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Author Topic: battery charger advice  (Read 2297 times)

jim w

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battery charger advice
« on: August 21, 2011, 10:57:25 PM »

I bought a lovely model today , probably built 30 years ago or so of a german fast patrol boat approx 30" long. It has a single motor powered by 2 blocks of 6 'c' size cells wired in series. In its current state of charge giving just over 15 volts. There are 2 basic single plug points to charge the batteries. The boat has no charger with it so my question is what output voltage and current would be needed to attach to this rig? I'd be grateful of any experience in the is set up. I hope to modernise the motor and fit a lead acid battery at at some point but it sails so well as it is I am loath to take it off the water.. Many thanks
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MikeA

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Re: battery charger advice
« Reply #1 on: August 21, 2011, 11:33:54 PM »

do you have a pic of them?
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jim w

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Re: battery charger advice
« Reply #2 on: August 21, 2011, 11:47:23 PM »






charger to attach to the single black and red female plugs near the middle. Thanks again
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nick_75au

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Re: battery charger advice
« Reply #3 on: August 22, 2011, 06:45:14 AM »

That is a lovely looking boat.

Keep the Ni -Cd's they are better than a Pb for this kind of boat, there is an indication on the batteries themselves indicating a charge rate( I cant quite make out the numbers but its something like 50 mAH for 16 Hours). The packs are wired in series so a charger capable of charging 12 cells Ni-XX  would be required if you wanted to use the banana plugs.

 Nominal charge voltage would be up to 20 volts al a low mAH. I would recommend purchasing a computerised charger like these
http://www.giantcod.co.uk/lipo-charger-c-27.html

They are all capable of charging these batteries except the top left (10 cell Ni-XX max) and the mini charger on the bottom left

 I would be concerned about the small gauge wiring and more importantly the fact that the wires are taped to the battery over the terminals, with PVC insulation there is a strong possibility of the insulation melting and shorting the battery. Use 12 gauge silicone wire (also available from Giant Cod) If it were me I would put deans connectors on the batteries and make a series harness to connect to the boat electrics. I would also put an ESC in but i am drifting away from the original question here.

Cheers
Nick

Nick

The motor looks (not an expert) like a plettenburg or similar, a high quality motor
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essex2visuvesi

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Re: battery charger advice
« Reply #4 on: August 22, 2011, 09:23:39 AM »

Charger wise the Imax B6 should do the job will handle up to 15 cell packs

I would seriously consider overhauling the wiring in there like others have said it looks a little lightweight.

Also I would personally look into upgrading the C cells to a pair or 7.4V Lipos or maybe a single 14.8V lipo. Either that or a pair of tamiya style racing packs
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jim w

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Re: battery charger advice
« Reply #5 on: August 22, 2011, 10:42:01 PM »

Many thanks for your help guys. I have ordered a charger and taken your comments and advice on board re wiring etc. I am hoping to get a few weeks sailing out of her while the sun is still shining and my eager sons are still on the school hols. The 'period' motor and wiring caused so comments and amusement at my local boating lake this evening but her smooth and near silent sailing couldnt fail to impress. I certainly fancy an electronic ESC as the first step. The motor looks truly ancient but runs beautifully and very cool. Now I need to do a little research into what type of craft she is.
Thanks again, jim
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jim w

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Re: battery charger advice
« Reply #6 on: September 02, 2011, 11:29:06 PM »

Have followed your suggestions re beefing up the wire with soft silicon cable and introduced Deans plugs which makes it all easier and neater. An now looking to going for a speed controller. As the batteries are in series and producing 15-16 volts does that mean the Viper ESC's are not suitable as they have a max recommendation of 12V?
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Shipmate60

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Re: battery charger advice
« Reply #7 on: September 03, 2011, 01:00:22 AM »

The motor looks very like a Ford Cortina Blower Motor.
Should run about 5000 rpm but have huge torque.

Bob
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jim w

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Re: battery charger advice
« Reply #8 on: September 03, 2011, 08:03:33 AM »




Thats really interesting Bob, that has caused a lot of headscratching in Sheringham. Its almost silent when its on the water, but a little slow! I can now charge the NiCads in seperate banks and hope I can get a bit more out of them now I have reworked some of the wiring. I think I may have a problem with the voltage if I want to convert to a modern reversing ESC though
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john s 2

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Re: battery charger advice
« Reply #9 on: September 03, 2011, 07:43:11 PM »

Hi jim.Do you use the boat lake up on the cliffs.Is it still there and usable? I have a homemade tape of the carnival showing a lot of boats on this lake,including one that i brought.Also envy you having a steam railway so near to you. Also a model shop which sometimes has preowned boats for sale.John.
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jim w

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Re: battery charger advice
« Reply #10 on: September 03, 2011, 08:01:19 PM »

Hi John, yes its still there and very well used. I started going up there with my boys sailing their little skipper yachts, and this current bout of enthusiasm started with this years carnival paper boat race! I bought this current motor gun boat at our local car boot and we have several other 'projects' on the go. Also had a few trips to the excellent Eaton Park in Norwich in recent weeks .....dont know if you have ever been there, but have a look on Google if you havn't, makes Sheringham look tiny!
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malcolmfrary

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Re: battery charger advice
« Reply #11 on: September 04, 2011, 09:09:32 AM »

Does it reverse at the moment?  Is it a permanent magnet motor or a field wound type?
Mtronics are good for a 12 volt SLA fully charged, which is more than 12 volts, but to connect one up to a battery that runs above the max expected SLA voltage might be pushing the luck a bit.  There are other manufacturers who do ESCs that are intended for higher voltages, Action and Electronise and Valley spring to mind.  One has a great reputation for service after the sale, others less so.
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jim w

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Re: battery charger advice
« Reply #12 on: September 04, 2011, 07:58:42 PM »

Thanks Malcolm,

It does reverse at the moment but through a very 'period' system of relays and micro switches. Having just tidied up some of the wiring I now realise that there are two speeds forward ( the first micro switch being limited through a resistor I think). Somehow I dont think I have achieved either full voltage in the batteries (due to wiring) or full throttle on the second micro switch ( due to a problem with the servo hitting a battery box).
I was hoping for a test run today but the weather has consired against me! I dont have a clue about the Motor but Bob's guess looks like a good one to me and would fit the period of construction. If all works well now I may leave well alone and keep it all original, but I will Google your suggestions about the other ESCs.

My original feeling was to start again and go for a SLA and a modern motor but I was interested in Nick's comments below about NiCads being better than SLAs. I wonder what the advantage is of one over the other?
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nick_75au

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Re: battery charger advice
« Reply #13 on: September 04, 2011, 08:16:49 PM »

Hi Jim,
As the boat is a planing hull SLA has 2 disadvantages over the Ni-cd's, weight and discharge characteristics, SLA are designed for relatively low current draw,  if you are happy to potter around the pond then SLA are fine, they are better suited to displacement boats where the weight is needed for ballast.
Planing hulls benefit from light weight and relatively high current draw to get them up to speed, Ni-xx are capable of higher discharge and have higher capacity by weight.
Cheers
Nick
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grasshopper

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Re: battery charger advice
« Reply #14 on: September 04, 2011, 08:34:49 PM »

Got to agree with the 'blower motor' suggestion, looks like one to me too. The NiCd cells at the top of the picture look like RS components and the number 529- seems familiar - there's a fair chance that they're on their way out and not delivering the current  anymore.....

If it was my boat and my budget would allow, improve ALL the power wiring and stick a couple of 2s li-po's in series and wire to the speed controller, 14.8 volts, lighter and better performance all the way.

With the comment about the speed control being switched and relayed - are you sure the builder has not used a series/parallel switching system that would give off, half voltage in parallel then full speed (and full voltage) in series.
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Shipmate60

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Re: battery charger advice
« Reply #15 on: September 04, 2011, 09:04:36 PM »

Jim,
What size prop is on her?
Those motors will deliver a lot of torque so can cope easily with a large prop.

Bob
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jim w

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Re: battery charger advice
« Reply #16 on: September 04, 2011, 10:03:39 PM »

@ Bob. It is a 50mm two bladed prop, quite a deep ...almost 'screw' pitch.

@ Grasshopper. Definately permanent serial wiring. I dug out a slightly faded circuit diagram whilst re-wiring and looks at fist glance to show a resistor at the first stage of the two forward switches.

Given the size of our boating lake I think she will perform enough to satisfy my needs, if my rewiring works!

I have absolutely no knowledge of using relays so its been a good learning exercise for me! I will try and re-draw the circuit diagram and make some sense of it. I'll see how she goes tomorrow weather permitting.

Thanks all for your comments and advice
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