Inverter/Charger Battery Drain

[Kerry1]

Hi from Whangarei, NZ.

I have a Heart Interface 1000 Inverter Charger that is creating a 1.5Amp load on the batteries with all circuits off. I measured this with MultiMeter set to 10Amps and placed probes between negative terminal of the inverter and negative terminal of house bank. The inverter/charger is directly wired to battery for instant charging when shore connected, and sensing need for inverter AC current when not connected but 230V AC is required.

With everything else switched off I isolated the inverter fairly quickly as the problem because the other main negative cable terminal is the return side for everything else as far as I can work out, and it showed a flawless 0 Amp load. I should mention I have two Alternators working off the same engine for charging the house bank and starter battery. I have a Next Step regulator for them or it(?). I don't know if one alternator is internally regulated for the starter battery alone or whether the smart regulator does both alternators. I also have a BEP battery monitor and shunt.

The standby load for this inverter/charger is specd @ .12 amps. When testing in situ the load was 1.5 Amps. I have four 232 Endurant 6v deep cycle house bank connected in series parllel to give 12, 464AH. They are less than 10 months old. The installation has been professionally wired and the original house bank lasted about 7 years.

Suspecting malfunction I removed the charger from the boat and brought it home for a closer look. What I found when I did the same test at home with no AC connections to the machine (either incoming or outgoing) whatever on the output side was a standby load of only 15 milliamps, which seems much closer to specs and certainly a long way from the 1.5amp drain I had with circuits connected but the AC panel switched off at the breakers.

Is there a standby load associated with circuit breakers? If they are switched to the off position, am I right in thinking there must be some draw/load between the inverter and the breakers? What could that be?

The only other standby load that I was aware of was the Stereo which was always powered even with main isolating battery switches off. I didn't like that so quite a while ago I rewired it to the distribution side of the main battery isolating switch.

Then I realized (only recently) why it was wired that way...now I have no stereo at all because the standby function kept the code alive!

The house bank and the starter battery were essentially dead after arriving at the boat to give the engine and systems a run after a prolonged absence from the boat. The house bank batteries were able to be brought up ok with an equalization charge by my supplier, but the starter battery was replaced.

I know there are people on this excellent forum that are very knowledgeable about these sort of issues, so thanks in advance for your responses.

[smac999]

Inverters generally have 4 modes. Off, standby (AC power available and inverter not needed but ready to step in if AC lost). Sleep / power save mode. No AC but nothing pluged into inverter. So no need to turn on. Need a certain amount of watts in order to turn on. And 4th is on

All 4 will draw different amounts off power. Off should not draw any. But some inverter / chargers you can not only turn off the inverter. But the charger as well in same switch. So if pluged into dock. Inverter must be left in standby. If dock power is lost. Inverter will drain batteries. Best to have an inverter / charger with separate switch for the charger and inverter.

Gernally an inverter is shut off when you leave the boat. Even if the boat is plugged into shore power.

Every inverter / charger should also have its own battery switch. so yiu can kill all power if needed. But this is generally only used for service.

I think 1.5a is a pretty normal for a big inverter in standby

If you are drawing different amounts on the boat vs at home it's probably because you have a draw on the boat causing it to turn on. Vs maybe a power save mode at home with no load. It's normally only 5w so pretty much anything pluged in will wake it up

If your start battery died either you have stuff wired wrong and are drawaing power from it, or you stayed away too long. A flooded battery will die in a couple months with no load. Agms 6 months

If you leave your boat not pluged in get some solar panels

[Kerry1]

Smac999: "If you leave your boat not pluged in get some solar panels"

Yep, true- have just invested in 70watt panel and MPPT controller to give continuous charging ability when I'm away from the boat. Will add other panels later on. The inverter/charger is wired to be on instant call for inverting or charging so does not have any isolating switch, I think it takes about a 4watt wake up to supply inverted current, and has internal switching for shore power supply. As far as I can see the only other standby load is 12ma which should not drain batteries that are reasonably new. I think 1.5 amps is significant enough to be a concern.

[smac999]

at 1.5a it is probably on. so something is probably still pluged in. alarm clock?, microwave clock?. etc. I would find out what is drawing AC and causeing the inverter to turn on.



you already said at home with nothing plugged into it, it was much less. so track down the cause on the boat.

unrelated to this problem. when you leave the boat the inverter should be turned off anyways. so it won't draw anything. especially if you don't have shore power. even with shore power it should be turned off.

[Kerry1]

"unrelated to this problem. when you leave the boat the inverter should be turned off anyways. so it won't draw anything. especially if you don't have shore power. even with shore power it should be turned off"

As far as I know there is no way to turn it off short of disconnecting it from AC or DC or both. The following diagram is how I think it's connected. With circuit breakers turned off, I am surprised if there is any load for inverter to draw 1.5A.
Unless the circuit breakers themselves, being AC powered draw that much current to keep working (?) Maybe the little AC current they use to keep "awake" translated to 1.5Amp DC current drain on battery? As you have said I stopped testing too soon. I will have to test more circuits after the inverter on the AC side.

[smac999]

I've never seen breakers that need power? I'm not sure what you mean.


every inverter I've ever seen has an on / off stich on the inverter itself or a remote panel with a control switch. (or both)

[Kerry1]

"I've never seen breakers that need power?"

Yeah probably quite true, I'm just taking a wild guess as one who doesn't know a lot about it! I just can't figure why the drain on the battery through the inverter system. I turned the AC Breakers off- so there should be no AC load on the inverter because as far as I'm aware all the possible AC power loads (about 8 outlets) are switched off by those two breakers. I can't figure why a 1000watt inverter should need 1.5amps to keep it awake. The only standby load in the manual says .12amps.


You are right, it does have a switch to turn inverter off, but it never was an issue before as to the standby load so I never switched it off. I figured switching off the AC panel breakers was enough as well as the main isolating Battery switch. At least if I don't find where the 1.5A is going I can switch inverter off.

But when I get back to the boat will definitely have a look behind that AC panel to see if there are any loads bypassing the breakers or other issues that might be evident. Thanks for your feedback smac99.

[paulajayne]

"it does have a switch to turn inverter off, but it never was an issue before as to the standby load so I never switched it off."


So what has changed - Have you fitted anything new recently? Even changing a like for like item?

[Kerry1]

In March 2011 replaced main alternator.

In March 2011 replaced two of four 6v House Batteries. (stupid, but all I could afford at time)

The original house batteries I bought with the boat did about 7 years service after which two were obviously on the way out. One morning I decided to give the boat engine a workout and after warm up motored out of our anchorage close to full power. Shortly later smoke poured from engine room and I had cooked the alternator. I figured with deeply discharged batteries, (two of which weren't going to charge well anyway) and after the evening workout from fridge and freezer, anchor light and whatever- I simply asked too much from the alternator. Combined with the extra revs on the motor gave the incentive to the alternator to work it to death. I now monitor the charging rate before I open the throttle.

Next blunder: I mixed two old with two new batteries. I was aware of the internal squabbles these were going to create so I used to disconnect them when leaving boat idle, but still did not help. After a couple of years I had trashed them. So it now has 4 new house batteries as of Feb 2015. These are the significant changes to the system.

[paulajayne]

Back to basics.

Put your ammeter in line (on the line in to the invertor) and power off every circuit at the trips.

What is the amp draw?

If still high then disconnect the battery feeds at the invertor, does it still remain high?

[Kerry1]

Ok, I think we have the answer, thanks for your help. But also some more questions!

Yesterday I reinstalled the inverter/charger and did some checking. The standby load consistently read 15 mA for the inverter, which means no problem. I have to confess with my 60 year old eyes in a dark cabin I may have had my multimeter set on milliamps thinking it was on Amps and thus it looked like a 1.5amp load. When I got the inverter home in better light it didn't show that sort of load because I could see better to stick the multimeter switch in the 10 Amp load position where it should have been.

Long story short, I think I just stayed away from the boat too long and the standby load bled the batteries down. Apart from all the angst it has been worthwhile getting to understand the systems better.

Now I know for instance that the inverter switch stops that residual load. When I leave the boat for a longer time I should switch off the inverter, something I never bothered to do before as I have to remove squab and reach up to find it on the inverter itself.

But this issue has raised more questions.

I have a BEP 600-DCM battery monitor and shunt and because am in the process of installing a solar panel, have taken on board the necessity of wiring the negative side of solar controller to the load side of the shunt so that the monitor can record it's input. What I have found, which I can't figure out why it should be wired this way since everything else seems to have been done really well, is that the
negative of the inverter/charger seems to have been wired directly to the house bank negative instead of the load side of the shunt. Is there any reason why they may have done this? It means that the input from the charger side is not accounted for by the Battery monitor when shore powered. So how can it accurately calculate state of charge when one of the charging systems is not monitored? The monitor shows charging from the engine alternator through a Next Step smart charge regulator, and also will show the solar when I hook it up, just can't understand why they wouldn't have wired in the Inverter/charger on the load side of the shunt also.

I am reluctant to change things because when I bought her, the agent suggested I don't let any old hacker (me) monkey with the sophisticated electronic systems on the boat.

The other thing that remains a mystery to me is how the two alternators are wired. Do they both get regulated through the Next Step regulator? Does only the house bank get charged through the smart charger regulator and the other alternator use internal regulation for charging the starter battery?

Also, since changing batteries from 220 Ah up to 232Ah (meaning I have theoretically 464 Ah capacity) I find that when I switch on main isolating switches, (house and starter) the monitor shows an impossible (to my mind) one or two amp charge on the house bank), with nothing running to give charge. Is it an anomoly with not recalibrating the new Amphour capacity? Ie. is the monitor fooled somehow, or is there one bank draining into the other?

[smac999]

the inverter / charger needs to go to load side of shunt. it's wired wrong.


I was on a boat today and they had the shunt between the inverter/charger and the battery. and was not reading any house loads. some people just don't know what they are doing. and this was a marine electrician that did the inverter and battery monitor install. client wondered why the readings never made sense.


you'd have to trace out your alternator wires. and yes it's possible that if you parallel 2 banks one will charge the other. but if you are just turning them on they shouldn't be paralleled. that is normally a third switch. sounds like you have some wire tracing to do. follow the alternator wires, and regulator wires. it should only be running one of them. it's possible one alt is external reg and feeding house bank and the other is interal feeding eng battery. or maybe they are running both alts off one reg which is not good.


and yes your monitor should be set for the new battery size. though that's a pretty minor difference. your battery % will be a little off.

[Kerry1]

Thanks for that Smac, now I'm starting to wonder if it was me who maybe put the negative from inverter back to the wrong side of the shunt when I replaced the batteries. I usually take digital photos of anything I disconnect but sometimes the photo doesn't show clearly what needs to be shown.

I guess it just goes to show there's nothing like actually knowing what you are doing! One thing about it is that lately I seldom do any charging from shore power.... but then again evertime I use AC power from the inverter that drain will not show on battery capacity so it is important. Hmmm.

The setup has three main isolating switches. House, Emergency Parallel, and Starter. So I think the standard engine alternator is wired to starter battery and internally regulated. And the bigger alternator is for the house bank, charged through the smart regulator. But will do as advised and do the wire tracing.

On another tack does anyone know if there is competing tendency between chargers, and regulators when using multiple systems? I mean with engine running the smart charger is doing its thing, then the sun comes up and the solar charger wants to do its thing- is that an issue?

Cheers thanks for your input.