An idiot's guide to building a big lithium bank

[GoneDiving]

Found ya. (-;


So how do you rate the slipway and trades ?
It's one we have on our list for our 60 ft, 65 tonne and 7.5ft draft

Generally very good. I'll expand via PM.

60ft and 65t wouldn't be a problem. For scale, I'm 54ft and the vessel behind is 60.

Check your messages

 

[GoneDiving]

I needed to calibrate the zero point on my battery monitor so used that as an opportunity to load test the system by running two aircons (2.5 & 3.2kw), a 2kw heater fan and two 2kw heat guns simultaneously. The actual draw was 6kw/~130amps for 4 hours then 8kw/~160amps for the final 2 hours (I forgot that the heat guns were on low so turned them up to full). That's no solar and no shore power, 100% battery.

130amps was easy. No overheating or other issues except I need to replace the main isolator with one rated for continuous use. The old chinesium model was fine for intermittent use but not 6 hours.

160amps warmed everything up. The main issue is that the inverters exhaust hot air to the bottom where all the cables, fuses etc are. If I need to consistently run this high, I'll just reverse the fans to exhaust to the top.

The only exception to normal running was that I had the main cabinet door open for the duration.

I'm pretty happy with the test. If anyone can recommend a high current, continuous duty isolator, let me know. I'm considering this one:

https://www.bluesea.com/products/6006/m-Series_Mini_On-Off_Battery_Switch_with__Knob_-_Red

 

[twistedtree]

With a 48V system it might be hard to find a switch with sufficient voltage rating. The one you linked is only good to 48V.


Allbright makes excellent products for this purpose, but they can be pricey.


https://www.albrightinternational.com/products/ed250/


When shopping, look very carefully at the descriptions because there are lots of Chinese knockoffs. Several of the links I looked at somewhere say Allbright ED250 type, or Allbright type somewhere. At least those hint that they are knockoffs, but I'm sure many don't.

 

[GoneDiving]

With a 48V system it might be hard to find a switch with sufficient voltage rating. The one you linked is only good to 48V.

Yep, absolute worst case will be 58v when the pack is at peak voltage and max current is 200amps so if I can get an honest continuous rating of 300amps, then I'd be comfortable with
a 48v rating. The switch will only be for isolation at low wattage, not opening and closing under load.

Bluesea is a well regarded OEM here. It wouldn't surprise me if the current unit is a Chinese copy of one of their models. As I said, an occasional 100amps was fine but 160 for hours was a bridge too far. I'll likely never need it to do again but it's better safe than sorry

Thanks