Parralel wiring what's the reality?

[George2324]

im looking into alternative drivers due to price of meanwells and currently id need 27 hlg-320h-c1450 and id rather not if I can help it.

There's another seller on alibaba who makes their own drivers bright star.


He said he can make me a 65v driver with 7500 ma which can run 5 cobs each. I don't even know if this is cheaper than meAnwell yet but less bulky drivers is an incentive on its own.

Now I understand all the concept of thermal runaway etc.

What I don't understand is surely a 65v driver can only give each cob a 65v charge so how does the amount of voltage each cob draws ever increase?

And can I wire this way safely by implementing any sort of protection?

 

[shadow_moose]

What COBs are you running at 65v?

 

[George2324]

Veros for example

 

[safety meeting]

it is inherent of the diode construction itself ...ie why does the vF change?

diodes require constant current and when heat fluctuates the voltage needed for a certain current (amperage) will rise or fall slightly over time....this is called temp droop ....probably less than 2% difference normally and probably less than 5% in extremes....

so 65volts warming down to op temp may fluctuate 2 or 3volts....


fuses are for over volts and relays could be used to break current ....both for safety

 

[George2324]

So couldn't thermal runaway even happen when ran in series?

 

[sixstring2112]

I think he wants to know how problems occur in parallel wiring.its not the volts,the amperage will multiple if a cob fails.so lets say you had a 4000ma driver running 4x cobs in parallel. Each cob would see 1/4 of that amp so 1000ma per cob.if a cob fails then the other 3 cobs take on the extra amp load,no biggie @ 1.33 amp per cob most times,but the new heat load needs to be considered.using decent heatsinks should keep you out of trouble.but if this extra heat cant be handled then the other 3 cobs could start having issues.you can fuse each cob so if there is a failure the other fuses blow and none of them work.or fuse so they keep working until 2 cobs fail.but in reality cobs dont fail too often and lots of guys run parallel wiring with no issue.i have 1 fixture wired this way,not a huge fan of it but i used 110w heatsinks for a 35w setup so im good unless 2 cobs fail.i think with quality cobs the failures would come from faulty Cobb holder's, poor soldering on the builders part,or under rated wire used in the build.

 

[safety meeting]

So couldn't thermal runaway even happen when ran in series?

thermal runaway is a condition of constant voltage i believe ....which is how most ac circuits operate....thats why constant current is recommended....but also some cv drivers will limit voltage as well....

google thermal runaway and the difference between voltage and current and the difference between series and parallel wiring....a basic wiring guide answers most of these questions...

 

[George2324]

I see how the effects get multiplied if one cob fails then... since I'm gonna have 80 cobs I don't want that happening. I guess I'll spend extra and make sure they are in series

 

[sixstring2112]

I see how the effects get multiplied if one cob fails then... since I'm gonna have 80 cobs I don't want that happening. I guess I'll spend extra and make sure they are in series

you could use one of these on all your positive leads and use any size fuse you want.would be about 70 bucks to do 80 cob leads plus another 20 maybe for the fuses so under 100 bucks for peace of mind.https://www.amazon.com/DIGITEN-5x20mm-Holder-Inline-screw/dp/B00VLBAF84/ref=sr_1_8?ie=UTF8&qid=1488933854&sr=8-8&keywords=fuse+holder

 

[DankaDank]

THESE will work as well.

 

[sixstring2112]

THESE will work as well.

Did you forget a link ?

 

[DankaDank]

Did you forget a link ?

Does it not work when you click on "these"?

 

[brewbeer]

Meanwell is a good quality driver with generally good rep and efficiency. Check the efficiency rating of the custom driver you are considering; depending on your price of power lower efficiency could negate the cost savings over the multiple meanwells. Also consider the extra cost associated with fusing parallel wired cobs. It's nice to have multiple drivers, if you have a driver failure you can keep running as opposed being in the dark for a while with a custom driver.

 

[DankaDank]

Meanwell is a good quality driver with generally good rep and efficiency. Check the efficiency rating of the custom driver you are considering; depending on your price of power lower efficiency could negate the cost savings over the multiple meanwells. Also consider the extra cost associated with fusing parallel wired cobs. It's nice to have multiple drivers, if you have a driver failure you can keep running as opposed being in the dark for a while with a custom driver.

Can't beat a 7 year warranty either.

 

[CobKits]

im looking into alternative drivers due to price of meanwells

theyre the best bargain out there IMO. for as much as cobs and electricity cost they pay for themselves pretty quick

 

[George2324]

I agree meanwell are best but just curious as this manufacturer says they give 5 year warranty and 90% efficient same as meanwell I believe.

Kingbrite sells hlg-320h-c1750a for 87.50 usd equilevant constant current 1750a driver from this guy with enough watts to run 3 x 52v at 1750a is 54 usd.

In regards to efficiency with drivers does it mean that if your total cob watts add up to say 1000w and you have a 90% eficient driver in total we would Have 1100w at the wall?

 

[OLD MOTHER SATIVA]

...sourced many[ almost ]similar to meanwel.. they are not much less in price..meanwell still best price imho

 

[CobKits]

I agree meanwell are best but just curious as this manufacturer says they give 5 year warranty and 90% efficient same as meanwell I believe.

Kingbrite sells hlg-320h-c1750a for 87.50 usd equilevant constant current 1750a driver from this guy with enough watts to run 3 x 52v at 1750a is 54 usd.

In regards to efficiency with drivers does it mean that if your total cob watts add up to say 1000w and you have a 90% eficient driver in total we would Have 1100w at the wall?

most meanies are 93-96% efficient.

as far as the 5 year guarantee, has the company even been around for 5 years?

 

[cdgmoney250]

most meanies are 93-96% efficient.

as far as the 5 year guarantee, has the company even been around for 5 years?

Since 1982. They started out making power supplies for computers.

http://www.meanwellusa.com/aboutEvents.aspx?c=9

I feel real comfortable about using Meanwell drivers.

 

[brewbeer]

With 80 cobs run at 50 watts each, that's 4000 watts. A 1% difference in driver efficiency at $0.10 per kWhr is about $18 per year at 12/12, or $26 per year at 18/6. Double the cost of power and double the difference in driver efficiency and the small differences in driver efficiency becomes significant quickly.