Battery regulator advice needed

[GeorgeC]

Hello everyone, I wonder if you can assist me:

I have a 'classic' Glastron T156 cathedral hull with a 1980 Johnson 70 Seahorse outboard (Model No: J70ELCSA).

My problem is that I have recently discovered that this outboard does not appear to have a battery regulator. Unfortunately for me this was a week after paying out for an expensive absorbed glass matt (AGM) sealed battery rated at 85AH.

Reading my owners manual Johnson recommends that no maintentance and or sealed batteries are not used with none regulated alternators!! Marvellous....

Can anyone advise me on my options.
i.e.
Is this really a problem?
Does anyone know a source of suitable aftermarket regulator's?
Will this cause the world to end?
Does anyone want to buy an unused Squadron AGM 85AH battery!

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[andyball]

Depending on how the alternator is wired up (eg is there a separate rectifier? & how many wires come from the alternator etc) you might be able to borrow one from a motorcycle & wire it in to work.(you have a wiring diagram in the manual?)

But....many bike ones will regulate to maybe 14.5V which is a bit high for agm batt's.

If there's really no regulation at all....the alternator may be fairly low power & not overcharge too much(under 15V, but no good at all for an agm)...or it might overcharge much more (blowing bulbs etc).

Sometimes people keep a close eye on the voltmeter & switch on lights etc if the voltage exceeds 14V....human powered regulation. Not ldeal, but otoh not as bad as it sounds on a smallish boat.

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[philip_stevens]

Phone Robin Curnow Outboard Motors (as mentioned in the June PBO), and ask to speak to David. He is a fountain of knowledge and advice on outboards.

01326 373438 - Penryn, Falmouth

<A target="_blank" HREF=http://www.webmachine.co.uk/robincurnow/>http://www.webmachine.co.uk/robincurnow/</A>

Tell him I recommended him - and listen to him insult me!! ;-)

But he may well have an answer.

<hr width=100% size=1>regards,
Philip

 

[GeorgeC]

Thank you both for your advice.

Robin Curnow are my local Johnson service centre. I will contact David and see what he thinks... about you... and my problem!!



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[tgalea]

Drop me a line if you still have problems. Should be able to help you.

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[snowleopard]

it just so happens...

that i have a regulator/rectifier which i bought to fit to an outboard that only had a lighting coil.

it's been sitting unused in my shed for 10 years waiting for a use. it's designed for a mariner 55 but would suit any engine with ac output.

pm me if you're interested

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[LeonF]

Did the dealer who sold you the battery advise you as to the compatibility of the AGM with your system? You may have cause for redress if he did and the battery is unsuitable. AGMs have quite specific charging needs--see previous postings. They are being touted as the new wonder batteries and though they are good products all the feed back I have had while trying to unravel my problem is that they need very careful handling re charging etc.

<hr width=100% size=1>L.A.R.Ferguson

 

[LeonF]

If the battery is unsuitable for your charger and was recommended by the dealer then make him take it back and refund your money. AGMs may be good products but they need specific charging and have some quirky characteristics. See previous postings. I have had a great deal of contrary opinion while trying to unravel my problem and this from some of the 'experts' who are writing from the mags we all buy.

<hr width=100% size=1>L.A.R.Ferguson

 

[GeorgeC]

Dear all,

WOW! Thank you all for your input and advice. Let me bring you up to date with my saga:

I spoke with Squadron Batteries this morning. They were very helpful and explained there is no danger of explosion; which was my main concern. They are of the opinion that as long as the alternator doesn't charge at greater than 15 volts no damage will occur. I can feel a 'warm and fuzzy feeling', returning!

I then spoke with Johnson who were very good. Their technical support engineer dug out the original performance sheet / service manual for the engine and confirmed that there is no regulator fitted, but as the engine / alternator only charges at between 5 and 6 amps there is very little chance of damage. Although he did add that as there is no 'electrical spike' protection sensitive electronic instruments may be damaged if this phonomenon occurs.

It now appears that the engine may not be suitably powerful to charge the battery on the go. But if that is the reality I will be very pleased to take the battery home with me whilst the boat is moored on the marina to be charged each night.

My only observation is that Squadron Batteries were quoting 'volts' and Johnson quoted 'amps'! I really regret not being more conscientious when studying physics at school....!

Would anyone care to make any comment or estimate what voltage a 5 amp alternator would be? In fact does the question make sense? Again any advice would be appreciated.

George

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[GeorgeC]

I forgot to mention in my last entry the following observation made by the Johnson technical engineer:

1/ When this engine was new Johnson never identifed a problem with
overcharging.

2/ They did advise owners to fit a battery rated at 80AH's or more to create excess capacity in the system i.e. absorb the excess charge.

I hope that with regard to 'physics' point 2 is accurate, as my battery is rated at 85AH's and would therefore have even more excess capacity. Can anyone confirm this as correct?

If it assists the only accessory that draws on the battery is an Attwood bilge pump 'rated' at about 1.4 amps.

Cheers
George

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[andyball]

If you run for any length of time, even with your small alternator, you'll exceed 15V. I used to ,with twice the battery capacity & an 80W coil.

You need to check with a voltmeter .

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[boatone]

The alternator will be nominally 12volts and nominally give 5amp/hours charge to the battery over 1 hour.
Best way to resolve all this is to get a digital voltmeter and measure the voltage at the battery terminals when the engine is running and the battery is fully charged. This will be the maximum volts as the reading will be lower if the battery is less than fully charged. You could also measure the voltage between alternator positive and battery positive which will tell you the voltage drop in the connecting cable. If its more than .1 or .2 volt a beefier cable would help improve charging.

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[Alex_Blackwood]

Think of your Alternator as a WATER PUMP, your Battery as a TANK.
You want to fill the TANK from the PUMP. To do this you need PRESSURE (VOLTS)
you also want the water to FLOW (CURRENT=AMPS). Some PUMPS are fitted with a PRESSURE REGULATING VALVE (VOLTAGE REGULATOR). Your one isn't.
The maximum pressure your PUMP can produce is 15 the maximum rate of flow is 5. OK so far?
Now! You can only fill the tank from a pipe that enters at the bottom. When the tank is empty (DISCHARGED) you will get maximum flow and pressure into it.
As the tank begins to fill (CHARGE) the pressure will remain nearly constant (System losses will reduce it slightly (VOLT DROP)).
The increase in level (CHARGE) in the tank will cause a resistance to the FLOW (OHMS) this will cause the flow to reduce until the pressure in the tank (CHARGE) is equal to the pressure from the PUMP (ALTERNATOR). At this point the FLOW will stop (FULLY CHARGED).
I am not familiar with the AGM battery but a normal fully charged battery would be 14.2volts. Allowing for system losses, internal resistance of your battery etc I wouldn't think that an alternator with a max. O/P of 15volts would do it any harm. Without a regulator that max. votage will tend to drop as the charge increases so you may in fact never reach the fully charged state. (Use a meter to check the ALT. voltage O/P with a fully charged battery). With a 5 amp output from your Alt. it would take approx. 20 Hrs. To recharge an 85ah. battery from flat. (8.5amps at the 10hour rate).
I hope the above is some help.
Happy charging.



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[andyball]

I have regularly exceeded 15V using an 80W charging coil & 150Amp-hours battery bank.

If you start from "flat" it may never happen, but fit new fully charged batteries & it can be alarmingly soon.

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