arthur49 Posted March 7, 2014 Share Posted March 7, 2014 Anybody taken an inverter off the starter battery rather than leisure battery (200Ah) and if so how did they get on? X250 PVC with standard starter battery - which I think is 85Ah Inverter is 1000w, to be used for 800w hairdryer - not mine - used 5 mins a day I'm told .... (Sterling B2B 45A being fitted) Reason for taking off starter battery is convenience only as its closer to desired installation point of inverter. Link to comment Share on other sites More sharing options...
Guest peter Posted March 7, 2014 Share Posted March 7, 2014 Don't do it. The starter battery is not designed to give a heavy load for sustained periods. You will eventually kill it, unless you also run the engine of course. Link to comment Share on other sites More sharing options...
Brian Kirby Posted March 7, 2014 Share Posted March 7, 2014 I agree with Peter, don't. It will draw about 85A when running, possibly more, and I think even your 200Ah habitation batteries will struggle at that load. Starter battery is, as Peter says, designed for high loads over short periods of time, habitation batteries are designed for low loads over long periods of time. What you are looking for is a high load over too long a period for the one battery, and too high a load over a fairly shotrt period of time for the other. Brambles will know far better than me, but there is a rule of thumb formula for relating maximum current draw to battery capacity, and I think 85/200 is probably outside what is wise. Link to comment Share on other sites More sharing options...
Tracker Posted March 7, 2014 Share Posted March 7, 2014 Agreed. Don't do it. Quite apart from all the theoretical stuff about damage to the battery you run the risk of having to push start your van as well as the theoretical possibility of disruption to the van engine electronics which would not only be inconvenient but possibly expensive as well? Much better to run it off the leisure batteries and even then personally I would run the engine whilst the inverter is banging 75 or so amperage out of them. And do make sure you have cables from batteries to inverter suitable for around 100 amps plus current to prevent overheating. One 200 ah leisure battery is better than two 100 ah but if you do have two I would take the positive for the inverter from one battery and the negative from the other to make both batteries work in tandem and not one as slave to the other. If you do choose to wire the inverter to one battery of a pair do make sure that the two are linked by the same 100 ah cable preferably with a 150 amp fuse on the positive to avoid the lightweight cable normally used from overheating with the potential for blown fuses at best and fire at worst. I use battery cables that can be purchased in various lengths with ring terminals already fitted from any motor factors. Link to comment Share on other sites More sharing options...
arthur49 Posted March 7, 2014 Author Share Posted March 7, 2014 Many thanks all ...... its back to the 12v hairdryer for her ........... Link to comment Share on other sites More sharing options...
Corky 8 Posted March 8, 2014 Share Posted March 8, 2014 The above is all good advice, I ,m considering fitting a 1500amp pure sine wave inverter for the same reason "wife's hair dryer " and charging my laptop, heres the advice from the people selling some inverters,Selecting inverter for right jobCheck the appliances you are going to use and find out by looking product label or manual how much power it draws in watts. Some appliances will give voltage and current consumption of appliance. To find out total power in watts just multiply them together. For example a Power drill is rated at 500W. For this we require 3 to 5 time power because it needs more power to startup (also known as inductive load). So inverter required will be between 1500W to 2500W.How much battery power required. If you want to run drill for 2 hours constantly then you will need 500w x 2 = 1000W. divide this by battery voltage 12v (or 24v) to get battery capacity required in AMPS. 1000W /12v = 83.33 Amps. No You do not need 83A or 85A battery because the inverter battery low alarm will kick in when battery falls below 50% and switch off. Battery capacity required will be 83.3 x 2 = 166Ah or 2 x 85Ah. If you are unsure contact us or speak to qualified electrician. Link to comment Share on other sites More sharing options...
Brian Kirby Posted March 8, 2014 Share Posted March 8, 2014 Corky, I wouldn't place too much store by what those folk are saying until you get a response from Brambles or someone else with expert knowledge. I think whoever wrote that has either a poor understanding of the physics of batteries, or a very poor understanding of how to explain them! The result, technically, seems to me (as a complete non-expert) total gobbledegook, and possibly designed to mislead. S/he seems not to understand the difference between Amps and Amp-hours for a start, and seems also not to take proper account of the affect high discharge rates have on available power (Peukert effect, I think). It looks technical, and it may actually be right, but I'm extremely suspicious that at the very least the author lacks proper understanding and, if correct, has got there using completely the wrong route, AKA by luck! So, potentially unreliable, I think, at least until someone who knows their stuff says I'm the one talking tosh (quite possible! :-)). Link to comment Share on other sites More sharing options...
Guest peter Posted March 8, 2014 Share Posted March 8, 2014 arthur49 - 2014-03-07 8:19 PM Many thanks all ...... its back to the 12v hairdryer for her ...........Get a small genny instead, far more usefull. Link to comment Share on other sites More sharing options...
Corky 8 Posted March 8, 2014 Share Posted March 8, 2014 Brian Kirby - 2014-03-08 5:55 PMCorky, I wouldn't place too much store by what those folk are saying until you get a response from Brambles or someone else with expert knowledge. I think whoever wrote that has either a poor understanding of the physics of batteries, or a very poor understanding of how to explain them! The result, technically, seems to me (as a complete non-expert) total gobbledegook, and possibly designed to mislead. S/he seems not to understand the difference between Amps and Amp-hours for a start, and seems also not to take proper account of the affect high discharge rates have on available power (Peukert effect, I think). It looks technical, and it may actually be right, but I'm extremely suspicious that at the very least the author lacks proper understanding and, if correct, has got there using completely the wrong route, AKA by luck! So, potentially unreliable, I think, at least until someone who knows their stuff says I'm the one talking tosh (quite possible! :-)).Brian Thank you, your input is always of value to me, I have read up a great deal on inverters also there is lots of information on Youtube, Anyone who is under impression that inverters will run 24/7from a bank of batteries is Misguided. I intend to use it as I stated for Wifeys hair dryer and the odd charging of laptop when in use checking the AutoRoute for the Aire Co ordinations I have stored ,never longer than minutes at a time with limited current draw on the two leisure batteries which are charge by a 120 watt solar panel, most good quality Inverters have low Battery voltage cut out as well as over voltage cut out to protect the Leisure batteries. but I will listen to anything anyone with genuine knowledge of inverters has to say. Keep safe keep well. Link to comment Share on other sites More sharing options...
Brambles Posted March 9, 2014 Share Posted March 9, 2014 Brian, you seem to really want me to respond so I will. The manufacturers advice you have corky is almost correct. You do need to add a bit on for inverter efficiency and also battery capacity being lower under heavy loads. In your case not really applicable if you are only using high power for a short time. It is silly folly to use the engine battery for an inverter. Too many risks of reducing available power to start the engine so no point in discussing engine batteries. Lead acid batteries are capable of very high drain for short periods and leisure batteries are no different in this respect. C/1 discharge rates are possible. So for a 100Ah battery you could draw 100 Amps. However at this rate of discharge some batteries could return as low as 50% of their capacity rating at C/20 ( 5 Amps for 100Ah battery). Also so as you can only discharge 50% anyway then you would only get 25Ah capacity available so at 100 Amps would be max 15 minutes. So now to a typical set up. 2 x 100Ah. Fully charge or fairly well charges at least. Lets say the 230 volt load is 1000 watts. We need to allow inefficiency of inverter which will be around 10 to 20%. lets use 15%. So the actual load is equivalent to 1150 watts. A 12 volts this is a current drain of 96 amps. This means each 100Ah battery as you have two is half this, so is 48 Amps. So for 10 minutes use we will use 10/60 x 50 = 8 Ah per battery. Now, the discharge rate is C/2 which means the battery is going to be less efficient so let us guess at around 70% so effective capacity used is around 11.5 Ah which is a little over 10% of its capacity so not a problem. During the 1st 20% discharge of a battery high currents have little effect on decreasing its cycle life but higher than 20% depth of discharge high currents start to have a much bigger effect in wearing out a battery. Also below 20 % dod the battery resistance starts to go up so more heat s generated in the battery. generally a battery can discharge at a 5C rate ( that is 350A) for about 8 to 10 minutes so you are well within that limit by a long shot. This is the remarkable thing about lead acid batteries, they have low internal resistance and very high current capability and can be discharged very much faster than they can be recharged. Forgotten what I was going to say now and how I was going to summarise all this above to make it simple. Ah yes..... Two batteries V one battery. For high current loads such as inverters running for any more than a couple of minutes I would recommend always using two batteries. The reason being if a battery was to become faulty and had to supply a heavy load it could become a danger. For example imagine a fault in say one of the internal connections and it starts to fracture and have higher resistance. Then the high currents could cause it to heat up and indeed even fracture completely. The resulting spark could ignite the gasses in the battery. Indeed it could just be the connection to the battery itself on the pillar and there is stray hydrogen gas around or indeed just teh PC insulation on cable burns. By using two batteries and as only one as failed the 2nd battery would carry on supplying power so reducing chance of a spark on the other battery. A guide would be around any current drains higher than C/5 rate then two batteries should be used for safety and integrity of the system. As we are using a discharge rate of around C/1 (1C) with a single battery then two batteries should be used in my opinion. Hope ths address the various questions posed and I havenot made a mess of what I have written. Time to hit the soft cottony cotton sheets and get some sleep. Link to comment Share on other sites More sharing options...
Brambles Posted March 9, 2014 Share Posted March 9, 2014 peter - 2014-03-08 5:58 PM arthur49 - 2014-03-07 8:19 PM Many thanks all ...... its back to the 12v hairdryer for her ...........Get a small genny instead, far more usefull. Asda sell quite nice towels at a very reasonable price! Link to comment Share on other sites More sharing options...
Corky 8 Posted March 9, 2014 Share Posted March 9, 2014 Brambles ,Thank you very much for a in-depth explanation of the use of inverters with 12v Batteries, and thanks for confirming my usage is within scope, I should have said the hair drier is a 150 watt model so not a large current draw, any problems I will certainly make people know so as to save them the trouble, Safe Journeys. Link to comment Share on other sites More sharing options...
Brian Kirby Posted March 9, 2014 Share Posted March 9, 2014 Corky 8 - 2014-03-08 9:26 PM..................Brian Thank you, your input is always of value to me, ................ Well Corky, despite your kind words it wasn't of much value this time! :-) I'm grateful to Jon (Brambles) for taking the trouble to lay it all out, because I felt uneasy about what I was reading. It's good to know the information from the seller was about right and my misgivings were unfounded. Thanks for explaining Jon, you have clarified several things for me as well. I was convinced there was a rate of discharge related to battery capacity that should not be exceeded. Clearly not. From what you say, it would presumably be preferable to start using the hairdryers with the battery fully charged, and possibly unwise to begin doing so if the battery is, say, 25% discharged? Link to comment Share on other sites More sharing options...
arthur49 Posted March 9, 2014 Author Share Posted March 9, 2014 peter - 2014-03-08 5:58 PM arthur49 - 2014-03-07 8:19 PM Many thanks all ...... its back to the 12v hairdryer for her ...........Get a small genny instead, far more usefull. .... or she can stick her head out the window whilst I drive ? :-D Link to comment Share on other sites More sharing options...
arthur49 Posted March 9, 2014 Author Share Posted March 9, 2014 Thanks again, particularly to Brambles ............ Link to comment Share on other sites More sharing options...
Brambles Posted March 9, 2014 Share Posted March 9, 2014 "From what you say, it would presumably be preferable to start using the hairdryers with the battery fully charged, and possibly unwise to begin doing so if the battery is, say, 25% discharged?" That about sums it up for decent battery life. The lower the battery charge the more damage is done by high currents, well not so much damage but wear and tear. Link to comment Share on other sites More sharing options...
Billggski Posted March 9, 2014 Share Posted March 9, 2014 I just think hair dryers and wild camping (no hook up) don't go together, or is it just me? . Link to comment Share on other sites More sharing options...
Brambles Posted March 9, 2014 Share Posted March 9, 2014 Totally agree, but if the lady wants the lady gets! When my wife wanted a hair dryer she got a hair dryer....just no where to plug it in. Actually what we use if we have to is the hot air heating, close all vents except one in shower and a hose gets stuck in it. Works a treat. Link to comment Share on other sites More sharing options...
Corky 8 Posted March 9, 2014 Share Posted March 9, 2014 Billggski - 2014-03-09 7:41 PMI just think hair dryers and wild camping (no hook up) don't go together, or is it just me?.Even when wild camping we have to have a night on a site for Mrs to shampoo and dry her hair, just the way she is so an Inverter will enable us to be more independent of sites ,and not all Aires in France (our favourite Place) have elec hook up, In this Modern world Progression of technology allows us to lead a more civil life style where ever we are so why not make use of what is available. each to his/her own, Safe Journeys. Link to comment Share on other sites More sharing options...
Corky 8 Posted March 9, 2014 Share Posted March 9, 2014 ruddy technology double post fumble fumble fum.... Link to comment Share on other sites More sharing options...
arthur49 Posted March 10, 2014 Author Share Posted March 10, 2014 Billggski - 2014-03-09 7:41 PM I just think hair dryers and wild camping (no hook up) don't go together, or is it just me? . Some women like nice hair ...... and stay on Aires/Stellplatz when there is no leccy.... so compromise needed, which is where options start to be considered and 12v hair dryer comes from..... simples....not a fan of genny though I fully respect other's view .... don't want to start the usual anti-genny rumpus 8-) Link to comment Share on other sites More sharing options...
lennyhb Posted March 10, 2014 Share Posted March 10, 2014 Got the OH a Bablyiss Gas Curling Tong takes a while to dry her hair it does the job though.They also do a larger one that's only 4 quid more. Link to comment Share on other sites More sharing options...
tonyishuk Posted March 10, 2014 Share Posted March 10, 2014 Go on ! Be Brave , Do it, Someone has to be first, and tell us how you get on. :D Rgds Link to comment Share on other sites More sharing options...
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