Voltage Regulator

[forrestmichael]

Me again... i've currently got a very simple one battery does all setup, i want to add an additional battery for equipment only leaving one for engine only and an isolator switch to choose which is charged and which is used etc. I can understand all that bit and unless i'm wrong don't need anything more.

I really want to limit engine running time for charging however, i've read that a charge regulator which feeds the battery more efficiently can greatly reduce charge times. If I wanted to later add a solar panel could I connect this into this charge regulator also.

And finally, can anyone recommend a charge regulator for this purpose.

Thanks as always

Michael

 

[Juggler7823]

Simplest way is to use a 1,2, 1+2 switch. No separate regulator needed!

 

[VicS]

Firstly if you connect the second battery using a 1, 2, both, off type switch make sure you use a good one as they have a very poor reputation. Alternatively just use separate isolating switches.

For a fancy regulator try looking at those offered by Merlin Powerstore, Sterling Power Products or Driftgate. While you are doing that you might like to look at the possibility of one with outputs for two batteries.

The solar panel together with any regulator (and they exist with two outputs) will be a separate issue to any smart regulator for the alternator although it can be combined with a wind generator if you are thinking along those lines. Look at the Rutland range.

 

[forrestmichael]

Thanks for a very helpful quick response... i'm sure i'll be back!

Mike

 

[morgandlm]

Having fitted one last year I would endorse the recommendation to fit a Sterling regulator. You don't "need" one but it makes a big difference to how many electrons you can stuff into a battery!
Morgan

 

[William_H]

If you are setting up your second battery system I would vote for simply removing the domestic systems from the engine battery to the new battery with an isolation switch. Add another isolation switch which connects the +ve of the 2 batteries together for charging. This last switch can be replaced by a voltage sensing relay when you get the urge. Connect the negatives permanently with heavy wire.

Regarding regulators for charging. A standard regulator limits the output of any charging device to precisely 14volts. (+or- .2 volt). This means that if a battery connected to it is discharged it will take current until the battery is charged. The charge current depends on the difference between the regulated voltage and the inherent voltage of the battery. (which is dependent on charge state but not in a linear manner).
So inevitably the first 1/3 of a battery charge is replaced quite quickly but the charge current falls until it takes an age for the last 1/3 charge. This method has the advantage and origins from motor vehicle charging where with long engine running times the battery is not overcharged.

It is very dismaying if you are running an engine for say 2 hours to recharge batteries only to find that in the last hour the current has been quite small. A charge amp meter can be very usefull.

One way to improve the charge current is to fit bigger batteries. The current even though small will double with battery capacity doubled. (and of course it gives you more capability without recharge and batteries less % discharged so they last longer)

A more recent technology is the smart charger. Here the regulator senses the battery voltage and then initially increases the charge voltage which increases the charge current until it senses the battery voltage has risen to that of a fully charged battery then reduces the voltage to the normal 14v for so called float charge. This form of regulating can be used for solar, wind, mains or engine driven charging.

This type of regulator is available but not so common with solar or wind gens. With solar the charge current is often so small that no harm can be done to batteries so they are connected with no regulator and from a open circuit voltage of 20 they push as much current into the batteries as they can. Wind gens more often have the normal 14volt regulator simply because fast charge is not a priority.

I don't have an engine gen but I have often thought if I did I would fit a simple regulator with variable voltage or even a current regulator with a timer on it. Such that for a limited time say 1/2 hour the generator (alternator) would run flat out then revert to normal voltage regulation with a sound warning or even auto engine stop.
One of the problems of doing this is that the voltage at the battery could be high enough to be a danger to some services like incandescent lights. It would be safest to do the engine run with most things turned off.

To sum up regulators are there to provide automatic protection of the battery from overcharge and in doing so they tend to limit the charge rate especially as you approach fully charged.
How you deal with this problem depends a lot on your boating habits. olewill