Arduino Fio and 35Ah LiPo battery

Hello everyone,

Has anyone powered an Arduino Fio with a high capacity battery like this Lithium-Ion Polymer 3.7V 35Ah battery : http://www.tenergy.com/Tenergy-Lithium-Ion-Polymer-3-7V-35Ah-95212223-Rechargeable-Battery

I have a Fio project currently running on a 6Ah battery and I get about 5 days out of it. It's just enough that I can recharge it over the weekend (it's at the office) but the battery is starting to show some signs of aging. So while I start looking for a replacement, I was thinking maybe I could find a larger battery and hopefully recharge it maybe once a month instead of once a week. On paper it looks like it should work but I am wondering if their might be something I am missing (like maybe the Fio can't charge a battery over a certain size or something like that).

Any feedback or advice would be greatly appreciated.

Cheers,

LP

No problem at all, the voltage is all that matters to the load. That cell has a 10% a month self-discharge rating, so recharging once a month expect it to start at 32Ah and gradually fall from there, so you may need to use a 3-week charging cycle.

However with a powerful battery like that you need to consider safety precautions (definitely a fuse to protect if there should be a short-circuit, good matched charger to safely charge it).

For LiPo a fireproof enclosure is highly recommended.

Thanks for the reply. I have heard of the safety concerns with LiPo batteries and I will take it into consideration. You mention a “good matched charger to safely charge it”, so far I have been using the Fio charge circuit to charge my 6Ah battery via micro-USB. Would you trust the board circuit to charge a 35Ah battery this way or recommend a dedicated charger?

Also the charging time might be an issue to consider, I have no idea how long it would take to charge a 35Ah battery.

Given its a single cell you don't need load-balancing, but you do need a LiPo charger with a good high current output (so it charges in a reasonable number of hours!) and correct voltage limiting.

LiPo don't tolerate over voltage, under voltage or over current, and the charger must respect this. The discharge circuit (the load) should sense voltage too and shutdown before the voltage drops below the lower limit.

OK, got it. I know from experience that the Fio shuts down when the 6Ah battery drops below 2.8V so I guess it's safe. But will probably need a faster charger than the Fio charging circuit. Removing the battery to charge it will also allow me to put it in a fire proof bag during that time.

"... During discharge on load, the load has to be removed as soon as the voltage drops below approximately 3.0 Volts, or else the battery will subsequently no longer accept a full charge and may experience problems holding voltage under load ..."