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snowflake View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2021 at 2:46pm
I've looked at a lot of batteries now. LiFEPo4 is a lot lighter for the same capacity, but they don't seem to be that much physically smaller - about 80% of the physical volume for same kWh. Have I got this right? I'm more concerned about the size than the weight so might end up going for lead.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bass*en*mass Quote  Post ReplyReply Direct Link To This Post Posted: 19 January 2021 at 9:00pm
the size difference depends on capacity, the lifepo4s need balancers and bms etc, those dont grow much with capacity, hence smaller ones are closer in size to lead ones, bigger ones much smaller..

weight is just one bonus, the stability on discharde/charging-current is much higher than lead, it also rises significantly with capacity, the discharge doesnt drop voltage as quick as with lead, hence load/current stay more healthy too.. (a decent capacitor/power cap might help on lead batt.)





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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2021 at 2:16pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2021 at 2:47pm
At £70 each plus possible import taxes, no not really *too* cheap...I'm cynical today so I'll say they probably won't test at quite 100Ah each - but that's not a crazy low price for prismatic 100Ah cells. Liitokala is quite an established brand now. 

 
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Post Options Post Options   Thanks (1) Thanks(1)   Quote bass*en*mass Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2021 at 8:39pm
snowflake, dont forget to buy/account for suitable balancers and a bms.. ;)
(those thin sheeted cells also require aditional care re. safe mounting, specially for mobile setups..)

SH/slightly used `integrated`60Ah ones go for about 150ish quid, if its just for some bletooth cabs without real lowend and rather small amps i guess those should give a better bang per buck diy :)


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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2021 at 10:19pm
Originally posted by bass*en*mass bass*en*mass wrote:

snowflake, dont forget to buy/account for suitable balancers and a bms.. ;)
(those thin sheeted cells also require aditional care re. safe mounting, specially for mobile setups..)

SH/slightly used `integrated`60Ah ones go for about 150ish quid, if its just for some bletooth cabs without real lowend and rather small amps i guess those should give a better bang per buck diy :)



on balance I was thinking of getting an integrated one - all the problems are dealt with 

I'm thinking of powering 2*15" FLH with it. Efficiency is a lot better than a vented box so 60Ah might actually give some decent output for a few hours. Looking at 100W solar panels to keep topped up. With British weather can probably rely on that giving about 20W on a cloudy day LOL

I ordered the Banda Elite 4000.4 amp yesterday. Will have loads of headroom but that should help maintain efficiency.

I think this is the best value new integrated battery from a UK supplier I have seen:
Ultramax LI84-12, 12v 84Ah Lithium Iron Phosphate LiFePO4 Battery | eBay

I will keep a lookout on ebay for a few weeks and see if anything used comes up.


Edited by snowflake - 20 January 2021 at 10:27pm
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Post Options Post Options   Thanks (1) Thanks(1)   Quote bass*en*mass Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2021 at 11:05pm
yeah, integrated balancer+bms module would do, just make sure it really matches your capc.
i am awaiting an esx QE80.4 this week, 240w at 4ohm bridged should allow for some headroom running efficient flh subs/horn loaded Tops.. :)
on a cloudy day solar panels are at about 5-10% wp, 100w? a standard 300w+ panel is fairly cheap nowadays.. ;)

those used 60Ah ones seem to sell well here, will pn you a link asap!


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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 21 January 2021 at 12:14pm
Originally posted by bass*en*mass bass*en*mass wrote:

yeah, integrated balancer+bms module would do, just make sure it really matches your capc.
i am awaiting an esx QE80.4 this week, 240w at 4ohm bridged should allow for some headroom running efficient flh subs/horn loaded Tops.. :)
on a cloudy day solar panels are at about 5-10% wp, 100w? a standard 300w+ panel is fairly cheap nowadays.. ;)

those used 60Ah ones seem to sell well here, will pn you a link asap!




they just get a bit big and cumbersome over 100W. weight seems to go up more than linearly too as they have to support their own weight. I could rig up three or four 100W panels on the trailer but they would be in different orientations - guess I would just have a separate cheap charge controller for each panel.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote eshroom Quote  Post ReplyReply Direct Link To This Post Posted: 21 January 2021 at 1:36pm
I made my battery using these cells. https://www.aliexpress.com/item/32970111444.html true capacity 6ah - not 7ah as advertised, but this is still very good for size/weight. It wasn't complicated to put together and I integrated a BMS.

Individual cells give you the option to distribute the battery within a space, rather than having a big battery block that needs a singe big space. You could split the battery in 4 and put it in 4 corners for example. I split mine to be on either side of my speaker's centre brace.

I paid about £45 for 12 cells and BMS creating a 12ah 19.8v battery. So I guess a 12v true 84ah battery would set you back around £160-£170 if you DIY it. Or if you want higher voltage, you just wire it straight to the voltage you require instead of losing energy with a step-up converter.




Edited by eshroom - 21 January 2021 at 1:42pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 03 February 2021 at 12:57pm
Banda Elite 4000.4 amp arrived:

output devices are four pairs of IRFP260M which look pretty decent - rated to 300W and 175C

caps on power supply are 4*2200uF 100V

2*1.5W cooling fans

heatsinks and case are substantial - amp weighs 5.5kg

kicking myself I didn't understand the spec properly. this amp doesn't have an adjustable crossover point, just switchable flat/90Hz LPF/90Hz HPF. Was hoping the amp would split my bass and mid/high and then use a passive mid/high crossover. But maybe I will just run it through and LMS to decide on crossover points and slopes and then design an active 3-way circuit - though that's another thing I have read about but never done before Confused I've got to quarantine for ten days at the moment so something to keep me busy!


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Post Options Post Options   Thanks (1) Thanks(1)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 04 February 2021 at 1:06pm
Originally posted by snowflake snowflake wrote:

Banda Elite 4000.4 amp arrived:

output devices are four pairs of IRFP260M which look pretty decent - rated to 300W and 175C


Heh....so right away I can see a bit of a hole in the specs then? Claims output of 650 watts RMS (not peak!) x4 at 12.6v into 4 ohms - but the MOSFETS are only rated for 300 watts each so the *absolute* max you could expect from a channel would be 600? And that would be using every last inch of the SOA which is likely to result in rapid failure. So I would bet this thing actually does something in the region of 300 watts a channel into 4 ohms at 12.6v. Maybe they just made a mistake and those ratings were supposed to be peak not RMS. 
The fact that the rating goes up with input voltage indicates the power supply isn't a boost *regulator* but just a fixed multiplier, probably x4 to give nominal 48v (that would also support the theory that this is a 300 watt per channel amp). So that internal power rail is likely to jump around quite a bit with current demand, especially if your wiring or batteries have any significant resistance. Could be a good application for a supercapacitor bank, to hold the input voltage steady. 
I like the look of the output filters though. Much beefier than you get with any TPA**** or TAS**** chip amp. It's always seemed a bit wrong to me to pass all the output current through a tiny inductor that gets rather warm in use. Those have nice thick wire and the caps look well sized too. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 04 February 2021 at 2:26pm
Originally posted by studio45 studio45 wrote:

Originally posted by snowflake snowflake wrote:

Banda Elite 4000.4 amp arrived:

output devices are four pairs of IRFP260M which look pretty decent - rated to 300W and 175C


Heh....so right away I can see a bit of a hole in the specs then? Claims output of 650 watts RMS (not peak!) x4 at 12.6v into 4 ohms - but the MOSFETS are only rated for 300 watts each so the *absolute* max you could expect from a channel would be 600? And that would be using every last inch of the SOA which is likely to result in rapid failure. So I would bet this thing actually does something in the region of 300 watts a channel into 4 ohms at 12.6v. Maybe they just made a mistake and those ratings were supposed to be peak not RMS. 
The fact that the rating goes up with input voltage indicates the power supply isn't a boost *regulator* but just a fixed multiplier, probably x4 to give nominal 48v (that would also support the theory that this is a 300 watt per channel amp). So that internal power rail is likely to jump around quite a bit with current demand, especially if your wiring or batteries have any significant resistance. Could be a good application for a supercapacitor bank, to hold the input voltage steady. 
I like the look of the output filters though. Much beefier than you get with any TPA**** or TAS**** chip amp. It's always seemed a bit wrong to me to pass all the output current through a tiny inductor that gets rather warm in use. Those have nice thick wire and the caps look well sized too. 


I'm trying to decide whether to bridge two channels into 8R or 4R load for the sub. I saw a video arguing that some car amp designs are current limited and that it is better to run them into a low impedance and keep the output voltage below the rail voltage, rather than run them into a higher impedance with more gain which means that it gets close to rail voltage and loses a lot of efficiency. I need to look into whether this is applicable to the Banda design or not.
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