DPI-48V17A Charger Mode Setting Discrepancy Label vs Manual

LATrvlr

Back in early 2012 I purchased a new DPI charger model 1-48017-04. On the charger s/n label the mode selector settings show Mode 3 for Trojan batteries. The manual that came with it shows mode 2 is for Trojans.

I previously ran a set of US batteries and when replacing with Trojan T-875's this week I went to change the mode jumper settings to Trojan and that's when I noticed the mismatch on the s/n label vs the table in the manual.

I'm thinking the s/n label would be more accurate than a manual as I know DPI makes many models and continually updates software etc but I'm concerned now and have sent an email to them for clarification.

Is there a way to determine expected voltage at a particular charging step for each of the four modes so one could verify the setting is actually correct for your battery?

Attached are photos of the s/n label, the manual and the faceplate. Any insight is appreciated.

Attached Images

	DPI Charger SN Label with Mode Setting Table.jpg (746.3 KB, 0 views)
	DPI Manual Mode Setting Table.jpg (582.5 KB, 0 views)
	DPI Charger Faceplate.jpg (526.1 KB, 0 views)

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scottyb

This is the info I have on this subject.

Trojan = 2.35VPC (Mode 2) - 56.4V for a 48V pack
Exide = 2.40VPG (Mode 3) - 57.6V for a 48V pack
Full River = 2.45VPC (Mode 4) - 58.8V for a 48V pack
US Battery = 2.50VPC (Mode 1) - 60.0V for a 48V pack

LATrvlr

Thanks Scotty. I should have mentioned that with jumpers set to MD3 (per the label) and after the first charge cycle on the new T875's with the DC cord still connected the float voltage is 52.6 VDC.

Attached Images

Batt Voltage.jpg (411.6 KB, 0 views)

scottyb

If that meter is reading voltage thru the key switch it will give a reduced read out due to the resistance in the switch Use a meter at the pack for a true reading if thats the case

LATrvlr

The meter is direct wired (with a fuse of course) to the pack. My DVM reads the same, 52.6V. The Trojan T-875 data sheet shows 52.8V as the proper charger float voltage setting.

Attached Images

T875 table.JPG (62.2 KB, 0 views)

JohnnieB

The DPI manuals I've seen are more generic than model specific, so I lean towards trusting the label on the specific charger more than a manual that broad-bands information over a wide range of models.

However, the modes listed on the label on your charger are different from the modes listed labels on every other DPI charger that I am aware of, so the best answer as to which mode is best for a Trojan brand battery is to send DPI an e-mail with the picture of the label of your specific charger attached and ask them.

As to the voltage measure while in Float-Charge, as long as it is significantly above the At-Rest voltage (50.93V) and significantly below the Gassing voltage (56.4V) it is okay and 52.6V is well inside that range.

Also, The Trojan spec is measured at 77°F.

LATrvlr

Hi JohnnieB and thanks! I sent an email to DPI this weekend with photos of the label and manual pointing out the discrepancy. No reply yet but I'll post it here when I do get it.

The T-875 daily charge voltage is listed on it's data sheet as 59.2 VDC @77 degF (see table above). ScottyB's DPI data he has shows the voltage for a Trojan as 56.4 VDC. Don't understand that variance unless the voltages are during different steps. What's with this JohnnieB???

cgtech

Im gonna go out on a limb, and guess that they dont make a specific manual for each "charge profile set" that they include in every model charger that they make. That would be far too many manuals to stock (and ensure the correct one got in each box). I would definitely go by the sticker on the charger for the correct mode to use.

JohnnieB

You hit the nail on the head.
The 59.2V listed by Trojan is for charger systems with user adjustable output voltages. (Solar and wind RE systems use Trojan batteries also)
The 56.4V is what the DPI puts out in the Absorption phase when in the Trojan mode.

Technically, the 59.2V is Trojan's recommended finish voltage, or the On-Charge voltage at which their batteries should have something close to a full charge, so the charger can be allowed to shut off. This is approximately the voltage that the legacy golf cart chargers shut off at.

A lead acid battery is fully charged when the specific gravity of the electrolyte ceases to increase while a charging current is passing through it. The voltage tracks the specific gravity, so it also ceases to climb and can be used to indirectly determine if the battery has reached full charge. Until microprocessors became small and dirt cheap, dV/dT (Change in Voltage over change in Time) technology didn't exist at the consumer level, so Trojan came up with a finish voltage that was high enough to nearly fully charge a good, mature battery without overcharging aged, but still usable, Trojan batteries.

The DPI uses dV/dT technology, so the 59.2V is more or less a moot point when a DPI or other dV/dT type charger is used.

The finish voltage that switches a DPI charge from the regular charge cycle over to float charge is determined by the batteries reaching full charge rather than a preselected voltage. I don't know the rate of change criteria used for Trojan batteries, but for US Battery batteries it is 4 milli-volts per cell per hour. Whatever change rate is used for Trojan batteries, will take the finish voltage above the 59.2V listed since 59.2V only gives Trojan batteries a nearly full charge rather than a full charge.

scottyb

Thanks Johnnie