Jump to content

DIY Lithium/LifePo4 battery build


Recommended Posts

On 2020/01/28 at 2:37 PM, Gerlach said:

You will see one some of the screen shots shows capacity 60AH , then i founded the lifepo4 setting on the BMS and all the settings was adjusted correctly and batteries was fully charge at 119.1AH / 100% SOC. 

FB_IMG_1580212894968.jpg

FB_IMG_1580212898313.jpg

FB_IMG_1580212902688.jpg

FB_IMG_1580212906184.jpg

FB_IMG_1580212910161.jpg

FB_IMG_1580212939945.jpg

FB_IMG_1580212933921.jpg

FB_IMG_1580212948166.jpg

FB_IMG_1580212958415.jpg

FB_IMG_1580213014838.jpg

Can you supply me with link to the bms that you use

Link to post
Share on other sites
  • Replies 146
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Popular Posts

The testing is not always done the same. If you test at 90% DoD and 1C discharge currents, the battery will be EOL (defined as having irreversibly lost 20% of its capacity) after 2000 cycles. If you t

I have around 250kWh of Leaf cells running Victron ESS  - not exactly a DIY task job as it all just bolts together.

True. I'm just making a point about how widely the advertised cycles can vary, to the extent that one manufacturer can advertise a number over 3 times bigger than the other, using the same cells 🙂

Posted Images

1 hour ago, Gerlach said:

@Kwagga hier is die link ZAR 801.03 24%OFF | Smart Bluetooth 7S-20S CELL Lifepo4 li-ion Battery protection Board BMS 400A 320A 300A 100A 80A PHONE APP 8S 10S 12S 13S 14S 16S https://s.click.aliexpress.com/e/_UeKHs

2de set of batteries is on there way to build a 2de bank. Other set is performing really good. 

Can you give me also the app in the play store.      Seems I am going to replace my lead to lithium

Thanks

Link to post
Share on other sites
5 hours ago, Kwagga said:

Can you give me also the app in the play store.      Seems I am going to replace my lead to lithium

Thanks

It's a APK app, i founded via a Youtube video but the seller send me all the info via a msg that's on a cloud. I will send you the link. 

Link to post
Share on other sites

What would the benefit be of using these cells over other technologies, apart from the safety etc.

As I see it you need 16 cells in series to make the "48V" but you still only have 120ah of capacity so it wouldn't last very long (dependent on load) or am I being daft and missing something?

Link to post
Share on other sites
On 2020/02/10 at 7:29 PM, Psion said:

As I see it you need 16 cells in series to make the "48V" but you still only have 120ah of capacity so it wouldn't last very long (dependent on load) or am I being daft and missing something?

I think what you may be missing is this: for the same load, a nominally 48 V system uses a quarter the current that a nominally 12 V system does. You probably have an idea what 120 Ah at 12 V can power; with a 48 V 120 Ah system, you can power that same load 4 times as long. Probably longer, as your idea of 120 Ah is probably based on lead acid batteries, which have a Peukert effect (they don't provide as much energy at high loads as at lower loads); lithium chemistries don't exhibit this effect, or if they do it's very small.

Think of a 12 V 10 A load; that's 120 W. A single 12 V 120 Ah battery could power that for about 12 hours (depending on Peukert effect, it may be a bit less). But then that's a 100% drain, not good for lead acid. So you only run it for  3 hours to preserve battery life. In a 48 V system, the load would be 2.5 A @ 48 V (still 2.5 x 48 = 120 W). So the set of 4 would last 12 hours.

Now you switch to a lithium 48 V battery, still at 120 Ah. Now the 120 W load is only 2.5 A (48 V x 2.5 A = 120 W). So the lithium battery could power that for 120/2.5 = 48 hours. But again, that's a total discharge, also not good for the lithium battery. But unlike lead, you can discharge to 80% DOD (20% SOC), so that's 48 x 80% = 38 hours. 38 hours versus 12 hours [ edit: was 3 hours ]. Now do you see the benefit? There is also less voltage sag, higher charge efficiency, and so on.

[ Edit: added lead acid on 48 V for fair comparison. Thanks, Ojeysky! ]

Edited by Coulomb
Fixed embarrassing error comparing 48 V with 12 V. Duh!
Link to post
Share on other sites

Does anybody perhaps know where in SA one can buy a Lifepo4 charger to charge a 48V 16s 120Ah pack? I am referring to a regular 220V AC charger and not a solar charger. It seems they are only available from China and obviously nothing coming from there now. Or any other ideas will be much appreciated.

Link to post
Share on other sites

I have batteries connected to my inverters but this is for a golfcart application and for somebody that does not have solar at all, thus needed to be charged frequently. Also bought the batteries from Bain but now charging is an issue. Power Supply only option I guess. Lots of them available on Aliexpress.

Link to post
Share on other sites
52 minutes ago, Hennie65 said:

And I mean lots of chargers available on Ali...

Well, none of my packages have shipped from Ali in 2020, and it seems like it is going to be that way for at least another month...

If they start shipping again after that, imagine the carnage at SAPO...

Link to post
Share on other sites
22 hours ago, Hennie65 said:

I have batteries connected to my inverters but this is for a golfcart application and for somebody that does not have solar at all, thus needed to be charged frequently. Also bought the batteries from Bain but now charging is an issue. Power Supply only option I guess. Lots of them available on Aliexpress.

Time to pump the Golfcart with some pannels on the roof and mppt on the that batteries ;) hahahahah!! i spotted the other day a setup like this on n guys cart, and it works. B) 

Link to post
Share on other sites
21 hours ago, P1000 said:

Well, none of my packages have shipped from Ali in 2020, and it seems like it is going to be that way for at least another month...

If they start shipping again after that, imagine the carnage at SAPO...

I was just lucky, some of stuff pitching up here and there after 3 months ordering. I guess SAPO had some time to sort out there 2 year back lock with now imports from China this 3 weeks. 

Link to post
Share on other sites
On 2020/02/12 at 1:49 PM, Gerlach said:

Time to pump the Golfcart with some pannels on the roof and mppt on the that batteries ;) hahahahah!! i spotted the other day a setup like this on n guys cart, and it works. B) 

Have done that one on my Lead Acid cart, I am using it for over a year already, works perfectly!

Link to post
Share on other sites
14 minutes ago, Henniem1 said:

cart

I can imagine that working quite well in some areas! In December we spent a few days on a golf course on the South coast, I mean, one of those places that really lends credence to the "white monopoly capital" conspiracy theory. Sunshine all the time, and golf-carts all over, driven inside the estate, parked outside the club house...

🙂

 

Link to post
Share on other sites

Just a quick question , i am building one of these DIY batteries , bought the batteries from Bain .

I notice most of the people bind /tape the batteries together , would it not be better with a slight gap between the batteries like a thick double sided tape or some thing (3 or 4MM)  ?

Any one have an opinion on this as far as cooling goes .

Link to post
Share on other sites
On 2020/02/10 at 10:59 AM, Coulomb said:

I think what you may be missing is this: for the same load, a nominally 48 V system uses a quarter the current that a nominally 12 V system does. You probably have an idea what 120 Ah at 12 V can power; with a 48 V 120 Ah system, you can power that same load 4 times as long. Probably longer, as your idea of 120 Ah is probably based on lead acid batteries, which have a Peukert effect (they don't provide as much energy at high loads as at lower loads); lithium chemistries don't exhibit this effect, or if they do it's very small.

Think of a 12 V 10 A load; that's 120 W. A single 12 V 120 Ah battery could power that for about 12 hours (depending on Peukert effect, it may be a bit less). But then that's a 100% drain, not good for lead acid. So you only run it for  3 hours to preserve battery life.

Now you switch to a lithium 48 V battery, still at 120 Ah. Now the 120 W load is only 2.5 A (48 V x 2.5 A = 120 W). So the lithium battery could power that for 120/2.5 = 48 hours. But again, that's a total discharge, also not good for the lithium battery. But unlike lead, you can discharge to 80% DOD (20% SOC), so that's 48 x 80% = 38 hours. 38 hours versus 3 hours. Now do you see the benefit? There is also less voltage sag, higher charge efficiency, and so on.

I think it will be 38hours versus 12hours since we should be working with a 48v Lead Acid as well, though it still does not remove the fact that lithium is much better and preferred. I have been using lithium for a month now and can say the experience is quite better....just like you noted, it reacts better to high load (high current draw)

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...