February 9, 201610 yr Author To cut a big cable if you do not have the correct tools... Take good nitto tape and wrap the section you would like to cut. About 5cm wide should do it. Make sure you have at least 5 layers wrapped tight. Now use a small hacksaw, or a big one, but with a dull blade reversed, and saw through the section without too much pressure. With welding cable the thin strands tend to pull, so be aware. Aaah, sounds like a plan
February 9, 201610 yr Viceroy, between the batteries, shortest possible cables, go as big as you can. From batts to inverters, no need to oversize, just follow the maths. It is a fine line. TTT, I beg to differ here. The same amount of current is going to flow between the batteries and to and from the batteries, therefor your cables should all be the same thickness - but of course always as short as possible and as thick as possible to have the least amount of losses.
February 9, 201610 yr I have a crimping tool with dies from 6mm2 up to 70mm2 so thats not a problem. I would have a problem cutting 50mm2 cable. with my cable cutter it's pretty much on its limit at 35mm2. I use a baby grinder with a 1mm blade to cut all my welding cable, 10mm2 and up - just get your timing right - not too fast, because then you won't have a clean cut, not too slow because then the cable will heat up too much and melt the insulation.
February 9, 201610 yr TTT, I beg to differ here. The same amount of current is going to flow between the batteries and to and from the batteries, therefor your cables should all be the same thickness - but of course always as short as possible and as thick as possible to have the least amount of losses. superdiy, I think it is still true for the cables between the batteries to be as thick as possible to have the smallest deviation between the batteries itself. Im using 70mm2 links between my batts and then 50mm2 all the way to the inverter
February 9, 201610 yr superdiy, I think it is still true for the cables between the batteries to be as thick as possible to have the smallest deviation between the batteries itself. It is irrelevant, as I've said the same amount of current is going to flow everywhere. Im using 70mm2 links between my batts and then 50mm2 all the way to the inverter You would actually want it the other way around - the longer cables should be thicker to have less losses. The only place where you want to have the same size and lengths of cables is when you have parallel strings of batteries connected to bussbars - the total length and cable size per string must be equal in all parallel strings.
February 9, 201610 yr You would actually want it the other way around - the longer cables should be thicker to have less losses. Makes sense but since my links were free, i'll stick to this
February 9, 201610 yr Makes sense but since my links were free, i'll stick to this Ah, OK, I forgot, you had a company who did the installation. That is probably why your links between your batteries are 70mm2. Sometimes the installers buy or make up links, but in only one size, which they then use in many different installations for battery banks of various capacities.
February 9, 201610 yr Ah, OK, I forgot, you had a company who did the installation. That is probably why your links between your batteries are 70mm2. Sometimes the installers buy or make up links, but in only one size, which they then use in many different installations for battery banks of various capacities. Nope all self install, just got them from a friend that removed them and used solid copper bars on a install he did using 4v 3300ah batts A bank like that would be so nice....Oh the dream maybe one day
February 9, 201610 yr "4v 3300ah batts" - no typo Nope Mark using 12 of them, would be nice. Only thing is they come in at 160kg a piece, he used a engine jack to offload them
February 9, 201610 yr Author Oh. My. God. I cannot believe how stupid people can be. I told the battery stand supplier to take away their "bendy" stand and to return my 100ah battery stand as I could reuse it in the garage. My wife just got home, and sent me this picture. I left instruction with my maid that they were to just take their stand, drop mine off and not to touch anything. They ignored that instruction, and proceeded to load up a smaller shelf with the batteries. I am beyond shocked!
February 9, 201610 yr TTT, I beg to differ here. The same amount of current is going to flow between the batteries and to and from the batteries, therefor your cables should all be the same thickness - but of course always as short as possible and as thick as possible to have the least amount of losses. Superdiy ... it was a compromise. In Viceroy's case, the smallest cable is sufficient to handle the potential amps, i.e. from the fuses to the inverters, for as you said, the current is the same all over.
February 9, 201610 yr Oh. My. God. I cannot believe how stupid people can be. I told the battery stand supplier to take away their "bendy" stand and to return my 100ah battery stand as I could reuse it in the garage. My wife just got home, and sent me this picture. I left instruction with my maid that they were to just take their stand, drop mine off and not to touch anything. They ignored that instruction, and proceeded to load up a smaller shelf with the batteries. I am beyond shocked! These kinds of things drive me insane! That is why I DIY everything - try to rely on others as little as possible.
February 9, 201610 yr I have learned I can drive myself insane sometimes, trying to get things done properly. So when I get grumpy with service, like i.e. a battery rack, I take over and do it right. Then once it is sorted, I ask the supplier, very calm and nicely, how we can resolve it, for now I am happy. 9.9 out of 10 time it works amicably.
February 10, 201610 yr Author All I wanted was the batteries & upgraded delivered. The upgraded stand wasn't up to spec so I asked for my old one back, and came back that. Luckily everything is disconnected except for the 3 batteries on the bottom shelf...they were just connected to each other, so no damage other than them being a nuisance.
February 10, 201610 yr To cut a big cable if you do not have the correct tools... Take good nitto tape and wrap the section you would like to cut. About 5cm wide should do it. Make sure you have at least 5 layers wrapped tight. Now use a small hacksaw, or a big one, but with a dull blade reversed, and saw through the section without too much pressure. With welding cable the thin strands tend to pull, so be aware. Once through, take a carpet knife and remove as much of the wayward strands as possable to give you a clean "cut". In the past I have also used a "biltong" cutter, but it was not mine This method works like a charm, recommend a junior hacksaw only.
February 14, 201610 yr Hi, Even a very small difference in resistance of the battery interconnecting cables, will eventually cause the batteries to be unbalanced. See the following: BATTERY CONNECTIONS.docx
February 24, 201610 yr Author The new battery stand is scheduled to arrive today just arrived, so cant wait to see how much better and stronger it is compared to that other piece of crap. 5mm steel allround, except the top sheet which is 3mm. Overall dimensions is 950mm x 1150mm x 600mm The batteries will be supported on 114mm x 600mm x 38mm wooden sections.
February 24, 201610 yr I would be please with that. Looks mooi. My batteries which are similar to yours rest on 38mm shelves - no warping.
February 24, 201610 yr Author 1 hour ago, Chris Hobson said: I would be please with that. Looks mooi. My batteries which are similar to yours rest on 38mm shelves - no warping. I'm glad to hear that. We had an engineer friend come up with the specs for it, so should be pretty sound. I asked him today how much weight he thinks it should hold. His response was "about 2 tons"
February 24, 201610 yr 7 minutes ago, viceroy said: We had an engineer friend come up with the specs for it, so should be pretty sound. I asked him today how much weight he thinks it should hold. His response was "about 2 tons" Unfortunately I did not do as detailed design specs. My calculations were that if a 4m scaffold plank can support 4 chaps, cement and bricks then a ½m piece should support 2 batteries.
February 29, 201610 yr Author Got a bit of work done this weekend in between my normal 9-5 and family commitments. The wood for the stand was cut and fitted, and the whole thing put in place. The DC cabling was shortened between the batteries and the fuse box and the shunt installed in a nice little box. I'll be flipping the box around so the top hole is on the bottom just to hide cables a bit better. *Please excuse the exposed connection in the pic above. It's since been covered with electric tape while I source bus bars. I also moved the inverters down on the wall and began shortening the cables but I ran out of lugs. I also have a new DB box for the AC side of things and a nice little switch over do I can bypass the solar system entirely but still keep power to the house if I need to. Unfortunately I don't have further pictures at this point, but will post once things look neater and I've completed all the new cabling. Finally I got AICC working with the BMV700 on Windows Vista. Not much to report on that side of things since the AC is not connected yet, but it looks to be working smoothly except for some strange animation issues, but the actual numbers seem solid.
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