Opinions please

[sometimewoodworker]

We have a reasonably low power (50W maxim draw) 12 fan for when the power goes out.

I’ve used an old battery from our pickup but don’t want to kill that. So think I need a deep cycle battery, I do have a charger for it, so am looking for opinions on this.

  
to run the fan for a few hours occasionally 

[nauseus]

Good idea.

[Crossy]

50W @ 12V is about 4A

 

You really don't want to go deeper than 50% discharge on your battery on any sort of regular basis, even for occasional use I wouldn't go past 75%.

 

So your 50Ah battery will run the fan for between 6 and 9 hours (longer at low power on the fan).

 

Long enough? Go for it.

 

 

[sometimewoodworker]

2 minutes ago, Crossy said:

50W @ 12V is about 4A

 

You really don't want to go deeper than 50% discharge on your battery on any sort of regular basis, even for occasional use I wouldn't go past 75%.

 

So your 50Ah battery will run the fan for between 6 and 9 hours (longer at low power on the fan).

 

Long enough? Go for it.

 

 

Plenty thanks

 

I don’t know battery chemistry so wondered about the Gel version.

[Muzzique]

Just buy your GF/wife a large hand fan. Its much cheaper, works 24/7 and runs on Som Tam.

 

[Metropolitian]

I have a fan here, Lumira 15W 

It is connected to two solarpanels 20W each and before with a gel battery.

Battery has worn and the fan only works during the day.

Made my own battery pack with lifepo cells 5Ah, an first try with this technology, and which is now able to feed the fan for at least 4 hours when there is no sun.

The management board prevents undervoltage and do the balancing of each cell, extending the life of the battery.

 

Last week I ordered 56Ah cells, with that I would have effectively the same capacity as the battery you are showing.

I don't know how long it will last, that experience is something that has to come ????

Pricing in the same area. 700b per cell, 4 needed. (2800b incl shipping)

 

For around 4000 you can buy a complete kit, made for you. Which last longer then the deep-charge batteries.

 

I give it a try, maybe you can do too.

[Metropolitian]

1 hour ago, Crossy said:

You really don't want to go deeper than 50% discharge on your battery on any sort of regular basis, even for occasional use I wouldn't go past 75%.

^^^

 

I would do for those cells 80% as limit.

But most of the time I wasn't able to prevent this; car headlight still turned on overnight and fan not stopping when voltage went under the 1.8v per cell (7.5 volt on a 12v batt.) ????

 

Some graphs for the aficionados , the lower you discharge the shorter the lifespan (in cycles)

from two different sources.

 

 

 

But with Lifepo , when the numbers are right the capacity is still around 80% after 3000 cycles and they can be down to 20% of their capacity.

 

 

And the curve with discharging ratio vs currents.

 

 

 

" It's all in the chemistry " ????

 

[Crossy]

No argument from here @Metropolitian

 

But I'd take the increase in life any day, 500-600 cycles at 80% vs 1000 or so at 50%.

 

Personally, I'd plan for 50% in regular use with the occasional foray to 80% if the need arose. I suspect that in reality @sometimewoodworker is going to be nearer 25% most of the time and 2000+ cycles.

 

Bring on the LiFePO as noted the pricing is becoming competitive. 

 

[Metropolitian]

1 hour ago, sometimewoodworker said:

I don’t know battery chemistry so wondered about the Gel version.

It's all combination of electrolytes and the plates.

The older type were liquid and lead plates, they need maintenance but done well they can last long time. They need to kept horizontal.

The maintenance free batteries, VRLA, Gel, AGM,.. can be positioned in all direction. The electrolyte is a gel or hard substance.

Better batteries were made by using of different plate technology which won't corrode easily the same as with the older 'lead-copper' method, corrosion are caused slowly in with normal use but speeded up when under and overcharging. Sulfite crystals is building up on the plates and the conduction of plates lowers. (In tech terms. Internal resisitance) This is causing the batteries heating up when trying to charge 'dead' batteries.

 

You can lookup the lifespan with the chemistry, and perhaps differs which each brand too. Use the keyword 'DoD' .

 

For the chemistries in general the charts are like this:

 

           

 

 

[Metropolitian]

3 minutes ago, Crossy said:

No argument from here @Metropolitian

 

But I'd take the increase in life any day, 500-600 cycles at 80% vs 1000 or so at 50%.

 

Personally, I'd plan for 50% in regular use with the occasional foray to 80% if the need arose. I suspect that in reality @sometimewoodworker is going to be nearer 25% most of the time and 2000+ cycles.

 

Bring on the LiFePO as noted the pricing is becoming competitive. 

 

Totally agree.. No lifepo4 batteries going into my clocks and remote controllers ????
It's a new area I am trying and think it would only be for those batteries for long term and high capacity discharges.

 

For the outdoor lights and solar, I'd stick with the VRLA Gel batteries.

No need for them being lifepo4, now.

 

If @sometimewoodworker keeps his eyes on the capacity of the deep cycle batteries and the duration the fans are working, he will can get enjoy long time with the deep cycle batteries.

 

Wouldn't 1 cycle equals 1 day, mostly?  Then 4 years minimum.. not bad.

[Crossy]

I just did a very quick and dirty price comparison for something rather larger (planning on more solar, grid-tie but with a zero-export hybrid system).

 

48V system with 200Ah of usable capacity.

 

Amorn Solar - Deep cycle lead/acid 12V 100Ah - 16 needed at 5,300 Baht (probably not the cheapest) = 85,000 Baht = 2,600 US

 

AliExpress - "Lithium" (I think it's actually Li-ion) battery pack (inc BMS) 48V 200Ahr - 2,340 US + free shipping + 10% duty + 7% VAT = 2,754 US !!!

 

For those prices there is really only one solution if you have the $$$ to shell all at once (need to check my sums again).

 

 

[Metropolitian]

57 minutes ago, Crossy said:

AliExpress - "Lithium" (I think it's actually Li-ion) battery pack (inc BMS) 48V 200Ahr - 2,340 US + free shipping + 10% duty + 7% VAT = 2,754 US !!!

Very high, hence I tried the small battery pack with 'second line'^* and other experiments with used^* batteries.

 

The ^*'second line' are the batteries that didn't pass the high QC in the factories.

As the good ones are sold as new when they pass the QC with capacitance on at least 110% of the rating.

Anything below are sold as 'second line' and much cheaper.

The same when the casing has a scratch or other cosmetically issues, but the internal (capacitance and resistance) are the same or near the 'good uns'

 

The ^*used batteries are from e-bikes and other likes, and still having minimum 80% of their rated capacity which is around the 3500 cycles and still good for another 3500 cycles, but with a price tag around the 5-15% of new.

 

I bought the 5Ah cell for 65b a piece. 

When you use the 'second line' method a Cell of 200Ah cost around the 2800b, and multiply with 16 is 44800thb. Add with the BMS, 46000 in total.

Rough calculation as I don't have exact numbers but it's not far off. 1420 USD.

 

I calculated the 56Ah pack that I am having on 90 Euros, 80 for the cells and 10 for the BMS. (12V 55Ah, 35Ah CC BMS)

 

 

 

Edited April 24, 2020 by Metropolitian
numbers

[Metropolitian]

48 minutes ago, Crossy said:

I just did a very quick and dirty price comparison for something rather larger (planning on more solar, grid-tie but with a zero-export hybrid system).

 

48V system with 200Ah of usable capacity.

 

Amorn Solar - Deep cycle lead/acid 12V 100Ah - 16 needed at 5,300 Baht (probably not the cheapest) = 85,000 Baht = 2,600 US

 

AliExpress - "Lithium" (I think it's actually Li-ion) battery pack (inc BMS) 48V 200Ahr - 2,340 US + free shipping + 10% duty + 7% VAT = 2,754 US !!!

 

For those prices there is really only one solution if you have the $$$ to shell all at once (need to check my sums again).

That last line is the deal-breaker for most.

Personally that is something I am not taking out of my budget now, and not wanting (never do) to pay with pay-plans in terms.

 

Do calculate also the lifetime of the Deepcycle vs Lithium.  We will be happy to see your sums ????

 

I think; If someone has a good budget for it, it pays back to go for Lithium.    I try to start with small pack.  Cells can be added later.

Investing in solar isn't much different from that.  Panels can be added.

 

[sometimewoodworker]

1 hour ago, Crossy said:

No argument from here @Metropolitian

 

But I'd take the increase in life any day, 500-600 cycles at 80% vs 1000 or so at 50%.

 

Personally, I'd plan for 50% in regular use with the occasional foray to 80% if the need arose. I suspect that in reality @sometimewoodworker is going to be nearer 25% most of the time and 2000+ cycles.

 

Bring on the LiFePO as noted the pricing is becoming competitive. 

 

The 25% or under use is most likely and at that only a few times per month, so while LiFePO Would be great for much more regular use the one I posted seems to be best value for money, unless anyone has seen a deep cycle 50Ah 12V battery of any kind flooded cell VRLA, Gel, AGM

 

1 hour ago, Metropolitian said:

 

[Susco]

14 minutes ago, sometimewoodworker said:

The 25% or under use is most likely and at that only a few times per month, so while LiFePO Would be great for much more regular use the one I posted seems to be best value for money, unless anyone has seen a deep cycle 50Ah 12V battery of any kind flooded cell VRLA, Gel, AGM

 

The advantage of Lifepo4 is that it doesn't discharge, so if you need the fan only once every 6 months, you don't have to worry that it not gonna start

[sometimewoodworker]

1 minute ago, Susco said:

The advantage of Lifepo4 is that it doesn't discharge, so if you need the fan only once every 6 months, you don't have to worry that it not gonna start

As I said a few times per month and I have a charger so discharging is not a factor and price is.

[Metropolitian]

4 hours ago, sometimewoodworker said:

So think I need a deep cycle battery, I do have a charger for it, so am looking for opinions on this.

  

Trying help to get the best deal ????
How much is the shipping with the voucher.

 

At shopee the same battery, from a seller I have bought from before, it cost 2800b and 190b shipping (voucher 40b).

If you are in Smut Prakan, it can save on the cost of delivery to pick it up.

 

There was another one for 2790 but voucher doesn't apply with them. (self delivery instead of post logistics)

 

LVTopSun battery 12V 50Ah spec.

 

[sometimewoodworker]

1 hour ago, Metropolitian said:

Trying help to get the best deal ????
How much is the shipping with the voucher.

230, I need to buy 3 to get 30 baht off ???? 

[sometimewoodworker]

1 hour ago, Metropolitian said:

Trying help to get the best deal ????
How much is the shipping with the voucher.

 

At shopee the same battery, from a seller I have bought from before, it cost 2800b and 190b shipping (voucher 40b).

If you are in Smut Prakan, it can save on the cost of delivery to pick it up.

 

There was another one for 2790 but voucher doesn't apply with them. (self delivery instead of post logistics)

 

LVTopSun battery 12V 50Ah spec.

 

I tried to sign up for shopee but the captcha code was not accepted about u times so can’t use them

[Metropolitian]

6 minutes ago, sometimewoodworker said:

I tried to sign up for shopee but the captcha code was not accepted about u times so can’t use them

They have a facebook page also and there they promote the battery for 2500b.  Delivery for 150b. 

https://www.facebook.com/SPNMenergy/

 

For Shopee, I had issue with the capcha at first, then tried on the phone (or the other way) and it worked.

It need the phonenumber for login.  Have 3 accounts, each their own number. (triple the vouchers ???? )

 

 

[Fruit Trader]

5 hours ago, Metropolitian said:

Made my own battery pack with lifepo cells 5Ah, an first try with this technology, and which is now able to feed the fan for at least 4 hours

I have been following Jehu Garcia on the tube for a few years and started collecting 18650 cells back in early 2019. I now have 50 quality various cells and plan to start building a pack and charger later this year.

This is just a fun project that will likely end up powering the yard LED floodlights and sign.

 

Enjoy..

 

 

 

[stouricks]

Would a UPS for a PC not do the job?

[Crossy]

1 minute ago, stouricks said:

Would a UPS for a PC not do the job?

 

For a 12V fan?

 

With larger external batteries PC UPSs can be very useful, but beware of overheating and charger limitations.

 

[stouricks]

Just now, Crossy said:

 

For a 12V fan?

 

With larger external batteries PC UPSs can be very useful, but beware of overheating and charger limitations.

 

Sorry, didn't read properly, but for a mains fan it should do for a few hours.

[Led Lolly Yellow Lolly]

I run a nationwide network of VPN connected offices. We use a spoke/hub topology for the VPNs and the hub being the most critical element runs on a 19 volt rail run from a 12 volt SLA bank. This particular system is like a baby to me and I'm always tweaking it, modifying, improving. I've yet to find a more practical or cost effective solution to lead acid. It's ancient tech but it's totally understood, very easy to charge, and provided you control the float charge according to ambient temperature you will get 5 year or more out of batteries. Personally I set the depth of discharge at 70% and if I every go below that (maybe a dire emergency to keep the gateway online, genset out of fuel), I will replace the bank, no questions.

[Yankeesvsredsox]

Good idea it sure beats those wet face cloth's