Charging.

[nb celestine]

About once a week I get the genny running and give the batteries a long absorbtion charge and get them up to float as this is supposed to help prevent sulphation.

 

Once they are up to float, I usually take them off charge as I thought they couldnt take any more, or it is pointless giving them any more.

 

Is this correct?

 

Should I give them longer on float and if so how much longer?

 

I have a victron bmv battery monitor to show me whats going on. Paul.

[grahame r]

There's a currently live topic in Equipment called Battery Nightmare which has a lot to say about the battery monitor readings and their meaning or lack of,

[GSer]

It can take ages for batteries to become fully charged, i've given up trying to charge it to fully charged, i just charge them until the batteries take approx 6 amps (660ah battery bank) and the voltage is on float in my case13.8v, as to get them to fully charged uses too much fuel if using a genny.

 

Paul

[dmr]

As Paul says, once the charger is in float mode the charge rate is negligable so you are just wasting fuel.

It is quite likely that the batteries are still not fully charged but its only worth going on if you can somehow get the charger out of float mode.

Turning it off and back on might work, but probably won't. Turning a few lights on might just work.

Sadly most (all?) chargers just do not understand the requirements of boaters, especially liveaboards, and go into float mode MUCH too soon.

.........Dave

[blodger]

If you liveaboard it seems obligatory to charge beyond float each week for a couple of hours to extend battery life. Easiest/cheapest done with solar panels but perhaps more capacity needed than you use straight after charging to get the job done.

[Arthur Brown]

There is a range of "float " voltages, Float is where lead acid batteries can stay for ever, at a well chosen float voltage then nothing significant should go in or out of the battery, yes it may be specified to three decimal places! -and different for each range of batteries!

 

Holding a battery at it's float point is a great use for a small solar cell, or a poor use for a generator.

 

Generators are good for putting the bulk charge into a battery by LV alternator or 240 supply and charger. The change to the absorption charge is best done by clever electronics, and once the absorption phase is completed the float phase continues as long as possible -all at the best voltages for your battery type.

Edited June 8, 2012 by Arthur Brown

[blackrose]

My Sterling charger goes onto float way too early if the batteries have previously been discharged significantly (the follies of adaptive charging I'm told). My battery monitor still shows about 6amps going into the batteries when the charger goes onto float, so I switch it off and then back on again for another hour and this reduces it to 1 or 2amps the next time it goes onto float. Then I switch the charger and generator off. I could keep going and switch it off & on again, but getting that last amp or two into the batteries uses a lot of fuel.

 

I thought that Victron chargers were meant to be better. What does your battery monitor show when your charger goes onto float Paul?

 

Mike

 

Edit: By the way, I'm not sure if you're living on the boat (or what size of battery bank you have), but if so it sounds like you have rather low power consumption - which of course is good. Anyway, charging once a week doesn't sound very often for a liveaboard so use your battery monitor to make sure you never reduce your domestic battery bank to below about 50% of its capacity otherwise you inflict damage. Apologies if you already know this - not trying to teach my granny to suck eggs.

Edited June 9, 2012 by blackrose

[Keeping Up]

My (rather old) Sterling charger has a set of DIP-switches to set the time before it goes into float. Experiments have shown that the switches make no difference at all, so I adopt the same solution as MIke, just turn it off and back on again until the current has dropped to the level that I like.

[Paul C]

My Sterling charger goes onto float way too early if the batteries have previously been discharged significantly (the follies of adaptive charging I'm told). My battery monitor still shows about 6amps going into the batteries when the charger goes onto float, so I switch it off and then back on again for another hour and this reduces it to 1 or 2amps the next time it goes onto float. Then I switch the charger and generator off. I could keep going and switch it off & on again, but getting that last amp or two into the batteries uses a lot of fuel.

 

I thought that Victron chargers were meant to be better. What does your battery monitor show when your charger goes onto float Paul?

 

Mike

 

Edit: By the way, I'm not sure if you're living on the boat (or what size of battery bank you have), but if so it sounds like you have rather low power consumption - which of course is good. Anyway, charging once a week doesn't sound very often for a liveaboard so use your battery monitor to make sure you never reduce your domestic battery bank to below about 50% of its capacity otherwise you inflict damage. Apologies if you already know this - not trying to teach my granny to suck eggs.

 

 

My (rather old) Sterling charger has a set of DIP-switches to set the time before it goes into float. Experiments have shown that the switches make no difference at all, so I adopt the same solution as MIke, just turn it off and back on again until the current has dropped to the level that I like.

 

 

Which model of Sterling are you both using?

[nicknorman]

Seems to me the best way to get 100% soc is to use the boat for the purpose intended -ie go cruising in it! A decent engine alternator will be set at 14.2 plus and maintain absorption indefinitely!

 

Back to my hole now!

[dmr]

Seems to me the best way to get 100% soc is to use the boat for the purpose intended -ie go cruising in it! A decent engine alternator will be set at 14.2 plus and maintain absorption indefinitely!

 

Back to my hole now!

 

You are correct, and after a winter of extended bridge hopping we are now out on our travels. We are doing 6 or 7 hours everyday, the batteries are 80 to 90% each morning and by the evening there is electricity spilling out all over the engine room floor. I might even need to turn the alternator voltage down a bit (currently 14.8). However we are probably going to get through 600 litres of fuel over the next few months.

Full batteries = Lots of diesel.

 

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

[nicknorman]

.

Full batteries = Lots of diesel.

 

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

 

True but lots of diesel = lots of cruising enjoyment too!

[Keeping Up]

Which model of Sterling are you both using?

 

I think mine's the Pro-charge, which I got cheap when it was replaced by the digital version.

[nb celestine]

My Sterling charger goes onto float way too early if the batteries have previously been discharged significantly (the follies of adaptive charging I'm told). My battery monitor still shows about 6amps going into the batteries when the charger goes onto float, so I switch it off and then back on again for another hour and this reduces it to 1 or 2amps the next time it goes onto float. Then I switch the charger and generator off. I could keep going and switch it off & on again, but getting that last amp or two into the batteries uses a lot of fuel.

 

I thought that Victron chargers were meant to be better. What does your battery monitor show when your charger goes onto float Paul?

 

Mike

 

Edit: By the way, I'm not sure if you're living on the boat (or what size of battery bank you have), but if so it sounds like you have rather low power consumption - which of course is good. Anyway, charging once a week doesn't sound very often for a liveaboard so use your battery monitor to make sure you never reduce your domestic battery bank to below about 50% of its capacity otherwise you inflict damage. Apologies if you already know this - not trying to teach my granny to suck eggs.

 

Thanhs for the info everyone.

I,ve got a sterling advanced digital 4 step switch mode charger , what ever that all means.

I,m sorry if I didnt make myself clear. Most of my charging is done by the engine,s 100 amp alternator but once a week or so I bung the genny on to do my washing and hoovering.( I know, but I,ve got a new springer pup)

The battery bank is 440 and after about 2 hours cruising its down to about 3amps going in, then if the genny go,s on, it gets below 2 then onto float. I do sometimes flick the charger off then on and I do get a bit more going in.

My main power usage is a 240 telly on freesat. I,m thinking about changing to 12v but would need a freeview tv and new aerial unless I go down the 12v freesat tv which is around £400, I think.

My tv at the minute takes about 4 1/2 amps including the inverter.

 

Cheers, Paul.

[blackrose]

Which model of Sterling are you both using?

 

Mine is the Pro-Digital. I have two, a 30 amp and a 40amp. I use both at the same time from the generator (the equivalent of a 70amp charger), and just the 30amp when on shore power which stays on permanently.

 

http://www.sterling-power.com/products-chargers-prodigital.htm