silverback Posted August 13, 2014 Share Posted August 13, 2014 Hi all i am thinking of getting an inverter,but i'm abit nervous about things concerning electricity! so my thoughts are to connect directly to 1 of my batteries, a 1800w inverter, so that when i am travelling i can plug a laptop in to charge up and also other things like mobs, tablets etc, would my alternator be able to manage this extra stuff? also the wife needs to plug in her hairdryer at 1200w sometimes when we are "off grid" would this work? and for how long ? i have 2 x 110a/h battteries and a 80w sola panel so am i thinking on the right lines and anything else i should need to know cheers Jonathan Link to comment Share on other sites More sharing options...
sshortcircuit Posted August 13, 2014 Share Posted August 13, 2014 Pure sine wave for a hair drier, NO WAY, a simple inverter will do To charge a laptop, etc a 150w inverter would be more than adequate. Have yet to find a problem with charging using a cheap and cheerful inverter and consider the "pure sine wave" to be a sales hype. I am open minded on this topic. You can easily charge mobiles, tablets etc using USB adapters into cigarette lighter sockets which your alternator can more than adequately cope with. 1800w inverter will easily cope with the 1200w hair drier. How long is her hair and allow about 37 secs per inch :-> You will have no problems with your battery set-up Link to comment Share on other sites More sharing options...
silverback Posted August 14, 2014 Author Share Posted August 14, 2014 thanks Hamish there is alot of hair 8-) compare it to a dulux dog 8-) (lol) the pure sine wave is because thats what i have been reading from the "experts" 8-) for charging and using the laptop. so could you tell me if it has to be layed on the floor or can it be mounted vertically? yeh i do charge the other stuff with the 12v feeds and usb just thought it might be quicker with the inverter whist driving to destinations B-) the missus drys her hair over the gas fire whist off grid *-) and as you can imagine in the height of summer it gets hot !! in the van 8-) (lol) cheers jon Link to comment Share on other sites More sharing options...
sshortcircuit Posted August 15, 2014 Share Posted August 15, 2014 I have a 2000w inverter that is on its side attached to wall. Does not appear to matter as it is infrequent use and plenty of space to allow air to flow around. I have charged laptops, tablets all sort of phones, electric bike all from my 300w cheap and cheerful with no problems. I have read on forums that electric toothbrushes not to happy :-S Link to comment Share on other sites More sharing options...
lennyhb Posted August 15, 2014 Share Posted August 15, 2014 If going for a modified sine wave inverter you need to check what you want to power will work OK. A lot of what you would think we're simple electrical products actually have electronic switching built in. One item in this category is hair straighteners they will only work on pure sine. A lot of laptop power supplies will only work off pure sine or can be damaged on modified sine. We try and run everything off 12 v for the boss's hair drying I brought her a Babylyiss gas hair styler. Unless you are certain your items will run off a modified sine wave I would go for a pure sine wave one or it could work out a lot more costly. An 80 watt solar panel will be OK for mid summer use, I would look at adding 1 or 2 more panels for spring & autumn use. I don't think connecting to only one battery is a good idea, especially if they are connected in parallel for charging. Link to comment Share on other sites More sharing options...
artheytrate Posted August 15, 2014 Share Posted August 15, 2014 Same as ssortcircuit I've used cheap inverters for years and only problem I had was to destroy the wife's tooth brush charger. ( didn't try it with mine ) John. Link to comment Share on other sites More sharing options...
Brian Kirby Posted August 15, 2014 Share Posted August 15, 2014 silverback - 2014-08-13 9:43 PM Hi all i am thinking of getting an inverter, but i'm a bit nervous about things concerning electricity! so my thoughts are to connect directly to 1 of my batteries, a 1800w inverter, so that when i am travelling i can plug a laptop in to charge up and also other things like mobs, tablets etc, would my alternator be able to manage this extra stuff? also the wife needs to plug in her hairdryer at 1200w sometimes when we are "off grid" would this work? and for how long ? i have 2 x 110a/h battteries and a 80w sola panel so am i thinking on the right lines and anything else i should need to know cheers Jonathan An 1800W inverter at full capacity will create a load of approx 150A, so you'll need stout, short, cables to connect to the battery, with an appropriate fuse. I think you'd also need similar gauge cables linking the two batteries. The 1200W hairdryer will create a load of approx 100A. You have 2x110Ah batteries. Assuming the batteries are actually 110Ah capacity (there are many posts on here about claimed, and actual, battery capacities!), that they are fully charged to start, and that they haven't degraded with age, you could reasonably expect to take C 130Ah from them without causing damage. So, on the basis of my simple assumptions, you could run the hairdryer for a maximum of 1 hour 20 minutes. This makes no allowance for inverter efficiency, so in practice, less than that time. At the end of that time the batteries would be as low as it would be safe to take them, so you would need to begin to recharge them immediately. In truth, I doubt they would start fully charged, that they will be in "as new" condition, and (based on precedent) that they possibly may not be of the claimed capacity. So, maybe an hour? I don't know the rate at which an 80W solar panel would re-charge the batteries (maybe about 6.5A), but to fully replenish them would clearly take a number of hours (If my guess at the solar charge rate is roughly correct, about 20 hours): longer if you were using other consumers at the same time (lights, pump, water/space heater, TV, satellite dish etc). But, in practice, you'd probably have the hairdryer on for only about 5 minutes, which would consume about 8.5Ah from the battery, so easily achievable - if I'm right in my above assumptions. However, with any luck someone who really knows will soon be along to correct my undoubted mistakes. :-) I suspect, however, that because of the high rate at which the hairdryer would deplete the batteries, their ability to sustain that 100A load for more than a few minutes would become a limiting factor. Leisure batteries are designed for long, slow, discharge and the hairdryer load is not in that category. It might be worth getting some idea of whether the small item chargers you mention can be powered without damage from a modified sine wave inverter, and/or how much they'd cost to replace if damaged. You would then have a rough idea of whether to pay for pure sine wave or not. If you drop the hairdryer idea and are only wanting to charge the small items, then a much smaller inverter, as suggested by sshortcircuit, would also be much cheaper to buy whether pure, or modified, sine wave type. It would also require lighter cable and/or could reasonably be mounted further from the batteries. Now all we need is someone to correct my arithmetic, and fill in some of the gaps! :-) Link to comment Share on other sites More sharing options...
lennyhb Posted August 15, 2014 Share Posted August 15, 2014 A fair assumption Brian apart from your solar charge rate, you are working it out at 12 v instead of the charge voltage of around 14.5 v. Mid June a couple of hours either side of midday with completely clear sky you may get 5.5 amps realistically 3.5 - 4 amps for a few hours on an average summer day reducing quite rapidly the further the time moves away from midday. Link to comment Share on other sites More sharing options...
silverback Posted August 15, 2014 Author Share Posted August 15, 2014 many thanks to everyone, i,ve stuff to ponder :-S as always you've come up trumps :-D i think the wife is gonna need a haircut :D i'm gonna go for pure sine wave (for the hell of it) cannot fit anything else on the roof so extra sola is out, many thanks to all agan cheers jon PS... Brian ...you said in practice (the hairdryer) would only be on for 5 mins!! nope.... 20 mins min.. then hairspray then even dry that *-) so i've baffelled her with science and the conclusion is "i will make do with the gas fire" RESULT (!) Link to comment Share on other sites More sharing options...
lennyhb Posted August 16, 2014 Share Posted August 16, 2014 silverback - 2014-08-15 10:12 PM ... 20 mins min.. then hairspray then even dry that *-) so i've baffelled her with science and the conclusion is "i will make do with the gas fire" RESULT (!) Blimey Hairspray in the confines of a Motorhome, do you wear a gas mask? Could get interesting results if the hob is alight. (lol) Link to comment Share on other sites More sharing options...
silverback Posted August 17, 2014 Author Share Posted August 17, 2014 lennyhb - 2014-08-16 9:32 AM silverback - 2014-08-15 10:12 PM ... 20 mins min.. then hairspray then even dry that *-) so i've baffelled her with science and the conclusion is "i will make do with the gas fire" RESULT (!) Blimey Hairspray in the confines of a Motorhome, do you wear a gas mask? Could get interesting results if the hob is alight. (lol) :D yeh gas mask (lol) Link to comment Share on other sites More sharing options...
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