Lamar TT28-2 Operator Manual

Revision 1.1 • November 23, 2020

NOTICE:

This Operator Manual applies to the TT28-2 True Blue Charger MX.

These units are manufactured by Lamar Technologies LLC for True Blue Power.

For similar Activator 282 chargers, contact Lamar Technologies for the appropriate manual.

Lamar Technologies LLC

14900 40th Ave. NE

Marysville, WA 98271

360-651-8869 office

360-651-6677 fax

www.lamartech.com

info@lamartech.com

2 Manual Number LI-282-101 • Revision 1.1, November 23, 2020

		TABLE OF CONTENTS
1.		Introduction .........................................................................	5
2.		Preparation for use .............................................................	6
3.		Principles of operation ........................................................	6
4.		Operating instructions .........................................................	8
	4.1	Charging a Battery........................................................	10
	4.2	TT28-2 Charging Cycles...............................................	11
	4.3 Unexpected Loss of Power...........................................		13
	4.4	Disconnecting from a Battery .......................................	13
	4.5	Emergency Shutdown ..................................................	13
	4.6	Lead-Acid Battery Considerations................................	13
5.	Maintenance and servicing (preventive and corrective) ...		14
	5.1	Verifying Charge Voltage..............................................	14
	5.2	Verifying Fan Operation................................................	15
6.		Preparation for shipment...................................................	15
7.		Storage..............................................................................	15
8.		Replacement Parts Listing ................................................	15
	8.1	Power Cord...................................................................	15
9.		Troubleshooting ................................................................	16
10.		Specifications................................................................	18
11.		Certificate of Calibration ...............................................	19
12.		Warranty .......................................................................	20
13.		Revisions ......................................................................	21

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WARNINGS

DANGER

The TT28-2 enclosure does not have electrical interlocks. Contact with the primary power input lines can be lethal. Only qualified electronics technicians should open the enclosure. There are no user-serviceable parts inside.

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1. Introduction

The TT28-2 is a compact aircraft battery maintenance charger, intended to be connected to an aircraft battery and left unattended for an extended time. It is lightweight and compact and connects directly to the aircraft battery terminals. It uses an IEC 60320 C13/C14 power inlet and can operate from any global line/mains AC power source. No other tools or equipment are required to use the TT28-2.

The unit will charge a 24 Volt lithium-ion or lead-acid aircraft battery using the standard MS3509-compatible connector. Do not use it on any other battery voltage or chemistry, such as nickel-cadmium. The TT28-2 displays the battery voltage and any fault codes on its Liquid Crystal Display (LCD) and shows its status with three lights on the front panel. The unit charges at about 2 to 3 Amperes maximum current and regulates the battery voltage to prevent overcharge. After the battery is fully charged, a short “topping” charge is applied. Then the unit shuts off all charging and monitors the battery open-circuit voltage. As the battery self-discharges to a low charge level, the TT28-2 starts another charge cycle. All operation is completely automatic and requires no user interaction.

The TT28-2 is intended for sheltered use (no water into the enclosure) at temperatures from -20°C to +50°C.

Items furnished	Note
TT28-2
Line cord for North	Line cords available for other
America	countries – see “Replacement Parts
	Listing” for details
Operator Manual

The TT28-2 is warranted against defects in materials and workmanship for one (1) year after shipment.

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2. Preparation for use

Inspect the shipping carton for obvious signs of damage or dampness.

Open the shipping carton and remove the contents. Check the contents against the shipping list and be sure all items are included.

When not in use, store the TT28-2 safe from shock, vibration, moisture, and excessive heat.

3. Principles of operation

The TT28-2 plugs into any global power outlet of 100 ~ 240 VAC, 50 ~ 60 Hz. It uses a switching power supply to efficiently convert the line/mains voltage to 24 ~ 32 Volts DC, regulated by its microcontroller.

Voltage limits stated in this section are for a Lithium-Ion battery. See the table in the section “TT28-2 Charging Cycles” for LeadAcid voltage levels.

When AC line power is applied, the display will light up with a white backlight and all three indicator lights will illuminate for several seconds. The TT28-2 will display the battery voltage for approximately five seconds if one is present, otherwise it will show a low voltage coming from its own power supply. If a battery is connected, the unit will begin charging the battery. If no battery is connected, the unit will display “Er1” and a red FAULT light. The power must be turned off to clear the error message “Er1”.

During charging, a yellow “CHARGE” light is on.

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When the battery reaches a transitional charge voltage of 28.2 Volts the TT28-2 continues with a “topping” charge for a short time. Voltage is regulated by the microcontroller to prevent overcharging. Counting from when AC power is first turned on, the first topping charge is about one hour.

After the topping charge is complete or when the battery reaches its nominal charge voltage of 28.8 Volts, the TT28-2 turns off the charge current and just monitors the open-circuit battery voltage. The green “READY” light is on. The TT28-2 draws its operating power from the AC and draws only 125 micro-amps (0.000125 Amps) from the battery while monitoring the self-discharge of the battery. As the battery self-discharges below 26.50 Volts the TT28-2 will automatically begin another charge cycle, lighting the yellow “CHARGE” light. At the end of this second charge cycle, the topping charge time is approximately 30 minutes. The battery is allowed to self-discharge again, and once 26.5 volts is reached a third charge cycle will occur. The topping charge for third and subsequent charge cycles is only two minutes.

The TT28-2 has an internal timer set for 26 hours. If a battery fails to reach a full charge within 26 hours, the TT28-2 will show a flashing red “FAULT” light and the error message “Er2”. Charging will be suspended. Cycling AC power on the TT28-2 will reset the timer and restart the charge cycle.

The TT28-2 monitors the temperature at the battery connector. At about 50°C (122°F), the TT28-2 will show a red “FAULT” light flashing about once per second, display the voltage detected and the message “Er3” on the LCD, and will suspend charging. The TT28-2 will resume charging only after the terminals have cooled by approximately 5°C and the AC power is cycled “OFF”, then back “ON”.

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