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Old 11-13-2019, 09:12 PM
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Originally Posted by jamesrxx951 View Post
I dont understand? Are you inferring that the smaller pack was outputting more amps than it could on its own?
No but at times the smaller battery would be supplying more current than the larger battery. Not for very long but long enough to be noticed but of course on average the larger battery always supplied more energy than the smaller one. This characteristic repeated itself with different batteries, same size batteries, etc. where the load would just sort of go from one battery to the other and back and forth. A chart of the discharge curve would have been interesting.
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Old 11-13-2019, 09:17 PM
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No but at times the smaller battery would be supplying more current than the larger battery. Not for very long but long enough to be noticed but of course on average the larger battery always supplied more energy than the smaller one. This characteristic repeated itself with different batteries, same size batteries, etc. where the load would just sort of go from one battery to the other and back and forth. A chart of the discharge curve would have been interesting.
Ok. I can see that. A graph would be really great to look at for sure.
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Old 11-13-2019, 09:17 PM
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Basically all I use the "checker" for is to check power lipos for charge state. 90%+ versus 50% kind of thing.

Since they do not apply a load they are worthless for actually checking a pack.

The connector are not the issue for this test. Same pack and connectors and a 1-amp load is well within the specs of the servo type connectors.
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Old 11-13-2019, 09:19 PM
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Originally Posted by Judge View Post
Basically all I use the "checker" for is to check power lipos for charge state. 90%+ versus 50% kind of thing.

Since they do not apply a load they are worthless for actually checking a pack.

The connector are not the issue for this test. Same pack and connectors and a 1-amp load is well within the specs of the servo type connectors.
I had similar results before I installed a Dean's on mine. But, as you say, it's close. I hardly use my 8 ball anyways. Telemetry kinda took care of needing to check for me.

Correction, checking voltage between each flight.
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Old 11-13-2019, 09:25 PM
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Originally Posted by jamesrxx951 View Post
in your first test you basically made a single battery. Nominal voltage will always be the same between the two at all times. They are acting as one. In a bat share system, the big battery share the majority of the load. The bat share looks at each battery several times a second and pulls from the higher voltage. It will tap into the smaller battery when it's nominal voltage is higher but its ability to out work the bigger one is not there. If i remember correctly the fromeco looks 40 times a second and pulls from the higher battery at each "look"
I completely understand the theory (lifetime work) but that wasn't the point. The point was that each battery connected in parallel to another supplied variable amounts of current to the total load even though the total load (voltage and current) was consistent. Thats why I found it so strange. All wiring was huge, clean new connectors where used, etc. Huge, high wattage fractional ohm meter shunts were used, etc. Batteries were even switched between legs of the circuit with the same results.

Regarding the bat share devices, I've always wanted to look at these in operation but unfortunately I no longer have access to the necessary lab equipment to do so. Was always curious if there were any switching transients, voids, etc. that could be seen when these were in operation. How do the ideal diodes that seem common in these cope with the servo feedback voltages some servos provide, etc. We all know Futaba's attempt at a power safe receiver was a failure and possibly because they couldn't cope well with voltage spikes, dips, etc. These days I'm just a consumer and rely on user reports for what what works and what doesn't.
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Old 11-13-2019, 09:36 PM
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I completely understand the theory (lifetime work) but that wasn't the point. The point was that each battery connected in parallel to another supplied variable amounts of current to the total load even though the total load (voltage and current) was consistent. Thats why I found it so strange. All wiring was huge, clean new connectors where used, etc. Huge, high wattage fractional ohm meter shunts were used, etc. Batteries were even switched between legs of the circuit with the same results.

Regarding the bat share devices, I've always wanted to look at these in operation but unfortunately I no longer have access to the necessary lab equipment to do so. Was always curious if there were any switching transients, voids, etc. that could be seen when these were in operation. How do the ideal diodes that seem common in these cope with the servo feedback voltages some servos provide, etc. We all know Futaba's attempt at a power safe receiver was a failure and possibly because they couldn't cope well with voltage spikes, dips, etc. These days I'm just a consumer and rely on user reports for what what works and what doesn't.
Did you happen to measure current from each battery during the test? I would love to see that data.
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Old 11-13-2019, 09:44 PM
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Did you happen to measure current from each battery during the test? I would love to see that data.
Yes go back and reread first post. Individual meter shunts and measurements on each battery. Those measurements are what was so surprising.
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Old 11-13-2019, 09:58 PM
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Yes go back and reread first post. Individual meter shunts and measurements on each battery. Those measurements are what was so surprising.
Had a brain fart. But I was thinking of a graph like was discussed prior.
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Old 02-02-2020, 04:30 AM
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Hi Gents. I just stumbled across this discussion. I own 2 of these RB 20's. I bought them for the same reason, to power a large scale aerie and to have more than 8 channels.
And so it happened. I took my Hitec rx out of the Extra 330 SC and I am short of a channel as I use a choke servo.
The RB20 will use the battery with the highest voltage. If that voltage drops below the previous low voltage it will switch and use the highest voltage again.
I have checked the telemetry as well. Using a Rx8R Pro and a XM+, it still reads the telemetry.
It will however read the telemetry from the active rx.

In conclusion, if a battery goes bad the voltage will drop, in which case the RB 20 will use the good battery. I hope this explains some of the issues discussed here.

I have a Horus X10S. I fly all my largescale planes with this radio and so far no problems. I use RX8R rx's with XM+ as redundancy.
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Last edited by grassie; 02-02-2020 at 04:34 AM. Reason: left something out.
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