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  View original topic: Propex parasitic drain
Pcforno Sat Aug 27, 2016 8:58 am

I don't know that this deserves its own topic but I wanted to put this out there so future folks can search it easily. Traced my aux battery drain problem to my propex hs2000. It has a parasitic drain of 50mA! Called propex and they said this is normal. Fortunately it only draws 5a Max while in use, so interrupting it with a small switch on the backseat cabinet was easy. Gotta say, weird design for a product that already contains an on-off switch.

Sodo Sat Aug 27, 2016 10:51 am

With so many propexii out there it seems someone would have mentioned this. In any case, I'm glad you posted it as a propex has been on my list. Probably good to have a master switch for all the "house" stuff.

Does it have a memory or something that needs to be maintained? Gotta wonder if there's a way to re-wire the existing on-off switch to eliminate the drain.

I appreciate threads with definitive subjects, they lead to quick answers in "the search". If this was simply in one of the many propex threads, I may never have seen it.

westyventures Sat Aug 27, 2016 11:02 am

Pcforno wrote: I don't know that this deserves its own topic but I wanted to put this out there so future folks can search it easily. Traced my aux battery drain problem to my propex hs2000. It has a parasitic drain of 50mA! Called propex and they said this is normal. Fortunately it only draws 5a Max while in use, so interrupting it with a small switch on the backseat cabinet was easy. Gotta say, weird design for a product that already contains an on-off switch.

I've never measured anything close to that in all the units I've serviced. How dirty is the top/bottom of the circuit board? I'd recommend a cleaning with PCB cleaner. FYI, Propex questions and concerns in the US should be directed to me, as the US importer/rep/warranty center. I'm curious as well when this question was sent, because normally everything sent to Propex UK is bounced back to me as a courtesy. Max current while running is 2A, no way possible for it to draw 5A.

FWIW, 50mA draw would take over a month to pull down a decent sized starting or aux battery. I'll test a couple new units on the bench for actual draw.

Pcforno Sat Aug 27, 2016 2:35 pm

Thanks Karl. I'll certainly contact you directly next time, I didn't know. I'm not sure who I talked to either other than that they were British and in the tech dept there! They said 50 mA was the exact draw. Circuit board has already been cleaned and all connections checked.
Yes you're right about he fact that it should take a month or so to draw down the battery as its parasitic draw is 1.2 amps/day, but for me this was still a little much so I put a switch in. The 5a figure was based on what they recommend for a fuse, not real world data.
Thanks again

Sodo Sun Aug 28, 2016 12:06 pm

Continuous 50mA takes a 44 AH battery down to 75% in 10 days, for example. Prob OK for a deep cycle, but not good to run a vehicle battery down like that.

Karl, I'm probably going to buy a Propex this fall and am still curious why there is ANY parasitic draw. If it's charging an internal memory battery and will 'stop when charged' that seems OK. But continuous must be dealt with, you'd have to plug the van in when parked. Still surprised this is not common knowledge, there MUST be some other details.

Easy to isolate it completely with a switch upstream though. Is there any reason NOT to cut power to the propex?

angrychicken Sun Aug 28, 2016 4:36 pm

I'd really be interesting in hearing the results on this. I've been wondering if my propex was a source of a continuous drawn. This could be cured with a simple kill switch when not in use.

Pcforno Sun Aug 28, 2016 7:25 pm

Angry chicken- I'd encourage you to test it yourself for additional data. You just need an ammeter (from a car multimeter). Disconnect the positive from your house battery, make sure everything is off, and put the ammeter in series between the positive pole of the battery and the positive battery cable. If there is no draw the reading should be zero. To find out what is causing the draw simply disconnect fuses until the draw goes away. My only draw in my entire 'house' system was the propex at 50 mA, which propex confirmed was the normal draw. I simply put a SPST switch next to the temp control, so I wouldn't have to reach two different places to turn it on in the middle of a cold night. Hope that helps, and please show us your real world testing if you can

eboone007 Sun Nov 08, 2020 9:31 pm

Hi Pcforno, I see this is an old post, but wondering if you are still out there. I would like more information on how you wired in a SPST switch for your Propex. I would like to do the same, and mount it near the heater control like you did. The thermostat has a cable coming out of it with 6 individual wires in it, I am wondering which wires get wired through the switch? I'm not super familiar with the Propex wiring, have you seen a wiring diagram anywhere? Any further info you have would be much appreciated, thanks!

VicVan Sun Nov 08, 2020 10:23 pm

Hi,
If you want to cut the power to the Propex, the switch would be on tha main +12V going to the unit, not on the wires to the thermostat.
Just make sure you don't turn off that switch while the propex is running, you could damage it (and maybe start a fire?). For now I remove the fuse to the Propex when I'm not using it. I'm thinking of installing one of these switches with a cover, so I don't turn it off by accident:

beach_creature Sun Nov 08, 2020 10:23 pm

When I had a propex, I wired a switch into the positive side of the heater power.

Corwyn Mon Nov 09, 2020 1:24 pm

I put a relay in line in the ignition switch, that cuts power to everything behind the driver's seat unless the key is in the ignition. I found the stereo and the propex were both drawing power when the van was turned off. No problem now

noahk Tue Nov 10, 2020 9:29 am

I had this problem as well, IIRC it was also about a 50ma parasitic drain. In a daily driver you'd never notice, but my van can sit for 2 or 3 weeks between trips and this fried my first aux battery before I noticed it. On the plus side it gave me an excuse to rip out the gowesty aux setup and put in a proper aux and combiner. Installed a simple switch for the propex while I was at it.

valvecovergasket Tue Nov 10, 2020 9:40 am

noahk wrote: I had this problem as well, IIRC it was also about a 50ma parasitic drain. In a daily driver you'd never notice

even then you might if its an old-ish battery and it sits for a couple days.

i chased a parasitic draw on an old w124 i had that was pulling ~50-60ma (turned out to be the power window controller).

typical OEM target for quiescent current on newer stuff is 25ma or under once everything on the vehicle is asleep. ive seen targets in the 10ma as well.

50ma is too high

atomatom Tue Nov 17, 2020 11:00 am

to those wondering, there are sensors in the propex and fans which run while it cools down. it is a shame it needs a kill switch, but if you install one, make sure you don't use that kill switch unless the unit is off and cool.

my current solution is pulling the fuse. if I put a kill switch in, it needs to be in a place that would not accidentally get switched while it is running.

this does stink. if your van sits and you go camping with a half drained battery, you won't get much time for heat. the propex is fussy and shuts off when your battery voltage drops. :(



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