Topping off a battery?

[jiva]

Generally speaking, when I take my phantom out, I bring it home, then immediately recharge the batteries. I'm still in the initial phases of ownership, so I take it out every few days. I don't see the need to drain the batteries to 1/2 for storage for such a short period... BUT...

Because I unplug the batteries after charging them and let them sit, before I head out for my next flight, I like to top them off with the charger one more time.

In other words, I charge them to full, then let them sit for a few days, then top them off one more time before I head out.

Is this destructive to the batteries? Should I just let them sit empty (from the previous run)? Or should I not worry about topping them off before heading out?

 

[EMCSQUAR]

Generally speaking, when I take my phantom out, I bring it home, then immediately recharge the batteries.

Your pre flight charging or topping up doesn't hurt anything. But your opening statement saying you immediately charge them is worth discussing. You should wait at least 15 minutes to let battery(s) stabilize and cool down after each flight.

 

[krb]

Generally speaking, when I take my phantom out, I bring it home, then immediately recharge the batteries.

Your pre flight charging or topping up doesn't hurt anything. But your opening statement saying you immediately charge them is worth discussing. You should wait at least 15 minutes to let battery(s) stabilize and cool down after each flight.

Assuming I let them cool down for at least 15min, can I still keep them charged at full? It's only a few days at a time, maybe five. But that's likely to be the pattern for a while, use them for a day or two, then let them sit (fully charged) for 4-5. I really don't like having to think about making sure the batteries are kept at half charge. If I keep them at half charge, it also means I can't just wake up and decide to go flying and expect to get the full flight time. I've got to charge them to full first. So I guess I just need more batteries and a discharger that cuts off at 50%. Ughh, this is getting expensive.

 

[Gizmo3000]

Assuming I let them cool down for at least 15min, can I still keep them charged at full? It's only a few days at a time, maybe five. But that's likely to be the pattern for a while, use them for a day or two, then let them sit (fully charged) for 4-5. I really don't like having to think about making sure the batteries are kept at half charge. If I keep them at half charge, it also means I can't just wake up and decide to go flying and expect to get the full flight time. I've got to charge them to full first. So I guess I just need more batteries and a discharger that cuts off at 50%. Ughh, this is getting expensive.

Well, on a good note, if you get into an additional charger (which can be had for less than $40), you'll have an extra charger on hand to charge things up with you choose to fly. (plus you could get into a parallel charger to charge up even more batteries at the same time, as well as do storage charge,.etc).

It's preferable to keep batteries in storage charge for longevity, but keeping them at full charge for a few days or so is unlikely to do any damage.
to be honest, I'm guilty of keeping mine charged for weeks at a time, (always thinking I might fly the next day )and they seem to hold up ok.

 

[krb]

Plus you could get into a parallel charger to charge up even more batteries at the same time, as well as do storage charge,.etc).[/quote]
You know I think I might want to do that. I'd need something that would parallel charge at 2 (or more?) batteries, but also discharge down to storage level. I could make my own connector or cut one off an OEM charger. Any ideas on what would work? I have no experience with real non-smart LiPo (I've read a bunch, but don't own any gear).

I'm guilty of keeping mine charged for weeks at a time, (always thinking I might fly the next day )and they seem to hold up ok.

Yea that right there is my problem too. I charge them at night because I'm going to show some work people at lunchtime then we get busy and don't do it for 4-5 days.

 

[ElGuano]

I really dislike the idea of using storage voltage and charging only immediately prior to flight, because it's incredibly inconvenient and makes it a lot more difficult for me to log and get instant feedback on my battery profile after each flight.

That being said, I do follow the practice assiduously, because I have a bit invested in my batteries and want them to last.

Topping off is fine, I'll even do it the morning of if I've charged my batteries the night before. The charger is smart enough to know the voltage of the pack as a whole and each cell individually, so there's no real risk.

If your batteries are always kept fully charged, they simply won't hold their charge as well on a long-term basis. After a year, you may find they're now at 80% capacity, whereas you'd be at 95% if you kept them in cooler temps at storage voltage. This matters to some people, not as much to others.

 

[iResq]

It's my understanding that fully charged batteries should be refrigerated. There is a ton of good info on the net. Nothing I have read on lipos suggested running down to 8 percent.

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[Peter Patricelli]

Now I am confused. I distinctly read somewhere that one should NOT "top off" a lipo battery....that the charger completely discharges the battery through the balancing plugs and wires....which are very small gauge..... and then recharges it . In general, with my stock charger I find neither the batteries nor the charger gets warm during charging.....EXCEPT......the one time I "topped off" a battery there was significant heat there. Never did it again.

 

[ElGuano]

Now I am confused. I distinctly read somewhere that one should NOT "top off" a lipo battery....that the charger completely discharges the battery through the balancing plugs and wires....which are very small gauge..... and then recharges it . In general, with my stock charger I find neither the batteries nor the charger gets warm during charging.....EXCEPT......the one time I "topped off" a battery there was significant heat there. Never did it again.

That probably depends on the charger. If your batteries are unbalanced, the charger may deep-cycle your battery (and at a ridiculously low rate like 0.1c) but most chargers don't do that for top-off. It's been months since I've used my stock charger, but there should be no heat when you top off - it'll be charging at 0.1-0.5A since you're already ~12.5v and should take no more than a few minutes. Yesterday my last top-off put in 500mah and ran for 8 mins.

The P2/PV have a specific procedure you can go through to initiate a top-off charge.