Build a Battery … Where to start?

[740GLE]

25a max continued charge current? Id up that to 200a.

I’d also adjust the Charge UTP to 4c and Charge UTPR to 6-7c.

 

[MattMan119]

Well good full charge today with 30min absorption… max out of balance was .012mv .. only picture I got it just a min ago when it was out of float…

 

[MattMan119]

Reviewing the high and low cells … I don’t see any trends that worry me.. anyone see anything I should look at closer?

 

[MattMan119]

Looks like no problem staying balanced…

 

[MattMan119]

I want to clean up the cables and finalize the wiring this weekend anyone used any track or other helpers other then zip ties, the little ones seem to be helpful..?

 

[Kornbread]

Thought about using trunking to run the busbar in but decided the silicone booties over the busbar lugs and shrink tube over the busbar should suffice. Used small zipties to route the balance cables and made a top for the battery box out of plywood, to cover it all up.

 

[robbob2112]

Thought about using trunking to run the busbar in but decided the silicone booties over the busbar lugs and shrink tube over the busbar should suffice. Used small zipties to route the balance cables and made a top for the battery box out of plywood, to cover it all up.

Unless the bus bars are very oversized and won't get hot it would be better to mount them where they get convection cooling. This also means no heatshrink, instead plexiglass shields to allow airflow. Or mount in a channel to do it.

 

[MattMan119]

Thought about using trunking to run the busbar in but decided the silicone booties over the busbar lugs and shrink tube over the busbar should suffice. Used small zipties to route the balance cables and made a top for the battery box out of plywood, to cover it all up.

I think I have a plan for this today … going to cover all with vinyl panel for protection and put wood top on entire box, mounting display screen toward front to have complete visibility of status and maintain access without disconnecting everything,

Unless the bus bars are very oversized and won't get hot it would be better to mount them where they get convection cooling. This also means no heatshrink, instead plexiglass shields to allow airflow. Or mount in a channel to do it.

Yes, I will keep them unwrapped, I have seen little to no heat at all for the rates I push and pull so should not be a problem.


Now new question .. how and where does everyone attach the temperature censors? How and where .. suggestions?

 

[wpns]

Now new question .. how and where does everyone attach the temperature censors? How and where .. suggestions?

Some people seem to put the temperature sensors between carefully chosen cells, but then you have to be careful to electrically insulate them from the cells on all sides.

A previous discussion in this forum seemed to indicate that the cell terminals were pretty well thermally connected to the internal cell temperatures, so putting temperature sensors with lugs on top of carefully selected bus bars also makes sense.

Does the BMS have a temperature sensor to measure its own (heatsink) temperature? If not, you might want to put one there.

 

[Kornbread]

I place one on the outside of an outside cell to give me an idea of room temp and what the outer cells might be, then one near the middle of the pack for the same reason.

 

[Rednecktek]

My leads I just grab some leftover packing foam and lay the probe on top nested in the groove between 2 cells. Some hot glue around a chunk of packing foam on top keeps it reading the cell temp more accurately than the air temp around it.

 

[OzSolar]

Shortening BMS leads?

Sorry to jump in but I can't find the answer.

What's the scoop on this? I've only built a few batteries. Tidying up the rats nest of BMS wires is a bit tedious for me. I'd like to trim the BMS leads so I can tidy up wiring but then I'd end up all different lengths. Is that a problem?

 

[Rednecktek]

Not an issue at all, we do it all the time. Pro tip though, most BMS leads are really thin and have a hard time getting a good crimp into ring terminals. Strip off about double the insulation you need and fold the wire over so the crimp has more meat to grab on to.

 

[MattMan119]

Some people seem to put the temperature sensors between carefully chosen cells, but then you have to be careful to electrically insulate them from the cells on all sides.

A previous discussion in this forum seemed to indicate that the cell terminals were pretty well thermally connected to the internal cell temperatures, so putting temperature sensors with lugs on top of carefully selected bus bars also makes sense.

Does the BMS have a temperature sensor to measure its own (heatsink) temperature? If not, you might want to put one there.

Yes it would appear I have three.. one build into the MOS Of the BMS and the other two I can place..

I place one on the outside of an outside cell to give me an idea of room temp and what the outer cells might be, then one near the middle of the pack for the same reason.

I have a temperature gauge int he bay just above the battery for room temperature … so I guess they can go on two parts of the pack cells…

My leads I just grab some leftover packing foam and lay the probe on top nested in the groove between 2 cells. Some hot glue around a chunk of packing foam on top keeps it reading the cell temp more accurately than the air temp around it.

Oh this is a good way to do it, gives a nice safety layer to ensure we have the cell temperature..


Thanks all this is very helpful …

 

[OzSolar]

Not an issue at all, we do it all the time. Pro tip though, most BMS leads are really thin and have a hard time getting a good crimp into ring terminals. Strip off about double the insulation you need and fold the wire over so the crimp has more meat to grab on to.

Thanks. I've got a nice new pair of strippers that do a great job with the ~22 AWG wire, nice crimper and quality crimps so that part is is going relatively smoothly.

 

[Kornbread]

Thanks. I've got a nice new pair of strippers that do a great job with the ~22 AWG wire, nice crimper and quality crimps so that part is is going relatively smoothly.

I have a pair of crimpers with maybe 16different sets of dies that make a longer crimp and folds it in much better than the standard pair of cheap crimpers. Before those, the ring terminals got soldered.

 

[Zwy]

I am building 2 x 12.8 314ah batteries - I've choosen 3mm poron for between the cells and a 300amp 4s JBD BMS..

Good choice on using Poron.

I am still working out if I want to use aluminum or steel plate or wood at the ends.

Minimum 3/8" thick 6061 aluminum. Buy the 8" wide bar stock if you have a way to cut it.

 

[robbob2112]

Good choice on using Poron.


Minimum 3/8" thick 6061 aluminum. Buy the 8" wide bar stock if you have a way to cut it.

I ordered endplates 1/2 thick cut to size..

 

[MattMan119]

Why did you do that.. anyone get these questions …

 

[robbob2112]

Why did you do that.. anyone get these questions …View attachment 275146

Nobody touched my tool but me, so no questions... and I use shrinkwrap - it has a better grip and feel

 

[MattMan119]

Ok, lots of cable clean up and new connections today .. but did not get the main cover on but got almost everything else finished.. looking nice and clean .. got one picture under the vinyl protection cover…

And a few extra pictures, the low voltage 12v side of things is a mess now, got to clean that up ..

 

[robbob2112]

Why do you leave the all thread long? I notice that with a lot of builds...long threaded rod

 

[MattMan119]

Why do you leave the all thread long? I notice that with a lot of builds...long threaded rod

They hold everything together and they can be purchased at Home Depot very cheep .. some used to use them for compression, I did not do any compression they are more their to hold pack right where I placed in and no movement.

EDIT: just reread.. I will not leave them I will trim them for sure..just have not finished yet. But whated a picture of all 6 so @Zwy would notice that I did have enough room for all 6 …

 

[Zwy]

Why did you do that.. anyone get these questions …View attachment 275146

I use a Harbor Freight composite handle 1/4" drive ratchet. Tape on the 10 mm socket, a cheapie works so you don't have to remove the wrap. The head of the ratchet is still metal but if dropped on a battery terminal, there isn't enough length of the metal to reach another terminal. Has a push button so socket won't come off.

 

[Zwy]

They hold everything together and they can be purchased at Home Depot very cheep .. some used to use them for compression, I did not do any compression they are more their to hold pack right where I placed in and no movement.

I think many think the compression I use is really hard compression but it isn't. It is enough to put pressure on the sides of the cells and also keep them in place.

EDIT: just reread.. I will not leave them I will trim them for sure..just have not finished yet. But whated a picture of all 6 so @Zwy would notice that I did have enough room for all 6 …

It looks good, just leave them long enough so it is easy to put the nut on if you ever have to disassemble.

That white foam from the packaging? Get rid of it, it is very flammable. Get some Lexan, you can drill and tap it easy. Plexiglas not as easy. This would give a spot for the screen.