DPI gen 3 never shuts off

[NCPW]

Here's the back label if that aids anyone in helping Luke with the diagnosis.

DPI.jpg

[LukeL]

What would you guys advise that I do then? I don’t want this thing boiling the acid out of $900 worth of batteries :-)


Club Car DS driver’s club #59

[dundeebarnbuggy]

I would clip a meter on one of your wires from the plug to the batteries and see if it is charging or just a defective ammeter. At the same time check for a draw on the pack by the cart JUST to be safe that is is the board. Hope this helps.

[JohnnieB]

Originally Posted by LukeL

What would you guys advise that I do then? I don’t want this thing boiling the acid out of $900 worth of batteries :-)


Club Car DS driver’s club #59

If I understand this correctly, NCPW bought the charger new, did not replace the board and the unit went into float after the regular charge cycle terminated when in the US battery mode. And only a solid green light showed when in float and only about 1A showed on ammeter.

The voltages NCPW mentioned for float in US Battery mode is mighty high and the voltage Luke is seeing when only the green LED is on is also high for float.

When I spoke to DPI back in about May-2012, I pried loose the following info.

Bulk charge = constant current.
Absorption charge = constant voltage USB=2.50VPC Trojan=2.35VPC Exide=2.40VPC.
Finish charge = dV/dT
Float charge: USB=2.21VPC Trojan=2.19VPC Exide=2.20VPC

When operating normally, the 48V DPI charger ought to go through its pre-qualification sequence with about 5A on ammeter, which climbs rapidly to about 17A when the charger advances to Bulk charge stay at 17A until the on-charge voltage climbs to 56.4V for Trojan or 60.0V for US Battery. The voltage is held at that value until the amps decrease to about 5A and the charger advances to the Finish charge phase where the current is once again held to about 5A and the on-charge voltage is allowed to climb until its rate of climb decreases to some predetermined value. For US Battery the dV/dT rate is something on the order of 0.004V/cell/hour (0.096V/hr for a 48V pack of US battery batteries). I don't know what the Trojan dV/dT rate is. When that criteria is reached, it goes into float at 53.07V for US Battery or 52.53V for Trojan.


Since Luke is seeing 57.5V and about 4A on the ammeter, plus batteries gassing, it appears the charger is staying in the finish charge mode.

That means the on-charge voltage is still climbing, or the board is bad.

(It may not be the right board for the charger, but it came from factory that way and used to work when NCPW had it.)


------------------
I'm guessing, but are you trying to charge a new set of Trojan batteries for the first time?

If so, the charger may be working the same way it was working when NCPW had it and will eventually advance to float charge. The first charge on new batteries can take 20 hours or more.

You don't lose acid during gassing, only water, so I'd disconnect everything except the charger for the battery pack and let the batteries alone charge for several more hours. Keep an eye on the electrolyte level and don't let the plates get exposed, but only add enough distilled water to raise level about 1/4" above tops of plates. (Fill them too full and they'll be bubbling over by the time they are fully charged and then you will actually be losing some acid.)

As stated above, the float voltage mentioned by NCPW is too high, so there might be something wrong with board in addition to the LEDs not lighting up in the normal sequence.

FWIW, both of the DPI charges I've used (36v and 42V) stayed plugged into AC power 24/7 and plugged into cart after each use or each day.

[cgtech]

Originally Posted by JohnnieB

If I understand this correctly, NCPW bought the charger new, did not replace the board and the unit went into float after the regular charge cycle terminated when in the US battery mode. And only a solid green light showed when in float and only about 1A showed on ammeter.

The voltages NCPW mentioned for float in US Battery mode is mighty high and the voltage Luke is seeing when only the green LED is on is also high for float.

When I spoke to DPI back in about May-2012, I pried loose the following info.

Bulk charge = constant current.
Absorption charge = constant voltage USB=2.50VPC Trojan=2.35VPC Exide=2.40VPC.
Finish charge = dV/dT
Float charge: USB=2.21VPC Trojan=2.19VPC Exide=2.20VPC

When operating normally, the 48V DPI charger ought to go through its pre-qualification sequence with about 5A on ammeter, which climbs rapidly to about 17A when the charger advances to Bulk charge stay at 17A until the on-charge voltage climbs to 56.4V for Trojan or 60.0V for US Battery. The voltage is held at that value until the amps decrease to about 5A and the charger advances to the Finish charge phase where the current is once again held to about 5A and the on-charge voltage is allowed to climb until its rate of climb decreases to some predetermined value. For US Battery the dV/dT rate is something on the order of 0.004V/cell/hour (0.096V/hr for a 48V pack of US battery batteries). I don't know what the Trojan dV/dT rate is. When that criteria is reached, it goes into float at 53.07V for US Battery or 52.53V for Trojan.


Since Luke is seeing 57.5V and about 4A on the ammeter, plus batteries gassing, it appears the charger is staying in the finish charge mode.

That means the on-charge voltage is still climbing, or the board is bad.

(It may not be the right board for the charger, but it came from factory that way and used to work when NCPW had it.)


------------------
I'm guessing, but are you trying to charge a new set of Trojan batteries for the first time?

If so, the charger may be working the same way it was working when NCPW had it and will eventually advance to float charge. The first charge on new batteries can take 20 hours or more.

You don't lose acid during gassing, only water, so I'd disconnect everything except the charger for the battery pack and let the batteries alone charge for several more hours. Keep an eye on the electrolyte level and don't let the plates get exposed, but only add enough distilled water to raise level about 1/4" above tops of plates. (Fill them too full and they'll be bubbling over by the time they are fully charged and then you will actually be losing some acid.)

As stated above, the float voltage mentioned by NCPW is too high, so there might be something wrong with board in addition to the LEDs not lighting up in the normal sequence.

FWIW, both of the DPI charges I've used (36v and 42V) stayed plugged into AC power 24/7 and plugged into cart after each use or each day.

This guy amazes me every time! Amazing again!

If it actually meets those voltages stated in OP, and never turns off, the board is likely bad. But hey, your batteries got one nice equalization charge! Now stop doing that until you get through DPIs new crappy tech support line. (I hate it too, and they will lose popular support if they don't fix it).

[LukeL]

I’m gonna try it one more time and watch it closely.

The batteries are actually not new. They are two years old but I had them charging with another charger with no problems that I’m aware of.

Thank you for the incredible information, JohhnieB.


Club Car DS driver’s club #59

[JohnnieB]

Originally Posted by LukeL

I’m gonna try it one more time and watch it closely.

The batteries are actually not new. They are two years old but I had them charging with another charger with no problems that I’m aware of.

Thank you for the incredible information, JohhnieB.


Club Car DS driver’s club #59

Middle aged rather than new, so they ought to charge from about 50% SoC in about 6hrs or so, unless they have been chronically undercharged.

If the charger they were previously charged with was the ferroresonant transformer type, or other type that shut off at a specific on-charge voltage, typically about 2.5VPC, or 60.0V for a 48V pack, they were never fully charged.

The fixed cut-off voltages the legacy chargers shut off at, was a compromise between being low enough not to seriously over-charge older batteries and high enough to "adequately" charge newer batteries.

Technically, a lead-acid battery of any age is not fully charged until the SG of the electrolyte ceases to increase while a charging current is passing through it. Since the voltage tracks the SG of the electrolyte, it can be inferred that the battery isn't fully charged until the on-charge voltage ceases to increase while a charging current is passing through the battery.

The more modern chargers the incorporate dV/dT technology come very close to fully charging FLA batteries, so the first time an older set of batteries that have previously been charged with ferroresonant transformer type chargers, may take a while, but should eventually reach a full charge.

The pack is reaching an on-charge voltage of 57.5V, which is lower than about 60V a ferroresonant transformer type charge would shut off at, so I'm starting to wonder if the batteries have an issue, or maybe there is something draining the pack while it is being charged.

As previously mentioned, I'd disconnect everything from the pack except the charge cables and see if the charger will eventually shut off.

On the Trojan charge profile (attached), they list a high of 2.79VPC for the on-charge voltage. That works out to 66.96V for a 48V pack, so it ought to be pretty safe to let to on-charge voltage to climb to about 64V on the 2 y.o. batteries.

You mention the batteries were gassing heavily, is there one or more cells not gassing?

[LukeL]

They were all gassing pretty bad but I haven’t opened all the cells. I may try this charger on my pack of brand new T875’s and see what it does.


Club Car DS driver’s club #59

[LukeL]

The charger is running now. I just started it a little bit ago. It is putting out 17A and the battery pack voltage is at 53.5. Lets see what happens...


Club Car DS driver’s club #59

[LukeL]

55.3


Club Car DS driver’s club #59