have any of you installed non mrbf fuses directly on the + terminals of the lifepo4 battery? it would be 3x200ah lifepo4 12v batteries, to which nh fuses should be added. It would also be interesting to know if Gg fuses are suitable or if you should get e.g. Gs fuses?Gg fuses are cheap here,but gbatt etc. It is hard to find. I allready have 3x nh00 fuse bases. Class-T fuses are too ecpensive here in Finland,but if that is the only way to go,then i buy them.The inverter is a victron multiplus 2 12/3000w, so the maximum load is 12v. with the devices there would be about 2500w continuous current, i.e. about max. 80A per battery. I can install them with adapters made from round copper rod etc. the purpose would be to avoid short wires without fuses. The strength of the conductors is 50mm2 and they are connected to their own victron lynx power in busbar, from where they go to the inverter etc.
Lifepo4 fuses/terminal fuses
- Thread starter pete75
- Start date
robbob2112
Doing more research, mosty harmless
You can just use a short jumper wire to the fuse holder....works fine
You want the aR rated NH style fuses, it has the same fast curve as the class T does. The gG or Gbat fuses are slow blowing curves.
You want the aR rated NH style fuses, it has the same fast curve as the class T does. The gG or Gbat fuses are slow blowing curves.
Thanks. How about gs or gff fuse? Are you sure ar is the right one?
I was thinking that maybe i buy bluesea class-T fuses and holders. I need a little help. I have 3x200ah lifepo4,but one has 200a bms with 200a continous output and other two have 155a continous output. Wires are equal length about 130cm each and 50mm2 wires. What size class-T fuses i need? Or do i need 70mm2 wires? Seems like ar fuses are also expensive here so it is same to buy class-T fuses.
robbob2112
Doing more research, mosty harmless
You can use the NH00, NH01, or BS88 series of fuses with holders instead of the class T - You want the aR series of those fuses and it has the very similar characteristics to the class T here in the US.
the gG or gBat series fuses are slow blow verse fast blow, but would also work in a pinch.
the gG or gBat series fuses are slow blow verse fast blow, but would also work in a pinch.
What can you say about those fuse and wire sizes?
robbob2112
Doing more research, mosty harmless
So,
You can fuse at 125% of the BMS continuous capacity or you can fuse so the combined parallel capacity is enough for the invert in question.
I always fuse and wire to the BMS capacity -
200a * 1.25 = 250amps
155a * 1.25 = 183amps - fuse and wire to that.
from this website - just get the cable that is the next nearest size over.
so 107mm^2 for the large battery and 67mm^2 for the smaller ones - this will need to be crossed to the nearest common size available in your country. For sizing I generally use the 60c line of the chart if it will be enclosed and if it is open air you can use the 90c line of the chart.
The only real problem with wiring different sized batteries in parallel is they will get used at different rates - so your 155ah batteries will be fully charged and discharged faster than the 200ah battery.
So unless you set the capacity accuratly on a meter and keep them in the flat of the charge curve - between 20% and 80% over the long run it can turn out you need to carry the whole load on just the 200ah battery after the 155s are exhausted.
NOTE - the below is overkill and overthinking
You can try to balance by using larger cables on the 155ah, and longer cables on the 200ah battery - but that will take experimentation and calculation. Then a YR-1035 meter to meassure the total loop resistance for each battery. Get them as close as you can.... but the battery resistance changes slightly with the state of charge.
You can fuse at 125% of the BMS continuous capacity or you can fuse so the combined parallel capacity is enough for the invert in question.
I always fuse and wire to the BMS capacity -
200a * 1.25 = 250amps
155a * 1.25 = 183amps - fuse and wire to that.
from this website - just get the cable that is the next nearest size over.
so 107mm^2 for the large battery and 67mm^2 for the smaller ones - this will need to be crossed to the nearest common size available in your country. For sizing I generally use the 60c line of the chart if it will be enclosed and if it is open air you can use the 90c line of the chart.
The only real problem with wiring different sized batteries in parallel is they will get used at different rates - so your 155ah batteries will be fully charged and discharged faster than the 200ah battery.
So unless you set the capacity accuratly on a meter and keep them in the flat of the charge curve - between 20% and 80% over the long run it can turn out you need to carry the whole load on just the 200ah battery after the 155s are exhausted.
NOTE - the below is overkill and overthinking
You can try to balance by using larger cables on the 155ah, and longer cables on the 200ah battery - but that will take experimentation and calculation. Then a YR-1035 meter to meassure the total loop resistance for each battery. Get them as close as you can.... but the battery resistance changes slightly with the state of charge.
Ok. Thanks. All my batteries are 200ah lifepo4. Only one of them is differend brand and so it has bigger bms. I think they all can share a about same load in my case. I have multiplus 12/3000. Usually the load is small. Only sometimes at full power. They are in my summerhouse and i have 1620wp solar panels and victron 150/100 mppt. In summer they are almost everyday full. We are there usually weekends and so they can do balancing 4 days a week. I had those 2 last summer and worked fine. My seller gave me one more from different brand for free because those 2 have heaters and they did not work as they should,and it's free, so i was thinking to use all of them in summer. So now i have 600ah lifepo4. Now in winter they are all in my home and about 50% charge. The one i got is a refund and they let me keep the other ones too. They all are heated but i only use them in summer. Winter they are in my home garage. So what do you think? Smaller bluesea holders ,150 amp fuses and 50mm2 wires? Use is low loads,vacuum cleaner,coffee machine,tv,airfryer etc. Only sometimes 20-30min. Full 2400w...
robbob2112
Doing more research, mosty harmless
Sounds like you should be fine and I would just fuse and wire them all at 200amps to keep them balanced. You may miss out on a bit of continuous load but not really a problem IMO.
Seems like the correct wire size would be 95cm^2 - which is close to the 4/0 we use. If you get a 105c sheath just remember the max load may be different but if it is touching something that can't take 105c there will be scorching.
That said - this is from the multiplus 12/3000 install guide - we know what we calculate, but always follow the install guide. Although you could use 95cm^2 instead of 2 x 50cm^2 if you want. The 400amp fuse to the inverter is so it can do surges. You would still use 200amp fuses to the bus bars where you bring the battery cables together.
Seems like the correct wire size would be 95cm^2 - which is close to the 4/0 we use. If you get a 105c sheath just remember the max load may be different but if it is touching something that can't take 105c there will be scorching.
That said - this is from the multiplus 12/3000 install guide - we know what we calculate, but always follow the install guide. Although you could use 95cm^2 instead of 2 x 50cm^2 if you want. The 400amp fuse to the inverter is so it can do surges. You would still use 200amp fuses to the bus bars where you bring the battery cables together.
Yes i know that. I have 95mm2 wires from bussbar to multiplus. Now i only need to decide what wire size and fuses from battery posts to bussbar because of the new extra battery. So I was thinking maybe 50mm2 and 150a fuses,but you say 2/0 (70mm2 here in Finland). And 200a fuses is better?
robbob2112
Doing more research, mosty harmless
that is what I would use - this way you won't starve the inverter of power and if you use the same overall loop length to each battery they should stay pretty balanced.
Ok. Thanks. I will buy 70mm2 wires,class-T fuses and mount them like this guy does in this video. That's how i think i'm safe
One more question. Is class-T 225amp fuses too big for those 70mm2 (2/0) wires in my case? Class-T 225-400 holders and fuses are easy to find here.
robbob2112
Doing more research, mosty harmless
the 4/0 cables should support the 225 holder no problem - you are just bolting down a lug and need the correct size hole.
the 2/0 70mm^2 wire is probably ok, but depends on the temp rating of the sheath.
the 2/0 70mm^2 wire is probably ok, but depends on the temp rating of the sheath.
This cable and these are from batteries to bussbar. All equal length cables. Distance from every battery to bussbar is about 4 feet long. I can't get them closer.
70mm² (485 Amp) Hi-Flex Battery Cable (Made in EC)
Our 70mm² Single Core Battery and Welding Cable (Rated at 485 Amps) is easy to install as it is highly flexible, whilst remaining seriously durable. Copper conductor with PVC insulation, (resistant to oils, petrol, diesel, lubes and a range of diluted acids). Manufactured in accordance to CE...
www.splitcharge.co.uk
robbob2112
Doing more research, mosty harmless
MFG say 485amps so you should be good
Can i rely on it? If so then 50mm2 will work with 225amps fuse too?It's so confusing because every forum says that 1/0 for 150amps and 2/0 for 200amps.
50mm² (345 Amp) Hi-Flex Battery Cable (Made in EC)
Our 50mm² Single Core Battery and Welding Cable (Rated at 345 Amps) is easy to install as it is highly flexible, whilst remaining seriously durable. Copper conductor with PVC insulation, (resistant to oils, petrol, diesel, lubes and a range of diluted acids). Manufactured in accordance to CE...
www.splitcharge.co.uk
robbob2112
Doing more research, mosty harmless
Well,
This is what happens with wire temperature ratings.
The actual amount of current carried is fixed by the cross-sectional area of the wire.
The strand count affect heating and cooling... i.e. the ability of the heat generated in the copper wire to get away from the wire and disipate in the air.
The sheath rating means it can stand up to a certain amount of heating before it breaks down. The problem is you have to make sure everything that touches it can handle the heat it generates.
The last bit is why I generally use the NEC 60c chart to size the wires - I know if I put that current through the wires they won't ever get hot enough to cause a problem. I also know I have wiggle room if I use one size smaller with a higher temperature rating I am still good.
So, yeah you can use 50cm^2 wire - but it WILL get quite a bit hotter than the 4/0 and because it has higher resistance per foot it will respond slower when there is a surge in demand. But will that extra heat cause you a problem? If you only plan to run at 50% capcacity then probably not. The occassional surge to full capacity will warm it up, but that takes time and it cools off.
And part of the rating depends on if it is in open air, conduit, wire way, enclosed box.... if the heat can't get out go bigger and generate less heat.
I know that isn't a clear answer of yes or know, but you need to decide based on your situation - the rules are there to keep the person that doesn't understand or the contractor that wants to cut corners from causing problems....
This is what happens with wire temperature ratings.
The actual amount of current carried is fixed by the cross-sectional area of the wire.
The strand count affect heating and cooling... i.e. the ability of the heat generated in the copper wire to get away from the wire and disipate in the air.
The sheath rating means it can stand up to a certain amount of heating before it breaks down. The problem is you have to make sure everything that touches it can handle the heat it generates.
The last bit is why I generally use the NEC 60c chart to size the wires - I know if I put that current through the wires they won't ever get hot enough to cause a problem. I also know I have wiggle room if I use one size smaller with a higher temperature rating I am still good.
So, yeah you can use 50cm^2 wire - but it WILL get quite a bit hotter than the 4/0 and because it has higher resistance per foot it will respond slower when there is a surge in demand. But will that extra heat cause you a problem? If you only plan to run at 50% capcacity then probably not. The occassional surge to full capacity will warm it up, but that takes time and it cools off.
And part of the rating depends on if it is in open air, conduit, wire way, enclosed box.... if the heat can't get out go bigger and generate less heat.
I know that isn't a clear answer of yes or know, but you need to decide based on your situation - the rules are there to keep the person that doesn't understand or the contractor that wants to cut corners from causing problems....
Ok. Thank you for all your help. You gave me the answer. 70mm2 hiflex wires and class-T 225 fuses. Thank you.have a nice weekendWell,
This is what happens with wire temperature ratings.
The actual amount of current carried is fixed by the cross-sectional area of the wire.
The strand count affect heating and cooling... i.e. the ability of the heat generated in the copper wire to get away from the wire and disipate in the air.
The sheath rating means it can stand up to a certain amount of heating before it breaks down. The problem is you have to make sure everything that touches it can handle the heat it generates.
The last bit is why I generally use the NEC 60c chart to size the wires - I know if I put that current through the wires they won't ever get hot enough to cause a problem. I also know I have wiggle room if I use one size smaller with a higher temperature rating I am still good.
So, yeah you can use 50cm^2 wire - but it WILL get quite a bit hotter than the 4/0 and because it has higher resistance per foot it will respond slower when there is a surge in demand. But will that extra heat cause you a problem? If you only plan to run at 50% capcacity then probably not. The occassional surge to full capacity will warm it up, but that takes time and it cools off.
And part of the rating depends on if it is in open air, conduit, wire way, enclosed box.... if the heat can't get out go bigger and generate less heat.
I know that isn't a clear answer of yes or know, but you need to decide based on your situation - the rules are there to keep the person that doesn't understand or the contractor that wants to cut corners from causing problems....
I think the only thing that worries me anymore is whether the 50mm2 wires with 225A fuses can withstand the fact that if the battery goes short, the fuse burns instead of the wire melts and is ignititing a fire? the thickness of the wires is probably enough for my use. but I can buy 70mm2 wires if they are definitely the right size for the 225A fuse. That is only 40€ more so nothing,but much more difficult to mount...Well,
This is what happens with wire temperature ratings.
The actual amount of current carried is fixed by the cross-sectional area of the wire.
The strand count affect heating and cooling... i.e. the ability of the heat generated in the copper wire to get away from the wire and disipate in the air.
The sheath rating means it can stand up to a certain amount of heating before it breaks down. The problem is you have to make sure everything that touches it can handle the heat it generates.
The last bit is why I generally use the NEC 60c chart to size the wires - I know if I put that current through the wires they won't ever get hot enough to cause a problem. I also know I have wiggle room if I use one size smaller with a higher temperature rating I am still good.
So, yeah you can use 50cm^2 wire - but it WILL get quite a bit hotter than the 4/0 and because it has higher resistance per foot it will respond slower when there is a surge in demand. But will that extra heat cause you a problem? If you only plan to run at 50% capcacity then probably not. The occassional surge to full capacity will warm it up, but that takes time and it cools off.
And part of the rating depends on if it is in open air, conduit, wire way, enclosed box.... if the heat can't get out go bigger and generate less heat.
I know that isn't a clear answer of yes or know, but you need to decide based on your situation - the rules are there to keep the person that doesn't understand or the contractor that wants to cut corners from causing problems....
robbob2112
Doing more research, mosty harmless
if you get a direct short the fuse will blow in 0.1 seconds or more likely a lot less. It takes several seconds to heat a piece of heavy duty cable to the point of smoking and damage. Minutes to get to the point of starting a fire.
Where things get dicey is with multiple parallel batteries so the current supplied can be a lot but still within the limits of the other batteries so they just keep pouring it on.
Where things get dicey is with multiple parallel batteries so the current supplied can be a lot but still within the limits of the other batteries so they just keep pouring it on.
Ok. 70mm2 is what i buy and 225 fuses. Am i right?
robbob2112
Doing more research, mosty harmless
that is how I would do it.
By the way. Do you know class-t fuses watt loss?
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