Optimum charge voltages?

[Timleech]

Following on from the SmartThingies discussion, I'm looking for suggstions from those who know, or even those who think they know

 

My situation is -

Boat currently used infrequently, most runs for a few hours only. I'm hoping this will change in the future.

24V system, 60A alternator. The boat has very limited no facilities at present, I'm adding inverter & 30 quid microwave and a 24V wagon drivers kettle as short term expedients, so the batts will get a bit of a caning at times. Two battery banks, VSR controlling 'domestic' bank charging.

The present alternator reg gives a charge voltage of about 28V. I've bought an adjustable regulator which can be set for anything up to 32V. What would be a sensible compromise charge voltage to give a good charge rate without boiling the batteries too much?

I'm thinking that later on, if plans for greater use/longer trips materialise, I could arrange switching between the two regulators either automatically or manually, so the fixed reg could be brought in after an initial high rate charging stage.

 

Suggestions welcomed, no fighting please

 

Tim

[matty40s]

I no longer use either of those items, kettle went after first 2 trips, and microwave since being parted from landline 12 months ago........do you really need them, surely a gas stove (even a camping one) and a kettle are easier.

The washing machine only gets used if I am cruising for a full day (and even then only turned on after about 2 hours progress so water it hot).

All those items put a lot of strain on both the invertor and the batteries, and also take a lot of putting the juice back afterwards

.

[Keeping Up]

I'm sure you'll get a variety of answers, probably using the formula V=28+4R where R is a random number between 0 and 1.

 

Personally I'd opt to start right in the middle at 30 volts and see how it goes, preferably (as you suggest) arranging to switch to a lower voltage when you're cruising.

[Chris Pink]

The present alternator reg gives a charge voltage of about 28V. I've bought an adjustable regulator which can be set for anything up to 32V. What would be a sensible compromise charge voltage to give a good charge rate without boiling the batteries too much?

 

 

Tim

 

Just to show i was paying attention, the advice from those who know is 29.6V for flooded batteries.

 

Most commercial battery chargers are set at 28.8V.

 

30V would only be appropriate if you were trying to break down previous sulphate and would need a very close eye keeping on water levels and the potential build up of hydrogen gas.

[Timleech]

I no longer use either of those items, kettle went after first 2 trips, and microwave since being parted from landline 12 months ago........do you really need them, surely a gas stove (even a camping one) and a kettle are easier.

The washing machine only gets used if I am cruising for a full day (and even then only turned on after about 2 hours progress so water it hot).

All those items put a lot of strain on both the invertor and the batteries, and also take a lot of putting the juice back afterwards

.

 

As I said, these are short term expedients, no gas of any sort until it can be done properly. Space is also a major constraint. It seemed the simplest arrangement in my particular circumstances, I'm sticking with it for the moment.

 

Washing machine? Who mentioned that?

 

Tim

[nb Innisfree]

Following on from the SmartThingies discussion, I'm looking for suggstions from those who know, or even those who think they know

 

My situation is -

Boat currently used infrequently, most runs for a few hours only. I'm hoping this will change in the future.

24V system, 60A alternator. The boat has very limited no facilities at present, I'm adding inverter & 30 quid microwave and a 24V wagon drivers kettle as short term expedients, so the batts will get a bit of a caning at times. Two battery banks, VSR controlling 'domestic' bank charging.

The present alternator reg gives a charge voltage of about 28V. I've bought an adjustable regulator which can be set for anything up to 32V. What would be a sensible compromise charge voltage to give a good charge rate without boiling the batteries too much?

I'm thinking that later on, if plans for greater use/longer trips materialise, I could arrange switching between the two regulators either automatically or manually, so the fixed reg could be brought in after an initial high rate charging stage.

 

Suggestions welcomed, no fighting please

 

Tim

 

We have had a burnt out Leece Neville and have discovered recently that the adjustable built in regulator has been replaced by a fixed one (28v) due, allegedly, to voltage being set too high, I am waiting for clarification on this from Prestolite. So in the meantime I have disconnected charge controller and charge at alternator voltage for a couple of hours untill charge drops to under 10 amps with a weekly equalising with genny and Victron (this regime is to keep our tired AGM batts up to a workable voltage) When we replace batts with cheapo wet lead acids I will do bulk charge only daily and absorption for several hours once a week with genny and Victron charger at 29.6v. If I decide sometime that a controller is needed I will reconnect our Adverc as I think it is easier on alternator than Sterling due to it pausing for 5 mins every 15 mins. The Adverc's factory setting works out at approx 28.8 volts reducing to 28.1 when fully charged. To make this a bit clearer (or less confusing!) bulk charge seems to finish when alternator voltage reaches 27.5 and Adverc then switches on and alternates between 27.5v and 28.8v, the 27.5 alternator voltage gradually increasing and 28.8 Adverc voltage decreasing until they meet at 28.1

 

Edited because my cut and paste has gone berserk

Edited March 7, 2010 by nb Innisfree

[smileypete]

The present alternator reg gives a charge voltage of about 28V. I've bought an adjustable regulator which can be set for anything up to 32V. What would be a sensible compromise charge voltage to give a good charge rate without boiling the batteries too much?

I'm thinking that later on, if plans for greater use/longer trips materialise, I could arrange switching between the two regulators either automatically or manually, so the fixed reg could be brought in after an initial high rate charging stage.

Depends on the temperature, see this table (for 12v bear in mind) and notes in the battery FAQ: http://jgdarden.com/batteryfaq/carfaq9.htm#temp

 

For normal flooded/non sealed 12v batteries I'd say 14.8v in winter, 14.4v in summer, and ideally 14v in high summer/heatwave conditions.

 

cheers,

Pete.

[Guest]

Following on from the SmartThingies discussion, I'm looking for suggstions from those who know, or even those who think they know

 

My situation is -

Boat currently used infrequently, most runs for a few hours only. I'm hoping this will change in the future.

24V system, 60A alternator. The boat has very limited no facilities at present, I'm adding inverter & 30 quid microwave and a 24V wagon drivers kettle as short term expedients, so the batts will get a bit of a caning at times. Two battery banks, VSR controlling 'domestic' bank charging.

The present alternator reg gives a charge voltage of about 28V. I've bought an adjustable regulator which can be set for anything up to 32V. What would be a sensible compromise charge voltage to give a good charge rate without boiling the batteries too much?

I'm thinking that later on, if plans for greater use/longer trips materialise, I could arrange switching between the two regulators either automatically or manually, so the fixed reg could be brought in after an initial high rate charging stage.

 

Suggestions welcomed, no fighting please

 

Tim

A little tip or two: Make sure your inverter has plenty of capacity for the microwave. Our cheapo microwave is rated at 750Watts but consumes around 1500Watts of power when cooking on full power. I understand that this is true of most microwaves.

We always use the microwave when the engine is running, and I suspect the same would be advisable for the 24V kettle.

[Timleech]

A little tip or two: Make sure your inverter has plenty of capacity for the microwave. Our cheapo microwave is rated at 750Watts but consumes around 1500Watts of power when cooking on full power. I understand that this is true of most microwaves.

We always use the microwave when the engine is running, and I suspect the same would be advisable for the 24V kettle.

 

Thanks, it's a 1500W MSW inverter, the rated consumption of the microwave is 1300W. I've checked that the two do work together, haven't measured the actual output of the microwave though.

I did pose the question in another thread, no-one responded though - If a microwave gives reduced output when run from a MSW inverter, presumably it also draws less power? I'll run some output and consumption tests in the fullness of time, when everything is properly set up.

The kettle 'only' draws about 25 A, nowhere near as much as the microwave/inverter combi, but is also correspondingly slower - it would be quicker to boil water in the microwave I think!

 

Tim

[GUMPY]

Only talking alternators here not chargers

My alternator has a new regulator (Thanks Sir Nibble) that is set at 29V works better than the last one, from memory 28.2V

29v is fine for all day on wet lead acids.

My alternator is about 50 amps and now takes 3 hours to bring the 400Ah battery bank back from 80% to 100% whereas before it used to take longer.

[Guest]

Thanks, it's a 1500W MSW inverter, the rated consumption of the microwave is 1300W. I've checked that the two do work together, haven't measured the actual output of the microwave though.

I did pose the question in another thread, no-one responded though - If a microwave gives reduced output when run from a MSW inverter, presumably it also draws less power? I'll run some output and consumption tests in the fullness of time, when everything is properly set up.

The kettle 'only' draws about 25 A, nowhere near as much as the microwave/inverter combi, but is also correspondingly slower - it would be quicker to boil water in the microwave I think!

 

Tim

I think you will be fine with the 1500 MSW. Good question about the MSW "downrating" the microwave: Don't know whether it will consume less power, or if it is a loss of efficiency, and will consume full power. I suspect the latter, but it is purely a guess.

[Keeping Up]

No it will consume less power too (thought I did reply in the other thread)

[Timleech]

No it will consume less power too (thought I did reply in the other thread)

 

Maybe I missed it.

 

I'll try to remember to report back when I've tested it (microwave + inverter)

 

Thanks

Tim

[matty40s]

they consume just as much power less efficiently.

My invertor is MSW and Microwave chips(pah, kids) came out still cold and soggy in the middle.

[Timleech]

they consume just as much power less efficiently.

 

If that's the case, the microwave must get hot - the extra energy has to go somewhere.

 

Tim

[Keeping Up]

No it will consume less power too (thought I did reply in the other thread)

they consume just as much power less efficiently.

My invertor is MSW and Microwave chips(pah, kids) came out still cold and soggy in the middle.

We appear to have a disagreement. A practical test is required. Or maybe, in Harry Hill style, a FIGHT.

 

I stand by my view that they consume less power, although I expect they will also also be less efficient. Although it will depend on the exact shape of the MSW because they vary considerably, my guess is that they will produce 20-25% less output and consume 15-20% less power.

 

I absolutely hate microwave chips, almost as much as I hate oven chips. Only properly fried chips will do, preferably from a newspaper.

 

 

ETA: I also stand by my initial suggestion of 30v for charging, for short periods and if you are watching things carefully (as you suggested). Yes I know it's above the normally recommended value of 29.6v, but it will get you a better charge with only a slight increase in the amount of gassing.

Edited March 7, 2010 by Keeping Up

[Guest]

We appear to have a disagreement. A practical test is required. Or maybe, in Harry Hill style, a FIGHT.

 

I stand by my view that they consume less power, although I expect they will also also be less efficient. Although it will depend on the exact shape of the MSW because they vary considerably, my guess is that they will produce 20-25% less output and consume 15-20% less power.

 

I absolutely hate microwave chips, almost as much as I hate oven chips. Only properly fried chips will do, preferably from a newspaper.

 

 

ETA: I also stand by my initial suggestion of 30v for charging, for short periods and if you are watching things carefully (as you suggested). Yes I know it's above the normally recommended value of 29.6v, but it will get you a better charge with only a slight increase in the amount of gassing.

Fried in lard?

[nb Innisfree]

Fried in lard?

 

No, dripping.

[MikeV]

If a microwave gives reduced output when run from a MSW inverter, presumably it also draws less power?

It does! How much less depends in part on the MSW waveform. We had a super-cheapo MSW (square wave probably) inverter which only drew about 70 amps from the inverter when powering the microwave on full power. The microwave was rated at 1400W maximum consumption, but 70 amps from 12V, allowing for inverter losses, is roughly 700W.

 

Its microwave power rating was 700W (heating effect on food) and it is reasonable to assume this was roughly halved meaning that it performed like a 350W microwave. This was borne out in practice as you had to roughly double the cooking times for the same heating effect.

 

The cheapo inverter blew up (running a 55W slow cooker incidentally!) and the new MSW inverter clearly has a better waveform as it now draws about 104 amps (roughly equivalent to 1040W) with the microwave on full power and cooking times are reduced.

 

There are some Panasonic microwaves with built in inverters which I believe would run on full power even from an MSW inverter but (1) they are more expensive and (2) are larger family sized and not necessarily suited to compact spaces on a boat.

Edited March 7, 2010 by MikeV

[Keeping Up]

Fried in lard?

No, dripping.

Difficult choice but I think the chips should be fried in lard - the dripping is then still available to be spread on a slice of toast for breakfast the next morning.

[Nickhlx]

Difficult choice but I think the chips should be fried in lard - the dripping is then still available to be spread on a slice of toast for breakfast the next morning.

 

 

.... ..

 

Nick

[luctor et emergo]

Deep fat fryers on boats? what will be next?

 

What happened to baked potatoes in the stove?

 

 

 

[John Orentas]

Following on from the SmartThingies discussion, I'm looking for suggstions from those who know, or even those who think they know :

Suggestions welcomed, no fighting please

 

Tim

 

 

I refer you to a previous post.

[Redeye]

I refer you to a previous post.

 

Hi guys,

 

Due to installing a 72v battery bank I have been doing a lot of research into the ideal charging and equalising voltages, the most interesting components seems to be the massive variation in charging voltages with temperature, this has been borne out in practice with me strugglung to charge batteies at around 86.5V. Trials up at 90V (15v per 12v equivalent) have been much more sucessful with the cells showing little tendancy to overheat. If you read the mountain of literature some sources recommend an equalisation charge upto 15.5V for flooded lead acid in order to really get the cells gassing and the electrolyte mixed. I estimate the temperature of my batteries to be around 5c which sort of ties in with comments earlier in this thread. It makes a real difference in getting that last 20% into the cells.

 

Just my thoughts, I've never been a dripping man

 

Cheers Redeye

[Nickhlx]

Hi guys,

 

Due to installing a 72v battery bank I have been doing a lot of research into the ideal charging and equalising voltages, the most interesting components seems to be the massive variation in charging voltages with temperature, this has been borne out in practice with me strugglung to charge batteies at around 86.5V. Trials up at 90V (15v per 12v equivalent) have been much more sucessful with the cells showing little tendancy to overheat. If you read the mountain of literature some sources recommend an equalisation charge upto 15.5V for flooded lead acid in order to really get the cells gassing and the electrolyte mixed. I estimate the temperature of my batteries to be around 5c which sort of ties in with comments earlier in this thread. It makes a real difference in getting that last 20% into the cells.

 

Just my thoughts, I've never been a dripping man

 

Cheers Redeye

 

 

 

Wow !! All those volts and getting into the territory of "being able to get a shock off the battery" - Scary stuff....

 

Nick