Heart Freedom 20 Inverter / Charger schematic

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ricknsharon

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Oct 8, 2012
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4
I attached a simple schematic that I created while I was troubleshooting a persistent problem I have been having for over 14 yrs. with my Heart Freedom 20.  Every now and then the battery charger function would not work.  I found that by giving the inverter a "Fonsey slap" it would start working again, sometimes just for a few days, other times for years. 

The symptoms were this.  The inverter always worked great.  When the charger would not work I would "Fonsey slap" it and after ten seconds it would start charging with a slow ramp up like it should.  Looking over the schematic I knew the problem had to be isolated to relay K1 or the circuit associated with it.  So I carefully inspected all the copper traces and solder connections using magnifier glasses and a flashlight.  Low and behold the solder joint was cracked at the high voltage side of the control power transformer.  The symptoms fit the find exactly.

A simple solder repair was made and all is well once again.  If this helps someone else please let me know that my time was not wasted in this message.

Thanks,
Rick Martin
Palmyra, WI
 

Attachments

  • Heart Freedom 20 schematic 1605.pdf
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Tom

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Jan 13, 2005
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49,638
Thanks for sharing the story and the schematic.
 

tatyanka

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Feb 23, 2022
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3
Location
Seattle,WA
On mine so far small transformer( board supply) has primary winding short's. Draw on 120volt side 450-510mA ( fuse was blown , fuse was 250mA). Primary resistance sometimes 90 ohms , later 140-150ohms.Little thing get hot in no time.
Output to board from secondary(3.2ohms) 16-18volts.
It's STANCOR SW-412.

Will see if i can get similar from ebay.
 

5essfun

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May 29, 2022
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Location
Wasilla, Alaska
HI RV Troubleshooters,

Any idea exactly how the Freedom 20 switches from bulk charge, to acceptance charge, to float charge? When mine tries to switch from 14.3 volt acceptance charge when the current gets to about 7A, as it should, the display goes dark for about 10 seconds, then it starts over at acceptance. This happens twice, then the charge voltage goes to about 15.5V. A full schematic would do the trick, wouldn't it. =-)
 

JayArr

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Jun 13, 2020
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Location
Mission British Columbia Canada
5essfun

Switching between charge modes is electronic and has to do with the power FETs. The relays are for AC switching only. Does your unit run inverter mode and produce a decent signal output?
 

5essfun

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May 29, 2022
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Location
Wasilla, Alaska
Hi JayArr,
Yes, the inverter output is 120.0V RMS, 117 or so with 1600 Watt load. Charges batteries fine too, until it tries to leave acceptance mode and float. Something amiss at that point. Thanks for your reply. Best regards from Alaska to our neighbors to the south in BC!
 

tatyanka

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Feb 23, 2022
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Seattle,WA
Mine have failed flash in MC705 microcontroller. Some old mercedes have same problem with those older outdated micro's.
 

5essfun

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May 29, 2022
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Location
Wasilla, Alaska
Interesting. Yes could be, but could also be whatever transistors/device the controller drives. I'll put it on the bench this winter and try to understand how it works and how it changes charging modes. In the mean time I just can't let it go past acceptance charge mode for long, and when parked I'll put a separate maintainer on the batteries. If anyone else has more knowledge or a schematic they have managed to work out, please share! Best regards.
 
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