Club 80-90 Forums

Hello - I've been Googling and Wiki-ing for ages now trying to understand the best thing to do with the leisure batteries I have got.

A colleague at work advertised 2 identical gel filled, well cared for 110Ah leisure batteries for sale (only a tenner each - bargain!). We're going to Glastonbury next Wednesday and ideally I'd like to be able to use them to power mobile phone chargers, a laptop, lights, iPod charger, 240v speakers which we'll use in the awning and 12v lights, though obviously not all at the same time.

We've also got an 85Ah leisure battery and one of those Halfords portable power packs which we have previously used. It was good, but all ran out after a few days, although we had (and will again have) press/backstage access so we can plug it in to recharge, but it means lugging it from the van to the press office behind the Pyramid stage - a helluva way to lug a heavy box! We do have one of those Maplins solar panel briefcase kits which came with a little regulator box and a 12v socket. It wasn't very good at charging up anything - not even a little O2 XDA on a bright sunny day, but the regulator connected to the 85Ah battery seemed to do the trick.

Anyway, that's the hardware. I was wondering whether to get a 240v inverter and if so, which one. There's a branch of Maplins nearby and they're doing a 1000w inverter for £89.99 http://www.maplin.co.uk/Module.aspx?ModuleNo=224283" onclick="window.open(this.href);return false; but Q&A at the bottom of the page, its a modified sine wave device - is that a bad thing? I've tried to find out but am no wiser.

So, any thoughts on what would be a good set up? Will it be okay to use the little regulator than came with the solar briefcase panel with the big batteries? Is there a better regulator anyone can recommend? And any recommendations re inverters? And as for the batteries themselves, is it better to use them one at a time or is there any benefit in connecting them together in series or parallel? I will be using the batteries in the awning, so don't want to connect them into the circuitry in the van.

I have tried to find answers but am more confused than I was when I started and given the risks of getting electrical setups wrong, I thought it better to ask. However, if I have asked something which is written up somewhere else, I apologise now and hope someone can post the relevant links - please don't linch me, just point me in the right direction if there is one.

Many thanks,

JB (former member returning to the forum)

Most invertas are modified sine wave, for genaral use they work perfectly well only some sensative equipment can be affected by the modified sine wave. if you need to replicate mains electricity you will need a pure sine wave inverta but they are about three times the price for the same output.

If you are on the inside, can't you just drive into the compound. Either way, I would want a sack truck or one of those four wheeled rubber tyred trollies rather than carry the stuff.

grumpyoldgit wrote:If you are on the inside, can't you just drive into the compound. Either way, I would want a sack truck or one of those four wheeled rubber tyred trollies rather than carry the stuff.

Hello - thanks for the reply. We can camp with a tent only in the backstage hospitality area, or with the van in the family camper van fields. Only VIPs and big cheeses get to camp in vans in the backstage - not press. Also, the backstage is too noisy late into the night to camp with two little ones (we have one 6 month old and one 6 year old).

We've got a Just Kampers version of a Radio Flyer - I can transport the power pack and batteries in that if they need recharging, but obviously would rather not, lol.

The issues of whether or not to join the batteries up (and how), and what voltage regulator and so on are more of a concern though than recharging them - I'm guessing that three fully charged batteries should keep even us in power for the six days we are there - I just don't know what the best way to ensure that is, hence the appeal for advice

Cheers,

JB

bigherb wrote:Most invertas are modified sine wave, for genaral use they work perfectly well only some sensative equipment can be affected by the modified sine wave. if you need to replicate mains electricity you will need a pure sine wave inverta but they are about three times the price for the same output.

Hello - thanks for that. You've neatly answered something that I couldn't find out from an afternoon of searching. Much appreciated!


Cheers,

JB

The Broons wrote:

grumpyoldgit wrote:If you are on the inside, can't you just drive into the compound. Either way, I would want a sack truck or one of those four wheeled rubber tyred trollies rather than carry the stuff.

Hello - thanks for the reply. We can camp with a tent only in the backstage hospitality area, or with the van in the family camper van fields. Only VIPs and big cheeses get to camp in vans in the backstage - not press. Also, the backstage is too noisy late into the night to camp with two little ones (we have one 6 month old and one 6 year old).

We've got a Just Kampers version of a Radio Flyer - I can transport the power pack and batteries in that if they need recharging, but obviously would rather not, lol.

The issues of whether or not to join the batteries up (and how), and what voltage regulator and so on are more of a concern though than recharging them - I'm guessing that three fully charged batteries should keep even us in power for the six days we are there - I just don't know what the best way to ensure that is, hence the appeal for advice

Cheers,

JB

And there was I thinking you were some sort of swanky bigwig that I could rub shoulders with!

At the Sunrise Festival at The Big Chill last year they seemed to be using batteries individually while the others were charging up on solar. I know this as half way through a performance one night everything failed and we had to sit in the dark for a few minutes while batteries were realigned. Perhaps you would be safer having one on charge at any time while the others were being used set up in parallel to give you increased capacity.

See example of batteries connected in parallel http://www.nyc-arecs.org/Connecting_Bat ... rallel.pdf

Get a fold-up sack barrow. Soon have the battery there and back with that.

Re: connecting batteries up...

Whatever you do, DON'T connect the batteries up in series! Unless you have equipment that is designed specifically for use in a 24 Volt system like in a truck (and you probably don't, because that equipment would be useless in a 12 Volt system) you will seriously cook it, and probably yourself in the process.

As for connecting batteries in parallel, I see little point. All that gives you is the ability to deliver more current. But a single, bog-standard, car battery can already supply several hundred amps. You won't need more than that.

The most you'll need is if you're running the 1kW inverter. If 100% efficient, it will pull 83.333 Amps. But realistically, nothing's that efficient, you'll probably need about 100 Amps. All the other equipment that you might plug in, even all at the same time, won't come anywhere near that.

So you won't need more than 100 Amps, and one battery can do that on its own. But what about the inverter AND everything else together? Well, the answer to that is simple, dedicate one battery to the inverter alone.

A 100Ah battery can supply (in theory) 100A for 1 hour, or 200A for 1/2 hour, or 400A for 1/4 hour, etc... However, what really happens is that as the battery runs down the voltage starts to drop, and most inverters will cut off when the supply drops below 10 Volts, so you'll never get the full time that you'd expect based on the above type of calculation. Its more like 50%. So that 1kW inverter will only run for 30 minutes off a 100Ah battery. After that, you'll need to charge the battery up again. And I guess going for a drive isn't really an option once you're camped up at a festy.

Because the inverter has the ability to discharge a battery so quickly, its best to dedicate a single battery to it, and make sure its NOT in parallel with anything else. Then you can still run all your other stuff off the other battery, of you accidentally leave the inverter on all night or something like that. I would keep them separate.

Another problem with connecting 2 batteries in parallel is that if one is low on charge, it will pull most of the available power from the other battery to charge itself up, until both batteries reach the same voltage. This means you won't get as much voltage from the parallel pair, compared to just the good battery on its own. Charging batteries up will also take longer if they are in parallel, because the charging current is usually quite low, it gets spread pretty thin... So its best to charge one up at a time and swap them over. One fully charged battery will be of more use to you than 2 half-charged batteries!

If you're taking 3 fully charged batteries out with you, and don't use the inverter too much (unless you want to leave another battery permanently on charge, backstage, and keep swapping them over) then you should be fine! And don't even bother with the solar charger, even the expensive ones don't touch the sides. For example Maplin sell a panel for 180 quid, rated at 18W which, at 12V, gives you 1.5A (max). An empty 100Ah battery will need about 60 hours of full sun, at that current, to reach full charge! Although if you are really serious about solar charging, they do sell even more expensive ones, going up to a 150W panel for £800

ambivert wrote:Re: connecting batteries up...

Whatever you do, DON'T connect the batteries up in series! Unless you have equipment that is designed specifically for use in a 24 Volt system like in a truck (and you probably don't, because that equipment would be useless in a 12 Volt system) you will seriously cook it, and probably yourself in the process.

As for connecting batteries in parallel, I see little point. All that gives you is the ability to deliver more current. But a single, bog-standard, car battery can already supply several hundred amps. You won't need more than that.

The most you'll need is if you're running the 1kW inverter. If 100% efficient, it will pull 83.333 Amps. But realistically, nothing's that efficient, you'll probably need about 100 Amps. All the other equipment that you might plug in, even all at the same time, won't come anywhere near that.

So you won't need more than 100 Amps, and one battery can do that on its own. But what about the inverter AND everything else together? Well, the answer to that is simple, dedicate one battery to the inverter alone.

A 100Ah battery can supply (in theory) 100A for 1 hour, or 200A for 1/2 hour, or 400A for 1/4 hour, etc... However, what really happens is that as the battery runs down the voltage starts to drop, and most inverters will cut off when the supply drops below 10 Volts, so you'll never get the full time that you'd expect based on the above type of calculation. Its more like 50%. So that 1kW inverter will only run for 30 minutes off a 100Ah battery. After that, you'll need to charge the battery up again. And I guess going for a drive isn't really an option once you're camped up at a festy.

Because the inverter has the ability to discharge a battery so quickly, its best to dedicate a single battery to it, and make sure its NOT in parallel with anything else. Then you can still run all your other stuff off the other battery, of you accidentally leave the inverter on all night or something like that. I would keep them separate.

Another problem with connecting 2 batteries in parallel is that if one is low on charge, it will pull most of the available power from the other battery to charge itself up, until both batteries reach the same voltage. This means you won't get as much voltage from the parallel pair, compared to just the good battery on its own. Charging batteries up will also take longer if they are in parallel, because the charging current is usually quite low, it gets spread pretty thin... So its best to charge one up at a time and swap them over. One fully charged battery will be of more use to you than 2 half-charged batteries!

If you're taking 3 fully charged batteries out with you, and don't use the inverter too much (unless you want to leave another battery permanently on charge, backstage, and keep swapping them over) then you should be fine! And don't even bother with the solar charger, even the expensive ones don't touch the sides. For example Maplin sell a panel for 180 quid, rated at 18W which, at 12V, gives you 1.5A (max). An empty 100Ah battery will need about 60 hours of full sun, at that current, to reach full charge! Although if you are really serious about solar charging, they do sell even more expensive ones, going up to a 150W panel for £800

Hi, Came here to post a question about inverter draw and longevity from a leisure battery after spending 3 hours studying said subject on interweb thingy and found the answer immediately & explained in a very understandable way! from your post . A BIG hearty thankyou Cheers MeDears , Nick.

grumpyoldgit wrote:

The Broons wrote:

grumpyoldgit wrote:If you are on the inside, can't you just drive into the compound. Either way, I would want a sack truck or one of those four wheeled rubber tyred trollies rather than carry the stuff.

Hello - thanks for the reply. We can camp with a tent only in the backstage hospitality area, or with the van in the family camper van fields. Only VIPs and big cheeses get to camp in vans in the backstage - not press. Also, the backstage is too noisy late into the night to camp with two little ones (we have one 6 month old and one 6 year old).

We've got a Just Kampers version of a Radio Flyer - I can transport the power pack and batteries in that if they need recharging, but obviously would rather not, lol.

The issues of whether or not to join the batteries up (and how), and what voltage regulator and so on are more of a concern though than recharging them - I'm guessing that three fully charged batteries should keep even us in power for the six days we are there - I just don't know what the best way to ensure that is, hence the appeal for advice

Cheers,

JB

And there was I thinking you were some sort of swanky bigwig that I could rub shoulders with!

At the Sunrise Festival at The Big Chill last year they seemed to be using batteries individually while the others were charging up on solar. I know this as half way through a performance one night everything failed and we had to sit in the dark for a few minutes while batteries were realigned. Perhaps you would be safer having one on charge at any time while the others were being used set up in parallel to give you increased capacity.

See example of batteries connected in parallel http://www.nyc-arecs.org/Connecting_Bat ... rallel.pdf

We were at The Big Chill last year too. I hated it - its the only festival I've been desperate to leave and thankfully we left early. Went to the Sunrise field - that was like a lovely little oasis of calm away from the main Big Chill festie which was just bad-bad-bad IMHO (very aggressive security and ridiculously heavy policing, £10 a time for 4 tiny little cans of Tiger beer, Bill Bailey in small tent, etc etc). Saw some great solar set ups in the Sunrise field - very inspiring! Made me want to go to Sunrise itself in 2009 but it clashed with Wychwood.

Cheers,

JB

ambivert wrote:Re: connecting batteries up...

Whatever you do, DON'T connect the batteries up in series! Unless you have equipment that is designed specifically for use in a 24 Volt system like in a truck (and you probably don't, because that equipment would be useless in a 12 Volt system) you will seriously cook it, and probably yourself in the process.

As for connecting batteries in parallel, I see little point. All that gives you is the ability to deliver more current. But a single, bog-standard, car battery can already supply several hundred amps. You won't need more than that.

The most you'll need is if you're running the 1kW inverter. If 100% efficient, it will pull 83.333 Amps. But realistically, nothing's that efficient, you'll probably need about 100 Amps. All the other equipment that you might plug in, even all at the same time, won't come anywhere near that.

So you won't need more than 100 Amps, and one battery can do that on its own. But what about the inverter AND everything else together? Well, the answer to that is simple, dedicate one battery to the inverter alone.

A 100Ah battery can supply (in theory) 100A for 1 hour, or 200A for 1/2 hour, or 400A for 1/4 hour, etc... However, what really happens is that as the battery runs down the voltage starts to drop, and most inverters will cut off when the supply drops below 10 Volts, so you'll never get the full time that you'd expect based on the above type of calculation. Its more like 50%. So that 1kW inverter will only run for 30 minutes off a 100Ah battery. After that, you'll need to charge the battery up again. And I guess going for a drive isn't really an option once you're camped up at a festy.

Because the inverter has the ability to discharge a battery so quickly, its best to dedicate a single battery to it, and make sure its NOT in parallel with anything else. Then you can still run all your other stuff off the other battery, of you accidentally leave the inverter on all night or something like that. I would keep them separate.

Another problem with connecting 2 batteries in parallel is that if one is low on charge, it will pull most of the available power from the other battery to charge itself up, until both batteries reach the same voltage. This means you won't get as much voltage from the parallel pair, compared to just the good battery on its own. Charging batteries up will also take longer if they are in parallel, because the charging current is usually quite low, it gets spread pretty thin... So its best to charge one up at a time and swap them over. One fully charged battery will be of more use to you than 2 half-charged batteries!

If you're taking 3 fully charged batteries out with you, and don't use the inverter too much (unless you want to leave another battery permanently on charge, backstage, and keep swapping them over) then you should be fine! And don't even bother with the solar charger, even the expensive ones don't touch the sides. For example Maplin sell a panel for 180 quid, rated at 18W which, at 12V, gives you 1.5A (max). An empty 100Ah battery will need about 60 hours of full sun, at that current, to reach full charge! Although if you are really serious about solar charging, they do sell even more expensive ones, going up to a 150W panel for £800

What a fantastic post! Many, many thanks for that - your advice is most helpful and very much appreciated

*buys ambivert virtual pint*


JB