Re: [MH-list] Never ending power struggle


Si B <musklebunny@...>
 

Hi Alan, thanks for the break down, sorry, i did mean to use the terms amphours as it applies to all of my references so, yes its just 16 ah we need each evening, I think our charging regulator off the engine battery is working fine, and our laptop is charged while driving from the cigar lighter through a 150w inverter.
Our stereo on the dash has a voltage meter which is handy when we have the radio on for a couple of hours because when it dips down to 11.9v we know we've drained as much power as we can and still be able to start the engine with no struggle on a cold morning.
Im fairly sure the regulator is keeping the engine battery well charged.
We estimate thge solar input from the varying readings so we can see when it has an hour at .4ah per hour an hour at 1.0ah per hour or an hour at 2.3 ah per hour and tot it up, thats where i was getting my initial email figures from , i did want it fitted with some way of tilting it but unfortunately, it was pretty heavy (nearly 20 kg) and the guy who fitted it was less imaginative than i about possible deckchair like simple ratchet mechanism on each of two adjacent edges to give us that optimal angle towards the sun, guess we will have to drive south instead!
The generator has a household socket that we use a normal electric hook up cable to connect into our mains hook up point.
One check by our local friendly mhome workshop indicated that our charger unit is faulty and the mains hook up isnt getting any charge into the leisure batteries and nor is the engine alternator, leaving the poor old solar panel to do all the work so now we are looking for a cheap charger unit to replace our faulty one.
Thanks for the advice and explanation,
M



To: motorhome-list@yahoogroups.co.ukFrom: aeclist@candt.waitrose.comDate: Sun, 19 Oct 2008 16:28:24 +0100Subject: Re: [MH-list] Never ending power struggle




Si B wrote:> Hi, its us again, not the long drawn out US elections we are asking> about but as full time free parkers on a tight budget we sometimes> struggle to get enough power to afford ourselves the home comfort> of some telly or watching a dvd every evening. Dont get me wrong,> we fill our days with walking, jogging, weight training, painting> and reading but its nice to cuddle up in front of the goggle box> and relax also. Over the past year we have made 3 adaptions to try> to get the 16 odd amps we need a day,It will be easier to understand the problem and possible solutions, if one is boring and pedantic about the numbers and measurements. The 16 amps needed - for how many hours? If 10 hours, you would gain 160 AH charge (approximately)It will be easier and more useful to think in terms of ampere-hours (AH) rather than just amps. For example your leisure batteries are two 110 AH (not 110amp).Two 110 AH batteries offer a huge capacity, so your initial design seems to be good.Two issues come to mind - the need to generate somehow and the need to get the charge into the leisure batteries.You do not say what type of vehicle you are using, but I would be surprised if any vehicle alternator would not beok - your starter battery gets charged ok I guess? Any problem is more likely to be associated with the battery voltage regulator (charging regulator). This regulator may be the one you are using also for the starter battery (??), anyway, part of the regulartors job is to stop th ebattery getting over charged. The engine battery is ok because it will be designed in place and will not get more than about half charged at most.In a manner of speaking, if your system is keeping the engine battery half charged, it will be ignoring the leisure batteries until they are almost flat. And stopping charging (them) when they look like the half charged starter battery.The situation may be worse because the cables connecting the leisure batteries to the charging system may be longer than the starter battery cables, and thinner, and maybe the connecting joints are not the best. all these things will double or treble the time it might take to charge your particular leisure batteries.It will help to reconsider your battery voltage regulator and its type (gel setting with wet acid batteries would be incorrect), also the length and size of all cables to and from the leisure batteries.Warning - an accidental short circuit of a battery to a metal part can be extremely dangerous, for example a metal watch strap getting red hot will more than spoil your day, so use all proper precautions for any work!>fitting a 180w solar panel,> which still peaks at 2 amp/hour on a sunny day in essex at this> time of year, but seems to on average only be giving us about 4-8> amps a day now.The terms here are at least confusing. The solar panel is a good size. However what you get from it is basically only amps, (not amp/hour), and 2 amps on a winter sunny day is not bad if the panel is flat down on the roof of the vehicle.If you can tilt the vehicle a little towards the sun you should see a small improvement. With a large tilt - say of the panel itself, a much better improvement while the sun shines. Wihout a tilt, a reflector to get more sun onto the panel will also help, but of course a reflector in a wind mighty be a problem. Even parking near to a high white painted wall will help a bit.2 amps from the panel for a period of 3 hours is 6 AH of charge. Not much to run a TV from for very long.> We early on changed our 85 amp leisure battery for> two 110 amp ones and last winter. Finally in spring and winter, if> we were somewhere deserted, away from houses we would run our ultra> quiet honda 1000w lpg converted generator from about 6pm to 9pm.A generator with a maximum capability of supplying 1000w will theoretically supply about 4 amps at mains voltage, which a mains powered battery charger could use to charge at a maximum of a huge current (80 amps?) - in theory this is - depending on the charger etc. and the charging controls if there are any.> Unfortunately the generator is an inverter jobbie and because the> sine curve of the ac power is squared off, although we are on230v> power; when the jenny runs it Barely trickles any surplus charge> into our starved leisure batteries.You are connecting the 230V generator output into - what, exactly? How is the 230V changed into battery charging voltage and current?What indication do you have that it is barely a trickle? a meter indication? Where?> We can only afford to drive on> average 30 miles a day, or about one hour of engine running and we> usually charge the laptop whilst we do thisHow do you connect the laptop to the batteries? Is your laptop charger a 12V one or do you use an inverter to get mains voltage for the laptop charger?> which also seems to> deny the leisure batteries of more than a tiny trickle of surplus> charge from the engine.> Can anyone offer any suggestions for> solutions please? We hope to get some work to pay for ferry tickets> and head south for the winter, optimistically thinking we will get> more from our solar panel which got us through the summer fine.One> (probably daft ) idea that i had was to ask a mechanic if its> possible to attatch a second alternator or appropriate doodah that> runs of the rotation of whatever drives the fan belt to take a> charge direct to the leisure battery? An extra alternator may be quite difficult to fit, and it would certainly need to be declared to your insurance company.Thoughts of charging direct to the leisure battery imply an avoidance of the existing charging controller, which may be some of the problem anyway. It would be better to ensure the charging controller and the installed system worked properly, or at least to your satisfaction.>I thought it probably> requires a miniscule amount of energy to operate this type of> electrical charger so it shouldn't impact the engine operation. But> is this a really stupid and impractical or possibly illegal> modification? I'd still need to find a mechanic who could do it. You are right, the amount of energy a battery needs to charge is small compared to what an engine can deliver, but you would still need a method of controlling the charging - another charge controller......> Also as a final closing request, can anyone confirm just what the> amps/hour rating is that goes into the leisure batteries when we> drive? I've been lead to beleive it trickles in about 3-4 amps/hour> driving or even ticking overIf the charge controller regulator thinks the battery is full (or even half full) the charge current (amps) will be reduced towards zero!It it thinks the battery is nearly flat it should supply about 20 amps with no problem, maybe much more.> and if we charge a laptop while we> drive, from the cigar lighter then this will impact and reduce the> amount spare flowing into the leisure batteries respectively, is> this correct? Not correct in terms of the possible current or power available probably. However, if the wiring is such that 7 amps in the cigar lighter causes a one volt drop in the local wiring, then, it is always possible that the charging regulator is getting the wrong information, or again, that the cabling is taking a voltage and restricting the system in other ways.All advice and experience welcomed as ever, thanks, Mgood luck-- alan cocksKubuntu user#10391Linux user #360648





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