Batteries and living aboard

[MtB]

However I think it would be reasonable to say that any sized battery bank (of the same technology) takes the same amount of time to recharge, PROVIDED the charging equipment is optimal. This is because the time it takes for the charge to propagate throughout the plates is reasonably constant.p and independent of bank capacity.

 

Therefore with a small bank and charger, one has to charge every day, and then say do a long charge once a week to ward off sulphation. With a much bigger bank, the weekend charge takes the same amount of time but there is no need for daily charging - as I said, provided the charging equipment is scaled up accordingly.

 

 

Yes this broadly sums it up.

 

BUT, one question I can't resolve in my head is, once bulk charging has finished, and with a charging system optimised for the batteries but charge current declining, how long does it take to reach a tail current of 1% when I do my 'proper' charge at the weekend?

 

Your post above (sort of) implies it will be much the same for any set of batteries with and optimum genny and charger.

[nicknorman]

Yes this broadly sums it up.

 

BUT, one question I can't resolve in my head is, once bulk charging has finished, and with a charging system optimised for the batteries but charge current declining, how long does it take to reach a tail current of 1% when I do my 'proper' charge at the weekend?

 

Your post above (sort of) implies it will be much the same for any set of batteries with and optimum genny and charger.

Yes I can't see why it wouldn't be the same, all other things being equal. Whether you have one battery, or 10 of the same batteries in parallel, is not going to affect the time it takes for each one to reach 1% presuming the charger is up to the job.

[Sir Nibble]

Nife batteries last seemingly for ever. The electrolyte deteriorates eventually but when you change it you've got new batteries again. The major drawback is that they are only about 70% efficient and would probably exacerbate the problem. The electrolyte is nasty stuff too, a violently powerful alkali called potassium hydroxide.

[WotEver]

How long it takes is probably going to be 6 hrs+

 

Tony

[peterboat]

That's good to hear, but you are in the fortunate position of being able to take good care of your batteries whereas Mike's work commitments don't allow adequate charging during the week.

It is possible a bigger bank of batteries which would take longer to over discharge and so last the working week and then be recharged at the weekend would help his battery life, but the downside is he would be spending a lot of his weekend battery charging............

my system is automatic the wispergen comes on by timer and off by timer so as well as heating the boat it charges at 70 amps max per hour it comes on twice a day in the winter. it can also have an auto setting where it comes on when batteries are down to a set level. they come in 24 volt models as well

[OldGoat]

 

Interesting! I hadn't heard of them until you posted.

 

Bimble flog 'em http://www.bimblesolar.com/nifebatteries

 

£1k for a 12v 200Ah bank that will last 40 years while you beat the hell out of it. I think that looks pretty attractive!

 

You've obviously been ignoring my posts - I've bee wittering on about them for years but nobody listens, sniff.

 

The issue with Nickel batteries is that they need a different charge regime from the standard Lead Acid chemistry so you would need to get the power from the alternator controlled by a different regulator.

 

I thought so and spent loadsa' monai in getting Adverc to modify their software for me. It transpires recently that all they did was to raise the voltage level slightly (Most equipment will tolerate up to 31V, so that's the setting

 

 

 

We keep being told that things will last 40 years, or lights will last 60,000 hours, or similar... yet these things havent existed long enough for us to know whether it could be true, or mere marketing puffery??

 

No it's not Bullsh-- - my set is probably 30 years old or even more; I've had them for twenty.

There are downsides:-

• Size,
• Weight
• New cost
• Inefficiency - need more power in
• relatively large voltage swings - mine run from 27V down to 22; would go lower but the fridge cuts out...
• (Higher) internal resistance
• Used cells are very hard to find

 

 

Upsides

• Difficult to destroy
• Can be left for ages at any state of charge
• Large excess electrolyte storage - don't really need topping up a lot

[bizzard]

All this is enough to make yer electrolyte boil.

[Paul C]

A fuel cell would do the job, albeit at a price

 

http://www.fuelcellsystems.co.uk/shop/SFC_Fuel_Cells.html

[peterboat]

A fuel cell would do the job, albeit at a price

 

http://www.fuelcellsystems.co.uk/shop/SFC_Fuel_Cells.html

they need to get better and cheaper to run

[MtB]

A fuel cell would do the job, albeit at a price

 

http://www.fuelcellsystems.co.uk/shop/SFC_Fuel_Cells.html

 

 

The Big Problem with those is the fuel. They run on methanol, not widely available from marinas and fuel boats.

 

Also, costs £4.38 a litre!

[MtB]

Yeah, Mike's problem (in the winter) is that he can't really use any worthwhile amounts of leccy at all.

 

Forget charging regimes (he doesn't (can't) have one), forget bank size.

 

Forget any kind of monitoring too - he already knows the answer.

 

 

 

So, getting back on topic, yes this is the problem. Now some more thinking aloud...

 

The problem is I get very little generator or engine running time between the hours of 8am and 8pm. But I still get some!

 

So I'm back to the idea in my other thread. Bulk charge my leisure bank using the genny powering the 24v 12a charger, and at the same time bulk charge a single 12v donkey battery with my 12v charger (can't remember the currrent rating) from the same genny at the same time.

 

Then once absorption is reached or 8pm or work time any number of reasons to stop the genny, connect the 12v donkey battery to the "Boost Converter Step-up Module" suggested by Nick the other day (which I purchased), and dial up an output of say 28.8v and connect it to my part charged leisure set and leave it to carry on charging silently.

 

Given my 24v domestic bank is totally goosed I'm fairly sure my reasonable donkey battery will cope for a few hours. If all that works as planned, I'll buy a new set of bargain basement leisures and see how charging them the same way works out.

 

The "Boost Converter Step-up Module" will need careful monitoring though, given the low price is I would imagine, inversely proportional to the likelihood of it spontaneously combusting...

[cereal tiller]

 

 

 

So, getting back on topic, yes this is the problem. Now some more thinking aloud...

 

The problem is I get very little generator or engine running time between the hours of 8am and 8pm. But I still get some!

 

So I'm back to the idea in my other thread. Bulk charge my leisure bank using the genny powering the 24v 12a charger, and at the same time bulk charge a single 12v donkey battery with my 12v charger (can't remember the currrent rating) from the same genny at the same time.

 

Then once absorption is reached or 8pm or work time any number of reasons to stop the genny, connect the 12v donkey battery to the "Boost Converter Step-up Module" suggested by Nick the other day (which I purchased), and dial up an output of say 28.8v and connect it to my part charged leisure set and leave it to carry on charging silently.

 

Given my 24v domestic bank is totally goosed I'm fairly sure my reasonable donkey battery will cope for a few hours. If all that works as planned, I'll buy a new set of bargain basement leisures and see how charging them the same way works out.

 

The "Boost Converter Step-up Module" will need careful monitoring though, given the low price is I would imagine, inversely proportional to the likelihood of it spontaneously combusting...

Don't lose sight of the fact that your Step up module is a converter and NOT a charger.

 

Have used one of that type for Equalising Batteries when the Charger has gone into Float so the current becomes a mere handful of amps.

 

CT

[MtB]

Don't lose sight of the fact that your Step up module is a converter and NOT a charger.

 

Have used one of that type for Equalising Batteries when the Charger has gone into Float so the current becomes a mere handful of amps.

 

CT

 

 

What would you suggest is a more appropriate device for final charging a 24v bank from a 12v battery?

[smileypete]

I doubt there is any easy cheap off-the-shelf way to solve this problem.

 

One way out may be to have 2 (for 24v - pairs of) batteries then using eg a 1 2 both switch charge both pairs together but use one pair for the loads. Then when the /other/ pair is /fully/ charged, switch the loads to the other pair and so on.

 

If there is a decent reliable genny available it may even be possible to forego the starting battery (for 24v -pair).

 

By doing this it may even be possible to breathe some life into the tired batteries somehow by using some sort of equalization which may depend on the battery type (which I believe Mike has not yet told us.)

 

cheers Pete.

Edited January 15, 2016 by smileypete

[nicknorman]

Don't lose sight of the fact that your Step up module is a converter and NOT a charger.

 

Have used one of that type for Equalising Batteries when the Charger has gone into Float so the current becomes a mere handful of amps.

 

CT

 

Within the context, I don't think that matters. The voltage will remain at the "absorption" voltage set by mike, say 29.6v, until he turns it off but that won't be unduly late. If by some miracle it reaches 1% tail current while he's away, so what? It's not like he's going to be leaving it on for days or weeks. If you mean at the other end of the scale, it claims to be current limited so should be able to put out the 10A or whatever even if the batteries want more.

[DHutch]

The other thing to consider might be the regulation of the charger, ie at what voltage does the current start to decrease? Obviously it doesn't maintain 40A to 14.8v, but with "soft" (ie low gain) regulation it will reduce earlier, perhaps still in the 13.x range. With "harder" (higher gain) regulation it might get to mid -14s before the current reduces. Perhaps the regulation is unduly soft?

My technical knowledge of the details of this area are limited, but I have often wondered if it would be advantageous to effectively force the batteries to take more charge later in the cycle. And hence reflect the fact that if using a standalone petrol generator the compromise comes in a different place than if you where charging from the mains.

 

However, is that something which can be changed/adjusted on most chargers?

my system is automatic the wispergen comes on by timer and off by timer so as well as heating the boat it charges at 70 amps max per hour it comes on twice a day in the winter. it can also have an auto setting where it comes on when batteries are down to a set level. they come in 24 volt models as well

Mmmmm, whispergen...... lovely kit, but not cheap, and no longer available new to my knowlage.

 

 

Daniel

[nicknorman]

However, is that something which can be changed/adjusted on most chargers?

 

Daniel

No I don't think so. On our mastervolt charger you can separately adjust bulk, absorption and float voltages but the regulation is pretty soft. If you set a high voltage, that is only achieved once the current has become quite low. I suspect it helps battery life to not to try to stuff in the charge too quickly, which is fine for a mains/shore powered charger. However in the real world there is a compromise between battery life and genny running time.

 

I think some of the after market alternator regulators (sterling and Adverc) do have much higher gain such that max current is retained pretty much until the set voltage is reached, that suggests that they consider the possible slight reduction in battery life worth the time lopped off charging. This really only affects the mid-range part of,the charge cycle. Once the current has fallen off significantly and the voltage is stabilised at its regulated value, it still takes a good while to get the tail current down to 1% or whatever.

[matty40s]

Came home tonight and my bank is at 88%.☺

 

Lots more sun over the weekend too...

Edited January 15, 2016 by matty40s

[Arthur Brown]

Ultimately if you want to make the most of a short generator period than you have to get the biggest charger that your supply will start, even get two, charge with one charger til the rate falls a bit then add the second so that you don't stall the generator but do use all the petrol that you burn.

 

Even better cruise via a shoreline for a while and plug in overnight. The Unit cost of electricity will be dramatically cheaper than the petrol to run a generator.

[Sir Nibble]

Ultimately if you want to make the most of a short generator period than you have to get the biggest charger that your supply will start, even get two, charge with one charger til the rate falls a bit then add the second

And get zero increase in charge. Futility can be fun.

[cuthound]

My technical knowledge of the details of this area are limited, but I have often wondered if it would be advantageous to effectively force the batteries to take more charge later in the cycle. And hence reflect the fact that if using a standalone petrol generator the compromise comes in a different place than if you where charging from the mains.

 

However, is that something which can be changed/adjusted on most chargers?

No, it just results in excessive gassing, an increase in battery temperature and increased forces in the plates, all of which can significantly shorten battery life.

 

If you want it shorten the time taken to charge it is better to force more current incat the early part of the charge cycle, before gassing starts, although this too will slightly shorten ultimate battery life.

 

Edited to add the last paragraph?

Edited January 15, 2016 by cuthound

[WotEver]

Ultimately if you want to make the most of a short generator period than you have to get the biggest charger that your supply will start, even get two, charge with one charger til the rate falls a bit then add the second...

Ummm... No.

[Dalslandia]

Here is a lot of interesting read on different battery and charging

 

http://www.solar-electric.com/deep-cycle-battery-faq.html

​

[by'eck]

My technical knowledge of the details of this area are limited, but I have often wondered if it would be advantageous to effectively force the batteries to take more charge later in the cycle. And hence reflect the fact that if using a standalone petrol generator the compromise comes in a different place than if you where charging from the mains.

 

However, is that something which can be changed/adjusted on most chargers?

 

 

Daniel

 

Increasing the absorb voltage achieves this to some degree but ultimately as the batteries approach full charge, gassing would occur which limits the current they would/could take by increasing the resistance near the plates surface, so it works against you.

 

Cycling charger off/on when its reached float stage will put it back in bulk then absorb phase for some time at least and squeeze a little more current in. This is maybe where the older multi-stage chargers scored as they had a manually adjustable timed absorb phase at the higher selected voltage before dropping to float. Current ones typically calculate the absorb time automatically and probably in an attempt to be kinder to batteries, switch to float voltage prematurely.

[OldGoat]

Here is a lot of interesting read on different battery and charging

 

http://www.solar-electric.com/deep-cycle-battery-faq.html

​

Greenie for that -

IMHO the article explains all? the points in an understandable format.

Not particularly - in the case of this thread - the results of various rates of charge in relation to the 100 hour rate.