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Will I harm my starter battery if charged at 14.8 volts?


Wrinkley

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Here's the background. Trojanoid domestic bank, wet cell standard starter battery, Victron Multi plus inverter charger and a Smartgauge/tbank controlling the split charge relay.

 

I am on a land line at present so thought I would set the Victron to charge at 13.2v float and 14.8v absorption. Will this harm my starter battery if I put the Victron into forced absorption, this will probably last 5 hours or so. I do not have the starter battery constantly connected to the float charge as the noise from the relay irritates me.

 

Regards

Graham

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I suspect I am missing something and will be given the CWDF equivalent of a good shoeing but can't you just disconnect the starter if you are worried?

 

I don't think it will worry your starter though.

Edited by Paringa
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14.8 is more than the starter battery needs because it is never more than very slightly discharged.

In the short term, or if this is just a temporary land line connection then its fine.

If this is a long term arrangement then you will need to top up the battery more often and it will reduce the life of the battery, but whether or not this is a significant reduction in life I can not tell you, though I suspect probably not.

If this is long term arrangement then you could get a diode splitter and wire this only into the starter battery wire to drop a bit of voltage.

 

................Dave

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The bit I missed was that I have fitted an Adverc Battery Management Controller that I want to adjust to make the alternator produce 14.8v required by the domestic bank. I don't know if it will fall back to 14v for the five minutes lower volts or a higher voltage that may harm the starter battery.

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The bit I missed was that I have fitted an Adverc Battery Management Controller that I want to adjust to make the alternator produce 14.8v required by the domestic bank. I don't know if it will fall back to 14v for the five minutes lower volts or a higher voltage that may harm the starter battery.

As has been previously suggested, why not put a split charge diode in the alternator feed to the starter batt? That'll drop the 14.8V down to around 14.15

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I have considered diode to reduce the voltage as you suggest and it is an option if I am likely to damage the battery. Just trying to find out if I am likely to damage the starter battery by charging it at a higher voltage. All the information I read tells me about under charging if the voltage is not sufficient but nothing about an upper voltage before damage will occur.

 

As Paringa says in post 5 "Crikey, five hours at point 4 over the usual... The haulage industry would grind to a halt if starters were worried about that." Its a thought but wondered if any one knew.

 

Regards

Graham

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In my view it all depends upon the starter battery type/materials and how well you look mater it. Undoubtedly charging for long periods at excess voltage will have a some poor effects on the plates but as DMR says how much of an effect no one can say.

 

If the starter battery is an open cell lead acid one using calcium plates AND you keep it topped up then I doubt there will be a marked effect. If it has lead-antinomy it will gas at a lower voltages will need even more topping up. Failure to keep topped up will result in plate damage markedly more serious than just a bit of over voltage for short periods.

 

If the battery is any form of sealed cell be it AGM or sealed wet cells then you need to find the maximum charging voltage from the manufacturer and not exceed it. {I know you say wet open cell but this paragraph is for the benefit of others who may be reading).

 

I suspect your adjusted Adverc will default to the alternator's regulated setting that may or may not be 14 volts unless you have removed or otherwise bypassed it totally.

 

Why not switch the engine battery out of circuit when doing 24/7 charging from the Victron and only switch it back in (say) once a month?

 

 

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I'd be tempted to just pull a spade (coil) connection off the relay.

 

If wanting it automatic, a small relay worked from the high voltage alarm on the Smartgauge could be connected do the same, but that would be getting away from the KISS principle a bit.

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Ian - at the moment I am using the 'disconnect at high voltage' facility set at 14,6v of the Smartgauge whilst on the landline, This will work with the Averc as well but the starter battery will receive no charge on the landline, don't know what it will get from the alternator.

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Most batteries have two voltage ranges for charging. Cyclic and Float. Cyclic will be higher, but require the charging to end at completion. Float charging assumes constant charging.

 

Landline is constant 24/7/365 so use the manufacturers table for float voltages.

 

14.7 is too high for the starter battery to sit there being overcharged. It will gas and need topping up. Add a diode to drop 0.5 volts or get two chargers.

 

A start should use no more than 5AH so very little charge is needed to replace that.

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I propose...

 

Don't worry about this stuff. Just carry on as you are. If the starter battery drops dead in the next year then that's the time to worry and make changes.

On the grand boating scheme of things the cost of a starter battery is really not that much.

 

..............Dave

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I propose...

 

Don't worry about this stuff. Just carry on as you are. If the starter battery drops dead in the next year then that's the time to worry and make changes.

On the grand boating scheme of things the cost of a starter battery is really not that much.

 

..............Dave

 

 

 

Yes but if the OP does this, we'll be one step closer to running out of batttery stuff to quibble about!

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Victron's have a separate charger output for the starter, disable the relay and use this connection instead.

A split charge diode is cheaper than a battery.

Not that anyone will listen.

And rewiring the start battery to the dedicated output for it on the Victron even easier again. That output is both voltage and current limited to avoid just this problem and it only needs a cable capable of carrying 5A, so really not a difficult job. Doing nothing could lead to an expensive bang and hot acid everywhere, so I don't think that's a safe option.

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And rewiring the start battery to the dedicated output for it on the Victron even easier again. That output is both voltage and current limited to avoid just this problem and it only needs a cable capable of carrying 5A, so really not a difficult job. Doing nothing could lead to an expensive bang and hot acid everywhere, so I don't think that's a safe option.

But what about when he is charging from the alternator that is now frigged to run at a higher voltage, I know a diode would fix that

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And the voltage can be set differently to the main bank?

Almost certainly, but the default is something like 13.5v, the assumption being that the starter battery is normally fully charged when you plug in and just needs a float voltage to keep it sweet.

But what about when he is charging from the alternator that is now frigged to run at a higher voltage, I know a diode would fix that

True, but I was dealing with the shoreline situation as originally described. I know nothing about using an Adverc to control the engine charge regime.

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