Petrol generator for farm use

Welding using a generator with modern welder is asking for trouble , would burn the card in the welder , with a handy size generator anyway

You'd need something around a 6000w generator to run a welder, and it wouldn't be a big welder at that.

We have a few generators here over the years. Some things to look out for:

• Cheaper generators are usually disposable if they go wrong in the alternator. You can replace AVR's and brushes etc, but if they go bang, then because of their weight, it usually works out cheaper to buy a new one. We have had first hand experience of this. Local company looked at it and said it wasn't worth fixing. I then contacted https://www.generatorguru.com/ and they said same thing - basically the cost of shipping that weight of a part from China was prohibitive. If you look on their site they do not show generator windings for sale.
• Make sure you know what phase you are buying. Some of the cheaper items are 3-phase with a single phase separated out. These are not worth buying as most stuff you will be running will be single phase - plus you won't get the full power rating in the single phase - so make sure the outlets are either 3-pin domestic/std sockets or it states it is a single phase generator.
• Ensure the power rating is the continuous power and not the start up power. Generators can provide a higher power output for short burst on start-up, the norm is to rate them from the continuous power figure, but watch for some sellers who might quote the higher start up power figure.
• Drills are around 1kW (0.8kW - 1.3kW usually), angle grinder is around 0.8kW and a large 9" grinder can be over 2kW. You need to think about what your likely power consumptions will be, add a margin to it and then look at generators with that output as a minimum. If you get close/exceed the max rating you could blow the AVR or burn the windings (blowing AVR is a easy fix, burnt windings can be fatal).
• In regards to brands, be careful - many are Chinese machines branded as German machines - i.e. Böhmer-AG, MIL Germany, etc. Rule of thumb that I use is if they are listed on Generator Guru - Portable Generator Parts and Spares, then chances are it is a Chinese sourced product. Nothing wrong with these as long as you take the above points into consideration relating to disposability and phases. There is always a tendency to tell posters to buy the recognised brand. In this instance I would agree to a certain point - you could buy 2 - 3 of these Chinese items for the price of an industry recognised brand, but conversely a higher chance of unfeasible repairs. So if you're not going to be relying on one and are willing to accept if the internals go that it is scrap, then go for it. If that doesn't sit well with you, then maybe a recognised brand would be better. The item you list is part of https://www.napbrands.co.uk/ and their website states that they source from China/Far East - plus it is on Generator Guru. I'm not saying it is a bad machine - I know nothing of it. Just be aware that at the lower end of the market, faults might not be repairable easily.
• When not in use keep it somewhere dry - sounds obvious but dampness can come in many forms - dew, condensation, etc. Any dampness on the windings can shorten their lifetime - this includes in with cattle/sheep as the breath can leave a dampness on the windings and corrode them over a winter.

We have both - a larger old generator which we use for welding and power heavy tasks and a Chinese one for powering lights in an off-grid shed - so I can appreciate the +/- points of both. The large generator has been rebuilt and we have 2 Chinese 2kW items - one of which the generator part is now a paperweight (albeit engine is still fine).

Question - should a petrol powered water pump be run at full revs or just enough to pump the water? ( was always told chainsaws should be run at max revs )