Amps at Rest

Mark S · 01-09-2019, 06:39 AM

I am trying to figure out if my batteries are working as they should be. With a full charge, I unplugged two days ago and this morning I have a reading of 12.3 volts on my inverter. Nothing besides the inverter was switched on.

With the inverter on and nothing else switched on I took a current reading off the two leads coming off the positive terminal and I got a reading of about 3.8 amps on the lead going to the selinoid and about 0.8 amps on the other.

Does 4.5 amps seem like a normal amperage draw with nothing but the “always on” devices?

Robbbyr · 01-09-2019, 07:51 AM

Mark,
Do you have a way to check voltage and current draw with the inverter off? Inverters, if turned on, consume current even without a load on the 120-volt side. I know your inverter is different than my Xantrex which I can turn completely off at my control panel.

I think that amp draw level with nothing on is excessive imho and will draw your batteries down in short order if not constantly plugged in and charging.

I checked mine some time ago with everything "off" and had about .75 amp draw at the coach batteries.

Rustynuts · 01-09-2019, 12:13 PM

Even with nothing on the appliances are all drawing a little bit. With 3 tv's on standby, video control box on, dvd player and Satellite box (if you have one) on standby and microwave oven is on. each unit has a minimal draw but all added up may be more than you might expect but I have never tested it. You may go around and unplug all these and test the draw.

jimp · 01-09-2019, 12:25 PM

Are you trying to determine if your battery is good or if the inverter is doing it's job of converting 12v dc current to 110 outlet power??

Mark S · 01-10-2019, 07:37 AM

The inverter is working like it supposed to. It just seems like my batteries go down quickly, especially considering I replaced the originals with four 6 volt golf car batteries. I am just wondering how large a parasitic draw is normal. I am also trying to find out how much power the inverter uses at “idle”.

I am dropping to about 12.3 volts, or 50%, in two days with only the inverter on and the attached appliances switched off.

I ordered a new DC clamp on Amp meter which will be here Saturday, thank you Amazon. Lol. I should be able to find some answers then.

And yes Rob, it does seem excessive. I’ll be able to test all the different states with the new meter.

Mark S · 01-10-2019, 11:22 AM

Acording to the Magnum-Dimensions tech person I just spoke to, the CSW-2012X inverter used on my Seneca, uses about 2.5 amps on its own. Add in the TVs and microwave in stand by and I guess 4.5 amps is not out of the question.

I guess that would explain why my batteries go down quicker than I expected.

Robbbyr · 01-10-2019, 11:40 AM

No "easy" way to just turn it off Mark? If not you may have to consider a true battery master cutoff switch like you likely had on your older, non-computerized fire trucks. That way you would have zero draw on the house batteries when not plugged in. It wouldn't affect the Freightliner modules since those are on the chassis batteries.

If I were doing it I would put it on the negative side. It would have to support big amps since the inverter is a huge draw at times. We used to use Cole-Hersee switches in Akron and those passed enough amps to crank over cold 8V-92 Detroit Diesels in our rigs!

Mark S · 01-10-2019, 12:10 PM

Thanks Rob. Yes, I can power off the inverter at the panel. When I get my meter I will go through all the different scenarios.

Most of the time it will not be an issue. When “off the grid” I can turn the inverter on as needed to preserve battery power.

SloPoke · 01-10-2019, 01:34 PM

Quote:

Originally Posted by Robbbyr

No "easy" way to just turn it off Mark? If not you may have to consider a true battery master cutoff switch like you likely had on your older, non-computerized fire trucks. That way you would have zero draw on the house batteries when not plugged in. It wouldn't affect the Freightliner modules since those are on the chassis batteries.

If I were doing it I would put it on the negative side. It would have to support big amps since the inverter is a huge draw at times. We used to use Cole-Hersee switches in Akron and those passed enough amps to crank over cold 8V-92 Detroit Diesels in our rigs!

What about putting the cutoff switch in only the Inverter Power cable since that seems to be the culprit?

Our Xantrex has dedicated cables from the inverter to the battery bank. I am assuming that the later model units are the same.

Mark S · 01-10-2019, 03:53 PM

Quote:

Originally Posted by SloPoke

What about putting the cutoff switch in only the Inverter Power cable since that seems to be the culprit?

Our Xantrex has dedicated cables from the inverter to the battery bank. I am assuming that the later model units are the same.

I do have a power shut off on the inverter panel. This weekend I will test to see what draws what.

SloPoke · 01-10-2019, 07:39 PM

Quote:

Originally Posted by Mark S

I do have a power shut off on the inverter panel. This weekend I will test to see what draws what.

That is really what I would like to understand... There seem to be some assumptions that your inverter is still drawing some 12v power from the batteries (whether on, off, or on/idle - I'm not really sure which)

Since my assumptions are different than others... I would think that when the Inverter is:
**OFF, there should be NO current draw - not even a parasitic draw of any kind.
**ON, it would be expected to be providing 120vac to the Microwave and TV's in whatever state they are drawing power.

Mark S · 01-11-2019, 06:18 AM

Quote:

Originally Posted by SloPoke

Since my assumptions are different than others... I would think that when the Inverter is:
**OFF, there should be NO current draw - not even a parasitic draw of any kind.
**ON, it would be expected to be providing 120vac to the Microwave and TV's in whatever state they are drawing power.

Hi Steve. Yes to both of the above. I am taking amperage readings off the two positive battery cables. With the inverter powered on I am getting a reading of about 4 amps, off less than 1 amp. Since I am taking the reading from the battery I am not sure what else that cable is powering.

Tomorrow my new DC Amp meter is arriving so I can test draw with every item on and off and will know more..

What prompted this is after two days of being unplugged with the inverter turned on and all of the attached appliances in standby mode my batteries were at 12.3 volts. As I am told by the inverter manufacturer tech person, the inverter draws about 2.5 amps with no load.

I am trying to figure out how long I can camp off grid on the battteries alone. As you may know, our off grid camping experience is limited to Walmart parking lots. Lol 😆

Right now the obvious answer is to leave the inverter off unless needed.

MFalcon · 01-11-2019, 08:41 AM

I would leave the invert off unless you need it. Recharge your batteries, let them reach resting voltage (should be about 12.6V) when fully charged. Leave the inverter off and check the voltage again after two days. My parasitic current draws were from the TV splitter amplifier (on all the time) the TV antenna amplifier, digital thermostat and LP/CO detector. Together the current draw was .6 amps. Not much I know but when I removed the fuses, one at a time, from the fuse panel. I could see which ones drew the most idle current. The only thing I couldn't quickly troubleshoot out of the system was the "ON" light for the battery disconnect solenoid switch. That draws .1 amp.

Johnny Lightning · 01-11-2019, 10:27 AM

The tech apparently didn't look at their spec sheet. It says that your inverter draws less than 1.5 amps DC.

See https://www.magnum-dimensions.com/si...revC_web_1.pdf.

Even with that, it's about 72 amp/hrs over 2 days.

But thanks for bringing up this topic as it's something I need to look at in my shopping.

Mark S · 01-11-2019, 01:31 PM

Wow, good find. No, obviously the tech did not read the spec sheet. I didn’t find it either. Thanks.

But as you say, that is still a good amount of amps over two days for standing by.

SkyBound · 01-11-2019, 01:36 PM

The chart that I use in my trailer for my Trojan T-105 batteries states that somewhere between 11.9V-12.0V is 50% charge (time to recharge). I think if you're at 12.3V you still have plenty of power to go before you need to recharge, unless you are referring to using 50% of your 50% usable capacity if you get what I mean.

**norty1** · 01-11-2019, 04:47 PM

You can get it at a steep discount on the used market!

ifallsguy · 01-11-2019, 05:01 PM

Hard wired propane gas and fire/smoke detectors will draw as long as they are hooked up. These are 12v draws. Unless you take everything drawing 12v down, including these safety devices, you will always show a draw.

Johnny Lightning · 01-11-2019, 06:48 PM

If you install household smoke and CO detectors you can reduce the parasitic draw to 0.00 amps. I put 10 year sealed battery smoke and CO alarms in my apartments. They seem to work OK now that the bugs have been worked out. At around $25 for the smoke detectors and I think $40 for the CO alarms,and about $50 for a combined unit (probably the best bet) it seems like a fairly cheap solution to me. You should probably check the operating temperature range (one that I saw had an operating range from 40 Deg. F to 100 deg. F) to make sure it won't damage them when it gets hot or cold in storage. Hopefully that will never be an issue in my apartments. Also I'm not sure if there are any restrictions on them in RVs but I wouldn't think so. I would be interested to know if anyone has used one.

Mark S · 01-15-2019, 11:44 AM

I just took my new Handy-Dandy clamp on Amp meter and took readings off the positive battery cable.

With the inverter switched off, the reading was 0.71 amps.

With the inverter switched on and everything else in standby, the reading was 1.75 amps. Inverter is using about 1 amp per hour.

So after 48 hours I have used about 85 amps (1.75 amps x 48 hours)and my voltage is 12.4-12.5.

Does this sound about right?

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