Question abut two inverter/charger/inverters

[jerry work]

This new to us bus has two Heart 2500 pure sine wave inverters that each charge the house battery bank and provide 12vdc to the many house circuits and provides very clean 120vac power for the appliances while dry camping with the big generator turned off.

My question pertains to how these two communicate with one another while both are charging the same battery bank. The techs at the selling dealer couldn't give me a clear explanation but obviously the system works. One inverter often reports a different state of charge than the other until the battery bank is fully charged, then both report the same. Any of you have experience with such a set up?

There is a 300 amp water cooled engine driven alternator that provides 24volts to the chassis circuits and a second air cooled 250 amp engine driven alternator for,the house battery bank. Curious minds would like to know how all of this really works.

Jerry

Jerry Work
The Dovetail Joint
Fine furniture designed & hand crafted
in the 1907 former Masonic Temple building
in historic Kerby, OR
http://jerrywork.com

 

[Ken B]

Man, That is a lot of power floating around there and way out of the range of anything I have ever worked on in a motorhome.

I have a friend that is a power plant operator. He runs four 600 megawatt generators with an average load of around 450 megawatts each. At that
level if one generator kicks off line, the other 3 can take over and cover the load. This coach sounds like something he should work on.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[Matt Colie]

> This new to us bus has two Heart 2500 pure sine wave inverters that each charge the house battery bank and provide 12vdc to the many house
> circuits and provides very clean 120vac power for the appliances while dry camping with the big generator turned off.
>
> My question pertains to how these two communicate with one another while both are charging the same battery bank. The techs at the selling dealer
> couldn't give me a clear explanation but obviously the system works. One inverter often reports a different state of charge than the other until
> the battery bank is fully charged, then both report the same. Any of you have experience with such a set up?
>
> There is a 300 amp water cooled engine driven alternator that provides 24volts to the chassis circuits and a second air cooled 250 amp engine
> driven alternator for,the house battery bank. Curious minds would like to know how all of this really works.
>
> Jerry
>
> Jerry Work

Jerry,

It is my experience that the two Heart inverter chargers will never agree. Even a tiny calibration error can cause that. Actually, even just a
little difference in cable resistance (I am talking about 0.01ohms) can do that. While the newer have digital controls and communication, I do not
believe that they actually "talk" to each other and there is no reason that they need to.

Question: Is the house bank lead or lithium?

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Still Loving OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[RF_Burns]

Jerry,
My guess is since you can see any communication wiring between them, they don't talk to each other. Each charger is likely operating independently
and when its done its charge cycle, it will report fully charged.

Lead acid battery chargers aren't all that smart. They basically start out in a current limited mode (boost charge) where the charger drops its
voltage to keep the charge current under a certain limit (say 50amps). As the battery charges, the charger voltage rises to maintain the 50Amp current
until the voltage hits its voltage limit (something around 14.5-14.8 volts). The charger then holds at that voltage and as the battery continues to
charge, the current will drop. Once the current drops below a certain level, the charger assumes the battery is charged and it drops its output
voltage to a float charge level (between 13.2 to 13.8 volts). At this time the charger reports the battery is charged.

If both inverters/chargers are connected to the same battery bank, the same thing would happen, except the current available in initial Boost mode
would be twice the charger limit current. The battery bank would hit the charger voltage limit in about 1/2 the time. At any point in the charge
cycle, one charger will be taking more of the charge load due to tolerances in the current limit and voltage limit settings in each charger, but
likely no more than 5% difference.

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

 

[Gene Fisher]

YOU SOB,s HAVE DIFFERENT PROBLEMS

> Jerry,
> My guess is since you can see any communication wiring between them, they
> don't talk to each other. Each charger is likely operating independently
> and when its done its charge cycle, it will report fully charged.
>
> Lead acid battery chargers aren't all that smart. They basically start
> out in a current limited mode (boost charge) where the charger drops its
> voltage to keep the charge current under a certain limit (say 50amps). As
> the battery charges, the charger voltage rises to maintain the 50Amp current
> until the voltage hits its voltage limit (something around 14.5-14.8
> volts). The charger then holds at that voltage and as the battery continues
> to
> charge, the current will drop. Once the current drops below a certain
> level, the charger assumes the battery is charged and it drops its output
> voltage to a float charge level (between 13.2 to 13.8 volts). At this time
> the charger reports the battery is charged.
>
> If both inverters/chargers are connected to the same battery bank, the
> same thing would happen, except the current available in initial Boost mode
> would be twice the charger limit current. The battery bank would hit the
> charger voltage limit in about 1/2 the time. At any point in the charge
> cycle, one charger will be taking more of the charge load due to
> tolerances in the current limit and voltage limit settings in each charger,
> but
> likely no more than 5% difference.
>
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
> Hubler 1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://bdub.net/gmcmotorhome.info/
Alternator Protection Cable
http://bdub.net/gmcmotorhome.info/APC.html

 

[RF_Burns]

I should clarify my answer above a bit. Since most of the chargers I've seen in RV installations are wired as "loaded battery" (battery is in
parallel with the house loads), the charger has no idea what charge current the battery is taking. Therefore there is a timer controlling the
various.

From Progressive Dynamics web site, their Charge Wizard is in Boost mode for 4 hours, the normal mode for the next 28 hours, then to maintenance mode
after that, with a equalization mode every mode 21 hrs after that. So it doesn't know or care what the charge state is, it just goes through its timed
modes each time you plug in whether the battery needs it or not.

They have a Lithium Iron Phosphate charger now as well. The manual shows it as being wired as a loaded battery. I'm not sure how the charger knows
what the current vs voltage at the battery is when there is no separate current and voltage sense for the battery!

--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that