How long to charge batteries?

[Glynn]

Sorry, I forgot to add that the fridge & freezer (12v) were also on as they always are.

[ditchcrawler]

Sorry, I forgot to add that the fridge & freezer (12v) were also on as they always are.

Were they actually running when you measured the voltage, if so they would depress the voltage a bit.

[Glynn]

Not sure, I have 4 hours sailing tomorrow so I will take a reading before we go and a reading with nothing taking power an hours after getting there.

[ditchcrawler]

Not sure, I have 4 hours sailing tomorrow so I will take a reading before we go and a reading with nothing taking power an hours after getting there.

can you measure amps as well?

[GUMPY]

Ok well anyway, while you're at it please could you tell me how long a piece of string is?

 

But if you ask me which piece of string, I might sulk.

Yes its length is from end to end.

[MtB]

I think you'll find it is usually be half as long as twice its length...

[Glynn]

I can only read what the amps draw meter displays but yes I will.

[ditchcrawler]

I can only read what the amps draw meter displays but yes I will.

All info helps

[nicknorman]

All I can tell you at this time is that it was reading 14.4 volts when running near the end of our trip.

In that case I'd say that your batteries are totally knackered.

 

In order to add weight to that opinion it would be helpful to know the voltage profile when you start to charge. ie when the voltage has been down at 12.3, you start the engine, how does the voltage rise? Does it take several hours to reach 14.4 or does it get there fairly quickly, say within an hour? If the latter, your batteries are definitely goosed.

[Richard10002]

Glynn.... It would be worth spending a hundred quid or so on something like a NASA BM1 or BM2. This way you can see Amps, volts and cumulative AmpHours. Takes most of the guesswork out of it.

 

Alternatively, if you want a simple solution, with not much information, a Smartguage.

 

Both give the ideal monitoring solution.

 

In reality, we have no idea what is going on with your charging and your batteries

[Glynn]

OK, from charges after a 4 hr run and nothing demanding power the meter is reading 13.1 volts and 0 amps.

 

The meter from starting engine does quickly rise to 14.4 volts and within an hour.

[nicknorman]

OK, from charges after a 4 hr run and nothing demanding power the meter is reading 13.1 volts and 0 amps.

 

The meter from starting engine does quickly rise to 14.4 volts and within an hour.

So the charging sounds fine which means the batteries are shot, unless there is some high current discharge going somewhere that you don't know about (unlikely). Batteries can lose capacity big time, so that they behave like a much much smaller battery. So after charging, they may show a nice high voltage (the 12.9 or 13.1 you mention) but as soon as they are asked to give much current the voltage can quickly plummet.

[Glynn]

Not good for 2 year old batteries

[nicknorman]

Not good for 2 year old batteries

Not that surprising either. Batteries can be killed very quickly by undercharging / over discharging etc especially if they are standard leisure types. Anyway if you are liveaboard, 2 years is pretty good for Leisure batteries. Our leisure batteries were down to 1/2 capacity after 2 years of leisure use, which is why I now have Trojans!

[Glynn]

What size & how many Trojans do you have ?.

[Alan de Enfield]

Not good for 2 year old batteries

 

It is remarkably good if they have not been 'looked after' (meant in the nicest possible way).

There have been people on here reporting killing batteries within 2 months.

 

Batteries are disposable items and at £200 for 3 its only £2 week (and you will get £5-£10 each back for them from the scrap man)

What size & how many Trojans do you have ?.

 

It would be worth taking some time to learn about electrical 'stuff' (battery capacities, recharging, what is 'full' etc) as you can kill Trojans just as quickly as 'cheapo' batteries, by not doing correct charging regimes.

[nicknorman]

What size & how many Trojans do you have ?.

Four T105s giving 450 AH at 12v. The T105 is the best value but check you have the space, they are a different size from normal leisures. It is also a 6v battery so you have to have them in pairs, so you can have 225AH, 450 AH etc.

[ditchcrawler]

Not that surprising either. Batteries can be killed very quickly by undercharging / over discharging etc especially if they are standard leisure types. Anyway if you are liveaboard, 2 years is pretty good for Leisure batteries. Our leisure batteries were down to 1/2 capacity after 2 years of leisure use, which is why I now have Trojans!

We were just the same, pain in the but changing them so went for Trojans

Four T105s giving 450 AH at 12v. The T105 is the best value but check you have the space, they are a different size from normal leisures. It is also a 6v battery so you have to have them in pairs, so you can have 225AH, 450 AH etc.

Same again but 4 in series, we are 24 volt

[Guest]

In that case I'd say that your batteries are totally knackered.

 

In order to add weight to that opinion it would be helpful to know the voltage profile when you start to charge. ie when the voltage has been down at 12.3, you start the engine, how does the voltage rise? Does it take several hours to reach 14.4 or does it get there fairly quickly, say within an hour? If the latter, your batteries are definitely goosed.

That is how knackered batteries have behaved on my boat in the past; quick to charge, quick to discharge. The capacity is greatly reduced causing the to behave like much smaller batteries.

[BruceinSanity]

That is how knackered batteries have behaved on my boat in the past; quick to charge, quick to discharge. The capacity is greatly reduced causing the to behave like much smaller batteries.

And they gas very readily during absorption, which is where we came in...

[Guest]

And they gas very readily during absorption, which is where we came in...

Never actually noticed that, but it does seem feasible.

ps I never get more than two years out of "leisure" batteries (start batteries with handles.) Only ones I had that lasted approx 4 years were Yuasa ex-standby which were seriously heavier than "leisure" batteries. These were secondhand when fitted, lasted about 4 years, but when I came to replace they were prohibitively expensive.

Edited July 30, 2016 by Guest

[Richard10002]

What size & how many Trojans do you have ?.

I had 3 x Varta Hobby 110Ah batteries before my current set, (4 x Trojan T105).

 

After about 4 months, the capacity of the Vartas had dropped dramatically, such that I had a useable 100Ah maximum, but I persisted with them, charging almost every day on board, until they were 2 years old.

 

Prior to the Varta Hobbys I had 3 x 110Ah no name batteries which lasted only a short time before their capacity was significantly reduced.

 

I wrote on here and elsewhere that I seemed to be a battery killer

 

Having learned a lot about batteries in my first 4 years of narrowboat ownership, and a previous 5 years of owning a seagoing boat, I decided to give a set of Trojans a try.

 

A year in, and so far so good. They seem to like to be run down to less than 50% SOC, and to be charged hard at at least 15V then 15.5V for a few hours once they are full, (drawing less than about 4A).

 

So.. if I were you, I'd buy the battery monitors, play around with how things work with your current set of batteries, (or maybe buy 3 cheap 110Ah replacements), and see how you get on. You also need a means of charging at a variety of voltages, (which could be preset, or customisable).

[Glynn]

Which battery monitor would you recommend ? and do they simply connect to the battery bank ?.

[nicknorman]

Which battery monitor would you recommend ? and do they simply connect to the battery bank ?.

You're really good at asking questions with difficult answers!

 

Unfortunately there is no one gauge that does everything well..

 

There is the Smartgauge - it is really easy to install and great for giving the State of Charge during discharge. The state of charge is based on the actual battery capacity, not the badged capacity. So if you find the SoC dropping faster than it used to, you know your batteries are losing capacity. However it does not show current and it is not particularly good at telling you when to stop charging. If you are mostly static and thus want to run the engine for the minimum time, this is not the best for that. However if you normally cruise every day for reasonably long days, your batteries will be charged anyway and the Smartgauge is fine.

 

There are various amp-hour counting gauges, such as the BMV701. These measure current and try to work out the State of Charge but since they don't know the actual (as opposed to badged) battery capacity they are pretty hopeless at that and won't alert you to a loss of capacity (until the lights go dim!). They are harder to install than a Smartgauge, but still not too difficult. Because they measure current, they are great for telling you when you can stop charging, and also for checking that the charging system is working well and for monitoring how much current you are using.

 

In my view therfore, the best setup is to have both of these devices! But a cheaper compromise is to have a Smartgauge and an ammeter that shows current going in and out of the battery. You use the ammeter to know when the batteries are fully charged, and the Smartgauge to know when you need to start charging and also to give you an idea of battery health.

 

See this thread to get an idea how difficult it is to install a Smartgauge:

 

http://www.canalworld.net/forums/index.php?showtopic=86285&hl=

Edited August 1, 2016 by nicknorman

[MtB]

But a cheaper compromise is to have a Smartgauge and an ammeter that shows current going in and out of the battery. You use the ammeter to know when the batteries are fully charged, and the Smartgauge to know when you need to start charging and also to give you an idea of battery health.

 

 

I am coming to the conclusion I'd like an ammeter in addition to my SG, in preparation for when I buy some Trojans.

 

Which make and model of ammeter does the team recommend?