Gabriël Posted March 1, 2018 Share Posted March 1, 2018 hi guys what would be the right cable size between the batteries [250ah] and the inverter for a 48v system where the total cable length in less than 4m Quote Link to comment Share on other sites More sharing options...
___ Posted March 1, 2018 Share Posted March 1, 2018 Depends on the maximum current draw of the inverter... the one thing you didn't specify :-) Let's say it is 5kva. That's about 100 amps give or take. You want a voltage drop of less than 3%, preferably around 1%. 35mm^2 has a resistance of 0.65Ω per kilometer. You have 0.004 kilometer. So 0.004 * 0.65 * 100 ~= 0.3V. That's less than 1%. 25mm^2 has a resistance of 0.9Ω per km. 0.004 * 0.9 * 100 ~= 0.4V. That's also less than 1%. If you look at some wiring ampacity tables (google) you'll see that the 25mm^2 will run quite hot at full load. So 25 in open air is fine if you only run full load for short periods. I'd go with 35. Clint and Gabriël 1 1 Quote Link to comment Share on other sites More sharing options...
Chris Hobson Posted March 1, 2018 Share Posted March 1, 2018 I used this tool http://www.solar-wind.co.uk/cable-sizing-DC-cables.html Gabriël 1 Quote Link to comment Share on other sites More sharing options...
Gnome Posted August 26, 2018 Share Posted August 26, 2018 So cable is expensive, that is true, but you buy it once. On the other hand, cable that is undersized hurts you day by day. Even Voltronic updated their latest manuals to say 0 gauge for the battery (that is approx 55mm cable). 50mm welding cable is about R65 per meter when I bought some recently (that was only phoning about 3 places, I'm confident I could have found cheaper if I tried). It is expensive but it is once off and considering the cost of everything else it is nothing. After 50mm things get expensive really quickly. 70mm I couldn't find cheaper than around R120 per meter. In that case I would simply double up on 50mm. Quote Link to comment Share on other sites More sharing options...
SilverNodashi Posted September 3, 2018 Share Posted September 3, 2018 35mm on that inverter is preferred, as @plonkster has pointed out mathematically. Interestingly, I have a client who runs their Axpert 4KW at 106% most of the time. don't skimp on cables and fuses, it's not worth-it. Quote Link to comment Share on other sites More sharing options...
Nonlinear Posted September 10, 2018 Share Posted September 10, 2018 So far I've gone with 35mm2 on a similar battery bank and inverter. For volt drop reasons but also for pragmatic reasons: anything above 35mm2 becomes a real pain to terminate. Both finding the right termination and the actual task of clamping/crimping (not to mention the cost of tooling). I'd like to hear from others who have used anything above 35mm2 what their termination methods are. Quote Link to comment Share on other sites More sharing options...
Jaco De Jongh Posted September 10, 2018 Share Posted September 10, 2018 15 minutes ago, Nonlinear said: 35mm2 what their termination methods are. 70mm and 95mm Using a Hydraulic crimper. I am lucky enough to have my own but did see some tool hire company's renting them out. Something similar to this Quote Link to comment Share on other sites More sharing options...
___ Posted September 10, 2018 Share Posted September 10, 2018 1 hour ago, Jaco de Jongh said: lucky enough to have my own For a long time I used to have my cables crimped at the shop where I bought the cable. Finally this came past on gumtree at half price. Then I got one of these as well, not this specific brand, this is a random picture from the internet, but it looks similar. Cheap, I think it was R130. Friend of mine says get a cheap set of garden shears, apparently nothing cuts copper cable cleaner than that :-) I love tools. I tend to not buy the Metabo/Makita, I don't use it enough to justify that, but it still helps to have a tool or two. Quote Link to comment Share on other sites More sharing options...
Jaco De Jongh Posted September 11, 2018 Share Posted September 11, 2018 19 hours ago, Nonlinear said: (not to mention the cost of tooling) After work I stopped at the Electrical wholesaler to pick up some spares, and found this on the counter.. 16mm to 240mm... And 16-300mm Special till end of September.. Its pretty decent prices... Quote Link to comment Share on other sites More sharing options...
___ Posted September 11, 2018 Share Posted September 11, 2018 21 minutes ago, Jaco de Jongh said: Its pretty decent prices That's less than I paid... secondhand. Quote Link to comment Share on other sites More sharing options...
Jaco De Jongh Posted September 11, 2018 Share Posted September 11, 2018 2 minutes ago, plonkster said: That's less than I paid... secondhand. I have paid R2500 for the top one above in 2007-2008 (Secondhand) New price then were about 4k.. Quote Link to comment Share on other sites More sharing options...
SilverNodashi Posted September 11, 2018 Share Posted September 11, 2018 3 hours ago, Jaco de Jongh said: After work I stopped at the Electrical wholesaler to pick up some spares, and found this on the counter.. 16mm to 240mm... And 16-300mm Special till end of September.. Its pretty decent prices... That's cheap, but a real pain in the arse to properly crimp anything above 120mm by hand. Next time I'll buy a battery driven one Quote Link to comment Share on other sites More sharing options...
Jaco De Jongh Posted September 11, 2018 Share Posted September 11, 2018 2 minutes ago, SilverNodashi said: but a real pain in the arse to properly crimp anything above 120mm by hand Takes two guys or a real gym bunny to do a 300mm properly.. Quote Link to comment Share on other sites More sharing options...
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