Best small diesel genny?

[maple flats]

At my cabin I have an off grid solar system, 6 @285W panels (3 strings of 2) a CC, inverter and they are connected to a 24V Rolls battery bank (4x6V, 6CS-21P batteries). I also have a 40A 24V battery charger ( it actually has 4 amp settings, 10A, 20A, 30A and 40A) I want to tie in for extended periods of rain or full cloud cover. Right now, I get about 3 days good and 4-5 days OK. I am looking for a good diesel generator to run the battery charger for even longer cloudy spells or times when I just need some extra power. I have a 6000 watt diesel at the sugarhouse, but I need to keep that there just in case I need it. I'm really looking for a 2000 watt or even a little smaller one in diesel. Diesel stores much longer and if the SHTF I could make my own diesel. An inverter genny would be best, but I only see those in gas. Propane is a distant second choice in this case. Any ideas? I don't see a spec tag on my charger, but are my calculation right? 40A @ 24V = 8A at 120V, then factor in the efficiency loss, I'm guessing I only need 9 or 10A at 120V. The charger is an old one and it says it is a rectifying charger, is that an issue, I have no idea what that means. I bought it from a municipality about 8 yrs ago when they decided to go with a bigger one. I don't know what it was used for.
Also, if I hook it up, the cables from the charger to the battery bank will be about 10' long (actually 1 will be about 6', the other about 10'. It has 8 ga. leads now but only 4' long, when I change them what Ga. should I use. I'm thinking 6 Ga?

[Mike90250]

Sadly, your rectifying charger is likely only 60% efficient. That means you need a
40A x 28V = 1120watts @ 60% = 1568 watts, maybe a bit more.

I have a 3.3Kw Robin/Subaru/Hatz diesel genset, but the alternator acts more like a 2Kw, It has poor power factor

http://www.temcoindustrialpower.com/products/Portable_Generators/GG0029.html

and even wallmart

https://www.walmart.com/ip/Robin-Subaru-Diesel-Generator-3300-Watts-Hatz-Engine/11344403

So define best. My goto generator is my Lister 6/1 clone, 6hp, 3 solid KW of output, but they are big and pricey

There is just not much in the small diesel gear, but that's all I know of

If you can stand shipping from Kansas, http://diesel-electric.us/ is the reliable place, for purchase

[inetdog]

I have a 3.3Kw Robin/Subaru/Hatz diesel genset, but the alternator acts more like a 2Kw, It has poor power factor

http://www.temcoindustrialpower.com/products/Portable_Generators/GG0029.html

and even wallmart

https://www.walmart.com/ip/Robin-Subaru-Diesel-Generator-3300-Watts-Hatz-Engine/11344403

So define best. My goto generator is my Lister 6/1 clone, 6hp, 3 solid KW of output, but they are big and pricey

You can find back discussions of generators which are very complimentary of the Subaru Robin ORIGINAL MODEL generators with the Robin diesel engine. Very reliable and easy to repair. Once they started fitting the Hatz diesel engine instead the complaints began of a sensitive engine with hard to get overpriced repair and maintenance parts.
If you can find an original model used you might get a very good deal.

[maple flats]

I don't want to buy problems. Based on Mike90250 I need more than I thought. I think for now, I'll use my 6000 watt diesel and use a 15KW gas I have if needed at the sugarhouse. I'll keep my eyes open for an old Lister genny or the older Robin Diesel. l can take my time looking, thanks for the input.

[inetdog]

I don't want to buy problems. Based on Mike90250 I need more than I thought. I think for now, I'll use my 6000 watt diesel and use a 15KW gas I have if needed at the sugarhouse. I'll keep my eyes open for an old Lister genny or the older Robin Diesel. l can take my time looking, thanks for the input.

FWIW, the term "Lister diesel" refers not to the general design but to a family of low RPM diesel engines, often single cylinder, made by the Lister company in England. It refers to that company's CS (cold start) engines which were last produced by them in 1987.

The CS is a slow-running (600 rpm) reliable engine, suitable for driving electric generators or irrigation pumps. CS type engines gained a reputation for longevity and reliability, especially in Commonwealth countries, to which they were widely exported. Some CS engines ran practically continuously for decades in agricultural, industrial and electrical applications.

Knock-offs of varying quality by other manufacturers to the same or similar design are most often referred to as "Listeroids". Some are OK, some are pure crap.
They can be started by hand, taking advantage of a compression release.
The enormous flywheel can only do an incomplete job of evening out the torque and speed pulses caused by the 600 rmp, 300 power stroke per minute, operation so they are best used where perfectly constant speed is not a requirement.