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Author Topic: In Boat Charging  (Read 3978 times)

asimmd

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In Boat Charging
« on: September 04, 2010, 10:23:55 AM »

Hi Guys

I am building the Modelslipway Loyal Class Tender,and it's time to install the batteries.

2 X 12volt 7Ah sealed Lead Acids to be mounted in a "T" shape.

The batteries will be mounted on a thin ply base which will sit on 1/4 x 1/2 x 1" blocks,so they don't
sit on the bottom of the hull.

Now the question is,when the decks are fitted,there will not be a lot of room for taking the batteries
in and out,so I need to know how to wire them.

I want to wire them so still have 12volts,but add the Ah together to make 14Ah.

I would also need some sort of take off so I could have a charging socket concealed on the deck so
the batteries can be charged without taling them out of the boat.

Any help/advice would be appreciated.I haven't done anything like this for 25 years,and I don't
want to mess up now.

Many thanks

Alan
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Bunkerbarge

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Re: In Boat Charging
« Reply #1 on: September 04, 2010, 10:32:49 AM »

Alan, wire them in parallel to maintain the same voltage, i.e. the positive lead from one is connected to the positive lead of the other and the negative leads are connected together as well.  The resultant battery should be 14 Ah, 12 V.

As for in boat charging there are those who would advocate removing the battery however I have a lot of models using the same battery and I charge them all in the boat.  One method is to connect a small 5 mm diameter socket, such as used in stereo Hi-Fi systems, and fit the plug to the other end of your charger.  Simply plugging the plug into the socket will allow you to charge the battery.  You can hide the socket behind a deck fitting somewhere.

A couple of my boats allow access to the tabs on the battery so I attach female fittings to them to charge the battery.  Another method i use on a couple of boats is to have a Tamiya type connector available somewhere and use the other part of the Tamiya fitting on your charging lead.
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asimmd

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Re: In Boat Charging
« Reply #2 on: September 04, 2010, 11:12:02 AM »

Hi Bunkerbarge

Many thanks for the reply,I had also heard that charging the batteries on board was not recommended,although
I don't know why,after all they are sealed Lead acid batteries,and as such don't need ventilating?

Thanks for the wiring explanation,I never know which is which.

Regarding a charging socket,could I use a Miniature Jack plug and Socket?

Alan
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FullLeatherJacket

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Re: In Boat Charging
« Reply #3 on: September 04, 2010, 11:27:06 AM »

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Circlip

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Re: In Boat Charging
« Reply #4 on: September 04, 2010, 11:32:48 AM »

You would be better using this type rather than a jack type unless you get a break before make type.

  http://www.maplin.co.uk/Module.aspx?ModuleNo=1416

 And the corresponding plug/s

  Regards  Ian.
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asimmd

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Re: In Boat Charging
« Reply #5 on: September 04, 2010, 11:41:16 AM »

Thanks for the replies everyone.

Just a thought,the battery leads terminate in a Tamiya plug.

If I wire them as Bunkerbarge suggests,can I just connect a Tamiya Female connector
to my charger leads,and just plug in to charge both batteries at the same time?

If that will work,what would the charge time be?

Alan
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derekwarner

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Re: In Boat Charging
« Reply #6 on: September 04, 2010, 11:53:19 AM »

Alan.....charge time will be dependent on the internal resistance of the battery and the state of existing charge/potential within the battery........& to a lessor degree....also the type of charger you use...as the newer electronically monitored units have a reduced current input relative to the increasing voltage potential......... O0 ....Derek
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oldiron

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Re: In Boat Charging
« Reply #7 on: September 04, 2010, 12:20:28 PM »

  For a little twist on charging access to a vessel bound battery, I connected my battery leads to a couple of forward deck mounted bollards. The bollards are brass and a wire from each is soldered to the appropriate battery wire. I use alligator clips on my charger to clip onto the bollards. Works great.

John
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Circlip

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Re: In Boat Charging
« Reply #8 on: September 04, 2010, 12:24:25 PM »

Chargers sold soley for SLA's are constant current types.

  Regards  Ian.
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asimmd

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Re: In Boat Charging
« Reply #9 on: September 04, 2010, 12:32:58 PM »

Charger is a "Tronic" 2 - 6 - 12 charger.

Stops charging when battery is OK.

I do like the Brass Bollards idea on the foredeck,I shall
keep that in mind.

Alan
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FullLeatherJacket

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Re: In Boat Charging
« Reply #10 on: September 04, 2010, 12:55:19 PM »

Chargers sold soley for SLA's are constant current types.

I think you may find that's constant voltage. Constant current types are used for NiCAD and NiMH packs.
FLJ
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malcolmfrary

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Re: In Boat Charging
« Reply #11 on: September 04, 2010, 01:47:49 PM »

"Sealed" in SLA means that they are sealed against the owner topping them up.  They will normally only vent when overcharged, but having vented, they will contain less electrolyte, and their life will be reduced.  What they vent is a mixture of hydrogen and oxygen, which is perfectly capable of recombining in an enclosed space, like a hull, given suitable provocation, like a spark.  If recharging in the boat, its a good idea to have the lid off, give any hydrogen somewhere to go.  Belt and braces thinking, you shouldn't ever need to guard against overcharging and venting, but it saves a lot of potential hassle if you do.
A proper SLA charger with constant voltage and current limiting, and, even better, a means of sensing when it has done enough, will pay its way in not having to buy new batteries.
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Netleyned

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Re: In Boat Charging
« Reply #12 on: September 04, 2010, 05:26:20 PM »

Just an idea......
http://www.action-electronics.co.uk/pdfs/Two%20Charging%20Jacks%20and%20P103.pdf
Suit yourselves.
FLJ
This is the way with two in parallel It stops the arguing between the two batteries
which can give overheating problems if the batteries are unbalanced
They wont try charging each other!



Ned
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Circlip

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Re: In Boat Charging
« Reply #13 on: September 04, 2010, 06:57:31 PM »

I think you may find that's constant voltage. Constant current types are used for NiCAD and NiMH packs.
FLJ

     http://www.batterychargerreviews.co.uk/yuasa/yuasa-ycp06a12-12v-600mah-sla-battery-charger/

 
Quote
Yuasa YCP06A12 SLA Battery Charger offers fast constant current bulk charge


  Seems Yuasa have it wrong too  {:-{

  Regards   Ian
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FullLeatherJacket

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Re: In Boat Charging
« Reply #14 on: September 04, 2010, 08:13:26 PM »

Suit yourself. They're your batteries..................
FLJ
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malcolmfrary

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Re: In Boat Charging
« Reply #15 on: September 05, 2010, 10:06:49 AM »

"Constant current" usually means "controlled limited current under a wide range of circumstances", but this is harder to write down.  To charge an SLA (and probably anything else) without putting its bits into orbit, the end voltage that it can get to needs to be limited.  So does the current at which it charges.  An old school dumb charger will offer current at the maximum that it can at the start of the charge, and this current will reduce as the battery charges and its voltage comes up.  A current limited charger (ie the fabled constant current) will charge at its limited current for the period of the charge, then stop, or reduce to a trickle.  Whether it relies on a timer or a clever sensor to decide on this point is a matter for the manufacturer.
A pair of matched batteries, connected in parallel, can safely be regarded as one larger battery, since they will stay matched.  The exception is when a cell in one of the banks gets old and tired and decrepit.  It will lose performance, and will drag its mate down, either by trying to take charge from the good one, or transferring load to it, depending on the mode of failure.
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asimmd

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Re: In Boat Charging
« Reply #16 on: September 05, 2010, 03:57:04 PM »

Hi All

Thanks for all the replies,I am interested in the Action Electronics Parallel Power Board,it would
make sense to fit this on such high power batteries.

The Board has + & - leads coming from it,do these go to my ESC?

Also mentioned is a Power Distribution Board,do I need that as well?

I can't get in touch with Action as they are closed for holidays.

Thanks

Alan
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barriew

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Re: In Boat Charging
« Reply #17 on: September 05, 2010, 05:10:54 PM »

Alan,

The leads from the Parallel Power Board can go the the ESC,  although it would be preferable to include a fuse and a switch. They can also go into the Power Distribution Board,when you will also get a BEC (Battery Elimination Circuit) which will power your receiver and save you having a separate 4.8v receiver battery, as well as fuses. You will still need a switch in the circuit somewhere ok2

If you use the Parallel Board I am not quite sure where you would connect a charging lead, as its purpose is to stop current flowing between the two batteries. Perhaps the best would be to connect a separate lead to each battery.

Barrie
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Umi_Ryuzuki

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Re: In Boat Charging
« Reply #18 on: September 05, 2010, 08:25:31 PM »

"Sealed" in SLA means that they are sealed against the owner topping them up.  They will normally only vent when overcharged, but having vented, they will contain less electrolyte, and their life will be reduced.  What they vent is a mixture of hydrogen and oxygen, which is perfectly capable of recombining in an enclosed space, like a hull, given suitable provocation, like a spark.  If recharging in the boat, its a good idea to have the lid off, give any hydrogen somewhere to go.  Belt and braces thinking, you shouldn't ever need to guard against overcharging and venting, but it saves a lot of potential hassle if you do.
A proper SLA charger with constant voltage and current limiting, and, even better, a means of sensing when it has done enough, will pay its way in not having to buy new batteries.

Yes, Gel Cell and sealed lead acid batteries will vent Hydrogen and oxygen.
Several years ago, we had a submariner "blow up" his submarine twice.

He put his SLA battery into his water tight compartment and sealed the whole lot.
He provided terminals for charging the battery, but did not provide a vent.

When he went to the pond, he launched the submarine and sailed away from the curb.
Upon actuating the ballast controls, the motor brushes arc'd, and the entire boat "blew up".
It cracked his perspex WTC, blew out several seals.

No one knew what had happened, so he went home and repaired everything.
Weeks later when he returned to the pond, the exact same thing happened.
It was then, that he deduced that charging the battery had filled the WTC with
volitile gases, and the the arcs from the ballast motor set them off.
He now has a small hole in the top of his water tight chamber, and he applies the
hose from his vacuum sweeper to it  before sealing up the boat.

Charging in the boat will probably be fine, be sure the batteries do not need to be in an
upright position when charging.  As long as the boat is well ventilated during and after
charging the batteries, you shouldn't experience any engine room explosions.

 ;)
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asimmd

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Re: In Boat Charging
« Reply #19 on: September 06, 2010, 02:54:57 PM »

OK,it's a call to Action Electronics next week to see what I can sort out.

I looked on their website,didn't know they did so much.

My ESC has a BEC already,so I won't need that,maybe I can just get away
with a P103,leaves some room for a sound module then.

Alan
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Re: In Boat Charging
« Reply #20 on: September 07, 2010, 10:40:41 AM »

Hmmm, constant current vs constant voltage for charging SLA - though Yuasa prefer the term VRLA (Valve Regulated Lead Acid)

Reading the datasheet and finding what the manufacturer recommends....

For cyclic charge Bulk charge is nominally constant current until the battery reaches 100% then a constant voltage top-off until trickle charge is started at a lower voltage. For float charging it is constant current until 80% of capacity then constant coltage. However looking at the curves in the data sheet the specification is actually calling for a constant voltage charge with a current limited output that folds back the output voltage. So current limited constant voltage rather than true constant current. Charge current must not exceed 0.25C (25% of AH capacity)

Wom
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