Home assemble LiFePo4

[Nabsim]

I can’t believe how much they are charging for bus bars or strips of copper to make your own. I am sure I sent some copper and brass strip to scrap yard when I moved last year

 

[wildebus]

This was my first thought David, but you need a larger hump than that to relieve the stress on the connector.
I was also thinking about high density foam between them too.

did you watch the video and notice the flex in those? much more than a solid bar with a hump. The flex-bar would straighten out if pulled on.

Also, how rigid is the connector on the cell internally? is it solid or is it cable? I don't know if anyone has actually opened up a cell and looked? For example, if you pulled the connector hard enough on the case of most 12V Lithium Batteries, it might distort the case but it will make no difference to the actual battery as the other (internal) end is on a flexible cable. I don't know if the same would be true of the individual cells? (the general assumption that is is a solid connection internal to each cell may be just wrong).

 

[SquirrellCook]

did you watch the video and notice the flex in those? much more than a solid bar with a hump. The flex-bar would straighten out if pulled on.

Also, how rigid is the connector on the cell internally? is it solid or is it cable? I don't know if anyone has actually opened up a cell and looked? For example, if you pulled the connector hard enough on the case of most 12V Lithium Batteries, it might distort the case but it will make no difference to the actual battery as the other (internal) end is on a flexible cable. I don't know if the same would be true of the individual cells? (the general assumption that is is a solid connection internal to each cell may be just wrong).

No I didn't David and made an assumption. They do look like they tick all the boxes, even though they are a little pricey.
As for the structure of the internal connections I don't know. Maybe our glorious leader Phil would like to put a hacksaw to one of his?

 

[Derekoak]

I don't know how much expansion you want to allow for but I had to make longer bus bars anyway because of my 4.5mm thick heat pads, so it was easy to make flat bars a couple of mm longer still from 1.5mm copper to allow for double sided gorilla tape which is about 2mm thick and squashy butyl rubber or something like.
The tape makes my cells into a unit as well as a squashy spacer.

 

[Sprinter 1 cup]

Can you turn off the victron 30amp B2B independently if temp is to low outside ?
And how dose my solar controller know it's to cold am I missing a temp leed. .?
Or is it the battery (relion ) has this or not ?

 

[Nabsim]

Can you turn off the victron 30amp B2B independently if temp is to low outside ?
And how dose my solar controller know it's to cold am I missing a temp leed. .?
Or is it the battery (relion ) has this or not ?

Does the Victron B2B not have a connection for a temperature sensor? I know on my Votronic B2B there is a connection ready but you had to buy the sensor separately

 

[SquirrellCook]

The temperature sensor is an option on the smart shunt as far as I know, but I'm sure our friendly expert David will be along shortly to correct me

 

[wildebus]

The temperature sensor is an option on the smart shunt as far as I know, but I'm sure our friendly expert David will be along shortly to correct me

Does the Victron B2B not have a connection for a temperature sensor? I know on my Votronic B2B there is a connection ready but you had to buy the sensor separately

The Smart Shunt and the BMV-712 both have a temp probe option, and there is also the Victron SBS (Smart Battery Sense). All those devices can send Temp info using Victrons VE Smart Network using Bluetooth.
However, the Victron B2B, although being bluetooth enabled cannot participate in the VE Smart Network and has no temp sensor input or temp control as far as I know (bit of an oversight really IMO. Later versions may have added them but I don't think so).
What you can do with the Victron Smart-Tr B2B is use the remote control feature and use a little temp probe device to disable the charger when the temp goes below the pre-selected setting.
Get something like this - https://amzn.to/3FJH5Sp - for £6 (less than 1/5th the price of the temp sensor cable for the BMV/Smartshunt or the SBS unit) and connect the relay up to the B2B Remote Control (connect K0 and K1 on temp board to H & L on B2B) and set the temp board up to open the relay (thereby turning off B2B) when under a certain temp. I use the same board to turn on a fan when temp goes above a set temperature.

There is a bit of a discussion on this thread - https://motorhomebuilder.com/threads/bit-of-an-electrical-quandary.67049/ - where I posted a schemetic of how I controlled multiple chargers using the single temp sensor board.

 

[SquirrellCook]

As a few have already I've jumped on the Chinese LiFePo4 boat. Though reading peoples complaints the Boat might have a small leak.

It seems they have been despatched early, but as yet no tracking details. I'll keep you all updated.



View attachment 4750

I asked a couple of days ago about the cells voyage to England. It seems they are still at sea, but should soon be hiding in a container in a UK port.

 

[wildebus]

I happened across this video today which I think may be interesting to anyone putting together their own battery packs.

Lots of things discussed and some things to consider

They fitted a nice big 20,000KW battery bank in their pretty small (euro sized, not US sized) RV as well.

 

[SquirrellCook]

Wow that was hard to stay awake.

 

[wildebus]

no useful tips then?

 

[SquirrellCook]

no useful tips then?

Not really, other than they consider them to be thermally stable. Then I won't be shoving in huge numbers of amps, or dragging them out again.
Now when I buy my DAF euro 7 hybrid 7.5 tonnes chassis Cab, I might be using the habitation to aid propulsion

 

[wildebus]

Not really, other than they consider them to be thermally stable. Then I won't be shoving in huge numbers of amps, or dragging them out again.
Now when I buy my DAF euro 7 hybrid 7.5 tonnes chassis Cab, I might be using the habitation to aid propulsion

I noted the point about temperature at non-silly loads

 

[Derekoak]

As we are getting li fe po4 and these batteries were lithium ion it was only of general interest.

 

[wildebus]

As we are getting li fe po4 and these batteries were lithium ion it was only of general interest.

They are LiFePO4 batteries.

 

[Derekoak]

OK they called them lithium ion. I am sure confusion abounds when Americans speak English.

 

[SquirrellCook]

They are here! Just typical, so much customer work on and so far behind with it means little time to play. Tracking their progress was rubbish, as they were supposed to be still on the boat yesterday.

Next job I guess is to buy some crimps and a big crimping tool for them. Heat pads are supposed to be here by the 30th of December.
At the moment I'm thinking of covering them with epdm foam and making a Buffalo board box to put them in. Still not sure about top balancing them as I'm sure they will not have a hard life. I think I'm three time over the capacity of Murky.

 

[Derekoak]

Great! So no disasters and 4 arrivals for these forums so far. Mine had labels saying they were at 3.27v and they all were and when attached to the bms they were close to balanced. If yours are too, perhaps top balancing is not needed. Are they from Basen?

 

[SquirrellCook]

Yes these were from Basen, it is always a problem when purchasing knowing what will happen with your order. There are too many what I call "bedroom businesses" They take your money and hold no stock. We don't take deposits for parts that are yet to be made. If they don't want the part when it's done, plenty of others will.
If you know your commissioning something bespoke to you, that's another story. Or you are unknown to the supplier you expect to pay up front.
Now I've done it once I will be more comfortable, I purchased a machine from Vietnam a few years back and fell into a few traps. It all worked out in the end.