Battery maintenance via solar

[VicS]

Is there an ignore feature on this forum ???

I'm not one to want stars or pat on the back .. but when a suggestion is made and then someone else makes same but gets the credit ??

Yes . Click on the posters name and you will be presented with that as an option

 

[Refueler]

Yes . Click on the posters name and you will be presented with that as an option

That explains it then.

 

[halcyon]

We float 12V batteries at 13.7V by the thousand. Have done for years.
For someone in the trade, you do talk some cobblers.

You can think what you like, I have been designing battery chargers since 1983, I have 1000's of multi-stage chargers fitted, dating from 1985.

I waqs just pointing out the problem with float voltage and were it came from.


Brian

 

[Quiddle]

Not sure who you mean by this but I certainly appreciate your input.

 

[Refueler]

Not sure who you mean by this but I certainly appreciate your input.

My apologies - not directed at you ....

Looking fwd to reading your final decision and how it works.

 

[PaulRainbow]

Many controllers start every day with a period of fairly high voltage.
A couple of hours a day of too much voltage adds up to drying out the electrolyte.
That carries a risk of one cell failing and a disastrous overcharging of what's now a 10V battery, but most likely it will just ruin the battery or shorten its life.

For someone not in the trade, you do talk some cobblers.

 

[Graham376]

As my post #2 suggested - I think it is the simplest way to do it ... as to whether you need diodes I( think depends on whether you have services connected to one battery that could cause an inbalance of the batterys. If no services - then in theory you should get charged up on both and that should be it till one battery drops a bit ...
The Diode of course would need to be selected of a type to avoid the common voltage drop you can get of around 0.7V ....

The problem you mention is what caused me to install the diodes. We were using the banks alternatively so they would be at different voltages/states of charge particularly during evening loads and by morning they would be balanced. Can't remember what diodes I used but in practice when charging, the effect on 21 ish volt panel output wasn't noticeable, they were between panels and regulators, not on battery side. These days, the banks are paralleled into a single Victron 100/30.

I do wonder why engine batteries need charging on the average boat when they are normally isolated when not in service. I disconnect my car battery for up to 6 or 7 months at a stretch when away sailing and it always starts first turn when reconnected. Boat engine battery gets charged when the engine's running, not via the solar.

 

[Refueler]

For someone not in the trade, you do talk some cobblers.

I wouldn't say total cobblers .. as I have actually dried out a cell or two on a battery by having repeated cycled full charge when not in use ..
Its why I now use a low power charger of no more than 4A and a timer that allows max 2 hrs 5 days out of 7 during the week.

 

[lw395]

....

I do wonder why engine batteries need charging on the average boat when they are normally isolated when not in service. I disconnect my car battery for up to 6 or 7 months at a stretch when away sailing and it always starts first turn when reconnected. Boat engine battery gets charged when the engine's running, not via the solar.

Batteries do vary in their self discharge habits.
Older batteries need more charging.
Some batteries as you say, will go a long time.
Others will not.
I have noticed that Yuasa motorbike batteries, which are the best in terms of CCA for their size, need more float charging than some cheaper brands.
Also, a lot of cars these days will start with pretty sick batteries.
I took a battery out of my neighbours car, changed because it was reluctant to start the car after a couple of weeks' neglect. Its current ability was pathetic.
Your car may be getting quite low. Modern starter motors and the 'push to start' button which doesn't need to be held down can cover up.

When in doubt, one could always consider the advice of battery manufacturers, who in general suggest charging every few months for a battery in storage.
It does vary, because batteries vary and once a battery has been out of the factory a while, it's not an exact science.

I think it's quite hard to come up with a 'one size fits all', failsafe, completely hands off battery maintenance scheme, with no checking or monitoring.

At least isolating the battery only risks the battery.

 

[tillergirl]

Oh Gawd. What should I make of all that? Am I stuffing my batteries or I looking after my batteries? I am confused. Mind you, last time I looked both controllers were 'dumping' charge consistently and the report said I have only needed 0.3 amp or shortly like that for the week on the 24v system - so it seemed to be behaving.

 

[PaulRainbow]

Oh Gawd. What should I make of all that? Am I stuffing my batteries or I looking after my batteries? I am confused. Mind you, last time I looked both controllers were 'dumping' charge consistently and the report said I have only needed 0.3 amp or shortly like that for the week on the 24v system - so it seemed to be behaving.

I have 390ah of domestic batteries and a starter battery. I also have 260w of solar panels, with a Victron solar controller. As i'm a bit short of Sunshine just now, the 30a mains charger is on too. Both battery banks are connected via a VSR. The starter battery is sealed lead acid and four years old. Still starts the engine, still full of electrolyte, doesn't gas, smoke or melt.

If such an installation is left unattended, all of the batteries might be subjected to some absorption voltages each day, for a while. How long will depend on the controller, as much as anything. But, if the batteries don't need any charge, they'll only be subjected to the raised voltage, they won't take any current.

If the domestic bank are being cycled, they will take some charge. The engine battery will still see elevated voltages, likely for longer periods of time than if the boat was unattended, they still won't take any current.

If the charging system, be it mains or solar, is set to a higher voltage than would be normal for the starter battery (say, the domestic bank are true deep cycle, operating at a higher charge voltage), then it's more likely to come to harm. Such an installation should not be fitted with a VSR.

 

[rotrax]

We keep an old clunker steel Hartley 32 in Wellington Harbout, NZ.

It has two 100 AH AGM's - ex computer emergency power bank, 7 years old, bought secondhand - and a far smaller flooded cell starter battery.

We are away for at least 7 months each year and the batteries are maintained very well by one very old and fairly discoloured solar panel, 40W, and two much newer 20W panels, monitored by a cheap regulator. Wired in parallel.

The batteries, even on a dull day, are always at 12.9V. With a bit of sun, 13.4V. Really good sun, 14V.

The control panel LCD reading is checked with my hand held digital voltmeter, both agree exactly.

I have covered the panels with a piece of ply, one at a time, the voltage drops each time, not so much with the discoloured one.

Been like that for nearly four years now, since I fitted the used AGM's and the cheap regulator.

Works for me!

 

[Graham376]

Your car may be getting quite low. Modern starter motors and the 'push to start' button which doesn't need to be held down can cover up.

My car was modern 13 years ago when new Bog standard 1.8 TDCI Focus estate. Don't want a brand new one, too many gadgets to go expensively wrong when out of warranty and even harder to DIY.

 

[rotrax]

A very good vehicle.

I have a son who is a poor driver and a mechanical incompetent. He should not be entrusted with the operation and maintenance of a wheelbarrow.

But even he could not kill our Ford Focus Diesel Estatel, and it had well over 200,000 miles on the clock when we gave it to him.

 

[halcyon]

Many controllers start every day with a period of fairly high voltage.
A couple of hours a day of too much voltage adds up to drying out the electrolyte.
That carries a risk of one cell failing and a disastrous overcharging of what's now a 10V battery, but most likely it will just ruin the battery or shorten its life.

That is due to bad design via lack of knowledge or just lazy work, we have gone backwards in product design.
Back in the late 80's we suffered problems with Sealine and badly boiled / over heated batteries which turned out to be a intermittent fault due to manufacturing error. But the charger switched to 13.6 volt float charge, which gave limited protection, while the more modern timed method, may be cheap, but causing massive problems.

Far better to use voltage control, turn on charge based on battery voltage, not pre programmed standard duty cycle.

Back in 1985 we started from, alternator charged engine then service battery, mains charger charged the service battery then the engine battery. Thus the engine battery recieved no charge till the service battery was charged and dropped to float as soon as the engine battery was charged. Thus no excessive charge to engine battery.

What we need to apply is the same system to solar battery charge for boat batteries, not controllers more suited to fixed solar panels supplying a constant current.

Brian