Running time of batteries

[chris ottawayParticipant @chrisottaway86119]

Hi newbie question sorry if its a silly one. Do you get any warning of your battery going flat, just don't want to end up with boat in the middle of the lake lol.

[chris ottawayParticipant @chrisottaway86119]

[Colin BishopModerator @colinbishop34627]

Rather depends on what sort of battery it is, they have different characteristics.

With conventional batteries, lead acid and NiMH the boat will simply slow down, in the latter case rather quickly.

With LiPo cells if they are discharged beyond a certain point they will be permanently damaged so you would normally fit a low voltage alarm system.

Have a read of this for more information.

http://www.modelboats.co.uk/news/article/but-i-don-t-understand-electronics/18054

Colin

Edited By Colin Bishop, Website Editor on 19/08/2017 19:36:06

[ashley needhamParticipant @ashleyneedham69188]

Hi Chris and welcome to the forum.

Not such a silly question. As Colin says. However you can get low voltage bleepers from various on line sources, but the voltage on a Nimh battery does tail off rather quickly. Experience is necessary really, sail your boat, notice when it starts to get sluggish, bring it in.

​Ashley

[chris ottawayParticipant @chrisottaway86119]

Thanks for your replies I have two batteries both LiPo one is 1800mAh the other 2700mAh

[Dodgy Geezer 1Participant @dodgygeezer1]

if you have a 'smart' charger – say, the IMax – you can set it to discharge at a specified rate as well as charging. That will then tell you how long your battery will last with a specified drain.

You can also get a cheap Watt Meter, such as this: **LINK** which will tell you how much power your motor is using while it is on the water. Armed with those tools you should have a pretty clear idea of how long your batteries will run for.

The web is also full of simple little low battery warning circuits – eg – **LINK**

[Malcolm FraryParticipant @malcolmfrary95515]

With LiPos, you do need some kind of warning since they have a very sudden drop off from being able to deliver full power to being so discharged as to be fatally damaged.

Some ESCs designed for use with LiPos restrict performance as a warning.

There are devices that monitor voltage and give an audible warning, hopefully before it is too late.

Some recent radio systems have telemetry that can show you the actual battery voltage in the model. But these require you to look at the transmitter display panel, away from the model being controlled.

[chris ottawayParticipant @chrisottaway86119]

Ok i went out for a run with it this morning at my local model boating lake, with a club there. The shop when i brought it said i should get about 15 mins off the battery. So I set a timer for 15mins at about 12 mins I had a loss of power then got power back. So decided to change battery over this one was told i should get about 30mins, set timer. at about 26mins I got the same thing loss of power. So would you say the ESC has a restricted performance warning, as suggested in last reply. Would I find this information on the ESC?

Also I been looking at meters, as well as the one in the link from Dodgy Geezer (great name lol). Would this one work? **LINK**

Sorry to be a total pain I am a complete novice on this hobby, so everything is a learning curve lol.

[Dodgy Geezer 1Participant @dodgygeezer1]

Being with a club helps – they should be the first people to turn to. We can only work at a distance, so we can easily miss something that might be apparent if we were on the spot.

1 – your shop seems to have given you quite accurate advice. You can never be precise to the second about when a battery will go. Note that as they wear they will hold power for a shorter and shorter time…

2 – you really have to look at your ESC manual. If you haven;t got one you can probably find one on the net.

3 – I don't know the device you have linked to – but I don't think it is a power meter. I think it is simply a volt meter, and will tell you what the voltage is for your battery. The power meters I linked to earlier will read volts and amps, display them with total watts, and store the maximum amp drain automatically during a run, so you can read out the peak and average power your boat drained from the battery after you have brought it in. Armed with this information you can calculate just how long a run you can get, and how much you can extend this if you cut back on the throttle a bit…

This is an example of one on Amazon…https://www.amazon.co.uk/T-Trees-Meter-Analyzer-Backlight-Precision/dp/B0177T09PC/ref=sr_1_1?s=electronics&ie=UTF8&qid=1503256919&sr=1-1&keywords=watt+meter

 

Edited By Dodgy Geezer on 20/08/2017 20:22:52

[chris ottawayParticipant @chrisottaway86119]

Ok thanks Dodge Geezer, think I may get the one in your last post, then work out how to get it wired lol.

[Dodgy Geezer 1Participant @dodgygeezer1]

There are lots of instruction manuals on the web.

Here is a simple one – **LINK**

Here is a more complicated one **LINK**

[Malcolm FraryParticipant @malcolmfrary95515]

Posted by chris ottaway on 20/08/2017 18:25:09:

Ok i went out for a run with it this morning at my local model boating lake, with a club there. The shop when i brought it said i should get about 15 mins off the battery. So I set a timer for 15mins at about 12 mins I had a loss of power then got power back. So decided to change battery over this one was told i should get about 30mins, set timer. at about 26mins I got the same thing loss of power. So would you say the ESC has a restricted performance warning, as suggested in last reply. Would I find this information on the ESC?

Also I been looking at meters, as well as the one in the link from Dodgy Geezer (great name lol). Would this one work? **LINK**

Sorry to be a total pain I am a complete novice on this hobby, so everything is a learning curve lol.

The item linked to (from the link) claims to –

Battery balancer

Battery discharger

Battery capacity checker

ESC / Servo PPM tester

Battery internal resistance tester

All out of the water, so not on-board. Still a useful device if used. When looking at Amazon links, it can be illuminating to scroll down the page to the Q&A section and the reviews.

https://hobbyking.com/en_us/hobbykingtm-lipoly-low-voltage-alarm-2s-4s.html?___store=en_us – is an on board audible alarm, useful while the boat is within earshot. but probably not needed if the ESC gives its own warning.

[ashley needhamParticipant @ashleyneedham69188]

Chris. What boat do you have and what motor/prop?

As per DG`s post, you need to know what current the motor draws before making any calculation as to run time. A static "by the edge of the pond" test will give a guide if the meter you get does not have a max value memory setting for dynamic runs.

​Any further discussion will simply be pure guesswork otherwise.

Ashley

[chris ottawayParticipant @chrisottaway86119]

Hope this may help still not got a clue lol.

This is a link to the boat I brought.

**LINK**

[Dave MilbournParticipant @davemilbourn48782]

This is all rather academic, chaps. The duration from a set of batteries is a consequence of capacity, current and time. If you're one of those loonies who throws the boat into the water, pushes the throttle stick all the way to its limit and leaves it there then the battery won't last long. If you slow down for corners; maybe cruise gently past the jetty and then open it up into a wide turn, or even stop the thing in the middle of the pond while you have a chat/cuppa/smoke whatever then the battery might last all morning. No amount of theoretical calculations will give an accurate answer because no two sailings are the same unless they're both at absolutely top speed all the time. You quickly get to know when the battery is getting low from the behaviour of the model.

Dave M

[Dodgy Geezer 1Participant @dodgygeezer1]

To extend DM's comments a little more – this is a 'ready-to-run' racing boat, so it probably won't be pottering around the lake at all. Battery time calculations are never going to be precise to the minute, so the shop's estimate of 1/4 hour or 1/2 hour are, I think, well estimated with 12 minutes and 26 minutes to when you first feel loss of power.

You have already found out that if you leave a battery for a while it will recover slightly. Running at less than full power, as DM points out, will increase run time – sometimes quite substantially.

Racing boat clubs tend to have a 'rescue boat' ready to recover stranded boats – either a rowboat with a person in or a small model with a 'scoop' at the front.. You will also find that it is beneficial to run on the leeward side of the lake (with the wind blowing towards you) so that any time required to drift in is lowered.

A major use of power meters is to determine efficiency of the motor/prop combination you have in your boat. Since you have an RTR boat, all this will have been optimised by the manufacturer, so you don't really need to do it yourself. You would only really need a power meter if you were going to re-engine or re-prop the boat.

This is a good example of what I was saying earlier – the club people at the lakeside are the first people you should be getting advice from. They would see instantly that you had an RTR boat – we have been giving advice based on general hobby boats you build yourself…

[chris ottawayParticipant @chrisottaway86119]

Thank you all for your replies. It's very helpful. I am starting with this RTR model, but I do tend to move on to a build so all information will be helpful.

[Dodgy Geezer 1Participant @dodgygeezer1]

This appears to be the manual for your boat. Is it? **LINK**

It contains the following paras:

"The included ESC features a ‘soft’ low voltage cutoff ( LVC ) that smoothly reduces power to the motor (regardless of the power level you have set with the throttle stick) to let you know the voltage of the battery is close to the 6.0V minimum.

However, even before this reduction in power , if you find that more than the typical amount of throttle/ power is required to cruise or climb you should land the model and disconnect the battery immediately to prevent over-discharge. And while it is possible to continue running the model after the soft LVC occurs, this is NOT recommended. Continued discharging can result in reaching the 5.0V ‘hard’ LVC which may cause permanent damage to the LiPo battery resulting in reduced power and flight duration during subsequent fights ( or failure of the battery entirely which is not covered under warranty). Also, it is not recommended that you run to the soft LVC every time you run. Instead you should be aware of the power level of the battery through out, and if at any time the boat begins to require more throttle/ power than typical to maintain speed you should let the boat run back and disconnect the LiPo battery immediately. Constantly discharging the battery to the soft LVC can still cause permanent damage to the battery so it’s best to use a timer or stop-watch to time the duration of your running and to stop flying at a reasonable time before the soft LVC is reached."

[Colin BishopModerator @colinbishop34627]

It's in the instructions then?

Colin

[Dave MilbournParticipant @davemilbourn48782]

Blimey! Who'd have thought? And not written in Chinglish either! It's a good job DG read them or we'd all still be in the dark.

Mind you, I do remember a customer once ringing me up with a question which was clearly covered in the instructions. When I pointed this out he said that he was calling "just to make sure they're correct"…

DM

[chris ottawayParticipant @chrisottaway86119]

I have mislaid the instructions, think they may of fell out at the shop.

[Dodgy Geezer 1Participant @dodgygeezer1]

In that case I hope the link I provided will be of use. It may not be for your precise model – I did not look too hard on the web for it, and I guess that there are manual downloads or help pages somewhere on the manufacturers web site – **LINK** but it's a manual for a similar boat in their range, so a lot of the advice – perhaps all of it – is going to be of value.

I might direct your attention specifically to the Safety and Maintenance pages, which should always be read and understood before operating a machine….

[chris ottawayParticipant @chrisottaway86119]

 

 

Well took it out today and this has happened.  Looked back on video I filmed at no time did it look like I hit anything.

 

Edited By chris ottaway on 21/08/2017 21:09:14

[Dodgy Geezer 1Participant @dodgygeezer1]

It looks as if you have a broken propshaft. Did you read the maintenance directions regarding lubrication, and use of loctight on the grub screws?

Edited By Dodgy Geezer on 21/08/2017 21:19:36

[chris ottawayParticipant @chrisottaway86119]

I was told at the shop to spray it with WD40 which I did, has to the grub screws shouldn't have that been done when it was fitted?

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