LiPo Question

[Richard SimpsonParticipant @richardsimpson88330]

OK gents, first time ever with a LiPo battery so don't want to get anything wrong and join the list of modellers with a big hole in their workbench as a result of not treating the battery correctly.

The battery is a 3S 1300mah LiPo. It says on the front of the battery 5C and it says on a label on the back of the battery charge at 1 to 3C. From what I can see on line most guidance seems to be to charge at 1C so my question is, what is a safe charging current?

Also when I charge is it worth using the balance charge facility on the battery charger? I can plug a board into my charger that then accepts the plug on the battery for balance charging. Is that all about balancing the cell voltages to ensure they are all the same?

[Richard SimpsonParticipant @richardsimpson88330]

[Colin BishopModerator @colinbishop34627]

Yes Richard you have it right. If the battery is 1300MAh then that is the optimum charging rate although you can go higher. It's not too critical.

Do use the balancing lead as this ensures that all cells are in the same state of charge which maintains battery health.

After use the battery should be charged/discharged to 3.8-3.85 volts per cell for storage. Your charger may well have this facility. When you next come to use it just top it up to full charge.

Colin

[Richard SimpsonParticipant @richardsimpson88330]

Thanks Colin, I think I saw something about a storage setting so I need to look into that as well.

[Chris FellowsParticipant @chrisfellows72943]

Hi Richard

I can charge my batteries at a higher rate as well but I always charge at 1C as higher rates can reduce the life of the battery and I'm more comfortable with charging at a lower rate.

It doesn't sound as though your charger is a smart/balance charger as it hasn't got the balance ports built in. I'd recommend getting one of these as it makes charging/storage charging safe and easy and you have to use the balance lead otherwise the charger won't play ball. As said it balances the cells and this type of charger indicates the volts of each.

I take it you know you need to use a LiPo safe ESC which cuts power at a preset level? Not essential as you could use a low level warning in the boat but it's safer and usual practice to use one.

Chris

[Ray Wood 3Participant @raywood3]

Hi Richard,

Yes as Chris says the balance plug is essential to monitor each cell as it charges and detect if a cell has failed, I have a couple of Lipo chargers which display each indicates the state of each cell.

A chap on Mayhem connected a 12volt lead acid charger to the power terminals on a Lipo and it blew up !! I think ignorance of the different type of battery causes most of the issues that hit the head lines, Lipos have the better power to weight ratio which is great for flying but not any better for boats in my opinion.

Regards Ray

[Ray Wood 3Participant @raywood3]

Hi Richard,

Just as an addendum to my last night post the 3 lights on the right come on as each cell is fully charged, so they are charged one after the other, this is my field charger set up I have known folk using their car batteries all day and not getting home in the evening hence the Halfords battery.

Regards Ray

[Richard SimpsonParticipant @richardsimpson88330]

Tanks for the help gents.

Chris I probably didn't explain very well, my charger has a port that you plug a board into. On this board are sockets for a range of LiPo cell numbers so you can balance charge any LiPo battery from 2S up to I think 6S, maybe more. It also tells you the individual cell voltage so you can see that they are balanced and it also charges to a storage condition.

Also I wasn't aware of the need for an ESC that cuts power at a pre-set voltage. This is precisely why I have avoided LiPos up until now, when this model being so small has forced the issue, because I see them as so ridiculously complicated. I'm now discovering I have to charge them to a specific voltage for storage! How long is 'storage'? Give me a Nimh any day. As I bought the ESC with the brushless motor I will assume there is a cut off facility but I'll check the instructions.

Ray, the model in question is a very narrow 19th Century torpedo boat so room is extreemly limited, hence using a LiPo and a brushless motor. I've never used LiPos before as I've never needed to. A 7.2 v Nimh pack would be way too heavy and a lower voltage wouldn't give the performance.

[Colin BishopModerator @colinbishop34627]

Richard,

This is the low warning indicator, it plugs into the battery balance lead and provides visual and audible cwarning of individual cell low voltage. I use just the visual one on my two Faireys as I can see it through the cabin windows.

**LINK**

Re storage, after running my boats I put them on the charger and select the storage option to bring them to the correct voltage.. Then top them up immediately before the next session. LiPos seem to have a low self discharge rate when treated correctly.

Quite agree that LiPos ar a faff compared with NiMH packs. They were needed for the Faireys but I normally prefer the latter although I do have a couple of 'legacy' lead acids.

Colin

[Richard SimpsonParticipant @richardsimpson88330]

Thanks Colin. I can't believe that will be the third time in a week I will have paid Component Shop a shipping charge!

I did buy a 2S cell for the Yarrow and the motor spins at a far less frightening rate now! I just need to get it on the water and give it a run and get a couple of shots of it.

Storage shouldn't be too onerous as I always charge up my batteries when I come back from the pond as well as prior to going.  I just need to charge to 'storage' condition for the LiPos.

Edited By Richard Simpson on 27/04/2023 10:20:15

[Richard SimpsonParticipant @richardsimpson88330]

After a dig around through the ESC instructions it turns out it does have a low voltage cut out. So I'll have a belt and braces job for this one as I ordered the item from Component Shop as well!

[ashley needhamParticipant @ashleyneedham69188]

Richard. Too much mystique associated with Lipo batts. Its easy.

1. use a proper Lipo charger (and use the balancing lead).

2. do not flatten them or go below (about) 3.3 v per cell or they die.

3. use a low voltage alarm to achieve (2).

4. best not to leave them charging unattended.

5. if they puff up, discard (responsibly obv)

Other than that, just treat them with the same precautions you would with any battery. I store mine in a tin. The low voltage alarm is a must as they hold voltage until the last minute and then the voltage drops very quickly.

Ashley

[Chris FellowsParticipant @chrisfellows72943]

Sounds like you are sorted then Richard.

I'll get one of those low-voltage alarms for those models I'm going to use my 30amp ESCs in. They do have low-voltage cut-off but I can't, annoyingly, use my program card with them and am wary of setting using beeps! Having said that I might not use LiPos.

Chris

[Richard SimpsonParticipant @richardsimpson88330]

I got lost in the number of 'beeps'. In the end I decided the default setting was fine!

[ashley needhamParticipant @ashleyneedham69188]

Program card the only way to go with esc that DO have them. Richard. The default setting is what I leave alone. It will be fine and besides, by the time the battery gets that low, it’s on its way out and should be changed anyway.

Ashley

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