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Lord Belvoir

Starter battery included

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I am connecting me solar panels....now I've only the one alternator so the starter battery is tied in with the leisure batterys...

So do I include the starter battery when connecting or do I just drop wiring on to the leisure...ie negative leisure and positive starter or positive leisure and negative leisure.....

 

 

 

 

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Personally, just connect to leisure batteries. Presumably you have some isolation (relay, diode or donkey switch) between the two circuits. If the panels work whilst you are moored, then if the starter goes flat, you can jump from them.

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How is the starter battery tied in with the leisures? Does it have a voltage sensing relay? If you use a dual sensing relay, the solar will charge the starter battery when the leisures reach a certain voltage and the alternator will charge the leisures when the engine is running. 

 

I think that's right anyway. Someone might be along shortly to correct me. 

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10 hours ago, stegra said:

How is the starter battery tied in with the leisures? Does it have a voltage sensing relay? If you use a dual sensing relay, the solar will charge the starter battery when the leisures reach a certain voltage and the alternator will charge the leisures when the engine is running. 

 

I think that's right anyway. Someone might be along shortly to correct me. 

That's the way you would have to do it if the main charge lead has been connected in the "lazy" way to the start battery but to minimise the chances of overloading the relay contact it should be connected to the domestic bank unless for seem odd reason the start battery is always the most deeply discharged.

 

In my view solar should be connected to the battery bank that is the most deeply discharged the most often (as should the main charge lead).

 

With an ordinary split charge relay solar can not charge the engine battery. With a single sensing VSR as long as the solar and alternator (and charger) are on the same bank either will charge both banks once the connected bank has reached around 13.6 to 13.8 volts. A dual sense VSR is not needed apart from when the alternator is connected to the engine battery, then a dual VSR will allow solar to be connected to the domestic bank and charge both banks. However I would strongly advocate swapping the main charge lead to the domestic bank as well.

 

Note:- Simply swapping the main charge lead would involve a bit more swapping if an alternator controller or battery sensed alternator is in use.

 

.

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My solar is connected to my domestic bank.

Should (for any reason) the starter battery need 'topping up' I'd simply put a jump lead across from the domestics and give it a 'days sunshine'.

 

Unless the battery is dying and self discharging there cannot be many circumstances where a starter battery needs 'topping up'. The current used to start the engine may be high but it is only for 'seconds' so the actual Ah used is very low and is replaced within a few minutes by running the engine.

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10 minutes ago, Alan de Enfield said:

My solar is connected to my domestic bank.

Should (for any reason) the starter battery need 'topping up' I'd simply put a jump lead across from the domestics and give it a 'days sunshine'.

 

Unless the battery is dying and self discharging there cannot be many circumstances where a starter battery needs 'topping up'. The current used to start the engine may be high but it is only for 'seconds' so the actual Ah used is very low and is replaced within a few minutes by running the engine.

This.

 

My philosophy is also to keep the systems separate with similar reasoning. Plus, a quick search on here will find any number of threads about charging issues which come down to faults on clever links between the battery banks. Keep it simple.

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1 minute ago, Sea Dog said:

This.

 

My philosophy is also to keep the systems separate with similar reasoning. Plus, a quick search on here will find any number of threads about charging issues which come down to faults on clever links between the battery banks. Keep it simple.

That's fine as long as you have two alternators but if you do not you are forced to do split charging by some means. A properly installed split charge diode system is as reliable as the basic charging system a long as you use an adequately rated and quality relay. Once the infant mortality period for the electronics is over I can't see a VSR being any less reliable but we have not had enough time with them to be sure yet. I agree there are always problems with ordinary split charge diodes unless battery sensing is used.

 

By far the two greatest "fault modes" with battery charging are user error, often through lack of knowledge, and inadequate installation (usually undersized cables and poor connections). It is to minimise the former that persuades me a relay of some sort beats manual switches hands down.

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3 minutes ago, Tony Brooks said:

That's fine as long as you have two alternators

Yes, you make a good point of course, and then a properly installed, reliable VSR comes into it's own. Sometimes we take our little luxuries for granted!  

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50 minutes ago, Tony Brooks said:

That's fine as long as you have two alternators but if you do not you are forced to do split charging by some means. A properly installed split charge diode system is as reliable as the basic charging system a long as you use an adequately rated and quality relay. Once the infant mortality period for the electronics is over I can't see a VSR being any less reliable but we have not had enough time with them to be sure yet. I agree there are always problems with ordinary split charge diodes unless battery sensing is used.

 

By far the two greatest "fault modes" with battery charging are user error, often through lack of knowledge, and inadequate installation (usually undersized cables and poor connections). It is to minimise the former that persuades me a relay of some sort beats manual switches hands down.

Would you suggest also using a VSR for Solar ?

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3 minutes ago, Alan de Enfield said:

Would you suggest also using a VSR for Solar ?

If you do that on a twin alternator boat you will also parallel the alternators when the direct connected battery reaches 13.6 to 13.8 Volts. Personally I think this may produce a small charging advantage at the expense of the potential for one alternator to shut down but then solar can cause an alternator to shut down with well  charged batteries. More likely the alternator will keep going on and off load causing the warning like to be on dimly or flickering and the buzzer to "chirp".

 

As Ex Brummie explained the start battery is almost always all but fully charged so if you have a twin alternator boat I can't see the point of using a VSR to solar charge the engine battery UNLESS you intend to leave the boat laid up for several months. In that case a VSR will help combat self discharge of the engine battery.

 

I suppose basically on a single alternator boat the answer is yes. The main job of a VSR in that case woudl be to split the alternator charge and splitting the solar charge only a very much secondary benefit - all supposing the system is optimally wired. On a twin alternator boat I think much depends upon whether your usage and layup practices make the cost and trouble of fitting one seem attractive. As someone said a jump lead between bank positives should do the same thing ----- until a cell shorts, but you will normally have some idea its imminent by the charge and discharge times/readings.

 

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6 minutes ago, Tony Brooks said:

As someone said a jump lead between bank positives should do the same thing

That twas me.

 

It all sounds a bit complicated for little if any gain - I'll stick with my occasional jump-lead.

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16 minutes ago, robtheplod said:

With this in mind... do others tend to keep jump leads on ya' boat?

Yes, but if you do make sure they are 'decent' :

Length (you may need to hook-up to another boat)

Thickness (conductors)

Copper conductors (not Aluminium)

 

Don't buy 'cheap' Halfords ones, they will melt and/or the croc-clips will fall off.

 

The 'main one', is one I have made up is a specific 'Domestic to starter battery' jump lead using welding cable and two heavy duty clips, it is just the right length and 'rolls up' and sits in the battery box.

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Having occasionally had to do the "hold a big spanner across the battery terminals" trick, whilst avoiding the whirly bits at the front, I decided I might do it, but I don't want my wife trying it.  OK yes it would be easier to use a jump lead, but I have got one on the boat.

 

So I have wired a HD isolator switch between the leisure battery and the starter battery.  This is, of course, normally left off, but can be turned on if the starter battery is being reluctant to start the engine.  It has the added benefit that, when the boat is unoccupied, it could be left on to allow the solar to charge the starter battery.  OK, this does mean that if something was left on, or bilge pump stuck on it could drain everything, but it hasn't happened yet.

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1 minute ago, dor said:

So I have wired a HD isolator switch between the leisure battery and the starter battery. 

That is similar (in principle) to a system that was on one of the sea-going cruisers I used to have.

Twin engine and twin 'starter batteries'.

 

There was a 'button' at the helm which in the event of one battery being a 'bit low' was simply pressed (whilst turning the key) and it linked the batteries together. Always thought it was a good idea.

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I've a single alternator through a splinter....ive always had twin alternators this is why I've come unstuck.....reading some of your replys I'm thinking to myself that some of you would be better off working on the space station as scientists lol

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13 minutes ago, Lord Belvoir said:

I've a single alternator through a splinter....ive always had twin alternators this is why I've come unstuck.....reading some of your replys I'm thinking to myself that some of you would be better off working on the space station as scientists lol

To give a simple answer requires us to know what type of "splitter" you have and exactly how the whole charging system is wired.

The fact we do not have this information means you will get alternatives in your answer.

 

However the simple answer is connect it to the domestic bank. From then on it may or may not also charge the engine battery epending upon the charging wiring and the splitter

 

 

 

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Right here we go.....its got a splitter relay(Durite 0-727-18-180amp) two feeds from one alternator......one straight to the starter battery and one into the Durite relay and from there that goes to the first of me leisure batterys

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Not sure if I should post this but you have a split charge relay not a voltage sensitive relay so connecting the solar to the domestic battery will not charge the engine battery but that is normally fine. Absolutely nothing wrong with that apart from noting is keeping your engine battery topped up when the boat is not in use.

 

If its worked OK for a number of years then ignore the next bit.

 

Wiring the alternator to the start battery give a risk that with very flat domestic batteries the relay contacts will be overloaded because of full alternator output PLUS extra charge from a fully charged engine battery passing through the relay. The contacts will also cause voltdrop between the  two batteries so domestic battery charging times will be extended top a certain extent. However if it works for you don't try to fix it. The reason its been done that way is the relay suppliers do not properly understand marine electrics and its far easier for the installer to do it that way, it saves running a heavy cable from the alternator to the domestic battery bank.

 

 

 

 

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5 hours ago, ditchcrawler said:

Strange Itis just came up on Facebook

Capture.JPG

"Only 4 wires needed" it says, then shows a device with three connections!

Should there not also be a fuse in the engine battery connection?

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I don't know what current a VSR takes but in winter solar can be well under an amp for a lot of the day, the voltage is there but with almost no power, if the VSR takes 5 or 6 watts, then the battery actually gets virtually no charge. I have a 20 Watt panel feeding the starter and the bigger panels feed the leisure batteries.

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9 hours ago, Detling said:

I don't know what current a VSR takes but in winter solar can be well under an amp for a lot of the day, the voltage is there but with almost no power, if the VSR takes 5 or 6 watts, then the battery actually gets virtually no charge. I have a 20 Watt panel feeding the starter and the bigger panels feed the leisure batteries.

As the boat has gone I can't measure the current but as its relay coil will be isolated by a zener diode below operating voltage I can't see it being more than a few mA. If it does close under solar charge alone then as soon as the coil current pulls the battery voltage to below 13.6 to 13.8 it will open and the coil will be isolated again. In practice it seems not to be a problem. For all I know there may not be a relay coil, they may be solid state but as there is no obvious heat sink I rather doubt that.

 

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