Is my WFCO converter/charger killing my batteries? |
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Rpod-Couple
Newbie Joined: 21 Jun 2021 Online Status: Offline Posts: 37 |
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Topic: Is my WFCO converter/charger killing my batteries? Posted: 27 Sep 2021 at 9:24pm |
My 2021 R-pods refrigerator is 120V or propane. It doesn’t have a 12v heater. The inside LED lights draw 0.33 amps each. I have 7 in my R-pod for total 2.3 amps if all are on. I believe the bathroom fan draws about 2 amps even though fused at 10 amps to handle startup current. The radio is less than 1 amp at moderate sound levels. Carbon monoxide/propane sensor is 0.1 amps. 22” TV is less than 3 amps. So…you could be up to 8 amps battery draw if all of the items I listed are turned on. I can imagine if TV is off, you could be around 6 amps. 13 hours x 6.1 amps = 79 amp-hours which sounds to be in the ball park especially if you were running at lower current of say 1 amp over 72 hours in addition to the 79 amp-hours for a total of 151 amp-hours. By my rough calculations, everything seems to be reasonable.
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Steve & Elaine
2021 R-pod 2023 VW Atlas Cross Sport |
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Welchsoft
Groupie Joined: 08 Jul 2020 Online Status: Offline Posts: 58 |
Post Options Quote Reply Posted: 27 Sep 2021 at 9:07pm |
Agree and I did not cross check amps with my meter. I did however check volts with my meter and battery monitor which agree at the battery. With the amount that the batteries were drawn down I would expect that even if the charger went to Absorption (not Bulk at 14.4) at 13.6 or Float at 13.2 I would see something higher than 13 at the charger going to the battery.
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Post Options Quote Reply Posted: 27 Sep 2021 at 6:37pm |
Only 6A load with everything turned on? That doesn't sound right. Seems low. Try turning the fridge on in 12V mode and see how much current that takes. Should be around 11-12A. If it's much less then maybe your battery current monitor needs to be recalibrated. Or, if you have a DC call on multimeter you could get a second current measurement that way for comparison.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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Welchsoft
Groupie Joined: 08 Jul 2020 Online Status: Offline Posts: 58 |
Post Options Quote Reply Posted: 27 Sep 2021 at 3:37pm |
Over the last three days I've been running a series of tests on my WFCO 8735P. With my factory installed WFCO 35a converter charger this is what I learned. I removed the solar and inverter from the battery and only connected #8 wires from the converter to the battery. I ran down my two 6v Trojan T-105's by running everything I could find on 12v in the camper. This created a draw of 6.17a which I paused at times but ran over a three day period. From 100% SOC to 60.8% it took approximately 13 continuous hours at 6.17a. Note that the 60.8% value was measured on my battery monitor which measured 12.4 volts, but according to Trojan's documentation this voltage is closer to 70%. My hydrometer read between 1225-1250 on all cells. I plugged in the camper to AC and turned on the converter/charger. Voltage at the charger was 13.1v and at the battery 12.9. I repeated readings every hour for three hours. Amps measured by my battery monitor were 7.6 at start and three hours later 5.8. In three hours my converter charger brought the battery from 60.8 to 64.4v. I turned off the shore power and plugged in my 2200w generator with the same results and never exceeding 12.9 volts of 5.8 amps. Any thoughts on if these numbers represents a problem?
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Post Options Quote Reply Posted: 26 Sep 2021 at 7:48am |
In theory yes but in practice you need to be sure the cables and fuses can handle the additional current first. You would want a minimum of 6 gauge for 55A and 4 gauge for 65A. Also you'd need to confirm the 120Vac supply wiring and circuit breaker can handle the higher input current load of the larger converter (they most likely can). Look in the converter manual for that requirement. Finally, the conversion process creates heat which has to be removed from the enclosure where the converter is located. The larger converter will produce more heat. So you'd need to be sure the bigger converter fits and also measure some operating temperatures and possibly add better ventilation or a cooling fan. IOW, like most things in life if you make one change there is a ripple effect that has to be dealt with. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Post Options Quote Reply Posted: 26 Sep 2021 at 7:35am |
Yes, you have that right. But I think the rating on the converter is higher than 35A. Mine was. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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Welchsoft
Groupie Joined: 08 Jul 2020 Online Status: Offline Posts: 58 |
Post Options Quote Reply Posted: 26 Sep 2021 at 7:31am |
And if I'm correct, can I just replace the converter/charger with something at a higher amperage, like 55 or 65A?
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Welchsoft
Groupie Joined: 08 Jul 2020 Online Status: Offline Posts: 58 |
Post Options Quote Reply Posted: 26 Sep 2021 at 7:30am |
Sorry not an EE person so I may not completely understand but that's ok. So my converter/charger unit is 35A. If my battery is down to about 50% I may never see 14.4 but something (some equasion..) lower because that's all the unit can push out at 35 amps?
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Post Options Quote Reply Posted: 24 Sep 2021 at 6:02pm |
What they should say is that in their bulk mode their charger can supply 14.4V open circuit (no current). But if the battery is deeply discharged then it will take the max current the charge puts our (I think that's 55A, not sure) at a lower voltage than 14.4. Once the charger hits it's current limit the voltage won't go any higher of course, because it can't produce enough current to do so. So the right way to look at bulk mode is the charger can produce up to 14.4 of 55A, whichever comes first.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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Welchsoft
Groupie Joined: 08 Jul 2020 Online Status: Offline Posts: 58 |
Post Options Quote Reply Posted: 24 Sep 2021 at 7:16am |
Starting my testing with a voltmeter to check actual charge current leaving the charger, and then going to the cables on the battery (while disconnected). I'm expecting to see 14.4 volts when charging in bulk mode but just read this in the WFCO manual and I think that it says that I will never se 14.4 even if it is putting that out. Confused...
"If the output current reaches its maximum (normally caused by a discharged battery), this will cause the converter to go into Bulk Mode, which means the target output voltage will change to 14.4 VDC and a timer will start. Although the converter is outputting 14.4 VDC, you will not be able to read that on a voltmeter due to the voltage-current relationship. From the paragraph above, as load current increases, output voltage decreases. The actual output voltage will not rise until the load current is reduced, which happens naturally as the battery charges or if 12 VDC appliances are turned off." |
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