14.7v or 15v

[bowten]

I have 4 Trojan T105s giving 220amps,Victron Multi 1600/70/16 the charger giving 50amps and a Travel Pack at 3.5kva.The question is the batts need 14.8v but the Multiplus is set by the dip switches to 14.5,14.7 or 15v.,should I go for the 14.7 or 15v setting?If I choose the 15v setting will this damage the batts or would they be better for it?Cheers.

Edited August 9, 2013 by bowten

[BEngo]

I'd go for 14.7. 15 is higher than recommended, close to equalisation territory, and will certainly use more water. 14.7 won't slow the charge that much.

 

N

[Nickhlx]

Agree - we have T-125s and it seems that 14.5 on the terminals is causing them to gas, so stirring the electrolyte, and they charge up fast enough at that voltage...

 

Nick

[nicknorman]

Or you could spash out £55 or so on the PC interface and set it to 14.8v using a laptop. Hours of fun available playing with all the other settings as well!

[DaveC]

Does 0.2 volt make a difference either way? Serious question BTW.

 

 

 

Dave

[nicknorman]

It might make a difference to the propensity to sulphate (rather than having any significant effect on the time it takes to charge). If one does an equalise charge (15.5v) reasonably often, it probably doesn't matter. The OP is in a good position since he is charging via his Victron, he can do an equalise whenever the fancy takes him.

[dmr]

Selecting charge voltage is almost as important as deciding between a proper pump out and a plastic suitcase!

Are you a liveaboard without shorepower?

 

If you generally manage to keep the batteries full because you either have access to mains electricity or cruise most days then I would go for 14.7.

If you struggle to get a full charge because you are having to run the engine/generator just to charge the batteries then 15v would be better.

I use 15 in winter when we move every week or two and 14.8 in summer when we move most days.

I don't think 15v will seriously reduce the life of the batteries but sulphation almost certainly will.

 

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

[bottle]

Set it to 14.7, you may see more when the temperature compensation kicks in, assuming you have temperature compensation. (not checked that Victron model, it will be in the manual)

 

or get the interface as Nick says.

Edited August 9, 2013 by bottle

[bowten]

Selecting charge voltage is almost as important as deciding between a proper pump out and a plastic suitcase!

Are you a liveaboard without shorepower?

 

If you generally manage to keep the batteries full because you either have access to mains electricity or cruise most days then I would go for 14.7.

If you struggle to get a full charge because you are having to run the engine/generator just to charge the batteries then 15v would be better.

I use 15 in winter when we move every week or two and 14.8 in summer when we move most days.

I don't think 15v will seriously reduce the life of the batteries but sulphation almost certainly will.

 

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

I have the Travel Pack so is the same as having shore power except I won't be running the engine as long as I would like apart from when I am cruising for most of the day(every two weeks or so)

[Dave_P]

I have 4 Trojan T105s giving 220amps,Victron Multi 1600/70/16 the charger giving 50amps and a Travel Pack at 3.5kva.The question is the batts need 14.8v but the Multiplus is set by the dip switches to 14.5,14.7 or 15v.,should I go for the 14.7 or 15v setting?If I choose the 15v setting will this damage the batts or would they be better for it?Cheers.

Am I the only one who feels like they're reading a foreign language? I'm guessing this has something to do with batteries?

[nicknorman]

Am I the only one who feels like they're reading a foreign language? I'm guessing this has something to do with batteries?

Yes, what's not to understand? 10 out of 10 for a clear and unambiguous question imparting all necessary information. Of course, you don't have to understand boat electrics, but if you don't you'll have to pay someone who does, when it goes wrong. That is presuming you can find someone when you are in the back of beyond in a dark boat!

[bowten]

Am I the only one who feels like they're reading a foreign language? I'm guessing this has something to do with batteries?

The question was meant for those that are in the know,that's why I used a foreign language.

[luctor et emergo]

What's wrong with oil lamps anyway?

[bowten]

What's wrong with oil lamps anyway?

Nothing I love em,when needed for seduction.

[smileypete]

IF you have effective temp compensation and are shoreline bound in winter then 14.7V should do.

 

But as dmr says 15V may be helpful in winter to off grid liveaboards with limited charging available.

 

Of course the EQ needs doing as called for by Trojan, to help to get the best from the batts.

 

cheers, Pete.

~smpt~

[blackrose]

I don't think 15v will seriously reduce the life of the batteries but sulphation almost certainly will.

 

 

Will 15v desulphate the battery plates or just prevent them getting sulphated in the first place?

 

A few years ago my alternator controllers were only going up to 14.6v and I was asking a question on the forum about why they weren't going to 14.8v. Gibbo asked me why I needed 14.8v and I replied that I thought the batteries wouldn't get sulphated at the higher voltage. He told me I'd need 16v to prevent or get rid of sulphation.

Edited August 10, 2013 by blackrose

[dmr]

Sulphation starts if batteries are left less than fully charged for more than a few days, so the objective is to get the batteries as full as we can at each charge, and if this involves running an engine, then also doing it in the shortest possible time. A higher voltage (14.8 or 15) helps to get the last 10% or so into the batteries quickly. Even so we still need a long 8 hour charge once a week or so to get right up to 100%.

So the higher voltage help prevent sulphation.

Charging at 15v (or even 14.8) will also probably remove existing sulphation but it will take a long long time. To remove sulphation its better/easier to charge at 15.5 or 16v for a few hours a few times every year....this is equalisation!

16v is a bit high unless you really know what you are doing, 15.5v is safer.

Another benefit of higher voltage charging is that it makes the batteries bubble a bit (gassing), and whilst most people appear to think this is bad and to be avoided at all costs, it is actually a good thing as it stirs up the acid. Only downside is that you need to top up the batteries a couple of times each year.

 

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

 

edited because I wrote too fast and did not proof read!

Edited August 10, 2013 by dmr

[bowten]

 

Will 15v desulphate the battery plates or just prevent them getting sulphated in the first place?

 

A few years ago my alternator controllers were only going up to 14.6v and I was asking a question on the forum about why they weren't going to 14.8v. Gibbo asked me why I needed 14.8v and I replied that I thought the batteries wouldn't get sulphated at the higher voltage. He told me I'd need 16v to prevent or get rid of sulphation.

The quoted figure from the Trojan website for these batts are 14.8volts.

[blackrose]

The quoted figure from the Trojan website for these batts are 14.8volts.

 

Yes, I think that's the same for most wet lead/adid batteries.

[dmr]

The quoted figure from the Trojan website for these batts are 14.8volts.

 

Yes, but if you speak to Trojan technical people and tell them that you live on a boat and struggle to keep your batteries fully charged they will most likely suggest charging at 15 volts!

 

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

[George94]

Would it be true to say that temperature is critical when charging at high voltages? And would it be safer to charge outside in winter in order to avoid over-heating?

[blackrose]

I think you would need temperature compensation on the charger being used.

[Hawkmoth]

Another vote for the 15V camp. I have full traction cells, and was told by the maker that they would stand up to 17V. While I wouldn't do that to them, I have found that charging at 15V has increased the available power for a given charge time. ie if you only charge for 3-4 hours you will be at a higher SOC at the end. Got to be good for the batteries.

Just keep an eye on the electrolyte levels.

BTW I cruise most days in summer, when quick charging is the ideal.

Bob

[bowten]

The consensus seems to be go for 15v as I am not on shoreline and this is what I will do taking care that I check electrolyte levels.Thanks for everyone's input.