Futaba PCM receiver sensitive to A123?

[tonyc9075]

Is the Futaba R129DP receiver sensitive to A123 voltage?

If I have one A123 plugged into the receiver and then plug in a second A123 battery on a different channel, the receiver will not power up on the second channel. It will on the one channel but not on the other.

Take away the second A123 and replace it with a 4.8 volt battery and it works? On both channels.

What is going on? Can I mix the A123 with a 4.8 volt and fly?

[dick hanson]

	Quote: Originally Posted by tonyc9075
	Is the Futaba R129DP receiver sensitive to A123 voltage? If I have one A123 plugged into the receiver and then plug in a second A123 battery on a different channel, the receiver will not power up on the second channel. It will on the one channel but not on the other. Take away the second A123 and replace it with a 4.8 volt battery and it works? On both channels. What is going on? Can I mix the A123 with a 4.8 volt and fly?

Never mix voltages - NEVER -I don't know what you have done -but apparantly something is amiss

[tonyc9075]

	Quote: Originally Posted by dick hanson
	Never mix voltages - NEVER -I don't know what you have done -but apparantly something is amiss

Thanks Dick,
I don't know what I did wrong, but something is not right. This is my first trip with the A123 and I have done several of the 2 tail light bulb discharg and recharge test. They A123 work without issue, except for this receiver. I think I will switch to a second PCM receiver and see if that one has any problem.

[Zeeb]

Well I'm not sure how you're charging the A123's but if you've set them up with the standard servo type connection for charging and they have a balance tap on the signal lead of the extension, you CAN NOT plug those into the rx as there is voltage on the signal lead going into the rx and it won't like that...

[tonyc9075]

	Quote: Originally Posted by Zeeb
	Well I'm not sure how you're charging the A123's but if you've set them up with the standard servo type connection for charging and they have a balance tap on the signal lead of the extension, you CAN NOT plug those into the rx as there is voltage on the signal lead going into the rx and it won't like that...

Good point, on the HD switch going into the receiver I did cut the white wire, but going from the switch to the battery its all 3 wires. This gives me a balance lead to the battery but not to the receiver. I also took out the diode from the original VPX white balance lead.

I switched to a different PCM receivers and the second one has no issues. I took the problem receiver out of the airplane and it will take the dual battery pack on a few of the channels but not all of the channels. However it will take the 4.8 volt on all the channels? This is a puzzel. My first thought is that the mail plug is not making proper contact, but this happens when I go through the switch, which just doesn't make any sense at all.
I may have a receiver problem or a receiver that only likes the lower voltage.

[Zeeb]

Well it sounds like you're on the right track, it may just be the rx has a problem with the buss or something because what you're trying to do should work.

What I did with my A123's was put a three wire servo extension on them for the charge lead with the balance tap, and a two wire servo lead goes to the three wire HD switches. That way I have access to the bind and data ports on my 2.4GHz rx's through the charge ports on those switches. I also cut the diode out of the VPX cell circuits and as far as I know, so is everyone else.

I think that diode was used to prevent charger issues with the little B&D charger as my CellPro 4S chargers had an issue with the VPX packs at first. If the packs weren't discharged significantly, the charger would go up toward 7.4 volts output and shut down indicating an over voltage situation on the error code. This only happened if the packs were not drawn down much, but the chargers worked fine if the packs were down a ways.

I talked with an engineer at FMA several times about this problem and he said they thought it was caused by the rapid rise in the voltage of the VPX size cells. Whatever it was, the latest firmware ver. 3.02 corrected the issue with those cells and I've not had any hiccups since.