fully charged batteries. Probably not much more than an hour for the next few charge cycles, and will get shorter as the battery's health improves.

The DPI compares change in voltage or current to elapsed time in a two or three of the charge phases, so around 10 minutes is probably about the minimum.

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For the next couple week, it might be a good idea to unplug the DPI while;e it is in float charge, wait a moment and then plug it back in. That will help the batteries regain some the the storage capacity they lost while being charged with the QE.