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The permanent magnet (PM) alternators used in the AeroVee and Jabiru engines create an alternating current (AC) output that varies as a function of RPM. PM alternators are paired with a voltage regulator/rectifier (VR) that converts the AC output to direct current (DC) - the "rectify" function, and then cap (e.g "regulate") the voltage at a set point of around 13.5 volts (this varies a bit from unit to unit). At idle speeds the output voltage is typically lower than battery bus voltage and the battery receives no useful charging current to recharge. At high rpm the alternator is making plenty of power and the output stabilizes at the regulator set point. This all works fine for traditional lead-acid batteries, but the output voltage is actually too low for Odyssey brand batteries as well as EarthX lithium batteries. Odyssey and EarthX batteries require a charging voltage of around 14.5-14.8 volts (edit: 13.9-14.7 as per the EarthX/Odyssey manuals), and the solution to keeping them fully recharged is to raise the regulator output set point to provide a higher charging voltage.

The stock AeroVee and Jabiru VRs are not user-adjustable for output voltage. However, there are two options that have been used as replacements and both work well. The Caltric brand VR model 11-2 (PN LD1293111RV) is set to a higher output set-point and is pretty much a drop-in replacement for the stock VRs. The newest option is the B&C AVC1 Voltage Regulator. This is a purpose-built aviation regulator, with a massive heat sink, over-voltage protection and an adjustable set point.

Either of these solutions will provide improved performance of your electrical system when using an Odyssey or EarthX battery, and are simple to use or retrofit to a flying airplane. Experience has shown that they key to long VR life is good cooling, so ensure you mount the VR to a solid surface that can serve as a heat sink and provide airflow through either natural circulation or a blast tube.

Links:
https://www.amazon.com/Caltric-Regulator-Rectifier-DEERE-AM101406/dp/B008HTBHUI
https://bandc.com/product/avc1-advanced ... lation-kit

For more reading on the subject, see the following threads:
https://www.sonexbuilders.net/viewtopic.php?f=8&t=5076
https://www.sonexbuilders.net/viewtopic.php?f=21&t=5581

I recently installed an EarthX battery in my Turbo Aerovee with the stock alternator/voltage regulator setup. I have a current sensor, and so far I haven't noticed any difference in the in-flight charging current between my old lead-acid battery and the EarthX. In either case, I'm getting 10-11 amps flowing into my battery during climb out, which slowly returns back to zero after 15-20 minutes. Admittedly I didn't also take note of the voltage, but it seems to me that my alternator/VR is having no trouble recharging the EarthX, at least after it has been discharged from engine start/taxi.

Disclaimer: I've used a battery tender after each flight. So if the EarthX was returning from each flight with a lower charge than the last I wouldn't know it yet, I just know that my current sensor is showing a good initial recharge and I haven't completely drained the battery yet.

Ryan,

I would be very interesting to see the state of charge in your battery at the end of a flight. With the very flat voltage drop curve that Lithium provides, the voltage only varies by a half a volt from mostly-charged to mostly-discharged (see EarthX graph below).

A great way to determine the exact state of charge would be to run a controlled discharge test and record the time the battery can supply power to your panel before the voltage drops to the cutoff voltage. The battery manual (link below) recommends 12.6 volts as the cutoff voltage for discharging, and page 11 shows the expected discharge profile. If you ran this test with a freshly-charged battery you'll have a baseline to establish performance, then you can easily run the test in the future to determine either battery health or charge state. It would also be good to know how long the battery will power your panel in an alternator-out situation.

EarthX Battery Manual: https://earthxbatteries.com/wp-content/ ... 17_Y-1.pdf
EarthX Battery Discharge Curve: https://earthxbatteries.com/wp-content/ ... charge.jpg

Jeff

sonex1374 wrote:https://www.amazon.com/Caltric-Regulator-Rectifier-DEERE-AM101406/dp/B008HTBHUI

I figured I'd give this unit a try. What I received looks a bit different, and has NO markings at the tabs. It has the same number of tabs, and the left one is offset from the others, like the one on Amazon, so I'll assume the identifiers are the same.

Question: which of the 3 AeroVee wires goes on which tab?

It seems a solution to the poor charging at idle would be to have a regulator that functions as a buck/boost regulator so that it always provides 14.x volts prior regardless of whether the rectified generator output is above or below that value. It wouldn't be a very complicated circuit, but I've never heard of such a thing being used. Anyone know why?

mike.smith wrote:Question: which of the 3 AeroVee wires goes on which tab?

Mike,

The two wires coming from the AeroVee alternator coil attach to the terminals labeled "AC", then the "B+" terminal connects to your battery/capacitor/battery bus. You can ignore the "L" (low-voltage light) and "IGW" (voltage sense) terminals. The terminal identification is not marked on the unit itself, but follows the picture below. There are several similar units sold by different companies that all use the same terminal functions (they are patterned after a John Deere voltage regulator). The grounding is done through the case, so either use a ground wire on a mounting bolt or attach the regulator to an airframe-grounded component.



Jeff

sonex1374 wrote:

mike.smith wrote:Question: which of the 3 AeroVee wires goes on which tab?

Mike,

The two wires coming from the AeroVee alternator coil attach to the terminals labeled "AC", then the "B+" terminal connects to your battery/capacitor/battery bus. You can ignore the "L" (low-voltage light) and "IGW" (voltage sense) terminals. The terminal identification is not marked on the unit itself, but follows the picture below. There are several similar units sold by different companies that all use the same terminal functions (they are patterned after a John Deere voltage regulator). The grounding is done through the case, so either use a ground wire on a mounting bolt or attach the regulator to an airframe-grounded component.

611CIaanvEL._AC_SL1000_.jpg

Jeff

Thanks, Jeff!

Think AeroVee-voltage regulator as supplied by Sonex (Onan unit I think)-and an EarthX battery.

Till this morning, the voltage would always stabilize at or slightly above 14.1V after 10-15 of flight time. This has been a constant for 18.5hrs.

This morning, all appeared normal with the voltage dropping into the high 12volt range during warm-up and taxi as usual. After the prescribed .2 hours of level flight, the voltage never rose above 13.1. The voltage would oscillate between 12.9v and 13.1v at 5-7 hippopotamus intervals. This went on till I landed 1.1 hours later.

My electrical load consists of a master contactor-red secondary coils-a half an amps worth of engine instruments-and a Garmin G5.

Is it possible to get this kind of partial failure with a voltage regulator, or might something else be brewing?

Searching for my "HeathkIt" instructions here @Area 51%.

I bought a John Deer one from Amazon that I used with my Rotax 912 ULS for a few months. It worked fine. I replaced it because I wanted one that had build in over voltage protection. So I put a Silent Hetik to use with my Rotax.

But the John Deer one worked fine with the Rotax and if you want it, I will give it to you, just pay for shipping. Pm me if you want it or your can call me at 295 531 9959.

John

sonex1374 wrote:

mike.smith wrote:Question: which of the 3 AeroVee wires goes on which tab?

Mike,

The two wires coming from the AeroVee alternator coil attach to the terminals labeled "AC", then the "B+" terminal connects to your battery/capacitor/battery bus. You can ignore the "L" (low-voltage light) and "IGW" (voltage sense) terminals. The terminal identification is not marked on the unit itself, but follows the picture below. There are several similar units sold by different companies that all use the same terminal functions (they are patterned after a John Deere voltage regulator). The grounding is done through the case, so either use a ground wire on a mounting bolt or attach the regulator to an airframe-grounded component.

611CIaanvEL._AC_SL1000_.jpg

Jeff

Thanks Jeff,

This information is very timely. My 3 year old EarthX began sending out BMS error warnings a few months ago. The BMS warning means either a) the cells are not charging at an uniform rate, or b) the cells are not discharging at at uniform rate. This ususally happened about 20-30 minutes into the flight. Therefore, I think it is a problem with uneven charging.

I'll replace the regulator to see if it corrects the problem.