Large Scale Central

Li Ion and Smart charger

Electronics Power and Sound
#21

Devon Sinsley said:

You mention safety time. How do I determine that? If I am charging at 1.3A would that be 120 minutes of charging for a 2600mAh battery and should I have it set to turn of at that time? Any thoughts o the ability to attach a temperature sensor?

Devon,

I made sure my Lithium batteries came with “PCB” protection. I’m using them with a tenergy “smart” dumb charger (it has to be set to the correct voltage) but the PCB protects the battery from overcharging or (hopefully) overheating.

#22

Yeah I made sure it was PCB protected so I am really just trying to cover all bases. I mean if the charger has the features might as well use them.

#23

Devon Sinsley said:

Yeah I made sure it was PCB protected so I am really just trying to cover all bases. I mean if the charger has the features might as well use them.

I’m sure someone will correct me if I’m wrong here, but I think that the true smart chargers (programmable) are better for the batteries - even packs with a PCB (I’ve not heard of a commercial LiIon pack without the protection PCB), since they do more than simply feed a straight current to the pack until the PCB cuts off the charge.

I used a “dumb” charger for years and it always worked well for me. It still gets me out of trouble when a pack goes “undervolt”. I got a great deal on the programmable one from Bruce who didn’t want to be bothered with the settings. There is something to be said for plug it in and forget it.

#24

I did actually see some non PCB protected packs on Ebay but then that goes back to the commercially available part; who knows who was making them but it is something someone should be aware of.

Now here is a hypothetical question at least for me. Two scenarios using two packs and on board charging with a smart charger. If a person where to use two 7.2v 2600 mAh packs in parallel to get 14.4v 2600mAh combination would he charge it as if it were a single 4cell 14.4v 2600 mAh pack? And if he were to wire them in series to get a 7.2v 5200 mAh would you charge them as a single 7.2v 5200 mAh pack. Or is the charger set up to charge 7.2v 2600 mAh? Or do you install separate jacks and charge individually with some sort of isolater between them like a switch?

#25

Devon,

You’d be wiring the batteries in series not parallel to garner 14.4V.

Best case is to charge the batteries separately in this circumstance. An isolating switch or simply accessing and unplugging the batteries would likely be the best approach IMO. Yet you could charge them as a single four cell battery.

I often use a charge jack that is wired to disconnect or isolate the battery while under charge. Two of these charge jacks would get the job done.

The 18650 batteries offered in the RC Aircraft world when first introduced were typically sans the PCB’s from multiple suppliers. I personally don’t use PCB’s on most of my batteries, I fit them all with balance pigtails and I have a few Li-Po’s that have PCB’s fitted as an experiment.

I get the plug it and forget approach, but inherently this approach has caveats too.

Michael

#26

Michael Glavin said:

You’d be wiring the batteries in series not parallel to garner 14.4V.

I knew I would get that backwards. Your answer is how I figured I would do it even before I asked the question. But I wanted to see what the experts said. I was thinking an isolating switch and a jack for each battery would be the best approach.

#27

Devon.

What chemistry are the 2 x 7.2 volt batteries?

#28

Tony Walsham said:

Devon.

What chemistry are the 2 x 7.2 volt batteries?

Tony that was a purely hypothetical question for future reference but seemed like a good time to ask it. I was thinking in my mind LiIon simply because that is pretty much the go to battery anymore it seems. I know you show in your instructions the ability to set up two jacks and that is kinda where I was heading when I was thinking about it. Like I said hypothetical at this point.