Using Electrics while battrey is not charging . . .

[Gazzetta]

Finally I decided which VHF I'm gonna buy, it's the Icom 550 from Caruana Marine. 

Now the reason of this thread is to ask what do you do when you have the auxilary motor on when trolling , which is not connected to the battrey, and would like to keep the VHF GPS and FISHFINDER switched on aswell !!

I know that a lot use a secondary battrey and a change over switch. Do you think it's the best solution ?
Also I know that one can use a type of alternator on the auxilary in order to charge the battrey with it aswell. Does anyone uses this equipment ?

What do you think is the best solution ?
Any other ideas ?

Thanks

Chris 

[benri]

Hi Chris. In my opinion I would choose a secondary battery as that would also be a back up to your main battery should it fail. Many batteries can fail without prior notice so it is always a good idea to have an extra one on board. I don't think that the VHF, GPS and Fishfinder use enough power to drain a charged battery with normal usage and therefore if you have an extra battery you won't need to charge from the auxiliary.

[skip]

As discussed Chris, I run two 110amp batteries. When I am running they are switched to 1+2 so that both are charging. When I start trolling I switch battery 1 so that if I end up draining that, I can just switch to battery 2 to start and then back to both so they re-charge.

For the price of the alternator on the aux I would rather have another battery and the changeover switch.

[Gazzetta]

It seem's that's the best option.
Thanks a lot for your help guys. 

Chris 

[fishfinder]

Skip,

please note that the maximum charging voltage for Outboards is 120Amps and if you switch them both 110+110 you will be charging them only up to 60amp each + you'll be loading the rectifier. ( this is what Zarb Stores told me).

I have 2 optima 75A each deep Cycle Gel + 2 Delphi 80A deep cycle (currently replaced one with 45A cause one of the Delphi Died early this summer) and I charge them one by one and when i stop for deep sea fishing I use the OPtima x2.

[Gazzetta]

So the best would be 2 65Amp I think !!

Chris 

[skip]

All I can say is that the 90 TLDI requires a minimum of 110amps for both cranking and running or they give problems. This is noted in their manual and the internet.

It's important to clarify Voltage, Amps and capacity and not get them confused. The battery switch puts them in parallel effectively giving me 12 V and a capacity of 220amps, so if both batteries are 50% run down I will still have 110amps needed to start and run my engine.

The alternator on my engine will give out 23Amps at 14volts or so, that means if both my batteries were flat it would take around 9.56 hours to full charge them +20%. As I never let both batteries get to that stage, because if I stop I switch to one only, I can rest assured that within 4.78 hours +20% my battery will be fully charged.

Once the batteries are at close to full capacity, the alternator is simply providing current to the onboard electronics and the engine ECU.

An alternator generates AC current by default, so a bridge rectifier is used to convert that to a pulsed DC waveform. Whilst I am no electrical engineer I fail to see/understand why you would be over-loading the rectifier. If the alternator is designed to produce a maximum of 23 amps (as in my case), I think you will find that the rectifier has some extra tolerance and should be able to happily run at 23amps all day.

Even if you put a 500Ah battery it would make no difference whatsoever to the alternator, as it would still only produce 23amps per hour at 14V, meaning this battery would take 21.7 hours +20% to fully charge!

Deep cycle batteries are designed as house batteries and should NOT be used for starting engines due to the surge that starter motors place. In fact you are likely to warp your plates if you start your engine from a deep cycle battery. Cranking batteries on the other hand don't last if you deep discharge them every time and will eventually fail.

That is why if you regularily run house services (like spending a weekend with a cabin cruiser with the engines switched off), you tend to have 1 or more house batteries (deep cycle) and 2 smaller start batteries (cranking batteries).

[fishfinder]

I've been speaking with 2 marine electricions ( one Is ERIC ERETRIC and the other is a friend of mione who works for PETER CRAFT) and they told me that the outboards can charge only up to 120AMP and then they will stop charging the rest so if you have a 200AMP battery you still have 90 AMP not yet Charged and if you over load it there's a risk of berning the alternator as well. That's why I charge one by one.

[skip]

Interesting to read but have to say still doesn't make any logical sense to me! If an alternator can only charge up to 120amps, what/how does it set it's cut off period. Obviously an alternator woul be useless if in it's lifespan it could only output 120amps and then you throw it away!!

So technically, all you need to do then if this theory holds up is turn off the engine and turn it back on again and then you 'reset' this 120amp limit that they are referring to!

Here's a Mercury Electrical FAQ http://www.mercurymarine.com/serviceandwarranty/outboardfaqs/electrical.php where I would expect something like this to be mentioned. The first part mentions deep cycle and start batteries although there are now some generic ones, but Charlot I still havent worked out why all your batts are deep cycle.

Have a look at this FAQ from Exide and take note of this part! http://www.becksgunsmithing.com/exide.htm

In an emergency, can a deep cycle battery be used to start an outboard motor?
Yes. But ONLY IN AN EMERGENCY! For maximum battery life, a two-battery system is recommended.

As a rule of thumb you should aim for a maximum charge rate of 20% of a batteries amp hour capacity, so 110AH batts would = 22amps max.

I can't find anything on the Internet anywhere that referes to this 120 amp limit, not saying it's not the case but I would expect to find it referenced somewhere.

We need to get more clarification on this one as it's quite an important thing.

[redbus9]

if you have the two batteries connected together i.e. pos to pos neg to neg and you put the charging lead to the pos of one battery and the neg to the other battery you will charge both batteries.dont put both leads on the same battery as this one will get fully charged but the second one wont due to the internal resistance of the battery and the resistance of the leads connecting the two batteries together,which you might think is very small but it has a suggnificant effect on charging the second battery.i dont know where the two "electricians" get their information from but trinity house lighthouse service in the uk is one of the world leaders in battery tecnology

[fishfinder]

Let's see this on a very basic way. IF you have a charger of a per hour and the instruction says that it can charge up to 60Amps and you charge a 75A battery, the meter will show the analog needle on 0 which means that's fully charged but in fact the battery will be charged at 60Amps and still need 15Amps more to be fully charged.

Now my motor charges 30Amps per hour and his limit is 120AMP.

I have 2 x 75amps and 2 x 80amps all connect in Parallel at a total of 310AMPS and all are connected with a seperate switch 2x on a 1+2 + both and the other 2 on another identical switch.

if I connect them all together the motor will read that the total AMp is over 120Amps and will not Charge any battery until the total of 310AMPs will reduce or better Dry below 120Amps and the he will start charging until 120-130Amps and then it will switch off but the batteries will still be all below half charged. so you need to charge them 1 by 1 or at least 2 for 2hrs and then an extra hour one each battery.

Eretric sells a sort of meter that can give an exact reading of the Amp in the battery and this reading can't be achieved from a normal multimeter.( Sorry I forgot the exact name of this meter)

[skip]

Charlot, I can understand what you're saying, but does Suzuki state that the alternators it fits on its engines will not charge a battery that has a capacity greater than 120AH? Thats the bit I find hard to accept as it makes no sense whatsoever for a manufacturer to do that.

[Gazzetta]

Alternators fijhom limit minalija kemm jiccargjaw, jigifieri mhux azla ta min jamel l muturi e ax alih ikun jista jamlu ikbar imma imbad jizdiedu l costs = increase in sale price !!

Split charger tuza Skip ?? Dak li tkun tazel bej 1 u 2 or both in parallel.  Xrajtu min barra jew Malta ?

Chris 

[camkev]

Jien split charger ghandi.Battery 1 jew 2 or both of them.About 60 euro from Ronnie marine.I found it very good.

[skip]

Have to say guys, I still can not find one reference on the Internet to a maximum battery capacity limit of an alternator, specifically this 120amps you keep mentioning. Maybe I'm not looking for the right thing!

If you run an engine therefore an alternator at a reasonable amount of revs it will produce DC current for as long as you want! When you're running with your boat, all the services, engine ECU, pumps, GPS, Fishfinder etc are all being supplied with the necessary current from the alternator, you are NOT draining your batteries as this is happening, unless you are exceeding the maximum current output of an alternator (-20%) by having totally drained batteries and too many services on.

What they may be referring to is having a battery that is too large for the alternator in terms of that alternator being unable to overcome the internal resistance of the battery plates/wiring and therefore being unable to charge it. Alternators as you know are rated in amps and that rating refers to the maximum output in one hour at optimal revs and conditions whereas in practice they give 80% of their ouput at optimum revs etc.

If you have both your batteries fully drained and also have your services all on, then yes from what I read you could be placing too much of a demand on the alternator and I think this is what they were referring to when they said damage the rectifier or other components.

Again I've done some more reading and this is what I managed to determine:

1) If you stop your boat for extended periods of time and drain your batteries below 60%, charge each battery individually when you start running again.

2) If you spend most of your time with the engine on, with something like 2 x 110amp batteries you can leave the battery switch on both and not worry, they will stay topped up.

I think the lesson to be learned is either do as Charlot is stating and be safe by charging batteries individually, in case you're not sure how much you've discharged it, or if you are paying attention as soon as you feel you've gone below 60%, charge them individually.

Kevin, you have a split charger because you probably plug into the shore power at the marina? If not I think what you're referring to is a battery isolator, which lets you charge more than one battery off the alternator without discharing or affecting the other.

Better than a battery isolator which suffers a voltage drop of around 1V, is to use a battery combiner:

These guys make the best combiner out there http://www.yandina.com/combInfo.htm

What they do is take the hassle out of forgetting to switch from both (1+2) to either position 1 or position 2.