UBEC voltage
Posted: Fri May 24, 2013 1:27 pm
I have an UBEC: I'm pretty sure it is one of these: http://www.hobbyking.com/hobbyking/stor ... ction.html - from ebay: http://www.ebay.co.uk/itm/180773848790? ... 1497.l2649
At first I powered it was 4 alkaline AAs. My multimeter recorded 5v across the output. Good! However the pi kept resetting itself. So I tried 6 alkaline AAs. The multimeter said 5.3V. I was suspicious but tried it anyway. It worked!
A few days later I was doing some robot-building, and tried powering my pi using the UBEC and 6 (cheap, pre-charged) NiMH AAs. This didn't seem to get a result. On some examination, I found that the pi wouldn't boot properly at all after that - not from one of those USB phone chargers either, not even from my normal power source. The red PWR led would light but not the green ACT led. I checked the voltage across TP1 and TP2 - 4.5v, which I remember reading was a bit low. Measuring the resistance across the polyfuse F3 was a bit tricky - I think 0.8 ohms. It doesn't seem to have recovered in the last couple of days.
I'm currently powering the UBEC (but nothing beyond that) off the 6 NiMH batteries - my multimeter says 5.15V.
As a stop-gap I got myself a new pi, and I'm reluctant to try unusual ways of powering it until I know what's going on.
Is it usual for UBECs to be 0.3 or so V above the stated 5V? Could this problem have fried my pi? Is the damage likely to be permanent or is it likely the polyfuse will recover?
At first I powered it was 4 alkaline AAs. My multimeter recorded 5v across the output. Good! However the pi kept resetting itself. So I tried 6 alkaline AAs. The multimeter said 5.3V. I was suspicious but tried it anyway. It worked!
A few days later I was doing some robot-building, and tried powering my pi using the UBEC and 6 (cheap, pre-charged) NiMH AAs. This didn't seem to get a result. On some examination, I found that the pi wouldn't boot properly at all after that - not from one of those USB phone chargers either, not even from my normal power source. The red PWR led would light but not the green ACT led. I checked the voltage across TP1 and TP2 - 4.5v, which I remember reading was a bit low. Measuring the resistance across the polyfuse F3 was a bit tricky - I think 0.8 ohms. It doesn't seem to have recovered in the last couple of days.
I'm currently powering the UBEC (but nothing beyond that) off the 6 NiMH batteries - my multimeter says 5.15V.
As a stop-gap I got myself a new pi, and I'm reluctant to try unusual ways of powering it until I know what's going on.
Is it usual for UBECs to be 0.3 or so V above the stated 5V? Could this problem have fried my pi? Is the damage likely to be permanent or is it likely the polyfuse will recover?