Jump to content

3S or 4S LiPo for Electric Starter.


David Davis
 Share

Recommended Posts

18 hours ago, Simon Clark said:

For what it's worth, I have two Just Engines geared starters. One is the 4:1 gear ratio version with standard sized spinner cone and the other is the 6.5:1 version with the large spinner cone. I use both with 4S LIPOs that are detachable and held with a velcro strap and connected with an XT60 connector. The larger one is used for 20-33cc two strokes (petrol and glow) and the smaller on is used for everything else. With 4S they both have bags of power and work really well. I have tried the smaller on with 3S and this is OK in most cases BUT it does not spin the engine as quick and for one (and only one) of my smaller glows, it does not start as easily due to the lower speed.

 

I charge the batteries before each session and discharge to storage level between sessions. Do not be tempted to use old and knackered batteries as a starter actually puts quite a load on the battery - it is only in use for a few seconds and in a whole day of flying will only run for a very few minutes but when it is running, it takes a lot of current, so you don't need a particularly high capacity but you do need a reasonable C rating. At the moment, I am using Turnigy 4S 1400 65C to good effect.

 

Simon

Simon

How much does it take out of the 1400 pack during a days flying. I'm just about to ditch the 12V gel battery for a lipo, and just trying to decide what size pack to buy.

 

Link to comment
Share on other sites

Hello Richard,

Of course it depends on how much flying you do, how many people borrow your starter (being a self contained unit does make it very popular to borrow for all those whose starters or batteries are not quite up to it!!) and how easy your engine starts! I used to use 1000mAh packs but these got a bit old and I knackered them by leaving charged over a winter (bad move). Even after a fairly heavy days flying, I never got anywhere close to the capacity. The choice of capacity is more to do with the current delivery ability - I am sure that a 500mAh would have enough capacity but it might not like delivering the high currents unless it is a very high C rating AND in good new condition. The final choice of 1400mAh was more to do with availability and price at the time and you can go a bit bigger or smaller without problem. The 1400mAh pack is still quite compact and light and does not get in the way or feel heavy in any way but you could go quite a bit bigger if you had to. I have just checked and the ones that I use are still available and cheap: https://hobbyking.com/en_us/turnigy-1400mah-4s-65c-lipo-pack-w-xt60.html?queryID=cd29d1cff0fec9f355fc9ebde828d21b&objectID=78391&indexName=hbk_live_magento_en_us_products

 

Good luck

Simon

Link to comment
Share on other sites

I've just done some checks.  6.5:1 JE starter on 4S LiPo:

 

No load: 6A

Stalled 40A

Typical mid range engine (cold and dry Irvine 53)  17A

 

Say you make 10 starts and they take 12 seconds average (that would be very badly set up engines...12 seconds may be longer than you'd imagine but it makes for a handy calculation!) - that's two minutes of use on a reasonably active day.  My retired from flying duties 3200 mAh is quite old so let's assume a very pessimistic 2000mAh capacity.  We'll throw in some larger engines and assume 20A average current.  It will last for 2000 mAh / 20000 mAh (20A) or 1/10 of an hour which is 6 minutes - or 3 days of busy use.

 

These are very pessimistic estimates. In practice, I charge my starter battery a few times a year - usually after helping someone with an recalcitrant engine.  It only takes an hour to recharge so I can usually fly an electric model, hand start an IC or two, find some instructing, have a chat while I wait or normally a combination of the aforementioned.

 

A 1400 mAh pack would require a rating of 40 000 / 1400 = 28C if it were stalled continuously (not recommended for the motor's sake!) and half that at a typical 20A load so virtually any pack should suffice as few are less that 15C these days.  The extreme example of a 500 mAh one mentioned would need to supply a fairly hefty 40C...

Link to comment
Share on other sites

Obviously, everyone has their own opinion, but the following is fact.

A couple of years ago, I became aware (on this forum!) that some people used Lipos to power engine starters.

I therefore tried one of my old Wot 4 foamie Lipos (3S, 2200 mAh) with my old Ripmax starter.

It worked great, and has been used ever since on all glow engines up to the ASP 120FS on my Wot4 XL, and I have actually started the 180FS with it.

In fact, I just transferred an XT plug from an old ESC onto the starter.

Previously, I had always avoided starters, mainly because I didn't fancy humping a 12V lead/acid battery around, but the Lipo solution is perfect.

My lifelong motto is: "If it ain't easy, I don't do it", and the starter/Lipo combination sure fits that!

Link to comment
Share on other sites

Strange one this.

I have had a JE starter for some years and the contacts never welded, even when I went up to 4s for a Laser 180. Then it suddenly died so with the season in full swing I ordered another. This one welded every time at the slightest touch and I tried everything I could think of to sort it so u/s to me at the time but I was able to repair the original in which the crimped tags to the brushes had melted due to loose fixing screws. I suppose I could take the newer one with me on 3s as a spare and try that on smaller motors.

Despite the problems they are probably the best on the market for the money.

Link to comment
Share on other sites

I agree with Martin that the JE starters are the best for the money. There is no doubt that the switches are a weak area but this applies to all the starters I have seen, including the expensive Sullivan ones. It is very difficult to predict if a switch will weld and to explain why one starter seems to suffer more than another. It is not commonly known that these switch contacts will actually weld every single time on closing without exception, it is just that in most cases the weld is weak and is easily broken by the mechanical opening force. If the weld is strong or the opening force is weak, then the contacts will remain welded. There are a whole host of factors that affect the weld strength and seemingly small differences can have a big effect. I think that I have been lucky and never had a switch remain welded but I am aware that this could happen which is one reason why I connect the batteries to the starter with a connector so that they can be quickly isolated if needed. I have always intended to investigate the possibility of upgrading the switch assembly but I have never got around to it - maybe this discussion has given me the push required to have another look at this.

 

Simon

Link to comment
Share on other sites

  • 2 weeks later...

Just some feedback, converted my Dynatron starter for Lipo use. Nothing fancy, just replaced the crocodile clips with an XT60 connector.

Used it yesterday, using a 3S 2200 pack.

3 starts of a Laser 120 and 2 starts of a Zenoah26, and it only used 8% of the pack. I may buy a smaller pack. 

I also tried it on a 4S pack, starting a Laser 155 last week, seemed to have a lot more go on the 4S. Both batteries definitely work better than the 12V gel battery.

Richard

ps only down side is, do i leave the Lipo charged after use or do i need to keep putting it back into storage charge?

Link to comment
Share on other sites

Hello Richard,

On the point of capacity, I agree that you will typically only use a fraction of it in a day but do remember the C rating - I know that Martin measured his JE at around 40A stalled but I have just measured mine and get around 50A on 2S so on 4S it would get close to 100A! I have cut the leads right down to just a few centimetres and so there is very little external resistance so this might be affecting it a bit, but even so, bearing in mind that C ratings are often over stated by the manufacturer, I think that the battery capacity will be limited by current rating. As stated before, I have found that a 1400mAH pack works well and a 1000mAh pack should be OK but I would not go much below this - is there any point?

 

Regarding the storage charge level, I have to admit that I used to be very lazy and just keep the starter Lipos charged between sessions, but after this winter, they were pretty knackered and needed replacing so I now religiously put all my Lipos into storage at the end of each session regardless - possibly unnecessary but I think it is not a bad habit to get into.

 

Simon

Link to comment
Share on other sites

I have 3000  4s pack. For years I charged to to storage, about every month. Then I got bored and settled for longer charge periods, and fuller charges, but not to  4.2 volts/ cell. The battery is a basic 20c Hobbyking pack. At 5 years old, it’s still nicely balanced, no swelling.

Link to comment
Share on other sites

For my starter I use HK unbranded bargain basement 4s 2650. I got some 2s 5000 at the same time for about £3 in each case. The latter are used to make up 5s packs which I fly with. All are way out of balance and cannot be balanced either, but they have been in use for many years and have never been put on storage. Naturally, I am careful when charging not to let a cell go way over voltage and cause a fire. You certainly cannot abuse the more expensive ones like this. They last for ages on the starter.

Link to comment
Share on other sites

  • 6 months later...

For a couple of years I have been using an Align starter with a 3s 2200ma Overlander battery. Recently it has been unable to turn over my Laser 180 engines from cold, though once they have run it does cope thereafter. However  that leaves me hand starting to get things going and I am not a fan as the engines have a fair kick when primed up. The battery is showing fully charged and I tried yesterday transporting it separately in a bag with a warm hot water bottle. Still not enough power. 
The Align has been a bit marginal for the 180’s but it is a very convenient starter. I have noted some people go to 4s on them but means strapping the battery to the outside. So what might have deteriorated on my set up? Battery of starter motor. As I am shortly going to be using a bigger engine in my next model should I cut my losses and sell it or is it worth exploring alternative new batteries. The JE starters I know are very reasonable but it’s surprising that they still haven’t upgraded the switch that has caused issues. Any advice appreciated. 

Link to comment
Share on other sites

Same problem with a 180 from cold so I put my original JE starter on a 2650 4s. This also works great on a 50cc petrol, but in the Stampe it is more of a matter of it slipping since there is no spinner to grip. I had to strip the lousy switch a couple of times because of welded contacts and replace the cable with very heavy duty silicone wire because the stuff supplied with them kept cracking. Had a problem with the brush gear falling apart and not wishing to get stuck I purchased another one similar since it performs well, but this one welds up every time on 4s. I have looked everywhere for something suitable to replace the switches but no luck yet.

When I purchased the first one I also looked at the Align but there were quite a few bad reports.

I use about a 1m lead to the pack so that I can also plug into my main flight box.

Link to comment
Share on other sites

I use a JE one on 5S and must be lucky as the switch has only got stuck once. With that setup it has no problem turning over any of my Lasers, from 80s through to V twins and the inline twins. It also quite happily turns over my petrol DLEs too if I can't be bothered flicking them. With the rubber cone reversed it also works very well on spinner less setups (my 240v is in a Bearcat therefore no spinner).

 

I should add that the starter has also survived being run over by a reversing car when up at the field, bent up the battery frame but also made a good job of flattening the puffed 5S that was powering it!

Link to comment
Share on other sites

I've had a Sullivan Dynatron for well over 10 years.  I bought it once I had a Saito 180 to start.  I used 2 gel cells in series to give the required 24 v for starting the Saito.  The weight of the 2 gel cells was annoying so I went the LiPo route and bought 2 x 3S 4000 Mah hard case of 25 C.  I use both in series for my DLE 35, great for getting the fuel up to the carb on the first start of the day but after that just using 12 v is fine as the engine starts at the first churn.

 

I have used the starter with just 1 LiPo and that works fine for my engines from 40 to 120 FS.  Beginning to wonder if I really do need 24 v ever.

 

Oh yes, I did get the switch welded on when using the 2 gel cells, but as the engine started I didn't realise the starter was still going when I put it down!  When the engine stopped, I heard the starter motor still going.  It was pretty HOT!  Disconnected the battery to stop it.  Bought 2 replacement switches and have so far only used 1.  The spark when switching off the starter motor when using 24 v is clearly a cause of the problem.  Never experienced the switch welding closed with 12 V.

Link to comment
Share on other sites

Most of my starters have gone up the creek on 3 and 4s, they just keep arcing so I used to take them apart to clean the black contacts, but most of the time I now use one of those Chinese starters with a reduction gear, they will more or less start anything on 3s up to 30cc,

 

Don't use a rubbish 3s  20c 2200mah it won't last long, I use 60c which 'in my opinion' are around 30c,,

and if you have another 5€ to spend use one of those alarms that the drone users use on the battery balancing plug,,

Link to comment
Share on other sites

  • 4 weeks later...

Having just acquired an old Kavan starter with planetary geared reduction, I wondered if anyone has experience of using one on LiPos? 
The starter is very compact compared to most, and according to what I have read, the switch actually pushes one of the carbon brushes in contact with the armature, so its not a metal to metal switch.
The Kavan starter I bought needs a thorough overhaul before it can be used, but with new ones costing over £, this one seemed worth a punt.  Kavan even offer a large range of spare parts for them.
This is the manufacturer's picture.  Mine looks as though its been kept in a bucket of sea water!

 

Kavan Planetary Geared Starter

Link to comment
Share on other sites

I have a Sullivan Dynatron that can use either 12 v or 24 v depending on the size of engine being started.  So, I've taken to using a single 3S or 2x 3S packs in series to give either 12 v or 24 v.  

 

While you are safe using a 3S for a 12 v supply, using a 4S will push you to a max 16 v.  Check what voltage the starter will take before trying a 4S.  Although for the same power current draw will be less with a 4S you might cause problems with arcing on the start button.  

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...