CV28

CV28 Accutest / Accualarm

Comparison value for the battery test input

1 x NiMH 1,2 Volt

2 x NiMH 2,4 Volt

3 x NiMH or LiPo 3,6 Volt

Volt	Value	Volt	Value	Volt	Value
1,5	84 good	3,0	174 good	4,1	240 good
1,4	78	2,9	168	4,0	234
1,3	72	2,8	162	3,9	228
1,2	66	2,7	156	3,8	222
1,1	60 empty	2,6	150	3,7	216
1,0	54	2,5	144	3,6	210
.	.	2,4	138	3,5	204
.	.	2,3	132	3,4	198
.	.	2,2	126 empty	3,3	192 empty
.	.	2,1	120	3,2	186
.	.	2,0	114	3,1	180

Note on practice:

Battery test function test

When the battery test is enabled in the CV27 (e.g., 2 or 10), the value set in CV28 is compared with the present battery voltage. If the value is too low, there is "Battery alarm" whose function CV26 is defined exactly.
e.g. CV26 = 1 hazard warning lights and stop

functional test

Set CV28 to 250.
This will immediately trigger the battery alarm when the vehicle is switched on, if everything is wired correctly.
Note the ..I decoders, the Akkuesteingang must be connected separately

Then set a value that matches the vehicle's equipment.

Battery alarm with CV-Programmer

If the CV-Programmer is used for setting and the programming button is not pressed when switching on the device, there is also a battery alarm for decoders with voltage transformers.
The reason: The decoder is supplied by the CV-Programmer with 4 volts.
There is no voltage at the battery input, so the comparator detects an "empty" battery.

Setting the correct value

without tools

Best start with the high value. This will alert you as soon as the battery gets low.
If the vehicle is to give an alarm later, the value can be corrected downward in steps of 6 experiment.
That's always about 0.1 volts.

diodes trick

Tip from practice:
A freshly charged 2.4 volt NiMH battery (2 cells) has 2.8 volts.
With a diode 1N400? in the battery line, the voltage is lowered by about 0.7 volts.
Now the value of the CV28 is lowered until the battery alarm is triggered.
Finally, set the value lower by 6

with a controllable power supply

Setting is faster with a regulator power supply. This is connected instead of the battery.
'Caution: Never set decoder with voltage transformer above 3.5 volts!
'

The CV28 is set to 130.
The voltage of 2.40 volts is lowered until Akkualram (hazard warning lights) is triggered.
e.g. at 2.15 volts
However, the Alaram should be released at:

1 cell NiMh 1.05 Volt This will cause the voltage transformer to jump.
2 cells NiMh 2.00 volts usual vehicles
3 cells NiMh 3.00 Volt operation con ..I-decoder without voltage converter
1 cell LiPo 3.00 volt operation con ..I decoder without voltage converter

If the voltage is still 0.10 volts too high, the value of the CV28 must be lowered
6 about 0.10 volts
3 about 0.05 volts
_____________
9 should lower 0.15 volts

130 (initial value) - 9 (reduction) = 121 (new value)
Now the test procedure is carried out again and possibly corrected.

current list in this WIKI

current list as PDF Download
CV-List DC07/DC08