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NickS

Battery checker recommendations

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NickS

Ok so I am new to using lipo batteries and dlg etc. as everything was old school nicads and crystals when I used to fly gliders a lot.  I have 3  x 600 1s batteries and an Overlander charger so tend to keep them all charged and then rotate them after what seems a sensible air time for each.  It would be useful to have a simple low cost battery checker though as I probably swap them round too often (though  potentially I could be regularly getting close to battery drain but just don't know).  Any recommendations on what to others are using would be much appreciated.

 

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mikef

If your charger tells you how much charge it is putting into your battery after a known amount of air time, you can judge how much charge you are using in a given time.

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SilentPilot

When you say keep them charged does that mean stored fully charged?

That's not good for LiPo batteries. Much better to store them at around 50% charge or 3.8v resting  :)

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satinet

Storage voltage is good for long term storage but you don't need it for stuff you use on a regular basis imho.

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Paul Gleeson

I have 2 batteries for each glider. 

Fly until it’s empty then switch over and charge the empty one. 

I have RX voltage telemetry in all my DLGs

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PaulR

Nick, any of the cheap battery checkers you can get on eBay or any of the usual online RC vendors will do the job. With a 1 cell Lipo you don’t need anything that points out unbalanced cells, purely one voltage measurement. You can just use a multimeter if you have one.

Google Lipo discharge curve to get an idea of how the voltage drops with capacity used. I tend to stop flying when my telemetry shows 3.7v (which is of course under load).

As Mike says, if you get an idea from your charger of how many mah you are putting back in after X minutes of flying then that is going to be a very good guide, but for that quick check to tell if you’ve picked up the charged or discharged battery, any cheap checker will do the job. They might not be hugely accurate but good enough.

 

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Dave Elam

I've got two of the black checkers that most folk have and they never show the same figure for a given battery pack. In fact I've tried the same experiment at the flying field with others and the same applies. They're a good guide as to battery status but I wouldn't trust one 100%.

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NickS

Thanks for the useful replies.  Particularly good to know about not storing fully charged.

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Mark Evans
16 hours ago, Paul Gleeson said:

I have 2 batteries for each glider. 

Fly until it’s empty then switch over and charge the empty one. 

I have RX voltage telemetry in all my DLGs

I'll stick my useless opinion in. I do as Paul. Although I very rarely take a spare battery to the field, especially if in the plane it's shoved right down into the nose and there's leads in the way etc. I use the ISDT Q6 charger and power it with a 3-4s Lipo and top up or charge at the filed. I charge between 2-5c so they take very little time. Although I already had this charger set up, would be cheaper to buy 2-3 1s batteries to take to the filed if you're charging at home.

I try to fly most days if the weather is kind, I rarely store at 50%, my packs are either fully charged or at 3.7v after a flying session. These 1s lipos are dirt cheap, if you shorten its life from leaving fully charged it's not much of an expense to replace. And it's 2019, I don't buy into keeping your packs at 3.8v while in regular use or only charging 1c, my packs at 5c charge stay stone cold still and I have never noticed any degrade in performance from any of my batteries from a 1s up to the 4-6s packs I used to use for freestyle quads. 

Rx batt telemetry on my radio and stop flying at 3.7v. I've never put a 1s lipo on a battery checker. 

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Marc Sinclair
Posted (edited)

3Very helpful thread, thanks.

Question if you please: I'm using a combo of 1600/950/300 NiMH batteries all running at 4.8Volts. 

Should I set alarms ringing through my TX when voltage drops to 3.7 as suggested above?

I have noticed how under load the battery life bar on TX drops but pops back up to almost full when resting after a bit...  I haven't kept an eye on the volts though.

 

 

Edited by Marc Sinclair
Messed up with 4.7 volts now corrected to 3.7

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mikef

3.7 volts is the nominal voltage of a single Lipo cell.  Nimh technology is different and the two type Lipo/Nimh need very different charging procedures.

Your Nimh 4.8 volt packs each have 4 cells.  The Nimh cell has a nominal voltage of 1.2 volts.

For a 4.8 volt Nimh pack, what's a sensible lower voltage limit under load?

You'd need to get an opinion on that from a person who knew your equipment.

Are you sure your Tx runs on 4.8 volts?

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Marc Sinclair

Thanks mike.  I was referring to the batteries inside my gliders which all run at 4.8 volts. I can check my tx battery if it helps.  

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mikef

No need to check Tx batteries.  I don't use telemetry so I missed the point - sorry.

If you can see the Rx voltage on the Tx display, why not put a recently charged Rx battery in the model, waggle your sticks in a frantic way to draw max current and get a feeling for what the lowest voltage is under load.  Then you can set you alarm a little below that as a starting point and see how you get on in practice.

Batteries with a lower capacity, like your 300 mah pack, will drop their voltage more under load and probably need a different setting for the low voltage alarm.   Another consideration is that your gear will quit working if the voltage goes too low during a high current demand, causing a so-called, 'brown out'.  The battery will recover if rested.

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Marc Sinclair

Yes that makes good sense about try the waggle stick approach  :). Will give it a go thank you. 

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SilentPilot
2 hours ago, Marc Sinclair said:

Question if you please: I'm using a combo of 1600/950/300 NiMH batteries all running at 4.8Volts. 

Should I set alarms ringing through my TX when voltage drops to 3.7 as suggested above?

I recommend setting the alarm for 5.0v for a 4.8 (4S) Rx pack.

Nixx packs are totally different from Lixx, you don't want to go below their rated voltage.

A 1S 3.7v LiPo has a working range between 3.6 and 4.2v

A 4S 4.8v NiMH can charge up to almost 6v but you don't want to let them get below 4.8v 

 

Tony :)

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Marc Sinclair

Thanks for taking the time to explain that Tony. 👍 

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StraightEdge

Marc

For my NiMH flight batteries  (in trad slope-soarers and IC models)  I use a Logic RC Battery Load Tester which can be set for 4.8/6V.

This checks the pack under a load of 0.5A.  If green LED goes to yellow when I press the load button I'll fly, but if yellow goes to red it's time to recharge the pack.

 https://www.logicrc.com/?s=c:0,c:50,c:50-70&ItemId=P-FS-BC04

Jon

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SilentPilot

I might get one of those myself :D

I've plenty of LiPo checkers but nothing suitable for NiMH/NiCd 

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Marc Sinclair
1 hour ago, StraightEdge said:

Marc

For my NiMH flight batteries  (in trad slope-soarers and IC models)  I use a Logic RC Battery Load Tester which can be set for 4.8/6V.

This checks the pack under a load of 0.5A.  If green LED goes to yellow when I press the load button I'll fly, but if yellow goes to red it's time to recharge the pack.

 https://www.logicrc.com/?s=c:0,c:50,c:50-70&ItemId=P-FS-BC04

Jon

Thanks for the advice Jon! That sounds like a great idea.

👍

Marc

 

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