Basic volts question for battery use

[sailinglegend420]

But modern external regulators, eg Sterling Pro Reg D, limit the duration of the absorption charge and then drop to float voltage, according to Sterling's literature, with only 4-6 hours of absorption charge (which is temperature regulated anyway).

Again you're missing the point. My posts are about overcharging a starter battery when a VSR combines a depleted house and a full starter. The house gets up to its absorption voltage for 4-6 hours and that is charging a starter battery that is already fully charged. Do this every day for a season and the starter will dry out - especially if it is sealed and can't be topped up.

 

[pvb]

Again you're missing the point. My posts are about overcharging a starter battery when a VSR combines a depleted house and a full starter. The house gets up to its absorption voltage for 4-6 hours and that is charging a starter battery that is already fully charged. Do this every day for a season and the starter will dry out - especially if it is sealed and can't be topped up.

I think you're missing the point that this "problem" which you keep emphasising doesn't seem to afflict many people in real life. In fact, the starter batteries on many boats outlast the domestics.

 

[lw395]

I think you're missing the point that this "problem" which you keep emphasising doesn't seem to afflict many people in real life. In fact, the starter batteries on many boats outlast the domestics.

This is true.
But a lot of people seem to get short lives from their batteries generally.
If you are wanting your separate start battery to have the best possible reliability, then it's worth thinking about if you have a lot of solar or other power.
We could also wonder why so many people get so few cycles out of their domestic batteries having spent so much on charging gadgetry.

 

[PaulRainbow]

This is true.
But a lot of people seem to get short lives from their batteries generally.
If you are wanting your separate start battery to have the best possible reliability, then it's worth thinking about if you have a lot of solar or other power.

I worried about that then don't fit a dual sensing VSR, just fit one that only closes when the engine battery is charged. But, that still leaves to issue of the alternator charging the battery for how ever many hours you have the engine running.

We could also wonder why so many people get so few cycles out of their domestic batteries having spent so much on charging gadgetry.

I'd guess because they have poorly designed systems that allow the domestic batteries to discharge more than is healthy.

 

[pvb]

I'd guess because they have poorly designed systems that allow the domestic batteries to discharge more than is healthy.

You're probably right; many people seem to expect to run lights, instruments, plotters and fridges with only a couple of domestic batteries, which are often never fully re-charged.

 

[sailinglegend420]

I think you're missing the point that this "problem" which you keep emphasising doesn't seem to afflict many people in real life.....

You might be right here in the UK, but in the Med where we motor a lot then their could be problems from overcharging - but you can never be sure - but why take the chance and ignore the potential problem.

My starter battery is not cheap - it's a Red Flash AGM that has lasted 13 years so far - and is solely charged by its own 10 watt solar panel. My house AGMs are also the same age - so I must be doing something right!

What we do see in the Med a lot is this overcharging problem with solar panels that are left on all winter and after 6 months when owners return to their boats their batteries are dried out. Every day they are getting up to their absorption voltage for 4 hours or more a day when all loads are disconnected and they are fully charged. This is a real world problem so people partly cover their panels or you can re-programme the solar controllers to a much lower absorption voltage. Maybe there is a switch setting for GEL which would take charging down to 14.1v.

 

[PaulRainbow]

You might be right here in the UK, but in the Med where we motor a lot then their could be problems from overcharging - but you can never be sure - but why take the chance and ignore the potential problem.

My starter battery is not cheap - it's a Red Flash AGM that has lasted 13 years so far - and is solely charged by its own 10 watt solar panel. My house AGMs are also the same age - so I must be doing something right!

What we do see in the Med a lot is this overcharging problem with solar panels that are left on all winter and after 6 months when owners return to their boats their batteries are dried out. Every day they are getting up to their absorption voltage for 4 hours or more a day when all loads are disconnected and they are fully charged. This is a real world problem so people partly cover their panels or you can re-programme the solar controllers to a much lower absorption voltage. Maybe there is a switch setting for GEL which would take charging down to 14.1v.

My Victron controller can be set to any voltage for absorption or float and i can set a max time for absorption.

As it is, i have it set for 14.4v and 13.4v respectively, with a 6hr max absorption time. Typical absorption time is around 1:30, most i've seen is 2:45 (once). My batteries usually only get down to 12.4/12.5v.

 

[Heckler]

My Victron controller can be set to any voltage for absorption or float and i can set a max time for absorption.

As it is, i have it set for 14.4v and 13.4v respectively, with a 6hr max absorption time. Typical absorption time is around 1:30, most i've seen is 2:45 (once). My batteries usually only get down to 12.4/12.5v.

Yours is the most sensible and pragmatic view coming forward. As detailed elsewhere, my 9 year old batteries finally gave up the ghost this summer cruise. Numax leisure 110 amphrs and a generic 65 amphr start battery. I fitted a Sterling alternator controller 9 years ago, check and "fill" the " sealed" batteries every six months and have 250 watts of solar that I have fitted as "wings" on the side rails, only extended when sailing or anchored. Also a dogs bollox Sterling mains charger. The Numaxs' boiled after an extended motor in 38deg, I had filled up with distilled water prior to setting off but I suspect that finally one Numax had cratered and was fooling the regulator in to continuing charging. I isolated the really bad one and got back to base ok. It is interesting to see reports on quite a few threads recently a out cooked batteries, perhaps due to summer heat pushing them over the top?
Stu