Bargain lithium battery.

[Drover]

While the subject is on batteries I'm after advice..
115 ah and 130ah joined as 12 volt .
I do understand that this is not advisable but would a battery balancer work ..both are lead acid leisure.
Google says as the difference is small it's OK to do..
Any advice would be appreciated.

 

[trevskoda]

While the subject is on batteries I'm after advice..
115 ah and 130ah joined as 12 volt .
I do understand that this is not advisable but would a battery balancer work ..both are lead acid leisure.
Google says as the difference is small it's OK to do..
Any advice would be appreciated.

No problem, safe and leave as is.

 

[MERL]

While the subject is on batteries I'm after advice..
115 ah and 130ah joined as 12 volt .
I do understand that this is not advisable but would a battery balancer work ..both are lead acid leisure.
Google says as the difference is small it's OK to do..
Any advice would be appreciated.

Perfectly safe assuming both batteries are OK and don't have a cell down, same voltage (12v) and the same chemistry (don't mix GEL and AGM etc)
They are connected together pos to pos and neg to neg, therefore they find their own equilibrium and MUST balance automatically. Just like 2 tanks of water sitting side by side, if they are connected by a pipe then it's impossible for the water level in one tank to be higher than the other.
One final thing, when you join them up make sure they are charged to approximately the same level as each other. If you don't then the balancing current that I mentioned could be quite significant as the high tank drains into the low tank. (The higher charged battery drains into to lower charged battery) In order to attain equilibrium.

 

[Drover]

Thanks to Trevskoda and Merl ive just saved around 30 or 40 quid.

 

[YeoBlade]

Perfectly safe assuming both batteries are OK and don't have a cell down, same voltage (12v) and the same chemistry (don't mix GEL and AGM etc)
They are connected together pos to pos and neg to neg, therefore they find their own equilibrium and MUST balance automatically. Just like 2 tanks of water sitting side by side, if they are connected by a pipe then it's impossible for the water level in one tank to be higher than the other.
One final thing, when you join them up make sure they are charged to approximately the same level as each other. If you don't then the balancing current that I mentioned could be quite significant as the high tank drains into the low tank. (The higher charged battery drains into to lower charged battery) In order to attain equilibrium.

I always like water/electric analogies, great way to demonstrate an invisible quantity.

 

[Phantom]

I always like water/electric analogies, great way to demonstrate an invisible quantity.

So water and electrics can sometimes mix!

 

[Tezza33]

I always like water/electric analogies, great way to demonstrate an invisible quantity.

As long as you don't mix them together

 

[marchie]

I always like water/electric analogies, great way to demonstrate an invisible quantity.

Isn't an analogy a pre-digital measure of electricity? Probably explains why Mr Roger Conibear told me not take O Level Physics, because I would be wasting the Examiner's time ...

Steve

 

[matbic]

Extremely unlikely that the car would have LFP cells.

Most car manufacturers use LFP batteries now - Tesla standard range, VW, BYD all use them. They are safe, cheaper and the energy density has improved. The majority of new EVs are move LFP.

This is quite interesting:

https://www.mckinsey.com/industries/automotive-and-assembly/our-insights/the-battery-chemistries-powering-the-future-of-electric-vehicles

 

[MERL]

Most car manufacturers use LFP batteries now - Tesla standard range, VW, BYD all use them. They are safe, cheaper and the energy density has improved. The majority of new EVs are move LFP.

This is quite interesting:

https://www.mckinsey.com/industries/automotive-and-assembly/our-insights/the-battery-chemistries-powering-the-future-of-electric-vehicles

Back a few years ago when lithium was expensive I explored the idea of using the cells from a EV battery to make up a leisure battery for the van, abandoned the idea when I realised that it was almost impossible to get LFP batteries on the scrap/used market because virtually everyone chose either LMO or NCA for the early EVs.
I know that some EVs have moved to LFP very recently but Id not heard of the LMFP tech so yes that's interesting. I did a little research and it seems the addition of manganese to the LFP battery increases it's energy density by about 30%, it's still almost as stable and safe as standard LFP too. Interestingly the cell voltage increases considerably meaning that they'll probably never be suitable for leisure batteries because a 4 cell pack would create battery of around 15+ volts so too high for compatibility and a 3 cell pack would only be around 11 volts so too low. The number of cycles drops from 6000 to only 1500 too so that's quite a down side as well.

 

[colinm]

I watched a interesting video with a owner of a company that does testing and certification of batteries for manufacturers. What became apparent due to the extra demands of EV's, is that batteries of all sorts are poorly understood from a scientific angle, any theory on what should and shouldn't work is very approximate, and often quite unexpected results come about due to what appears to be minor changes in chemistry. Right now companies are throwing together all sorts of mixes of materials with only a vague idea of what the outcome might be until it's tested.

 

[trevskoda]

I always like water/electric analogies, great way to demonstrate an invisible quantity.

Same prinsable for electric and central heating, balance flow etc.

 

[MERL]

I watched a interesting video with a owner of a company that does testing and certification of batteries for manufacturers. What became apparent due to the extra demands of EV's, is that batteries of all sorts are poorly understood from a scientific angle, any theory on what should and shouldn't work is very approximate, and often quite unexpected results come about due to what appears to be minor changes in chemistry. Right now companies are throwing together all sorts of mixes of materials with only a vague idea of what the outcome might be until it's tested.

It's always puzzled me why science doesn't instantly know which elements/compounds will make a good battery and which ones won't. I'd have expected it all to be pretty fundamental physics but it's obviously not for some reason.
I've seen it touted more than once that AI should be able to suggest new chemistries soon.

 

[colinm]

I can't find the video now, but he was basically saying that you add a 'bit of fairy dust' and see what happens, i.e. say you added 1% potassium to a mix, and it has little effect, so you add 5% once again it has little effect, so you might give up on it, but you might find adding 3% makes a differance, or it could be you needed to add 1% but adjust something else to get a better outcome, as you can imagine the amount of different combinations are endless. The Chinese have been pouring vast amounts of resources into battery mixes, now we in the west are moaning about how they are 'taking over the world', but no western government had wanted to make the investment to anywhere near the extent.

 

[Boris7]

As an aside I’ve just changed my lithium 100ah x 2 for FogstarDrift 460ah the ones I removed are these

Cost £1k each 2 years ago, nowt wrong with them that a new SWMBO wouldn’t fix. We stay at race circuits a lot, not moving for several days at a time and she doesn’t understand why even with 200ah I have to use a generator. So now between Fogstar and Eco Flow I have 910ah and these and the generator will be getting sold. I’m thinking £250 for the batteries if anyone is interested.

 

[marchie]

It's always puzzled me why science doesn't instantly know which elements/compounds will make a good battery and which ones won't. I'd have expected it all to be pretty fundamental physics but it's obviously not for some reason.
I've seen it touted more than once that AI should be able to suggest new chemistries soon.

But the ink jet printer was 'invented' by a couple of employees who were 'experimenting' with syringes (spraying each other with squirted ink a la water pistol fights?), and look what that led to!

Steve