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Is my WFCO converter/charger killing my batteries? |
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Welchsoft 
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Joined: 08 Jul 2020 Online Status: Offline Posts: 58 |
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 Topic: Is my WFCO converter/charger killing my batteries?Posted: 26 Sep 2021 at 7:30am |
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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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Welchsoft
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Joined: 08 Jul 2020 Online Status: Offline Posts: 58 |
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Posted: 26 Sep 2021 at 7:31am |
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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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offgrid
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Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
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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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offgrid
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Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
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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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Welchsoft
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Posted: 27 Sep 2021 at 3:37pm |
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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
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Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
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Posted: 27 Sep 2021 at 6:37pm |
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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
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Posted: 27 Sep 2021 at 9:07pm |
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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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Rpod-Couple
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Joined: 21 Jun 2021 Online Status: Offline Posts: 37 |
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Posted: 27 Sep 2021 at 9:24pm |
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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
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Posted: 27 Sep 2021 at 10:07pm |
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TV was on as was the range top exhaust fan. With nothing running there was about a .25 draw from sensors I would imagine.
Your thinking that the 13v charge would be expected? That is what has me thinking that the WFCO isn't putting out what it should.
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offgrid
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Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
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Posted: 28 Sep 2021 at 7:35am |
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13 or 13.1 sounds like it's in float mode and not going into absorption. Bring the battery SOC down with a heavier load (like the fridge in 12V as I suggested earlier) and when you get to to around 12V or 50% SOC turn on the converter and see if it stays around 13.6V. Leave the loads on when you do that to try to keep it in absorption mode. Measure your battery current before and after turning the WFCO back on.
Not sure if you have an alternate ammeter you can use to check calibration on your battery current monitor. What kind of current measuring device does it use? If a shunt then you can check voltage at the shut itself with a voltmeter. If a Hall Effect donut then try zeroing it. Those are notorious for drifting. Many folks report not being able to keep the WFCOs in bulk mode so don't be surprised by that. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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