Calling all you lithium battery experts. (1 Viewer)

[berni109]

Bit of an ask here but could anyone who understands the details of bms have a read of the attached and tell me if this system is suitable for control of a lithium battery in the MH.
I am assured that although this refers to a 50v battery it's the generic bms thats in the 12v 100ah Ultramax that is at a very good price on Ebay and it comes with a dedicated external lithium mains charger as well. I have never heard of ultramax batteries so it my will be a case of 'you get what you pay for'.
My ebl will only do agm or gel but the solar control has several adjustable settings for lithium.
TIA
bern

 

[DBK]

I would say no - although I haven't read all of the document. I got to this bit:

"...specially designed for communication base station backup type of lithium power supply..."

So I think it is designed to keep an "emergency" radio battery topped up for when it is needed. This may explain why it current limited to 10A which is much lower than you need in a MH. This may also explain why it has no display - it is a fit and forget device.

 

[Robert Clark]

Would it not be easier to buy a battery with a built in BMS?

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[berni109]

Robert Clark thats what they are telling me is built into the battery.
ManTheVan just found your post - how are you getting on with the ultramax battery any problems

 

[Robert Clark]

Robert Clark thats what they are telling me is built into the battery.
ManTheVan just found your post - how are you getting on with the ultramax battery any problems

Can you provide a link to the batteries themselves?

 

[Pausim]

If it is what the manufacturer installed in the battery it should be set up properly for the job and there should be nothing for you to do or worry about. A good BMS is there to protect and balance the cells but it does not control the battery, it is up to the user what goes in and out of the battery.

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[berni109]

Robert Clark here u go https://www.ebay.co.uk/itm/131402654613
Raul see you referenced these batteries earlier this year. Were you recommending them or just commenting they were cheap?

 

[Robert Clark]

Robert Clark here u go https://www.ebay.co.uk/itm/131402654613
Raul see you referenced these batteries earlier this year. Were you recommending them or just commenting they were cheap?

I’d be worried about the warning on the battery to only use the charger supplied.

Does this mean you can’t charge with solar or a B2B?

 

[berni109]

No idea Robert. That's why I need the technical expertise to decipher the generic technical spec.
DBK it's a generic spec for all of the ultramax batteries(or so they told me) and printed on the battery case is max 80amp charge 100amp discharge. From my reading of the spec you can set charge limit between 0 and 25 or switch that off(good knows how) when it defaults 65amp and cuts the battery off from the charge input at 80amp.

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[Lenny HB]

I notice they only offer a one year warranty all the better branded LiPo4 batteries its between 5 to 10 years.

 

[DBK]

No idea Robert. That's why I need the technical expertise to decipher the generic technical spec.
DBK it's a generic spec for all of the ultramax batteries(or so they told me) and printed on the battery case is max 80amp charge 100amp discharge. From my reading of the spec you can set charge limit between 0 and 25 or switch that off(good knows how) when it defaults 65amp and cuts the battery off from the charge input at 80amp.

Sorry, I thought you were buying it as a standalone gadget.

 

[Robert Clark]

No idea Robert. That's why I need the technical expertise to decipher the generic technical spec.
DBK it's a generic spec for all of the ultramax batteries(or so they told me) and printed on the battery case is max 80amp charge 100amp discharge. From my reading of the spec you can set charge limit between 0 and 25 or switch that off(good knows how) when it defaults 65amp and cuts the battery off from the charge input at 80amp.

When I switched to lithium I chose Relion RB100 batteries
Swapped 6 lead acids for 2 lithium’s
Never had any issues in two years of use

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[Raul]

Robert Clark here u go https://www.ebay.co.uk/itm/131402654613
Raul see you referenced these batteries earlier this year. Were you recommending them or just commenting they were cheap?

I have two 200ah ultramax and I can tell you from my experience that they take 120a discharge and 80a charge, each without bms shutting down. I have not pushed them any higher it was a test, and with two batteries, these values will be shared by two. So at 400ah that would be 240 discharge and 160 charge. Will never happen on the van. I wanted to put them through their paces within the return guarantee to make sure I can rely on them later. They came with a 20a wall charger each, and give them the initial charge with that. It cuts of at exactly 14,40v dead. No float. So I set my charge controller to 13,8v absorb and 13,40v float. The B2B is set at 13,55v since it can’t do 3 stage and I don’t want a full charge from alternator. The sun can do that in the morning.

The bms you linked is a generic 48v bank 16s. I doubt they use 16s in a four cell battery, it will be a 4s bms with different settings for each battery size. You only need something like that if you build a 16cell 48v bank.

The battery you linked 100ah is a ultramax, with a 80a charge limit and 100a max discharge. It says on it, that’s pretty high values. Since discharge is max 100a, it means it’s got a 100a Bms inside, and limited in the settings to 80a charge. Any more, it will disconnect and resume when within parameters again. That’s Spot on if you don’t have very high demands.

Ultramax has been a while in UK ( based in Edmonton) and their main distributer is Battery masters UK. I have spoken with one of the tech guy before I did my purchase back in 2019. I was happy with the price and product so I made my move. One of the question I was insisting was, what cells they use, and did not disclose, but I was assured is from a main manufactures that supplies most of western lfp battery builder. That was enough for me. Victron uses winston cells and you could build your own bank at 1/2 cost of victron and still have change. For my curiosity I was going to drill the case and probe a camera in to see what cells and bms they use. It will be after warranty period.

 

[Raul]

I’d be worried about the warning on the battery to only use the charger supplied.

Does this mean you can’t charge with solar or a B2B?

The battery does not communicate with the charger, so any source that’s within parameters of original charger will do. The mention of using supplied charger is to cover themselves against the inexperienced user.

 

[Robert Clark]

The mention of using supplied charger is to cover themselves against the inexperienced user.

I’d avoid them based on that assumption

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[Raul]

I’d avoid them based on that assumption

Your choice. They sell allot to mobility users and golf carts. You expect them to charge with what? Besides a 20a charger to a 200ah monster is just a tickle.
I’m happy with the choice and so far superb. Horses for courses.

 

[Robert Clark]

These are supporters on FUN

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ecotreelithium.co.uk

 

[autorouter]

I would say no - although I haven't read all of the document. I got to this bit:

"...specially designed for communication base station backup type of lithium power supply..."

So I think it is designed to keep an "emergency" radio battery topped up for when it is needed. This may explain why it current limited to 10A which is much lower than you need in a MH. This may also explain why it has no display - it is a fit and forget device.

I think it's the kind of thing you find in the big boxes next to a mobile phone mast. 48V is the standard voltage for telecom systems.

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[two]

There are several different types of Lithium battery and each one requires a different regime of protection.
For that reason, I'd make sure that the BMS was matched to the battery you intend to use. Better still, get one with an integrated BMS. Even better, get an experienced installer to do the lot.

 

[Pausim]

Better still, get one with an integrated BMS. Even better, get an experienced installer to do the lot.

I think the op is thinking of buying an Ultramax LiFePO4 battery with a built in BMS. He has been told this is the BMS within the battery.

 

[berni109]

Pausim yes exactly!
Before ordering an ultramax battery I wanted to understand a little more how their bms which it is claimed is built in works.
They sent the document I originally attached saying it's their generic spec which they tailor for use in specific batteries. So while its referencing 48v all the various parameter are adjusted for 12v.
It's far to technical for me to understand completely which is why I was hoping someone might be able to decipher it for me.

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[Two on Tour]

Tinker2 bought and fitted a couple of Ultramax 100Ah LifePo4 batteries last month and seems pretty happy with them.

 

[berni109]

two "I'd make sure that the BMS was matched to the battery you intend to use. Better still, get one with an integrated BMS"
Just what I was trying to do!
Tinker2 if you have the time I would love to know what 'chargers' you have in the van putting amps back into the batteries.

 

[Tinker2]

Perhaps Paul two on tour, could answer for me.
My Oracle

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[Two on Tour]

Perhaps Paul two on tour, could answer for me.
My Oracle

Tinker2 is using the charger supplied with the Ultramax batteries for EHU in place of the original EHU battery charger, plus a Sterling BB1260 - B2B charger and a Voltronic MPP 250 Duo Digital for solar.

 

[ManTheVan]

berni109, I can only echo Raul ’s experience and say that I’ve been delighted with the Ultramax. I decided to swap out the old CBE mains hookup charger at the same time, for one that had a LiFePO4 profile (Sterling do lots of ex-demo clearance items on their website) and also installed a Sterling B2B.

We have 100W solar with a Victron Smartsolar controller that tops the LiFePO4 up every day. We have had no need of hookup since the upgrade and I feel that our power generation exceeds our demands most of the time. We’d probably hook up if we were on a shady site for a while in the winter, but otherwise not.

I hope this gives you confidence to go ahead with an Ultramax. I’ve got to say that I probably wouldn’t have taken the plunge if I’d had to pay £800-£1k, but it’s been very worthwhile so far and no regrets.

 

[two]

The one time I'd worry about an internal BMS would be if putting two such batteries together in parallel. I'm not sure that they would communicate with each other and balancing seems to be important.

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[Two on Tour]

The one time I'd worry about an internal BMS would be if putting two such batteries together in parallel. I'm not sure that they would communicate with each other and balancing seems to be important.

Batteries joined in parallel will naturally balance themselves anyway.
When I built my 240Ah LifePo4 battery pack, I discharged all the cells, then all were joined in parallel and left for 2 days to naturally bottom balance before putting the pack together.
I use an active balancer rather than the more common passive type and in the last year I have never seen more than .05 of a volt difference across the cells.
Properly matched cells with a matched internal resistance will rarely go out of balance and the more important job of a BMS is to protect from over voltage, low voltage as well as high charge and discharge rates.

 

[Pausim]

Batteries joined in parallel will naturally balance themselves anyway.
When I built my 240Ah LifePo4 battery pack, I discharged all the cells, then all were joined in parallel and left for 2 days to naturally bottom balance before putting the pack together.
I use an active balancer rather than the more common passive type and in the last year I have never seen more than .05 of a volt difference across the cells.
Properly matched cells with a matched internal resistance will rarely go out of balance and the more important job of a BMS is to protect from over voltage, low voltage as well as high charge and discharge rates.

That depends on how well the manufacturer matched the cells to start with. Apparently some don’t bother, in which case the BMS cell balancing function is important. The voltage may equalise between the parallel connections but there are also banks of 4 cells in series that have to be balanced too. They need lengthways and cross balancing, which is what the BMS should do. The best Li batteries will have full cell balancing and use matched cells.

This picture shows the set up for cell balancing.

 

[Two on Tour]

That depends on how well the manufacturer matched the cells to start with. Apparently some don’t bother, in which case the BMS cell balancing function is important. The voltage may equalise between the parallel connections but there are also banks of 4 cells in series that have to be balanced too. They need lengthways and cross balancing, which is what the BMS should do. The best Li batteries will have full cell balancing and use matched cells.

This picture shows the set up for cell balancing.
View attachment 449333

I agree that some manufactures don't bother to match cells and I would also imagine that their BMS would also not be up to par which would negate any real chance of having their battery in balance as a BMS is not a silver bullet to correct poor cell matching, plus the likelihood they would use passive balancing which discharges cells down to the cell with the lowest voltage rather than active balancing which in simple terms passes voltage from higher voltage cells to the lower voltage cells until they equalize.

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