Energy Matters Forums

[australsolarier]

half a year ago or so i ordered the batrium bms. on my battery i have the ev-power bms. the disadvantage thereof is the balancing voltage is 3.6V , not adjustable and too high in my opinion. it however works. just plugging together the data string and the thing works.
so, batrium having adjustable balancing voltages and being australian, i wanted to give them my support. even though the batrium is a first class product, theoretically, my experience with the batrium and their customer support has not been first class at all.

first off one of the cell cables (leading to the cell terminals) had the wires reverse hard wired. right out of the box. the data cable box, (the last one before it goes to the batrium circuit controller board) i could not plug in with the the data cable. i think the female plug was distorted from soldering or something. so i bypassed that plug and soldered directly to the small circuit board.
on doing the first bypass test, one of the tiny plugs between the cell terminals and the bypass board (they call it longmon) disconnected. the disconnect is between the very fine wire and the pin inside the plug, not between the male pin and the female socket.
so far i had 10 faulty cell wires, out of 16. the problem seems to be that for some reason they put hotmelt glue where the wire joins the plug. i don't know whether the blank wires got contaminated when they crimped the plug or whether some chemical from the hotmelt glue run down into the socket when bypassing (gets to 70 degrees).
the newest wires do not have the hotmelt glue anymore and so far i did not have a problem with those wires.
the interaction with batrium support however was total denial. i am sure there are more people with the same problem. and even though i sent them back two sets of the faulty wires. quite easy to establish with a simple ohm meter that the disconnect is between the pin and the wire. they wanted to make me video of the disconnect, which i duly did. here: https://www.youtube.com/watch?v=x1FxSt5boZA&t=24s
and sending pictures and "snapshots". and all kinds of other well meant advice.
3 of the cellmons have incorrect voltage. this is totally contradictory to balancing. on has 40mV and two 20mV too high read outs. when i contacted batrium i was told, the advertised tolerance of the cellmons is -+ 50mV. now that does not seem much, on first glance, but absolutely not acceptable for a lifpo4 battery. 100mV difference between cells is a very large difference. so i bought four more on my own cost. i also bought 10 more cell wires next to the 6 batrium generously provided for free. i mean, those wires can't cost more than 20c wholesale.
yes theoretically a first class product. i am still watching the damned thing to check if there is another cell wire failing. the good news is, so far none of the hotmelt glue free wires have failed .

would i trust it as an emergency disconnect? absolutely not.
to watch what the cell voltages are doing? yes, with the caveat that the voltages can be slightly out, or more if you are unlucky.
it does do the bypassing up to 2A and with my aircon going it will do it without having to reduce because of heat build up (70 degrees). in the winter without aircon blowing on the longmons after a while the bypass current will reduce. which is not a problem.

[angusjones8]

I have the EV BMS too and think the 3.6v is too high.
I’m not sure if it’s the correct thing to do but once a fortnight or so I increase my bulk charge to 58v and watch that the cells come up to voltage at the same time.
Once all the red lights are on the cell balancers I drop it back to 55v.
This seems to be working for me 18 months on.

[australsolarier]

hi, angusjones,
try to avoid the 58V. (you have 16 lifepo4 cells i take it?.)
it has been found those high voltages reduce the life of the battery. this has been found out by experience. hence the ev-power 3.6v balancing threshold.(the original chinese specs) you might contact Rod from ev-power for a good deal of the new bypass moduls at 3.5V. i think the only difference is a different small resistor.
my float V is 53.6 and absorption is 56V.
to balance the battery, the red lights have to be on for some time and every day, theoretically. so the bypass modules have time to actually bypass some current. like the first cell to hit the threshold V will bleed more than the last.
Kurt hand balanced so every 3months or 6months at 57.6V. like using a big resistor or an external isolated charging source. (there is a long thread on this forum somewhere).
temperature is also an important life shortening factor. therefore my power room has AC. the idea is, if it lenghtens the life of the battery for just 10%, the AC has paid for itself. besides all the electronics run at cool temperatures and are more efficient and longer lasting as well.
the ev-power bms is a dream to put together compared to the batrium. and unless you want to watch the cell voltages obsessively (like me) i would settle for the ev-power bms only. i mean it works. it does disconnect. and has a precharge feature. etc

[angusjones8]

Very interesting thanks for that.
I might see about those 3.7v balancers, sounds a bit better. I do like the EV BMS for it simplicity.
I think my v absorb is around 56v and v float around 54v.

[angusjones8]

3.5v I mean