Club 80-90 Forums

Just wondering about charging a battery from a genny vs running the engine.

Alternator is 90A

So if I have a 90 AH battery and it's say 50% charge will it recharge to full with 30 minuites of running my engine?
I'm thinking not because the current will fall as it charges.

I'd guess if battery is very flat alternator will charge the first 50% perhaps in 30 miniutes, quicker than a battery charger because it can supply much more current, but typically you just want to top up the last 50% daily.

Any idea how long the last 50% takes with a standard charger vs an alternator?

Solar is probably better I know but I'm thinking uk campsites ( not much sun) and not something I need very often.

Please don't give the the antisocial genny lecture it would only be a remote campsite daytime activity where nobody is close.

Cheers

Nowt wrong with a genny - depends where you are. I camp off the grid all the time and have run the engine for anything up to an hour if pushed. Doesn't matter. Solar is ok if you have enough light otherwise it can take a very long time to replenish a battery on a wet miserable day. I'm actually looking for a generator myself. I won't use it often but sometimes its the fastest most economical option - must be cheaper than running the engine for starters.

Iwas looking at the clarke ig 1000, 4 stroke and sine wave.
Cheaper seems to be 2 stroke and noisy.

I just wonder if I would ever recover the costs over runnng the engine on lpg?

I have often mused over how economical it is to run a WBX at tickover on LPG.

It would be quite easy on Petrol, just use a graduated millilitre measure and time it, then do some maths. But mixture at tickover on LPG might be too "different" to make a comparison, as in = same as petrol minus 10% type calculation. Mind you, it would give us a ball park figure perhaps, I can feel an experiment coming on

Very slight aside. I have measured the current flowing into a somewhat depleted leisure battery (say ~11.8 V) from the alternator. As Itchy points out, it does tail off, and boy does it tail off. 20 Amps for only a few seconds, rapidly falling to less than 10 Amps for a couple of minutes, then sat at around 4 amps for until I got bored Sorry about the unscientific measurements, it was a quick "on the spot" empirical test. i.e. I was just messin about

This was one reason I choose to go down my poor man's Sterling set-up and I have to say, I wouldn't go back to simple split charge.

P.S.= My "poor man's Sterling" = Normal split charge relay wire to leisure battery removed and now connected to a 300W inverter, so the inverter comes on when the engine is running. A 12 Amp "smart" charger is plugged into the inverter and is connected to the leisure battery. Equals "smart charging" whenever the engine is running. Dead simple to do and works just great.

Note, the 300W inverter is only pulling about 150W max, (when the smart charger is on full output), but this soon drops to less than 100W as the battery charges up, and less later on in the cycle.

Anyway, back on topic = "I have often mused over how economical it is to run a WBX at tickover on LPG."

ghost123uk wrote:. 20 Amps for only a few seconds, rapidly falling to less than 10 Amps for a couple of minutes, then sat at around 4 amps for until I got bored.

Very interesting this is whwt I wanted to know and probably why most chargers are around 5A

So no quicker on lternator then genny probably.

itchyfeet wrote:So no quicker on lternator then genny probably.

Agreed.

This is where proper Sterling chargers come in good (and to a reasonable extent, my version). Proper Sterlings ain't cheap though.

I suppose you might want to consider the additional fuel comsumed lugging a generator around, and the space it takes up, and add all this into your calculations.

Just to complicate matters, you understand. I have no opinion either way.

colinthefox wrote:I suppose you might want to consider the additional fuel comsumed lugging a generator.

I'd say for a vehicle that does 20 mpg you won't be able to measure extra fuel consumption, we are talking under 20kg.
Space yes but as soon as you arrive it gets chucked out.
Noise is my biggest concern

charging it from 50% just on tickover would take hours and down to 50% is not good for the battery anyway but.........


what else will you use your genny for as it seems you are wanting to spend much more on a genny than you would on a decent solar set-up but you discount solar as not something you need much ?

ive got a 100w panel, a good controller, one leisure battery, ive never run out of power yet..even when stationary for a week and i have a shower,blown air heating, etc in my van plus the other half uses a hairdryer (via an inverter) after showering... all in the uk's finest weather

busbuddy wrote:charging it from 50% just on tickover would take hours and down to 50% is not good for the battery anyway but.........


what else will you use your genny for as it seems you are wanting to spend much more on a genny than you would on a decent solar set-up but you discount solar as not something you need much ?

ive got a 100w panel, a good controller, one leisure battery, ive never run out of power yet..even when stationary for a week and i have a shower,blown air heating, etc in my van plus the other half uses a hairdryer (via an inverter) after showering... all in the uk's finest weather

No not discounted solar but I rarely need it and a 100w solar panel seems large to carry and needs to point in the right direction, great if you want to permanently install it on your roof but with a tin top I can't see that would be good for occasional use.

The cost of the genny is not such a big problem to me, was really wondering if running an engine would be just as good as a genny, I'm trying to convince myself not to buy one really but I can't see a better alternative to occasional need for guaranteed power.

itchyfeet wrote:I'm trying to convince myself not to buy one really but I can't see a better alternative to occasional need for guaranteed power.

ghost123uk wrote:I reckon a couple of hours at tick-over (esp with a decent charging system ) is the most cost effective and convenient option

Also of course, simply firing up your engine is a lot simpler than getting the genny out, setting it up and then starting it up.

Wondering also, I reckon the consumption of LPG might be comparably cost effective, so by the time you have bought and paid for the genny, then it's fuel, then weighed up the downsides (including as above ^^^ = convenience) then, again, firing up your engine at tickover for an hour or two seems to me to be favourable. Oh, and you can then get heat inside the van too

I couldnt bear to be somewhere nice and peaceful and then kick up a genny.

keith wrote:I couldnt bear to be somewhere nice and peaceful and then kick up a genny.

Yes my main concern is noise but the van engine is noisy too.

I'm also concerned running a wbx for extended periods at tickover, oil pressure in these vans is poor at best of times on tickover hot it's very low indeed, what damage us that doing?

Going to look at solar too I think before deciding, I guess if what I'm hearing is true and most of the charging is done by 4A or less then a 50W panel is in theory enough but I guess thats 50W with good sun so a 100W is needed.

Quite a large panel but I suppose just like a genny it gets kicked out as soon as you arrive.

Anybody got a suggestion of brands to go for? Don't want a self adhesive one on the roof, free standing I think.

itchyfeet wrote:
I'm also concerned running a wbx for extended periods at tickover,

It is the quickest way to kill an alternator especially a 90A. Alternators aren't designed to produce high outputs at low speed there is not enough airflow through them to adequately cool them. A 90A alternator still has the same size fan as a 45A alternator trying to cool twice the output, overheating reduces the output and shortens the life of the rectifier diodes, under normal condition it is not a problem as the manufactures not unreasonably expect people to normally start up and drive where the higher rotational speeds provide adequate cooling. Vehicles that needed high outputs a low speeds either fitted two alternators or additional cooling or jacked up the idle speed.