DIY Lithium

GeoffL

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I'm intrigued. I had thought of building my own battery as I've seen several YouTubes where people harvest type 18650 cells from various sources (e.g. laptop batteries) and then build up batteries from the good cells. Typically, a low number of bad cells bring a battery down and the remainder tend to have better than 80% of original capacity. However, I haven't found a UK source of 'salvageable' cells or of the nickel strips and spot welder needed to build the batteries. The USA has several specialist suppliers for these, but by the time you've paid shipping and taxes they don't seem viable for UK. FWIW, a 200Ah Lithium pack would give me all the power I need -- and I know I'd need to swap out the current mains charger for one suitable for lithium and also replace the current split-charge relay with a B2B system.
 

Philip Tomlinson

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I'm intrigued. I had thought of building my own battery as I've seen several YouTubes where people harvest type 18650 cells from various sources (e.g. laptop batteries) and then build up batteries from the good cells. Typically, a low number of bad cells bring a battery down and the remainder tend to have better than 80% of original capacity. However, I haven't found a UK source of 'salvageable' cells or of the nickel strips and spot welder needed to build the batteries. The USA has several specialist suppliers for these, but by the time you've paid shipping and taxes they don't seem viable for UK. FWIW, a 200Ah Lithium pack would give me all the power I need -- and I know I'd need to swap out the current mains charger for one suitable for lithium and also replace the current split-charge relay with a B2B system.
I don't have a B2B as LiFePO4 does not require absorption or float, it only needs a voltage of bulk of 14v - 14.6v. Victron makes a split charge "Cyrix" relay made for charging LiFePO4 batteries from the starter battery (not directly from the alternator).
 

wildebus

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I don't have a B2B as LiFePO4 does not require absorption or float, it only needs a voltage of bulk of 14v - 14.6v. Victron makes a split charge "Cyrix" relay made for charging LiFePO4 batteries from the starter battery (not directly from the alternator).
That does assume that the Alternator will put out a voltage of sufficient voltage though, does it not? Lots of Van Alternators are not capable of that.
 

Philip Tomlinson

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That does assume that the Alternator will put out a voltage of sufficient voltage though, does it not? Lots of Van Alternators are not capable of that.
Most modern vans built in the last 20 years will have a 14v alternator which will most likely be regulated to between 14.25v and 14.55v. There are of course exceptions which is why I always check the alternator type for the vehicle on the pre-install survey. My point was that it should not be assumed that you require a B2B for LiFePO4 batteries.
 

rugbyken

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i love it when david and phil are conversing it’s a whole new world or certainly a different language, i once travelled on a train sitting opposite two welsh ladies talking in the cymraeg after we had travelled about 100 miles i realised that the one word in ten that i recognised was a modern word with no gaelic origin the other 90% i hadn’t got a clue much like any technical discussion lol,
sam (scotia) was explaining the brewing process now i am passionately interested in this and my grandad was a brewer with Ruddles for 50 years so i understood almost 50% of what he was talking about, one topic he explained was ( burtonising the water) where they alter the chemical balance of the water to match the water found at burton on trent , i quoted this to a group of freinds one went of to check the fact & came back very impressed with my knowledge thanks sam owe you a pork pie lol
 

Derekoak

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Most modern vans built in the last 20 years will have a 14v alternator which will most likely be regulated to between 14.25v and 14.55v. There are of course exceptions which is why I always check the alternator type for the vehicle on the pre-install survey. My point was that it should not be assumed that you require a B2B for LiFePO4 batteries.
I am curious that means your lithium has 14.4v say, continuously even when fully charged? I thought being charged when fully charged was bad? I guess the answer is use a battery with its own well set BMS?
 

Philip Tomlinson

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I am curious that means your lithium has 14.4v say, continuously even when fully charged? I thought being charged when fully charged was bad? I guess the answer is use a battery with its own well set BMS?

Most LiFePO4 cells have a max charge voltage of 3.65v per cell (3.65v x 4 = 14.6v) it is unlikely that your alternator will increase the battery voltage to 14.6v, so they won't be full to the point where continuous charging when full becomes an issue. When I discussed motor vehicle alternator charging with three battery manufactures they said it would not be a problem as they do not consider even 8-12 hours of charging to be continuous, and how often do we have our engines running longer than that? The problem is with off-grid installations, standby power or even boats where the charge can for days, weeks or months without any discharge.
 

SquirrellCook

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Most LiFePO4 cells have a max charge voltage of 3.65v per cell (3.65v x 4 = 14.6v) it is unlikely that your alternator will increase the battery voltage to 14.6v, so they won't be full to the point where continuous charging when full becomes an issue. When I discussed motor vehicle alternator charging with three battery manufactures they said it would not be a problem as they do not consider even 8-12 hours of charging to be continuous, and how often do we have our engines running longer than that? The problem is with off-grid installations, standby power or even boats where the charge can for days, weeks or months without any discharge.
So is no one worried about invalidating the euro 5 or 6 specifications
 

SquirrellCook

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Ok, I will bite.
No Phil, it's not about biting. It's a genuine concern about electrical loading on a managed and optimized system.
I never hang on to them, but I'm sometimes sent technical bulletins on new emission standards and the implication of them.
Adding to the electrical loading was one such topic.
Looking at new Mercedes specs was shocking, (not cheap!) due to the fact a larger alternator was required if you had trailer lighting. I'd have thought 200amps would have been more than adequate for most normal applications. Trying to get a technical explanation out of the sales manager was next to impossible.
I think with potential demand your upgrade could have, it goes beyond "Accessories"
Just a thought.
 

Harryw

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silly emissions aside, by going straight to alternator without limitation/regulation the large current demand from the lifepo4 could fry the alternator in pretty short order though?

I will say though You’ve really piqued my interest in a self build single 4s 280ah pack though. However the direct purchase of the batts seems like a minefield with apparently different brands all outwardly looking the same. I note you’re stated you intend to use for the Eve ones, any reason?
 

Philip Tomlinson

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silly emissions aside, by going straight to alternator without limitation/regulation the large current demand from the lifepo4 could fry the alternator in pretty short order though?

I will say though You’ve really piqued my interest in a self build single 4s 280ah pack though. However the direct purchase of the batts seems like a minefield with apparently different brands all outwardly looking the same. I note you’re stated you intend to use for the Eve ones, any reason?

I would never connect directly to the alternator, I always connect to the starter battery this adds the required resistance to limit over current situations. Most modern alternators have an IC the prevents overcurrent and overheating.
 

GeoffL

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Most LiFePO4 cells have a max charge voltage of 3.65v per cell (3.65v x 4 = 14.6v) it is unlikely that your alternator will increase the battery voltage to 14.6v, so they won't be full to the point where continuous charging when full becomes an issue. When I discussed motor vehicle alternator charging with three battery manufactures they said it would not be a problem as they do not consider even 8-12 hours of charging to be continuous, and how often do we have our engines running longer than that? The problem is with off-grid installations, standby power or even boats where the charge can for days, weeks or months without any discharge.
Thanks for that insight. I'm not sure how to tell whether my alternator is up to the task (I have a 2001 Ducato 2.8 TDi). Neither am I sure how it should be wired to provide charge for both the cranking and leisure batteries. (Just connect the split charge relay to the cranking battery +ve rather than the alternator output?)

Another think I'm confused about is whether I need the more expensive 'protected' cells -- or does the BMS provide adequate protection. Methinks a lot of research is required before biting the bullet!
 

Philip Tomlinson

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Thanks for that insight. I'm not sure how to tell whether my alternator is up to the task (I have a 2001 Ducato 2.8 TDi). Neither am I sure how it should be wired to provide charge for both the cranking and leisure batteries. (Just connect the split charge relay to the cranking battery +ve rather than the alternator output?)

Another think I'm confused about is whether I need the more expensive 'protected' cells -- or does the BMS provide adequate protection. Methinks a lot of research is required before biting the bullet!
If in doubt with the alternator I would install a 30A B2B charger from the starter battery.

I have only really seen protected li-ion cells. I am using prismatic LiFePO4 cells with BMS protection.
 

Harryw

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I would never connect directly to the alternator, I always connect to the starter battery this adds the required resistance to limit over current situations. Most modern alternators have an IC the prevents overcurrent and overheating.
Thanks, I suppose that’s bit like having headlights on when jump starting.

re the other point I made about piquing my interest in a self build single 280ah pack and the minefield it is to trawl through the direct Chinese sites. I’m presuming you’ve spent a bit of time researching suppliers etc...
A bit cheeky, but as you’re not ordering to the new year I assume you’ve not clicked buy yet, would it be possible to piggy back your order and add 4 cells + 1 bms to what you are doing? I’m happy to transfer the dues upfront etc...
 

Philip Tomlinson

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Thanks, I suppose that’s bit like having headlights on when jump starting.

re the other point I made about piquing my interest in a self build single 280ah pack and the minefield it is to trawl through the direct Chinese sites. I’m presuming you’ve spent a bit of time researching suppliers etc...
A bit cheeky, but as you’re not ordering to the new year I assume you’ve not clicked buy yet, would it be possible to piggy back your order and add 4 cells + 1 bms to what you are doing? I’m happy to transfer the dues upfront etc...
Sorry, they came back with the (all-inclusive DDP) price 1858.4USD (£1,381.52) Yesterday and I paid it via Alibaba. I can give you all the details of the company that I am dealing with which is Basen through the Alibaba website.

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Harryw

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Sorry, they came back with the (all-inclusive DDP) price 1858.4USD (£1,381.52) Yesterday and I paid it via Alibaba. I can give you all the details of the company that I am dealing with which is Basen through the Alibaba website.
Ok, thanks anyway, he who snoozes..... I’ve seen that Basen one recommended via Wills tutorials and threads, one of the few that offer balanced sets from what I can see etc. Just in case could you send me link as I’ve found when scrolling through alibaba you can end up on a different page somehow!

edited to add did you get Eve or Lishen ones in the end?
 

Philip Tomlinson

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Ok, thanks anyway, he who snoozes..... I’ve seen that Basen one recommended via Wills tutorials and threads, one of the few that offer balanced sets from what I can see etc. Just in case could you send me link as I’ve found when scrolling through alibaba you can end up on a different page somehow!

edited to add did you get Eve or Lishen ones in the end?

I went for the Lishen batteries and their brand Basen BMS (which is a rebadge Daly BMS)
 

Markd

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2001 Ducato alternator will have a decent rated current output - enough for what you want.
All you can really check yourself is the voltage which again should be high enough.
One advantage of old style alternators is that they don't have any fancy controls stopping them 'working'
 
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