ML SERIES 24V 500A REMOTE BATTERY SWITCH BS-7717B

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Timmeh

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Jul 17, 2021, 12:28:57 AMJul 17
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Hello i have on order a sbms0 and wanting to know the easiest way to use a ML SERIES 24V 500A REMOTE BATTERY SWITCH BS-7717B to control battery connection to my system? is there a switched output on the sbms0 capable of switching the signal wire on the the mentioned contactor?

Plamen

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Jul 17, 2021, 8:46:15 AMJul 17
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Timmeh, i have that switch just the 12V version. It's connected but just the power side. I think to use it as a second level of protection (type 5) if anything goes wrong. I took some pictures inside before mount it.
Just checked i have 7700 model and beside the slightly different label i can't find other difference.

20190624_194534.jpg

 Also in the manual you attached there is no 'Remote control switch current'. In mine it says <100mA. So if assume that you have the same you'll need an external SSRelay capable of that current as SBMS0 IOs are only 50mA. 
  This is half of the equation. As its controlled by a two button push switch i'm not sure (have not tested)it can stay long time with the on or off signal applayed.

bat switch.jpg

 I know for sure that there is a switch inside to turn on the led inside the push button and its wired outside. I would connect the off signal cable in series with that switch so when the relay is off the control wire (for off switching only) is disconnected too. 
What will be you using that relay for exactly? If it's just for Low Voltage disconnect the Victron Smart Battery Protect is a better choice as it's solid state relay. And its in 65, 100 and 220A versions.

Plamen

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Jul 17, 2021, 8:50:31 AMJul 17
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Plamen

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Jul 17, 2021, 10:16:54 AMJul 17
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  The differnce is in control cables mine with 5 your with6. The one i have is with permanent magnet latching so uses power only to change state. The one you have is consuming <13mA continuous. Not sure how your works so maybe what i've written above not applys to you.

Dacian Todea

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Jul 17, 2021, 11:47:48 AMJul 17
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Latched relays are of no use as they will not be safe. If one of the remote wire where to become open circuit the relay should also be open but since it is latched that will not happen it will not change state so it offers no protection at all.
You should also not need a relay anywhere. 

Plamen

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Jul 17, 2021, 12:00:56 PMJul 17
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It's valid only if used for charging/loads or as type 5 too? If the cable to the trip coil is broken somewhere it will not be safe too.

Timmeh

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Jul 18, 2021, 7:07:24 AMJul 18
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The model i was looking at is auto release. only needs power to turn on. i was going to use it for battery main outlet for high and low cut off but then realised if bms shuts off relay due to low soc then chargers do not have ability to charge battery. So instead now i will use bp220 for fuse block loads with low voltage set and sbms also can switch if cell voltages are low and use sbms0 to switch the multiplus 2 inverter and charger when needed plus that will have low voltage cut off set as well. and also use the sbms0 to switch the victron mppt and dcdc chargers on and off when needed. My only worry is even if bms shuts off the bp220 due to low soc or low cell voltage i will be ok with small load bank due to battery protect being off but since mppt and dcdc and inverter are tied to battery directly if for any reason no charge is coming in for long period then the parasitic draw from inverter logic and mppt and dcdc can still drain battery further being directly tied. this may not be an issue so long as the battery gets charge every day from solar or dcdc which it will but i am just thinking worse case. I guess if i know there is not going to be charge for a while and battery is in lvc then i should manually isolate the battery until i can be sure there will be enough charge to keep the parasitic drain from over discharging the battery. As i understand victron smart batteries rely on the system to do all this the same way and don't have a bms inside? So my diy battery should be able to function the same with the sbms0 controlling loads. 

Plamen

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Jul 22, 2021, 5:08:36 PMJul 22
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Anyone knows what are those yellow elements? It's some kind of resettable fuse i think but can't find it.


yellow elements.jpg

J.W van de Poll

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Jul 22, 2021, 7:07:56 PMJul 22
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Hi All

They look like MOV's (Metal Oxide varistors) although they are usually red.
They are rated at a voltage at which they become a dead short.
Usually used to protect other devices from spikes.

If you can lift them there may be a voltage rating on the other side.

Regards

J.W van de Poll

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Jul 22, 2021, 7:11:32 PMJul 22
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PS: If the high voltage is sustained then they stay dead short permanently.

Dacian Todea

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Jul 22, 2021, 7:31:33 PMJul 22
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They look like PTC fuses so yes resealable fuses. 

Plamen

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Jul 22, 2021, 7:37:44 PMJul 22
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They are inside my Blue Sea battery switch. I took the pic. months ago before the install. There are two MOSFETs inside that control two coils. One to turn on and one for off. The yellow elements are in series with the coil and the mosfet. I think they protect the coil if someone keeps the button (on or off) pushed so the coil is disconnected after few seconds.

Plamen

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Jul 22, 2021, 7:41:04 PMJul 22
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Dacian, could you tell from the front sign what PTC is it. Or there should be marks on the back too?
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