Slight Current Drain (0.07 amps) from Hella Flasher Unit, is this normal?

[kenscs]

Hi there,

My truck's ('71 Series IIa, EX-MOD) battery will discharge after about a 1 to 2 weeks if left off trickle charger or not run regularly. I have tracked the issue down to a 0.07 amp current drain that is coming from the blinker and flasher circuit. When I bring that circuit online, I can hear the Hella 4DM001 863 relay click on and it begins to draw a small amount of current. Is this normal? I cannot find any specs on the unit from Hella themselves. I would think it is not normal.

Maybe it is an aftermarket addition to add the Emergency Flashers when it was converted from MOD to Street Legal and mis-wired? The Fuse box is a Lucas but has 4 fuses, which does not seem to match what the manuals wiring diagrams describe as just a two fuse circuit.

Here is a photo of the unit.

10279

[kenscs]

Update on this issue.

I have tracked the drain most definitely down to the Flasher Unit. It is a consistent 70 milliamp draw. I have not determined if this is normal yet. I sent Hella an email, but have not heard back. However, I spent a fair amount of hours hunting down this info, so thought I would post this update.

1. 70 ma draw, on a 70 Amp Hour Battery (relatively normal spec), will take 1000 hours to drain (approx 41 days). So, if the alternator works, the battery is in good condition, and one drives it enough, this should not be a problem that will kill the battery. It is likely my battery is getting old, so the 70 ma drain just highlighted the issue. I am replacing battery today.

2. My truck is an Ex-MOD, and the wiring is much different than Civilian Specs. Their are I.R. Light Circuits, Convoy light circuits, trailer sockets, NATO wiring blocks, etc etc. The basic Schematics are not as much use. I did however find a GREAT resource for anyone who has a ex_MOD truck. Historic Military Vehicle Forum has been a huge help. hmvf.co.uk has all sorts of schematics, photos, etc to help with MOD trucks. It seems the Hella flasher unit above was standard equipment.

3. It looks like the Flasher unit, which includes the turn signal indicator lights, is alway powered on, with a feed from the flasher switch which has a direct line to the fuse box. This means it always has power. If if changed the circuit to only power up when the ignition switch is turned into a running light position, it would cut out the constant draw. Or, I may actually just use my Old IR light switch to power on or off, since for flashers, it seems one would want to be able to turn them on even without the ignition switch on (it is also probably the law).

In recent car production, it seems the typical standing drain is between 30 and 70 ma, since cars are running things like clocks, computers, alarm systems, etc , etc. Therefore, it is not completely crazy to have a 70 ma consistent draw from a car to the battery and as per above, shouldn't kill a battery under normal conditions. However, to me, just for a simple flasher unit, that draw seems high or defective.

I will post any final results on the "typical" draw for this flasher unit. If anyone has any data on their own trucks "off" current drain that would be helpful to me. One can use an amp meter in series with the battery. Make sure to have all the lights, etc turned off, ignition off, etc and start with meters 10amp setting in case some light or circuit is on so you don't blow a fuse in the meter if it is. 0.1 amps is 100 milliamps.

[Landylouwho]

I have the identical Hella relay unit in my 73 ExMOD. It stopped working last week resulting in a faulty right indicator. When it's working properly you should hear and feel the relay switching on and off.