Gas Generators

Kizzy43

Hi we need some advice regarding generators. We have never had one for the campervan but would love to know if there is a solar/gas generator we could purchase as it would be less noisy. It would only be used to run a toaster or at the most a microwave. (Can you use an ordinary microwave in a campervan). ???

It's not the fuel that makes the noise it's the combustion engine.

Toasters or microwaves aren't practical to run off batteries.
A 500W (heat output) microwave runs about 1kW+ (electrical input AC) so that's about 10 minutes before you discharge a 100Ah battery to recommended limits (compensating for inverter losses and discharge curve). Toasters are in the 1kW+ range too.

Microwaves take twice as long to cook on cheap inverters.

I'd suggest a gas grill/oven.

As a very rough rule of thumb (late Spring to early Autumn) flat-mounted solar will give you 2.5 times it's rating in watt-hours on a cloudy day and 5 times on a sunny day.

So 100W solar on cloudy day = 300Wh or 25Ah @ 12v, or ~6 slices of toast per day, but not at the same time or 15 minutes of microwave per day, but not at the same time and a very unhappy battery.

If you had 500Ah+ of batteries, an efficient true sine wave 1.5kW inverter and 600W solar then yes...possible.

Or a petrol electric generator in a ventilated, sound insulated enclosure...careful not to insulate it too much if it's air cooled.

Or gene and batteries, just run the gene when you need the microwave and use the battery to run the lights and what-have-yous. The gene can also charge the batteries if needed.

I hear Hondas are the reliable ones.

nailer8

I dont have a toaster but bought a low power microwave to deal with babies dinners.
The setup i am using and it seems to work ok is.

Modified 500w microwave - Draws c.900w when running.
1000w pure sine inverter
two 80AH leisure batteries.
100w solar panel.

To be on the safe side we avoid using the microwave only when we have to and i always use it on low power so it cycles from 100w to 900w every 30sec or so.
I also start the engine when i want to run the microwave to bring in the 3rd battery and the alternator.
Some hassle to warm up a frozen dinner but thats kids for you.
Other than that its gas all the way.

nailer8

I forgot about the alternator

Have you ever measured what's coming into the house batteries from it. It's usually a very long and convoluted run. I think the most I've ever seen from mine (55A) is 20A at the house bank. Problem is the wiring is very thin and indirect and without a B2B charger/dedicated alternator or re-wire the starter battery often fools the regulator into thinking the house bank is a higher SOC than it is.
20A * 12v = 240W...so probably a good idea run the engine 3 times as long as the microwave.

nailer8 wrote: »

two 80AH leisure batteries.

Did you just derate your Elecsols? :pac:

nailer8

Well to be honest if they are 40ah they are doing well but if i ever get around to replacing them with a normal brand (e.g. Banner) then that size will be 80ah so id say that is all they ever were when new.

Not much science behind my setup, just run the engine to help the cause.
I was getting hardly any amps down to the house batteries so ran a second cable but even then not too much getting back and also with a full engine battery the reg in the alternator is going to restrict the output.
I often thought if you are running the engine to charge the house batteries probably a good idea to remove the engine battery lead or fit one of these .

Nice electron tap
It's a good idea if wired correctly. If the house bank is downstream of the starter then it'll be very upsetting. Alternator with no load will toast your autoleckytronics, everything with a PCB will fry.

There's a few cheap ways improve it.
The important thing to consider when souping up an alternator for idle output is; Is it temperature regulated?
Mine isn't so without the draught from driving or the high RPM to drive the fan I just thought I'd stop under the half-way point. That and I'm not going to get my 600, 000 mile marker on the odometer if I'm running idle all the time.


Method one is pull all the cabling and upgrade the wire gauge for 7.5mmᴓ (34mm²) and more direct to batteries (shorter runs and less connections). Perhaps take the B+ Y'd through D+ relay instead of the D+ switching a battery to battery conductor.

If your alternator has a removable regulator then have a look on Ebay for spares. I got one for €2 that just needed brushes, stole another from my car's spare alternator and another from scrap. Second hand is better because they drift out of calibration...at least mine do anyways.
I've a 14.7v, a 14.4v a 14.8v and a 15.0V I change them seasonally. If you're always running heavy loads like fridge etc. going high isn't a big ordeal...as long as you test it and have a meter in the cockpit that's not wired on load carrying conductors. [EDIT:] The reason for the voltmeter in the dash is if it gets too high for your liking just turn on some driving lights.


More Smartgauge links (yes I will keep harping on about his work!!:P):
Problem with alternator wiring
Good setup if you don't mind house bank assisted starting.

nailer8

Funny you say that. Whatever brain wired my camper, the leisure batteries come on with ignition rather than D+ (engine). Helps i suppose giving extra batteries for starting but on the negative side my automatic fridge switches over to DC as soon as the ignition is on so could flatten the batteries in no time if i left the ignition on without starting the van for any reason.

I only camp for a few days so usually with the solar get away without running the engine to charge, cant stand it when parked up beside people that keep running the engine to charge batteries.

It's a bit messy really. I wouldn't use my deep cycles to starter assist unless it was required and after the 3rd time in a row I'd replace the starter battery. Even then I'd use some jump leads and not under-rated relays and connections. They'll fair ok in the support role it's not hugely taxing as they're only doing a little of the work I just don't like it as an idea.

I suppose you could just turn the fridge off at the unit if you need the ignition on for any reason. I can reach my DC "distribution board" from the driver seat so I just switch it off from the MCB when I need to. My split charge relay is manual anyways...I prefer it that way.