Hi Chris
Apparently not on this Hydra15 system. It does recognise the type of battery based on the battery voltage which is not ideal as a discharged or faulty cell battery may result in the wrong type. Balanced and fully charged batteries should not be at risk.
I do believe we have established that LiPos should be:
Fully charged, preferably with a balanced charger, before use;
Not discharged below the recommended safe voltage (3v - 3.5v as per manufacturers specs, preferably by an ESC that will reduce the current output;
Stored at the recommended voltage between usage;
Not mentioned but important:
Not used or charged if the battery temperature is above room temp or the battery is damaged or shows signs of "puffing".
Hopefully this will help Stuart and others new to LiPo batteries to sail safely
Dave

Good stuff Dave. I know it's generally accepted that 3.0v is the cut-off for LiPos but some manufacturers state a higher voltage, like I said for the Giant I use it's 3.4v per cell so I set the ESC at 7.0v for a 2S.

Do you know if it's adjustable on the MTronic?

Chris

Hi Stuart
I looked up the literature on the ESC and it is LiPo friendly. I spoke to Mtronik today and confirmed it is LiPo friendly in that the battery is identified when connected and a cut off voltage of 3v per cell applied. In your case 6v. Once this voltage is reached the motor receives reduced power, which was the slow down you experienced. As we have already discussed you believed the batteries were charged and ready to go when received. Possibly the battery was also unbalanced and that is the cause of the demise. The ESC measures the overall voltage so one cell 3.5v and the other 2.5v maybe. With your new charger I would expect the new charged battery to give you no problem and a timed run would ensure you stop sailing before the cut off point is reached.
Dave

Hi Stuart
Glad to hear you have bought a Giant Power charger and it has successfully charged your new battery.
The two old batteries are not recoverable as they have been in a discharged state for too long Please do not even consider trying to revive them as due to the time they have been in such a low discharge state the internal chemistry will have changed making the batteries very unstable if you attempt to recharge. You were lucky they did not cause problems when you did a fast charge. Disposal is the only option you should now consider.
As other have said you do need something actually on the boat monitoring the battery voltage and warning you when it approaches the recommended low state. Modern batteries seem to recommend 3.5 volts as the safe limit and I have used this on my Sea Queen without problem. I can actually see the individual cell voltages on a screen on my TX and as soon as the voltage nears 3.6v on any cell I bring the boat back a slow speed as the voltage drops very quickly once the cells are depleted.
Many modern ESC are LiPo friendly and offer a set up you can set to the recommended cut - off, they also reduce the power when the voltage is too low. There are also warning devices you can fit that emit a loud noise to warn of low voltage. They work fine but may be difficult to hear at a distance in a noisy environment.
At full throttle using an 11.1v LiPo and drawing 27amps my Sea Queen lasts between 15-20 mins so you could use a stop watch to monitor your time on the water. As watts is the product of the voltage and current, using 7.4 volts would result in higher current draw and a shorter run time.
Another useful piece of equipment is a Wattmeter that will measure your current draw whilst you hold and run the model in water. This will give you an indication of the max draw as the prop will draw less current when in motion.
What motor and prop do you have installed?
Dave

Hi Chris,

The boat is in my harbour as I ran a build blog here on this site for it over a year ago. Fairey Huntsman - Roaslie.
The ESC I used was an Mtroniks G2 Hydra15, which I dont think has a cut-off system, but I'll check the instruction booklet or look up on the website.

Do not think your batteries are scrap. Think worth seeking out advice on recovery as have done it successfully.
Not familiar with your Huntress model; but on my 34" long brushless, triple screw Brave Borderer running on a 5000mAh 3S battery running at speed gives under 60 mins operating duration.
If you operating at near full speeds your run time is not unreasonable.
Do recommed using a battery discharge warning though. They work well, protect the cells and allow for max. duration operation.
Glad you are getting the hang of Li Pos, they do offer many advantages in higher speed models.

Hi Stuart

Great that you bought the Giant charger. Yes those two batteries are scrap! And your new one is in danger of going the same way as you can't rely on judging when the performance is dropping off - by then the voltage may well have dropped too low. You were lucky that it was still 3.2v per cell. Your particular batteries should tell you what minimum voltage is acceptable. I use Giant Power and they state 3.4v per cell so I set the cut-off at 3.5v

As Nonsuch says ideally you need an ESC that has the facility to set a low voltage cut-off. I take it you bought the boat ready built with the ESC etc. already installed? A low-voltage buzzer as already mentioned is another option.

Be interested in a photo of the boat, I'm a big Fairey fan, but more importantly, can you provide details of the ESC so that we advise on the suitability of it or not for use with LiPos.

I must confess to having no experience of electric powered boats at all. I do however have 15 years of flying LiPo powered fixed wing 3D and helicopters. I have always used a balance charger and have never had an issue with either 2S or 3S LiPo.
What I find disturbing is you say that you "noticed a drop in performance" so brought the boat back in. That suggests that you are not using LiPo compatible ESCs as these have low voltage protection, shutting off or reducing power as a warning of low voltage. Shutting off and then reapplying the power from the transmitter then accesses a "power reserve" to get the model back safely before damage to the LiPo's occurs.
If your ESC is not for LiPo, that's the problem, not the charger.

Hi all......an update!
I bought the GIANT battery charger as has been suggested and connected both dead LiPo's, one at a time. The first one connected gave a cell charge of 0.88V and 0V and the second 1.03V an 0.34V.
I first tried a Balance charge on each of the batteries and the Charger responded immediately with a Voltage error. I then tried a fast charge and after 25mins, the battery cells would only charge to 1.3V and 0.8*V. neither battery would charge any higher.
So am I right to assume they are now both unchargeable and disposable?
I did buy another 4000mH 7.4V 2S and that charged nicely on balance charge to 4.1V from 3.4V and used it for about 30mins in the Huntsmann. I noticed performance drop and quickly bought the boat back.
Once at home, I put the battery on the charger and both cells were down to 3.2V, so charged them to storage charge before putting away for next outing.
Thanks for all your help guys!

I do much the same.
Always use a cell discharge monitor whilst using a Li-Po. I usually set the warning to a minimum of 3.2 volts per cell.
After use, recharge to storage setting. The evening before use fully charge.
Always take the charging precautions and I never charge at more than 1.5 Amps.
Have an intelligent balance charger and am quiet satisfied with Li-Po batteries.

Hi Stuart

Sorry to keep harping on about a better, intelligent charger, but one other thing, after which I will shut up!

I've kept my LiPos fully charged for weeks on end in the past, except for during the winter, off-season, when I've storage charged them. But at the club last week we were having a chat because one guy's fully charged LiPos had begun to swell and so the thought was that if you aren't going to use them for a few days then it is a good idea to storage charge them.

So my regime now is to fully charge them the night before use and after use or not then storage charge them. You can't do this with a cheap LED only charger. To know exactly where you are with LiPos and safety you need an intelligent charger.

What are other folks views on this?

Chris - lips now sealed!

Hi Stuart

Yep, dig that multimeter out or get a battery checker before you do anything else as you need to know the current (pun intended!) voltage of the batteries and ideally get the Giant battery charger that myself and Dave have mentioned because this will give you the voltage of the individual cells and tell you whether either have dropped below the minimum voltage. Also before buying new batteries a charger of this quality will stand a good chance of recharging your existing batteries and doing it safely. If it doesn't recharge the batteries it will prove that they are irreplaceable damaged rather than just guessing that they are.

I was being diplomatic before about your existing chargers as I wouldn't use them for LiPos and would only use them for lower capacity batteries which only have balance charge type leads which only have the capacity for very low charging rates and very limited monitoring of the actual charging.

In my opinion for the safe and efficient charging and effective/meaningful monitoring (i.e. not just LEDs which tell you little) it is essential to have a good quality intelligent charger of sufficient power.

Chris

Hi Stuart
As you are new to modelling and LiPos I did not suggest you try to revive your batteries as this is risky and not something a novice should ever attempt. There is a real risk of fire and damage to you and/or your property. If there are any model flying or model car racing clubs local you may be able to seek help but as RCGroups advise damaged batteries are only recoverable to some extent in certain circumstances and once damaged will always pose a risk. I have used LiPos for several years and only had one incident whilst at the lake. All my fault as I ignored severe swelling of the battery due to my mistaken belief that they should be stored fully charged. The safe voltage is 3.7v per cell where the individual battery elements are at equilibrium and stable.
Dave

Sorry Stuart
www.rcgroups.com
Finger trouble
Rowen

www.regroups.com, look into forums and then by explore the site. Very interesting.
Am away all day, but will respond to any further questions this evening
Good luck
Rowen

What is the website address Rowen?

Li-Pos that are over discharged can be carefully recovered. The technique is described on the RC Groups website and has worked for me.
Follow the precautions carefully though, the process itself is quite straightforward

Thank you all so much for your responses....Dave, you are correct. Being new to using LiPo's and modelling, i used the batteries straight out of the box as you say, they appeared totally charged and worked well in the Huntsmann.

Both LiPo's have balanced charge leads.

I do have a multimeter stored away in the shed somewhere, so I'll dig it out over the weekend and see what the Voltage is.

If I read correctly, if the voltage is below 3.5V then there is no way it will charge and that is why there is a flashing error led on the chargers?

Unfortunately, I dont have a local club nearby or know anyone else who does Modelling apart from you guys on this site that I could ask. My nearest modelling shop is about 12 miles away near Heathrow Airport so not convenient to just pop in and ask the shop owner!

I'll invest in buying a LiPo cell checker when I order some more parts from Cornwall Model Boats or similar web site, as I need some items for my new build....AND a new couple of LiPo's to replace the dead ones I have now.

Will update you on Voltages of the batteries tomorrow.

An expensive learning curve!

Hi Chris
I agree but if the batteries are below a certain voltage no LiPo charger will charge even using the main power lead. Re-reading the initial post it appears both batteries were possibly used from a storage charge without being charged. A multimeter would show 7.4 v on a two cell (the safe storage charge) and anyone new to LiPos may believe this is fully charged. Using in this state would not give a long run time which is what I suspect has happened. I use several different chargers and agree they can perform more effectively. Component shop sell a Giant Power mains LiPo for £37.95 and I have used one for several years. LiPo battery testers are available on Flea Bay for less than a tenner. I do hope Stuart manages to find a solution to his battery issuses.
Dave

Trouble is though Dave he can't charge either of the batteries as the chargers are showing an error as soon as he connects up.

Good idea to get a battery tester or multimeter as really need to know the existing voltage of the batteries.

I stand by what I said about a better charger as it will charge via the much thicker battery leads and will have more sophisticated circuitry for balance charging etc.

As said, I'm very happy with my Accucel 6 but it's very difficult to find one with the AC power source now. There are other models though and Component Shop have the Giant equivalent in stock.

Chris

Hi Stuart
I agree with all that has been said. I doubt if your chargers are at fault as they are showing fault lights. LiPos do not like being discharged below a certain voltage, and for most modern cells this is 3.5volts. Discharging below this figure can cause the lithium to deposit on the battery plates, similar to the sulphation on a lead acid battery. This reduces the cell capacity which is one of the symptoms you experienced. The chargers you have both charge via the balance lead so providing you allow sufficient time for each charge the batteries should give the rated output. It is possible the battery was faulty and if it is a recent purchase you could contact the seller. I would advise buying a cheap battery tester so you can check each cell in your battery and a device to warn you when the voltage is low whilst on the water. If your ESC is LiPo friendly it may have a built in cut off voltage (it is adjustable both to battery type and cut off voltage) and this may be the source of your lack of power. Hope you manage to solve the problem. If you have a local club they may have an expert who could help. Dave

Hi Stuart

I've Googled what you've got and the battery and chargers do have balance leads. If you go on the Sky RC web-site it tells you what the sequence of error lights mean.

I know that the chargers should do what they are supposed to do but for charging LiPos I would recommend spending more on one for peace of mind and safety and providing more information via a text display rather than just LEDs on what is happening when charging. Those batteries aren't cheap afterall!

For example I have a Turnigy Accucell 6 and am very happy with it. Your chargers have quite a low power output which may be part of the problem. Do you know anyone with a better charger who could do a test?

Chris

Hi Stuart

I do have a an ESC with a low voltage cut-off but like you I bring the boat in when the performance drops off.

Do your batteries have a balance lead and if so can it be plugged into the chargers?

Chris

Thanks for the reply.

No, I did not check voltage on LiPo's before sailing but they both worked fine. I don't have the battery check items you mention, just the fact that the performance was degrading and so brought the boat in and took out the battery for charging.
The new battery bought still works ok, but performance reduced, so not used either again.☹️

Did you check the voltage before you started sailing Stuart? voltage should have read 8.6v roundabout
fully charged, did you use a 'Low Voltage Buzzer' or something similar? it lets you know when your lipo cells are nearing the limit of discharge, and you need to bring your boat in, have you got a lipo voltage cell checker? great things to have, lets you know what each cell is storing at, hope this may have been some help, can't understand why your chargers are reading ERRROR, only that you have discharged the battery cells below 3.4v.

Cheers, Pete