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Looking for a 24V Dc to DC.

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(@dickson)
Noble Member
Joined: 3 years ago
Posts: 1043
 

And the idea is to use all four of them in parallel. If a string shorts, they can put out between 300 and 400 Amps per cell. That means between 900 and 1200 Amps per battery. I intend to solve that problem by fusing them for no more than 100 Amps each battery and then the buss itself at 300 Amps. Depending on what I find, I might change them to 7S4P units times 3 

 

Yes for a  24v inverter  you need to  fuse and  circuit breaker  each of the  4 banks of battery  and the bus bar  is fuse for 300 amps .   I  have a 48v inverter and do the same  for 12 banks of battery in parallel  16s12p  with  12 fuse  and  12 circuit breaker  and  12 voltage regulator  and 12  separate  charging  circiut  with  65v MSB  solar chatger during day or  10 67v e-bike charger at night  and  my bus bar  is fuse 400 amps .   Six feet of pure copper bar 1 1/2 x  1 1/2  inch square  is 700 dollars  and is  3 times larger than  three 1/2 inch  copper bar bolted together .   Yes  three 3/0  welding cable  in a  short  2 inch copper pipe  will  be cheaper .  


   
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(@waterman)
Reputable Member
Joined: 3 years ago
Posts: 313
 

Well the batteries did arrive yesterday and by 2100 I had one partly taken apart. The cells are as I suspected so I'll be able to convert the 4 units down to three units and still have the same Ah rating as the 4 would have had with them only taking the space of the original 3. Now I just wish I had bought more of them at the price. Oh well, as I won't need as many cell holders, I can just order more individual cells and make a 4th one.


   
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(@waterman)
Reputable Member
Joined: 3 years ago
Posts: 313
 

Well they must have found some more so 4 more are ordered.


   
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(@the-blind-wolf)
Prominent Member
Joined: 3 years ago
Posts: 878
Topic starter  
On 10/17/2021 at 9:55 PM, Waterman said:

3 # 3-0 wires would handle that. How about soldering and crimping terminals on one end then strip the length needed plus the extra for the same terminals on the other end. Then insert in a 2" copper pipe. Compress the pipe till almost flat keeping the bundles loose on the end without the terminals yet. Crimp and solder on the terminals. Finish compressing the pipe. Solder the pipe full at the ends. That would give you a buss bar with 3 terminals on each end and just about equal the size you mention. I'm about to have to worry about the same sort of thing because the batteries to be delivered tomorrow can output 200 Amps per cell normally and they are in 7S3P configurations. And the idea is to use all four of them in parallel. If a string shorts, they can put out between 300 and 400 Amps per cell. That means between 900 and 1200 Amps per battery. I intend to solve that problem by fusing them for no more than 100 Amps each battery and then the buss itself at 300 Amps. Depending on what I find, I might change them to 7S4P units times 3 to save space as the single cell packs should be the same thickness as the doubles from looking at the pictures. They are SPIM08HP 3.7V 8AH 200A Lithium Ion Cells.

And these are what I had in mind when I ordered my order of Sid's balancers.

Haha, I got around 100 of those hp spims laying around, well not that many but, darn enough to make a hell of a battery, just never could figure out how to solder or weld on the tabs, since they are the type of metal you can't solder or weld on hardly.  When I got them they didn't have the holders you can get with them now form battery hook up.alauminm


   
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(@waterman)
Reputable Member
Joined: 3 years ago
Posts: 313
 
Posted by: @the-blind-wolf
Haha, I got around 100 of those hp spims laying around, well not that many but, darn enough to make a hell of a battery, just never could figure out how to solder or weld on the tabs, since they are the type of metal you can't solder or weld on hardly. When I got them they didn't have the holders you can get with them now form battery hook up.alauminm

Were the tabs cut? The way they were designed to be used was with a steel block on the battery side of the tab and the copper and steel plate on the top with the bolts going thru the upper part and threaded into the steel bar. Some people have drilled and pop riveted then together. In a set of 4, in a 4S1P configuration, they will start a car or small truck. One person made a 3S1P and it was able to pull over 400 Amps and start a car so these things are plenty powerful enough.

Well the next orders are ready to be shipped so I'll soon have a total of 224 of those cells. That will make a total string of 8 units at 32Ah each. Was going to buy one of the 36V units from BatteryHookup until I saw the shipping costs for it. Nearly the same costs as the unit itself.

If you want some of the cell holders and bars, I soon will have more than I need.


   
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(@waterman)
Reputable Member
Joined: 3 years ago
Posts: 313
 

Picture of an assembled 24V32Ah battery. Terminal strip is to allow hooking up things like the GS shunts.

20211111_173059.jpg


   
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(@weldman)
Active Member
Joined: 3 years ago
Posts: 12
 
On 10/16/2021 at 11:41 PM, dickson said:

I've though about running each battery bank to a bus bar, but there are no bus bar big enough to handle 600 amps at 24v, and I would need one that can handle that 

 

You are  right  about no bus bar to handle  600  amps  .  The  wire  size needed  will be  1 and 1/8  inch  copper  or 700 kcmil  .   The  cost of wire  and breaker and fuse and switch for  24 volt  and 12 volt  inverter  will cost more than one GS inverter .    Has to go with  48 v or 60 v  inverter .    Thank you for your information  as I did not know your situation before  and why  the fire  and the melted  bus bar .     

https://www.bluesea.com/products/1991/PowerBar_1000_-_12_3_8in_Terminal_Studs


   
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(@waterman)
Reputable Member
Joined: 3 years ago
Posts: 313
 

Now that I started making my own panel, that would have saved me some costs and time.  I did have a change in plans as instead of 8 of the batteries there are going to be 10. Each protected by a 100A fuse ( - ) and a 150A breaker ( + ). Then the buss itself will be protected by a 300A breaker on each leg. The breaker is to allow disconnecting without fuse removal and the batteries are all hooked to the fuses and breakers thru 175A Anderson style connectors.


   
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