Battery confusion

[Kantara]

I am getting very conflicting information about batteries, with some people telling me that they are best kept topped up (some keep their charger on 24/7 when on a shore line) and others saying it is best to deplete them regularly to avoid them "forgetting" how to retain charge. Faced with these two sets of advice, I have opted for the latter practice. The boat had new batteries back at the end of August, but we have not run the engine for more than a few days of cruising, so we are on 240v most of the time. I have read that when the voltage across the batteries drops to below 12v, it is time to charge them. So, this I do. I switch on my charger to run for two hours. In that time, it runs through phases building up to 14.6v, and than back down to around 13.2. But I find I need to do this every day, and this surprises me. We are running a central heating pump now for most of the day, plus the water pump for nothing more than normal use. I checked the batteries, and the fluid levels are fine (on the 50% of the cells that I can see into!). Please can someone authoritative and experienced out there help a confused, concerned noob?

[Robbo]

Your screwing your batteries, keep them on a 3 stage charger when ever possible if on a shore line. The other advice is incorrect and I'm guessing you got it from laptop/phone "experts"?

Edited November 9, 2011 by Robbo

[bottle]

Kantara

 

Batteries do not like to be left dischraged, they like to be fully charged (and not used)

 

If you are on shoreline and you charger is a 'three stage' charger then leave it on all the time.

 

Here are two sites that will answer all your questions:

 

http://www.batteryfaq.org/

 

http://www.smartgauge.co.uk/technical1.html

[Alan de Enfield]

......it is best to deplete them regularly to avoid them "forgetting" how to retain charge.

 

I think this advice refers to Ni-Cad batteries that should be 'flat' before re-charging - or they do retain a 'memory' and will not take a full charge.

[Nickhlx]

Your screwing your batteries, keep them on a 3 stage charger when ever possible if on a shore line. The other advice is incorrect and I'm guessing you got it from laptop/phone "experts"?

 

Assuming you have "conventional lead acid" wet cells or AGM batteries, I second Robbo - you should only deep cycle Ni-Cad batteries - even NiMH and Li-Ion should avoid being deep cycled, so it is old and inappropriate advice you were given.

 

Moreover you should replace depleted charge asap and should not run batteries down to more than half capacity for preserving longevity - every discharge takes a bit of life out of the battery (bank) and typical quoted "lives" are around 100 cycles for cheaper / starter batteries, around 500 cycles for "average" batteries, and ballpark 1200 cycles for Trojan / US Batteries

semi-traction types.

 

Keep the batteries fully charged / on float, deplete to a max of 50%, keep topped with distilled water (never tap) if not sealed, and re-charge as soon as possible after discharge. Never leave discharged for any longer period than you have to.

 

Hope that helps

 

Nick

[Bob18]

As others have said, batteries need to be kept charged, and as near fully charged as you can get.

 

A decent multi-stage charger will do this for you, by charging rapidly when needed, and just trickle charging when needed.

 

So assuming you are in a position to have the charger on 24/7, and its a multi-stage charger then leaving it on all the time will ensure your batteries are in the best possible state.

 

 

 

 

Two things to know:

First is that batteries take a long time to charge properly, the first stage only puts a charge on the surface of the plates, the next stage(s) ensure that the charge is "forced" into the whole of the plate.

Second batteries discharge themselves with time, how fast they do this depends on lots of things, the longer you leave a battery not being looked after the longer it will take to get back to health, and more likely it is to have suffered some damage.

 

 

 

 

 

(I say multi-stage because not all battery or charger manufacturers use the same names for the different charge stages, three is the minimum, and a good charger will vary the time spent in each stage depending on the condition of the battery)

[deletedaccount]

I think this advice refers to Ni-Cad batteries that should be 'flat' before re-charging - or they do retain a 'memory' and will not take a full charge.

 

this is also a myth

[Kantara]

Thanks for all of that, but how does this work out on the cut? Surely, the batteries will regularly get depleted every time the engine is off. What's the point of an inverter if one can't use the batteries without the engine running anyway? Why not then just use a 240v alternator for all domestic electrical needs? Is cruising condemning us to damaging our batteries, or are we advised to run the engine all evening as well?

[deletedaccount]

Thanks for all of that, but how does this work out on the cut? Surely, the batteries will regularly get depleted every time the engine is off. What's the point of an inverter if one can't use the batteries without the engine running anyway? Why not then just use a 240v alternator for all domestic electrical needs? Is cruising condemning us to damaging our batteries, or are we advised to run the engine all evening as well?

 

I run my engine once a day and try to keep them half full or better (12.2v). The older the batteries get the more and more this becomes a dream rather than reality. At two years old I frequently hit 11.8.

 

It's ok to use your batteries, that's what they're for. Just try not to deplete them too much before recharging. The more you batter then, the shorter their lifespan. It's a balance between buying new batteries all the time and convenience really. Standard lead acids should last two years. More if you're really anal, less if you treat them badly.

 

Hope that helps.

[Nickhlx]

this is also a myth

 

I don't think so - The "myth" arose when people thought it "good" to run a pack down to very low volts - the problem with this is that along the way some of the weaker cells got reverse charged which IS very bad for them and then some thought, as the pack was then damaged, that (incorrectly) deep cycling Ni-Cad cells was bad for them. It isn't but cells should be individually deep cycled or individually monitored to avoid this.

 

Nick

[AlanM6]

I am just about to replace my charger with this one http://www.caravantechnology.com/Premium-Caravan-and-Leisure-25A-Charger-P112C15.aspx my old charger stopped working for some reason. The new charger has 5 mode settings 1=for lead storage battery 2=for gel battery 3=sutible for recharging lead storage battery which is in good condition and completley disconnected from the devices it runs 4=for recovery of sulfated(aging) gel battery 5=for recovery of sulfated(aging)lead storage battery. given that my lead storage batteries are at least 2-3 years old am I correct in assuming that I should select mode 5

Thanks

[Nickhlx]

I am just about to replace my charger with this one http://www.caravante...er-P112C15.aspx my old charger stopped working for some reason. The new charger has 5 mode settings 1=for lead storage battery 2=for gel battery 3=sutible for recharging lead storage battery which is in good condition and completley disconnected from the devices it runs 4=for recovery of sulfated(aging) gel battery 5=for recovery of sulfated(aging)lead storage battery. given that my lead storage batteries are at least 2-3 years old am I correct in assuming that I should select mode 5

Thanks

 

I guess the user manual on use should be primarily the guidance that should be followed... Looking at the spec though it seems to switch to 15.3 volts for " sulphation and recovery modes". Depending on the type of battery you have, I would check that this is not dangerous for them, as overvoltage for too long on some types of batteries could cause a problem !

 

If good old conventional wet lead acid that you can top up when needed, they would be fine though...

 

Nick

[deletedaccount]

I don't think so - The "myth" arose when people thought it "good" to run a pack down to very low volts - the problem with this is that along the way some of the weaker cells got reverse charged which IS very bad for them and then some thought, as the pack was then damaged, that (incorrectly) deep cycling Ni-Cad cells was bad for them. It isn't but cells should be individually deep cycled or individually monitored to avoid this.

 

Nick

 

Interesting, but I was referring to the 'memory' myth associated with nicad/nimh. And it is a myth.

 

I read recently that it arose out of misinterpreting satalite battery usage data or somesuch. But that could also be a myth tbh

[Chris Pink]

I am just about to replace my charger with this one http://www.caravantechnology.com/Premium-Caravan-and-Leisure-25A-Charger-P112C15.aspx my old charger stopped working for some reason. The new charger has 5 mode settings 1=for lead storage battery 2=for gel battery 3=sutible for recharging lead storage battery which is in good condition and completley disconnected from the devices it runs 4=for recovery of sulfated(aging) gel battery 5=for recovery of sulfated(aging)lead storage battery. given that my lead storage batteries are at least 2-3 years old am I correct in assuming that I should select mode 5

Thanks

 

if you're going to stuff 15.3 volts into a battery then you want to monitor the temperature pretty closely and not to just leave it and go away.

 

I have often thought that this does look like a very nice battery charger, especially for the money.

 

i see it does have a battery temperature input but no indication if a sensor is supplied.

 

I would have liked to see some figures on their graphs in the spec sheets.

[Nickhlx]

Interesting, but I was referring to the 'memory' myth associated with nicad/nimh. And it is a myth.

 

I read recently that it arose out of misinterpreting satalite battery usage data or somesuch. But that could also be a myth tbh

 

I was only referring to Ni-Cad - and my opinion remains... so we'll have to agree to differ then...

 

Nick

[deletedaccount]

I was only referring to Ni-Cad - and my opinion remains... so we'll have to agree to differ then...

 

Nick

 

I think we're talking about different things tbh.

 

Here's what I'm talking about: http://www.aukweb.net/lights/martschg.htm

[WotEver]

this is also a myth

Indeed. I was about to post the same.

 

I think we're talking about different things tbh.

 

Here's what I'm talking about: http://www.aukweb.net/lights/martschg.htm

There are many more sites backing this up. Here's one at random: http://www.repairfaq.org/ELE/F_NiCd_Memory.html

 

Tony

[Nickhlx]

Indeed. I was about to post the same.

 

Oddly, I think we are agreeing - its more to do about one side saying memory effect in a pack is actually cell-reversal, and the other side saying it isn't because they don't discharge to the level where this occurs ( premature shut-off) but as individual cells in consumer applications don't get individually monitored, this is glossed over and the effect on the "whole" is being seen and reacted to / commented on...

 

On the other hand, reasoned debates aren't as much fun without mayhem and guns blazing (Bring back Chris W and Gibbo ?) Oooops...

although possibly more productive..

 

Nick

[Slim]

To go off on a slight tangent for a moment.

 

Does anyone know where I can buy an 'automatic cutoff' battery top up bottle?

 

Years ago I had one that I think was made by Tudor. Very simple in design you simply inverted it, stuck the spout into the individual cells, it went "glug glug" and stopped when the liquid was about 1/4 " above the plates.

 

My present batteries, which are budget AGMs are coming to the end of their useful life and I'm minded to replace them with wet cell ones. Topping them up would be difficult as they're tucked away under the side deck.

 

I've looked on E Bay but I can't find one.

 

Many thanks

 

 

Frank

[deletedaccount]

I quite like sealed because I'm utterly lazy and forgetful.

[Ark Right]

To go off on a slight tangent for a moment.

 

Does anyone know where I can buy an 'automatic cutoff' battery top up bottle?

 

Years ago I had one that I think was made by Tudor. Very simple in design you simply inverted it, stuck the spout into the individual cells, it went "glug glug" and stopped when the liquid was about 1/4 " above the plates.

 

My present batteries, which are budget AGMs are coming to the end of their useful life and I'm minded to replace them with wet cell ones. Topping them up would be difficult as they're tucked away under the side deck.

 

I've looked on E Bay but I can't find one.

 

Many thanks

 

 

Frank

Here

Cheers

A

[Nickhlx]

Here

Cheers

A

 

Complete with recommended improvement from (our?) Chris W himself !!

 

Nick

[Bob18]

Depending on the exact battery in use it is possible to get a centralised topping up system. There are tubes running to each cell from a central header tanks, you add water to the header tank, wait for the glugging to stop and all cells are topped up in one go. On some systems the header tank is left connected and filled so it all happens automagically, others you have to connect the header tank when you want to do a check/top-up.

Upside is obvious, down side is you can't see if one cell is being greedy.

 

Of course these only really work with wet cell batteries, and do require the use of the correct battery caps to stop muck getting into the battery, or electrolyte escaping.

[WotEver]

I quite like sealed because I'm utterly lazy and forgetful.

I resemble that remark

[Proper Job]

To go off on a slight tangent for a moment.

 

Does anyone know where I can buy an 'automatic cutoff' battery top up bottle?

 

Years ago I had one that I think was made by Tudor. Very simple in design you simply inverted it, stuck the spout into the individual cells, it went "glug glug" and stopped when the liquid was about 1/4 " above the plates.

 

My present batteries, which are budget AGMs are coming to the end of their useful life and I'm minded to replace them with wet cell ones. Topping them up would be difficult as they're tucked away under the side deck.

 

I've looked on E Bay but I can't find one.

 

Many thanks

 

 

Frank

 

Like this:

 

link