It's not as simple as that - there are potentially complex questions as to whether the particular combination of inverter and load are compatible. Some inverters are, staying polite, "not as good" as others - and while they may run something light a light of universal motor (light hand tool) OK, they may not cope with a complex load from a poorly designed switch mode power supply. So the results may be anywhere in a spectrum that ranges from "no problem at all" to "who let the smoke out ?".
Pump Conundrum
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I'd definitely be looking at a decent DC-DC power supply. I built one to run a pc in a car once upon a time. No problems at all and far more efficient!
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Think I'll be going with the DC lead from the manufacturer, costly though it is.
It's a two part thing, luckily supplied separately, the second item is a pair of croc clips with a short length of flex feeding a ciggie lighter socket. There's a fuse in the +ve line.
They want £28.80 + VAT for it.
Now, I've Googled, and there are a few around, but they all look cheap and nasty and none seem to be fused.
Maybe I could make my own.....
It's a two part thing, luckily supplied separately, the second item is a pair of croc clips with a short length of flex feeding a ciggie lighter socket. There's a fuse in the +ve line.
They want £28.80 + VAT for it.
Now, I've Googled, and there are a few around, but they all look cheap and nasty and none seem to be fused.
Maybe I could make my own.....
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Caterpillar made 8v batteries to give better starting and lights on their old track laying machines in the days of donkey engine start. Starting at a slightly higher voltage gives room for the 0.6 volt drop on a power transistor but with a 12 volt battery which will be up to 14.8 volt when charged with a step charger there is not enough voltage to start with to use simple regulation to control it.
The only way to get 12 volt from a 12 volt battery over it's voltage range of 11.5 to 14.8 volts is to first step it up. It would be a good project but unless doing it for the fun of doing it then likely buying ready built unit is the way to do it.
I had same problem in reverse when I wanted to stop overcharging leisure batteries used in a caravan. The cheap battery charger over charged the batteries but to buy just the transformer to build a regulated battery charger was more then the whole battery charger cost. But putting a 2N3055 transistor in the supply even when turned fully on reduced the output from an 8 amp charger to 0.5 amp. The method I used was to build a system similar to that used on the old wind chargers which just turned the excess into heat.
As to supplying a switch mode power supply from an inverter well my laptops have not had a problem even with a modified sin wave inverter which is in essence the same as you wanted to do.
However charging my mothers mobility scooter was not successful. I tested the idea before going on holiday scooter charger plugged into inverter in the car and all seemed to work A1. However when on holiday it failed. I think the scooter charger was a step charger and first test it was on float charge mode so current draw was low. But once the batteries were discharged a little it went into full output mode which overloaded the inverter.
I had of course checked the wattages and it should have worked. As it was the inverter was bought really to use the PC so not really worried but had I got it just to charge scooter I would have been upset.
So if you already have an inverter I would give it a go. But if you need to buy the inverter special then I would play safe and buy ready made unit.
The only way to get 12 volt from a 12 volt battery over it's voltage range of 11.5 to 14.8 volts is to first step it up. It would be a good project but unless doing it for the fun of doing it then likely buying ready built unit is the way to do it.
I had same problem in reverse when I wanted to stop overcharging leisure batteries used in a caravan. The cheap battery charger over charged the batteries but to buy just the transformer to build a regulated battery charger was more then the whole battery charger cost. But putting a 2N3055 transistor in the supply even when turned fully on reduced the output from an 8 amp charger to 0.5 amp. The method I used was to build a system similar to that used on the old wind chargers which just turned the excess into heat.
As to supplying a switch mode power supply from an inverter well my laptops have not had a problem even with a modified sin wave inverter which is in essence the same as you wanted to do.
However charging my mothers mobility scooter was not successful. I tested the idea before going on holiday scooter charger plugged into inverter in the car and all seemed to work A1. However when on holiday it failed. I think the scooter charger was a step charger and first test it was on float charge mode so current draw was low. But once the batteries were discharged a little it went into full output mode which overloaded the inverter.
I had of course checked the wattages and it should have worked. As it was the inverter was bought really to use the PC so not really worried but had I got it just to charge scooter I would have been upset.
So if you already have an inverter I would give it a go. But if you need to buy the inverter special then I would play safe and buy ready made unit.
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As a P.S. some inverters have charger built in clearly designed as UPS I would guess these would work better for you.
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The company claim their own (grossly expensive battery) at 14.4Ah (odd size!) will run the air pump for 20 hours at a rate slightly reduced from maximum air flow.
By that reckoning, assuming I connect direct, I should easily get 24 hours full use from a 75 or 90 Ah battery.
I want a bigger one so I can use its capacity for other things.
Moving on, what do people rate for leisure batteries, brand-wise?
I can get a Numax 100Ah for £54.
Or a Numax DP 110Ah for £70: Not sure what the difference is here, apart from increased capacity, also has 3 year warranty.
Alphaline for £95: 125Ah. - 4 year wty.
By that reckoning, assuming I connect direct, I should easily get 24 hours full use from a 75 or 90 Ah battery.
I want a bigger one so I can use its capacity for other things.
Moving on, what do people rate for leisure batteries, brand-wise?
I can get a Numax 100Ah for £54.
Or a Numax DP 110Ah for £70: Not sure what the difference is here, apart from increased capacity, also has 3 year warranty.
Alphaline for £95: 125Ah. - 4 year wty.
If you get a sealed battery you don't have to be so careful carrying it, or check electrolyte levels every time it gets moved (eg if someone else is moving it...). Presumably safer too, no acid to spill out. Apart from that Numax 100Ah @ £54 sounds a good price, but non-sealed I'm guessing. Other than looking into actual v stated performance (can't help there except to say get a quality brand...Numax seem good) you might want to compare size, weight, and how easy it is to carry (the smaller lighter ones typically cost more).
You might get a decent battery at a scrapyard (take a voltmeter) but you would need to charge and test/drain it. The big ones (more Ah) go quickly.
You might get a decent battery at a scrapyard (take a voltmeter) but you would need to charge and test/drain it. The big ones (more Ah) go quickly.
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£54 battery here: looks sealed....
http://www.batteries4leisure.co.uk/...h-LV26MF/42/?gclid=CPb53P3jo7YCFfLLtAodMxwABw
Good value, when same one at Go Outdoors is £90....
http://www.gooutdoors.co.uk/numax-100ah-sealed-leisure-battery-p96549
http://www.batteries4leisure.co.uk/...h-LV26MF/42/?gclid=CPb53P3jo7YCFfLLtAodMxwABw
Good value, when same one at Go Outdoors is £90....
http://www.gooutdoors.co.uk/numax-100ah-sealed-leisure-battery-p96549
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Batteries are made as two major types. The traction battery designed for deep cycling and the car battery designed for high amps. The leisure battery is a hybrid where it's not as good as a traction battery at keeping the active material on the plated but better than a car battery. But is can give more amps than traction battery but not as many as the car battery.
A traction battery would last longer than a leisure battery and the leisure battery will last longer than a car battery. But where you are doing some deep cycling of a battery one also needs a way to recharge it quicker than with a simple float charge.
So most battery chargers are what we call step chargers with a flat battery they give max output. As the battery voltage starts to rise they fix the voltage to a high value (14.8 volt) then as the current starts to drop they drop the voltage to a float voltage (13.2).
The problem is this process gets rid of water. Low antinomian (stuff used to stick spongy lead to plates) and water catchers can reduce the loss and the sealed battery has the advantage of not allowing the water which likely has a little acid into the atmosphere around the battery. But the open cells allow you to top them up so battery can last a lot longer.
On my sons boat where batteries were cycled he would top up once a month. With fork lift twice a week. With the leisure battery in the caravan it is used for maybe 4 weeks of the year and so really does not get much use or water loss.
Selecting the battery is very much dependent on the charger used. Today there are even pulse chargers where they sample the voltage between pulses. And of course what the battery is used for.
A milk float battery can last 7 years in spite of deep cycling. A Ni/iron used with buses and milk tankers can last 25 years.
If the battery is a back-up for a home built UPS then it will not be used much and a cheap sealed would do. If however it is regular cycled then look at a traction as used with golf trolley or mobility scooter.
There are many different types and the voltage on the step charger has to be set to match battery type. Also with a step charger putting too large of a battery on the charger can cause the charger not to go into float charge mode and so over charge the battery.
A traction battery would last longer than a leisure battery and the leisure battery will last longer than a car battery. But where you are doing some deep cycling of a battery one also needs a way to recharge it quicker than with a simple float charge.
So most battery chargers are what we call step chargers with a flat battery they give max output. As the battery voltage starts to rise they fix the voltage to a high value (14.8 volt) then as the current starts to drop they drop the voltage to a float voltage (13.2).
The problem is this process gets rid of water. Low antinomian (stuff used to stick spongy lead to plates) and water catchers can reduce the loss and the sealed battery has the advantage of not allowing the water which likely has a little acid into the atmosphere around the battery. But the open cells allow you to top them up so battery can last a lot longer.
On my sons boat where batteries were cycled he would top up once a month. With fork lift twice a week. With the leisure battery in the caravan it is used for maybe 4 weeks of the year and so really does not get much use or water loss.
Selecting the battery is very much dependent on the charger used. Today there are even pulse chargers where they sample the voltage between pulses. And of course what the battery is used for.
A milk float battery can last 7 years in spite of deep cycling. A Ni/iron used with buses and milk tankers can last 25 years.
If the battery is a back-up for a home built UPS then it will not be used much and a cheap sealed would do. If however it is regular cycled then look at a traction as used with golf trolley or mobility scooter.
There are many different types and the voltage on the step charger has to be set to match battery type. Also with a step charger putting too large of a battery on the charger can cause the charger not to go into float charge mode and so over charge the battery.
I'd agree pretty much with everything there, apart from one detail. The manufacturers no longer use the term "sealed" for the "dry" type batteries. They mostly use the term Valve Regulated lead Acid (VRLA) which is more accurate.
As you more or less state, even normal charging causes some of the water in the electrolyte to disassociate into hydrogen and oxygen - VRLA batteries have chemistry designed to promote recombination and (in theory at least) as long as you stay within specs then you don't lose any water.
In practical terms this is complete b***ocks. It's so difficult to actually use a VRLA battyer and stay within the limitations that their life it typically quite short - even the manufacturers only give (say) 5 years under good conditions, as little as 12 months if it's hot I swap quite a few UPS batteries out for customers at work - and often they've only been in service for a couple of years.
So there is a school of thought that involves unsealing the "sealed" battery and adding a tiny* amount of water. Whether you do this from new, or only when it's showing signs of loss of capacity is another matter. I often try this with the batteries I've pulled out of customers' UPSs - and often the addition of a few ml of water will revive them enough to make them usable for other less demanding tasks. If it doesn't work, then they get weighed in and the proceeds go in the kitty for the office Christmas do.
* I think the last ones I tried were something like 7Ah and I put about 3ml/cell into them.
For all the above reasons, I'd been looking into using forklift batteries for the big UPS at work. Trouble is that they start at "quite large" and when you need 120V (60 cells) then it becomes quite expensive and quite heavy. it would give us a great runtime though
As you more or less state, even normal charging causes some of the water in the electrolyte to disassociate into hydrogen and oxygen - VRLA batteries have chemistry designed to promote recombination and (in theory at least) as long as you stay within specs then you don't lose any water.
In practical terms this is complete b***ocks. It's so difficult to actually use a VRLA battyer and stay within the limitations that their life it typically quite short - even the manufacturers only give (say) 5 years under good conditions, as little as 12 months if it's hot
I swap quite a few UPS batteries out for customers at work - and often they've only been in service for a couple of years.So there is a school of thought that involves unsealing the "sealed" battery and adding a tiny* amount of water. Whether you do this from new, or only when it's showing signs of loss of capacity is another matter. I often try this with the batteries I've pulled out of customers' UPSs - and often the addition of a few ml of water will revive them enough to make them usable for other less demanding tasks. If it doesn't work, then they get weighed in and the proceeds go in the kitty for the office Christmas do.
* I think the last ones I tried were something like 7Ah and I put about 3ml/cell into them.
For all the above reasons, I'd been looking into using forklift batteries for the big UPS at work. Trouble is that they start at "quite large" and when you need 120V (60 cells) then it becomes quite expensive and quite heavy. it would give us a great runtime though
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I still have a hollow post drill for changing the cells on forklift batteries but only ever done it in the Falklands. The traction battery does come in smaller sizes we got three x 160AH batteries for my sons narrow boat but the problem when you try to increase the size is the charger.
Every battery has some internal leakage and the stage battery charger is designed to take that into account. They also have an emergency timer so if within a set time it has not gone into float charge mode it will drop into that mode anyway.
The boat battery charger would re-trigger the charge once the battery dropped below a set level but the fork lift charger would switch off and stay off until disconnected and re-connected again.
The Sterling battery charger which used pulses may be different but not so many of them around. And at 120A there is a need for some special method of regulating.
I have seen it so many times with narrow boats where the owner thought the more batteries the better but as a result they were never fully charged and lasted around one year instead of seven.
Using an alkaline battery is very different and they are stored flat rather than charged and leaving them flat will clearly not harm them except for crystal growth. But chemical memory can be a problem when left charged for a long time.
The new batteries are very different but here the problem is detecting when charged. With a single cell the Delta V charger works well but with a bank of cells it's hard to know when charged.
Every battery has some internal leakage and the stage battery charger is designed to take that into account. They also have an emergency timer so if within a set time it has not gone into float charge mode it will drop into that mode anyway.
The boat battery charger would re-trigger the charge once the battery dropped below a set level but the fork lift charger would switch off and stay off until disconnected and re-connected again.
The Sterling battery charger which used pulses may be different but not so many of them around. And at 120A there is a need for some special method of regulating.
I have seen it so many times with narrow boats where the owner thought the more batteries the better but as a result they were never fully charged and lasted around one year instead of seven.
Using an alkaline battery is very different and they are stored flat rather than charged and leaving them flat will clearly not harm them except for crystal growth. But chemical memory can be a problem when left charged for a long time.
The new batteries are very different but here the problem is detecting when charged. With a single cell the Delta V charger works well but with a bank of cells it's hard to know when charged.
Yep that one at £72 delivered incl VAT is decent. No secondary threaded terminals though and those handles will start hurting pretty quick carrying with one hand (a single chunky handle is better if transporting by hand)
As far as future requirements go... I use inline fuses, battery clamps
http://www.vehicle-wiring-products.eu/VWP-onlinestore/battconns/photo/b167n.jpg
and (not ideal but) 16A click JB's
http://www.tlc-direct.co.uk/Products/TLCT100C.html
wired 1jb (3 terminals...48A) for each cable. Make up fused leads as required. Have also used 'outdoor' flex connectors.
http://www.tlc-direct.co.uk/Products/TLRC3.html http://www.tlc-direct.co.uk/Products/TLRC3.html
but seems wrong as I think they have a standard pin pattern so could be misused, also rated lower even though they seem more substantial than the 16A click's.
Plug-and-play, no hassle in the field (especially if it IS a field!), no chance of croc clips making a poor connection under high load or getting dislodged. Add and remove loads easily without disturbing other gear. No temptation to piggy-back croc clips as the clamp is fully covered (but get one with dual terminals anyway...only crimp, crimper, and spanner required to add something on-the-fly, or a high load like an inverter. Clamps come off easily for transport, storage etc (or set up split charge (one relay) wiring in your van (if you have one) and clamp it in there when not in the field - i've switched my interior lights, power (12 sockets) and stereo circuits over to avoid accidental main battery drain and stereo switching off when you switch off the engine (switch in cab)). You can also recharge your main battery from the leisure one if you do manage to drain the main one by accident.
The problem with click jb's is the lack of cord grip but this can be improved with a bit of improvisation.
Couldn't find a cheapish alternative for a plug & socket arrangement. Obviously ones that could be plugged in to standard 230/400v outlets would be unsuitable.
Worth getting one of these, very handy and you don't even have to get your voltmeter out to keep an eye on battery condition
http://www.halfords.com/webapp/wcs/..._productId_839075_langId_-1_categoryId_165489
Chop off the plug and wire to battery via preferred distribution method. It has mounting clips underneath.
A piece or pieces of plywood gives you something to mount things to and provide a flat surface if needed outdoors. You could get more elaborate with enclosures, and rain is a factor (got any spare umbrella's lying around?) but bits of ply suffice if weight etc if a factor.
As far as future requirements go... I use inline fuses, battery clamps
http://www.vehicle-wiring-products.eu/VWP-onlinestore/battconns/photo/b167n.jpg
and (not ideal but) 16A click JB's
http://www.tlc-direct.co.uk/Products/TLCT100C.html
wired 1jb (3 terminals...48A) for each cable. Make up fused leads as required. Have also used 'outdoor' flex connectors.
http://www.tlc-direct.co.uk/Products/TLRC3.html http://www.tlc-direct.co.uk/Products/TLRC3.html
but seems wrong as I think they have a standard pin pattern so could be misused, also rated lower even though they seem more substantial than the 16A click's.
Plug-and-play, no hassle in the field (especially if it IS a field!), no chance of croc clips making a poor connection under high load or getting dislodged. Add and remove loads easily without disturbing other gear. No temptation to piggy-back croc clips as the clamp is fully covered (but get one with dual terminals anyway...only crimp, crimper, and spanner required to add something on-the-fly, or a high load like an inverter. Clamps come off easily for transport, storage etc (or set up split charge (one relay) wiring in your van (if you have one) and clamp it in there when not in the field - i've switched my interior lights, power (12 sockets) and stereo circuits over to avoid accidental main battery drain and stereo switching off when you switch off the engine (switch in cab)). You can also recharge your main battery from the leisure one if you do manage to drain the main one by accident.
The problem with click jb's is the lack of cord grip but this can be improved with a bit of improvisation.
Couldn't find a cheapish alternative for a plug & socket arrangement. Obviously ones that could be plugged in to standard 230/400v outlets would be unsuitable.
Worth getting one of these, very handy and you don't even have to get your voltmeter out to keep an eye on battery condition
http://www.halfords.com/webapp/wcs/..._productId_839075_langId_-1_categoryId_165489
Chop off the plug and wire to battery via preferred distribution method. It has mounting clips underneath.
A piece or pieces of plywood gives you something to mount things to and provide a flat surface if needed outdoors. You could get more elaborate with enclosures, and rain is a factor (got any spare umbrella's lying around?) but bits of ply suffice if weight etc if a factor.
Skenk, would you like to edit your post and put the right image URL in there :
http://www.vehicle-wiring-products.eu/VWP-onlinestore/battconns/photo/b167n.jpg
It'll stop the forum expanding the page width to some stupid hard to read width.
There are a few low voltage connectors about, and what you use depends a lot on your needs.
The Anderson connectors are quite good, and (if used correctly) are not mate-able with the wrong voltage. However, many people use the wrong housings because they pick the colour for aesthetic reasons rather than to follow the manufacturer's recommendations. The different colour housings are not interchangeable by design - and that is used to prevent different voltages being connected together.
The 50A version is not too large, and they are unisex which means you don't need to worry about whether you have the right end of the cable when connecting things up.
Also on VWP's website (which doesn't seem to be working for me at the moment) are some smaller terminals which are similarly unisex - as in two of the same terminals plug together - but are smaller and can be built up into multipole connectors by clipping them together.
http://www.vehicle-wiring-products.eu/VWP-onlinestore/battconns/photo/b167n.jpg
It'll stop the forum expanding the page width to some stupid hard to read width.
There are a few low voltage connectors about, and what you use depends a lot on your needs.
The Anderson connectors are quite good, and (if used correctly) are not mate-able with the wrong voltage. However, many people use the wrong housings because they pick the colour for aesthetic reasons rather than to follow the manufacturer's recommendations. The different colour housings are not interchangeable by design - and that is used to prevent different voltages being connected together.
The 50A version is not too large, and they are unisex which means you don't need to worry about whether you have the right end of the cable when connecting things up.
Also on VWP's website (which doesn't seem to be working for me at the moment) are some smaller terminals which are similarly unisex - as in two of the same terminals plug together - but are smaller and can be built up into multipole connectors by clipping them together.
No width problem here, I is your browser set up correctly? I have edited though. Cheers for the Anderson connector tip, they look like the right thing for the job, haven't come across them before. Yellow for 12v then?
It's the same problem as when people post large images, the width of the page element gets expanded and then everything else stretches out. It's fixed now though.
Yes, it probably is the Yellow version for the Anderson (but I assume you've looked that up - it's a while since I've looked). You'll probably find they aren't as cheap and plentiful as red or grey as people seem to prefer choosing by colour and ignore the specs.
And VWP's site seems to be back from it's lie down, the other connector I had in mind is the Powerpole near the bottom here : http://www.vehicle-wiring-products.eu/VWP-onlinestore/connectors/multiconnectors.php
Yes, it probably is the Yellow version for the Anderson (but I assume you've looked that up - it's a while since I've looked). You'll probably find they aren't as cheap and plentiful as red or grey as people seem to prefer choosing by colour and ignore the specs.
And VWP's site seems to be back from it's lie down, the other connector I had in mind is the Powerpole near the bottom here : http://www.vehicle-wiring-products.eu/VWP-onlinestore/connectors/multiconnectors.php
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