Heart Interface Inverter/Charger

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Heart Interface Inverter/Charger

August 13, 2010, 07:25:38 pm

As I store my coach for extended periods of time, I disconnect the coach & starting batteries. My starting procedures have been to start the generator for about 30 minutes with the boost turned on and the engine block heater during the 30 minutes of generator charging. Once I start the engine I shut-off the genset.

My question is...with the engine running would running the genset provide the primary (or only) power to the inverter/charger to provide less of a load on the alternator? Not sure how the battery isolator works under these circumstances. How does the "boost" switch operate under the same circumstance?

Re: Heart Interface Inverter/Charger

Reply #1 – August 13, 2010, 08:21:38 pm

Always an interesting question. What happens when solar, battery charger, engine alternator are all charging the batteries at the same time.

Probably no perfect answer, but each charging source has a volt setting that tells that charging source that the batteries are 'full' and that charging device should stop charging or step down its charging voltage.

But things never work real well.
1) For example only, solar panels are charging at 14.2 volts, although at
quite low amps, like 10 amps, even though the battery bank is down 150 amps, which is far from 'full'.
2) Battery charger is pumping 100 amps into battery, checks battery voltage
and sees 14.2, so it thinks battery is 'full' which is far from the truth, so the battery charger steps down its charge rate.

The problem with multiple chargers at the same time, each is designed to think it is the only charging source and the only easy way it knows
'fullness' of battery is to check voltage, which can be easily fooled.

So instead of the battery charger pumping in 100 amps for a while, the solar panels pump in 10 amps for a long time. The answer is to be aware and manage multiple chargers. Also shows that two 50 amp chargers may not charge batteries at 100 amps.

Boost switch just connects both battery banks. It is either on or off and does not have any built-in ability to manage charging.

Isolator shares alternator amps to both battery banks and has no built-in charging logic.

As with all batteries, the fuller they are greater resistance to charging amps. This is a natural built-in control of each battery in a bank. To charge a battery it takes a charging voltage that is much higher than the battery to 'push in' current/amps. After a while, even though the battery charger is willing to supply up to 100 amps, the battery will only accept 3-10 amps and nothing can be done about it. A high-tech battery charger recognizes this and steps down its charging voltage to a float level of about 13.2 volts, just to maintain the battery. Some chargers actually shut off when sensing batteries have only been accepting 3-10 amps during the last 2 hours of charging. All these setting may be adjustable, like on our
Prosine 2.0.

Re: Heart Interface Inverter/Charger

Reply #2 – August 13, 2010, 08:51:01 pm

Hi Barry,

So...if you were to try to resolve your proposed multi-charger dilemma, how about installing a switch or a rather large relay to open the alternator connection if all day solar might keep your batteries up while driving? Maybe the only real benefit might be to give your alternator a rest. At least the other sources can be shut off at will. Some owners have installed amp meters on each source to monitor what's happening.

Idealists might spend tons of money to install a far more solar. And then there is the wild idea of a wind charger. I know of two coaches with both. Oh the fun projects we can envision!

Jim
2002 U320

Re: Heart Interface Inverter/Charger

Reply #3 – August 13, 2010, 09:25:41 pm

Barry, thanks for the explanation.

So let me see if I got this right:

The isolator is a 12v routing device. Its only purpose is to route alternator generated power to the starting battery bank as well as the house battery bank when the engine is running. (So does this alternator current bypass the inverter/charger and is wired directly to the house batteries?)

The battery isolator does not perform any function when the "boost switch" is on.

With shore or genset power, the 110v AC is supplied to the inverter charger via the transfer switch. The appropriate AC circuit in the main panel (not the inverter circuit sub-panel) then supplies power to the inverter/charger so the batteries can be charged as needed.

I'm still not clear as to whether the battery state of charge determines which source to use to charge them? Or, is there logic built-in to the charger so when the engine and genset are running (or shore power) only the charger is supplying the power to the batteries during charging.

I was kinda hoping that the 110v AC generated by the genset (or shore power) would over-ride the alternator. This way the alternator doesn't fry when trying to charge the batteries in a low state of charge while both the engine & genset are running.

Re: Heart Interface Inverter/Charger

Reply #4 – August 13, 2010, 09:52:02 pm

Quote

So...if you were to try to resolve your proposed multi-charger dilemma, how about installing a switch or a rather large relay to open the alternator connection if all day solar might keep your batteries up while driving? Maybe the only real benefit might be to give your alternator a rest.

I added a solenoid & toggle switch for that reason.
I added a digital voltage and amperage meters with shunts and toggles to monitor house, chassis and alternator.
I wanted some accuracy in my readings.

When I start the coach I have the house batteries removed from the alternator charging system.
I watch the amperage going into the chassis batteries.
When the chassis batteries are reading 10 amps they are charged & then I flip the toggle to bring the house batteries on line to charge.
When they are reading 10 amps and are charged I flip another toggle switch and remove them from the charging system & run the 12vdc coach needs from the alternator.

No need to keep the house batteries in the charging system once they are charged since the alternator does not have a 3 stage charging system.

Re: Heart Interface Inverter/Charger

Reply #5 – August 13, 2010, 10:03:27 pm

Peter,
I think you have it right. Rest assured that you are offloading the alternator (at least a significant amount) when the genset (or shore power) is on while the engine is running. There isn't any brains between both sources. What the exact ratio is between them will probably change with conditions but it will definitely be easier on the alternator. I've played around with this on my coach and can see the voltmeter jump up and the RPM rise slightly when I manually activate the changer on the inverter. It might be more noticeable on mine since I have upgraded my inverter to a RS3000 with a 150 amp charger.

Re: Heart Interface Inverter/Charger

Reply #6 – August 14, 2010, 12:25:46 am

Peter,

Alternator is connected to both start & house, but start & house are isolated from each other, hence the name 'isolator'. Isolator is directly connected to house batteries. Battery charger is directly connected to house batteries.

Boost on connects house & start together, so they are not isolated. With boost on or off, isolator still lowers alternator voltage going to batteries by about 6/10 of a volt.

Yes, main panel supplies 120 volts to battery charger.

See Barry Beam's mod to remove house battery load from alternator when desired.

Batteries have no idea how or what is charging them. When a battery feel full, it just won't take any more current/amps. Each charger (solar, alt, chgr) has logic on how much voltage / current it will put out at any moment, without knowledge of what else is also charging the same batteries.

When alternator & battery charger are both charging house batteries, both may be charging equally, or one may be charging more than the other. There is nothing that automatically turns either one off, but we can manually turn off battery charger or alternator with Barry Beam's mod.

Re: Heart Interface Inverter/Charger

Reply #7 – August 14, 2010, 12:39:32 am

Got it, finally! Thanks to all for great input. Barry B., great installation and illustration of a very usefull modification.

Re: Heart Interface Inverter/Charger

Reply #8 – August 14, 2010, 12:40:50 am

Well said, Barry.

Only comment is that while a diode (not solenoid) based isolator DOES loose around .6 VDC across the diodes, the sense wire for the alternator/regulator is on the battery side of the isolator. Said another way, the alternator will put out around 14.8 VDC and the batteries will see about 14.2 VDC.

And NEVER put a cut off switch in line with alternator output-- it will blow the diodes in the alternator.

But, you can do a variation on that which I did over a decade ago.

Being a KISS theory guy from all our years of off shore sailing, I threw our diode-based isolator in the trash the day we got our coach.

Wired alternator output and chassis battery to one side of a Perko marine 360 amp continuous duty ON-OFF switch. Wired house battery to the other side of the switch. With engine running and switch off, only the chassis battery is charged. With switch on, both banks are charged.

Now for how you can use it:

If on shore power overnight and heading for a CG tonight, leave switch OFF. Why burn diesel to run the alternator harder to OVER-charge the house batteries all day (and yes, keeping fully charged batteries at 14 VDC all day is overcharging them).

Some coaches do not charge the chassis battery from the converter or charger. Turning the switch on "combines" both battery banks for charging with no relays or solenoids involved.

If using the house batteries for starting (boost), that marine 360 amp continuous duty mechanical switch provides an excellent "combiner".

Brett Wolfe

Re: Heart Interface Inverter/Charger

Reply #9 – August 14, 2010, 01:09:10 am

Brett,

That mod. definitely qualifies as a KISS winner of all time. Where is your switch installed? I assume it's all wired with the high amp wire used for the alternator/batteries?

Re: Heart Interface Inverter/Charger

Reply #10 – August 14, 2010, 08:31:26 am

Peter,

Perhaps the simplest approach is to do what you're doing, but not start your engine until amps from the gen drop significantly, like in half, so you are sure the alternator won't be taxed unreasonably. I'd switch off the block heater to check how much your house batteries are still accepting.

Re: Heart Interface Inverter/Charger

Reply #11 – August 14, 2010, 08:48:57 am

Are you saying you are using the alternator to charge your house batteries even when they are significantly discharged?
___

best, paul
"Thriving not surviving" <(*¿*)>
Paul Schaye (at 2008 NYC Marathon)
See our blog at LazyDazers.com

Quote

When I start the coach I have the house batteries removed from the alternator charging system. I watch the amperage going into the chassis batteries. When the chassis batteries are reading 10 amps they are charged & then I flip the toggle to bring the house batteries on line to charge. When they are reading 10 amps and are charged I flip another toggle switch and remove them from the charging system & run the 12vdc coach needs from the alternator.

Re: Heart Interface Inverter/Charger

Reply #12 – August 14, 2010, 09:35:26 am

Paul, perhaps I've been doing just that w/o knowing it. I let the genset run for 30 minutes with the boost on and block heater on. Usually the battery voltages after storage are reading in the range of 12.2 to 12.6 volts as well as the engine batteries. I just figured 30 minutes would bring the charge bck up enough to not tax the alternator unduly.

Re: Heart Interface Inverter/Charger

Reply #13 – August 14, 2010, 09:49:19 am

An example with potentially more problems is:

1. After boondocking a night or so, start the generator and charger
2. Then start the engine

Does the example below mean an alternator at 14.2v might cause the generator charger to step down its charge rate thereby putting more charging load on the alternator?

If so, does this mean I need to run the generator until amps are 10 or so and then start the engine?
___

best, paul
"Thriving not surviving" <(*¿*)>
Paul Schaye (at 2008 NYC Marathon)
See our blog at LazyDazers.com

Quote

But things never work real well.
1) For example only, solar panels are charging at 14.2 volts, although at quite low amps, like 10 amps, even though the battery bank is down 150 amps, which is far from 'full'.
2) Battery charger is pumping 100 amps into battery, checks battery voltage and sees 14.2, so it thinks battery is 'full' which is far from the truth, so the battery charger steps down its charge rate.

Re: Heart Interface Inverter/Charger

Reply #14 – August 14, 2010, 09:52:34 am

Quote

Are you saying you are using the alternator to charge your house batteries even when they are significantly discharged?

NO. If I dry camp, I will usually have the Genset running 1st thing in the AM.
Gotta have my coffee

By the time I leave the batteries have been charging for awhile.
But by having the option of charging the chassis batteries 1st before putting the house batteries on line,
it is much less taxing on the alternator.

Re: Heart Interface Inverter/Charger

Reply #15 – August 14, 2010, 10:04:09 am

Paul,

I've set my battery charging at 14.1 amps, and the alternator voltage after the isolator at 13.5, so the genset controls. After boondocking I run the generator for at least two hours before starting the engine. By then charging amps have dropped below 50. I keep the generator running as I run down the road until charging goes into float. After replacing two alternators in two years before adopting this practice, I've stopped replacing alternators.

Re: Heart Interface Inverter/Charger

Reply #16 – August 14, 2010, 10:10:21 am

Paul, not sure how to answer that question. From what I understand, batteries will accept the charge from the charger as well as the alternator. What is not clear is at what proportion is the charge being taken by the batteries. For example, my alternator puts out 130 amps, and if I read Brett's data correctly at 14.8 volts before the isolator. The charger puts out 100 amps at 14.2 volts (not 100% sure on that, and if these values degrade over the years). My intuitive response would be that the alternator will win this battle as it is providing more electrical flow (amps). I'm certain someone with more understanding can amplify this topic.

Re: Heart Interface Inverter/Charger

Reply #17 – August 14, 2010, 10:31:15 am

Quote

For example, my alternator puts out 130 amps, and if I read Brett's data correctly at 14.8 volts before the isolator.

The voltage off the alternator is AFTER the isolator at 13.5 vdc

Quote

The charger puts out 100 amps at 14.2 volts (not 100% sure on that, and if these values degrade over the years).
My intuitive response would be that the alternator will win this battle as it is providing more electrical flow (amps).

The Genset has the higher voltage so "it will win the battle"
The Batteries determine how many amps are accepted by how charged they are.

Re: Heart Interface Inverter/Charger

Reply #18 – August 14, 2010, 11:54:06 am

Quote

RE: Does the example below mean an alternator at 14.2v might cause the generator charger to step down its charge rate thereby putting more charging load on the alternator?
If so, does this mean I need to run the generator until amps are 10 or so and then start the engine?

Answer is Yes.
The only way to know how full a battery bank is with an amp meter.

Amp meters use inexpensive shunts and a millivolt meter to measure DC amps at this moment.
Add clock-time & memory to the millivolt meter, to keep track of amps over time, and you now have a 'hour-meter', which keeps track of amps over time. Store battery amp size in memory and you now have a percent readout on how full the battery bank, displayed in amps and how many hours left to discharge or charge bank.

By the way, our alternator has a 3-step voltage regulator and will float charge both battery banks through the isolator at a lower voltage after driving a while.
There are many types of voltage regulators that will fit into our Prestolite-Leese-Neville alternators. Some adjustable, some 3-stage, some fixed, etc.

Re: Heart Interface Inverter/Charger

Reply #19 – August 16, 2010, 06:58:08 pm

Since we are fulltime boondockers and seldom hook up to shore power we have to manage our alternative electrical resources.
Our solar controller is set to a maximum charge voltage of 14.1 volts (temperature compensated) and to float at 13.8 volts
Our wind generator is set to a maximum of 13.8 volts
Our engine alternator is set to a maximum of 13.5 volts
The above systems are wired independent of each other to the batteries.
The inverter/charger is set for Gel Cells and from readings I have taken, the charging rate is similar to the solar controller.
We would most likely NEVER be using the inverter/charger if any of the first three systems are running and supplying energy.
The majority of our power is supplied by solar.
The number two supplier is wind power.
The third is an external Yamaha EF2400i generator which charges via the inverter/charger.
I would like to find some kind of an effective voltage regulator that I could put in line between the isolator and the alternator in the event of an alternator failure where it produces high voltage and high amperages, to protect the rest of the system.
I suggest that "others" verify the voltage produced by their alternators at the coach batteries and adjust it to the preferred level.
Regards,

Re: Heart Interface Inverter/Charger

Reply #20 – August 16, 2010, 08:39:11 pm

Quote from: (from Barry and Cindy:)

"By the way, our alternator has a 3-step voltage regulator and will float charge both battery banks through the isolator at a lower voltage after driving a while.
There are many types of voltage regulators that will fit into our Prestolite-Leese-Neville alternators. Some adjustable, some 3-stage, some fixed, etc."

Barry - where did you get the 3 stage regulator for your alternator? Is that standard with some Leese-Neville models?
How to tell what regulator is in the alternator without taking it apart? xxx - never mind that last - just read Barry's Beamalarm writeup which tells how to identify them...

Re: Heart Interface Inverter/Charger

Reply #21 – August 17, 2010, 01:45:58 am

Dave,
When we had our alternator rebuilt at one of those old-time shops in Delaware, that KNOW Leese-Neville's, they told me what I needed and I learned about out alternator from them. Not sure how to tell regulators apart. I do see voltage changes while driving. Barry Beam may have some more info on this. Our repair shop also knew all about our small voltage sense and ignition sense wires and modified a new regulator with the additional terminals. We lucked out finding that small shop.

Re: Heart Interface Inverter/Charger

Reply #22 – August 19, 2010, 07:15:59 pm

I get the feeling that someone is confusing three stage intelligent charging, with three position physical voltage settings.....I would however, be interested in a clarification.

Regards,
JON TWORK KB8RSA

Re: Heart Interface Inverter/Charger

Reply #23 – August 19, 2010, 08:05:55 pm

Jon,

You are very right about confusing. The reason I asked was due to Javelina voltage readout (the dash Volt reading is comparable, but not as readable as the Javelina monitor. I've observed various readings while driving. Most of the time the reading is at 13.8 volts and it may get as low as 13.2 after batteries are fully charged. Although other times the reading is 14.1 volts. And, I have a feeling this is when the alternator is being really taxed by the coach & starting batteries, but not at all sure. Coincidentally, the 14.1 volt readings are when the batteries are not fully charged, like early on during the first hours of driving.

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