How to install a cell Low Voltage alarm?

[imorton]

Hi Guys, I have bought a 48v LifePo4 http://www.ebay.ca/sch/Multipurpose...?_nkw=&_armrs=1&_ipg=&_from=&_ssn=sun-thing28 from eBay seller Sun-Thing28. It should be here in a few weeks..

I was contemplating installing two 8S Lipo Battery Tester Low Voltage Alarms to monitor and verify the 16 cell voltages. http://www.ebay.ca/itm/New-1-8S-Lip...LH_DefaultDomain_0&hash=item4ad413f96e&_uhb=1

Now my questions are, what do I buy as to the connector/cable, and how do I install it?

Which of these two connector/cables should I buy?

#1) http://www.ebay.ca/itm/Mini-Micro-J...LH_DefaultDomain_0&hash=item27e5516657&_uhb=1

#2) http://www.ebay.com/itm/10pcs-JST-X...Control_Parts_Accessories&hash=item58a474eb76

Now as to installing them, can I just parallel the sixteen wires coming from the BMS, and run 16 parallel wires to my two 8S Battery Testers linked to above…? I guess the buzzer/alarms should be disconnected when not in use in order to not drain the 48v battery, or can they be left on permanently?

Thanks for all your help with this, IAN…

 

[drebikes]

First things first, I don't know about others, but I think having a pack of 16 buzzers can be a bit big and cumbersome, especially since your pack is equipped with a BMS which I assume has per cell low voltage protection. This out of the way...

For a 16S pack you have 17 wires, the 17th is a ground wire. The 17 connection points are probably available from the BMS, though you'd probably have to unpack the battery pack to access them. If you have access to the wires thru a connector you could buy a Y connector with the right amount of wires; otherwise (like my case for an EM3EV battery) I'd have to solder the 17 wires on the PCB of the BMS. As such I can't really say which connector is best, I would like to see the wiring of the BMS before.

I have heard about the BMS / buzzers consuming power and they do, but I don't think it's significative. It could be in two cases: either the quality is really poor, or if the battery is left in storage; anyway, if you decide to mount the buzzers they'd be useful when getting close to 0% Battery charge, so when in use. I mean if you decide to have them as real-time diagnostic, then they have to be connected.

 

[imorton]

Hi, I would only need TWO of the low voltage alarms as each one handles 8S.

I would like to install this in order to easily monitor/visualize each of the individual 16 cell voltages, and not really for low voltage (as the controller can do that).

Now as to the type of cable/connector to buy…. since these little indicators are 8S….hmmm….?

And since I haven't received the battery yet, I don't know if it is attachable to a Signalab BMS (16 or 17 wires…?)

Anyone have any experience with these buzzer/monitors, and a Sun-Thing28 style pouch LifePo4 batteries?

Thanks a million, IAN…

 

[dumbass]

On my 48v packs lifepo4 packs (actually 2 - 24v packs connected) I use a set of
Cellog 8s. Each with an on/off switch and a 90db alarm connected to each Cellog 8, The alarms are also on an on/off switch. The Cellog 8 can be programed for any high/low voltage to want for setting off the alarm based on each individual cell or pack. And you cn use standard 9 lead balancing plug and wires from Ebay for under $5 each.

Bob

 

[Gregory]

#2 because you need 9 pins. The ""middle"" wire of the BMS sense wires is shared between the two 8S plugs you are adding i.e. negative of plug one and first positive pin of plug number two.

Yes you can parallel them with the BMS sense wires, it may be easier IF you can solder them direct to the BMS rather than splice 16 wires.

 

[imorton]

On my 48v packs lifepo4 packs (actually 2 - 24v packs connected) I use a set of
Cellog 8s. Each with an on/off switch and a 90db alarm connected to each Cellog 8, The alarms are also on an on/off switch. The Cellog 8 can be programed for any high/low voltage to want for setting off the alarm based on each individual cell or pack. And you cn use standard 9 lead balancing plug and wires from Ebay for under $5 each.

Bob

Thanks for the reply. What is the difference between the "cell logs" and the Low Voltage Alarm ( that I linked to/ photo above)…?

PS: I guess I will order the cable/connector (#2 in Red) to connect to the Low Voltage Alarms.

 

[imorton]

#2 because you need 9 pins. The ""middle"" wire of the BMS sense wires is shared between the two 8S plugs you are adding i.e. negative of plug one and first positive pin of plug number two.

Yes you can parallel them with the BMS sense wires, it may be easier IF you can solder them direct to the BMS rather than splice 16 wires.

I guess #2 in red, would be the correct cable/connector to use to go with the Low Voltage Alarm. I will try and wire it up, and use them to monitor the 16S LifePo4 cell voltages.

 

[dogman dan]

However you get there is up to you. But you will want to splice in two 8s female jst plugs to your balance wires on the battery.

Just splice it to the wires, you don't have to open the whole pack.

99% sure, that the negative of cell number one will be the large negative wire, not the small balance wire. That's wire zero. After that, all small wires are positive ends of each cell, 1,2,3 etc.

DO NOT leave these things in the plugs all the time. It's not needed, and will unbalance the pack.

You don't need them connected all the time. Just use them to check how the pack is doing, by using them periodically to check the voltage. Check when the pack is done charging, or you can use them to watch them charge if you like. Interesting to actually see that the bms works. You will see some pretty high voltages on some cells as the pack begins balancing.

If you want to have them as a low voltage warning on the longer rides, that's fine. Just don't leave them on the pack for long periods of time. If your LV alarm is adjustable, you could then use them to give you advance warning of a bms lvc shutdown. Or use them as a backup, so you don't fail to stop if the bms does not shut down.

In general, once a bms checks out as fully functional, you can just ride till it pops. Just be aware of how the bike slows just before it pops, and don't ride miles in that condition.

 

[imorton]

Dogman, thanks for taking the time to fully explain the procedure. I will have to wait to receive the Sun-Thing28 battery to see how the BMS is installed and how many wires are available or setup…?

The two "8S monitor/alarms" are not for constant use, but more for occasional verification and simplicity…

Thanks again, IAN

 

[dogman dan]

I did the mod to an ageing pingbattery. I had no need for it for 2 1/2 years, but in the last 6 months I ran that pack, it was needing more balancing than the bms could do. So the plugs and ability to check cells fast was very nice for that last few months.

Highly recommend that you install the plugs, but it's not like you should have to do it right away.

 

[imorton]

Dogman, thanks again for the info, much appreciated. It appears that for a few bucks, I can have a very simple way to verify/monitor the 16 LifePo4 pouches.

I wonder how many other people use these inexpensive alarms to monitor the cells?

IAN…

 

[quamau]

I am.

Very convenient, so far, at the cost of a little additional burden when you set things up (and a few more wires lying around in your battery box). Once you have the taps, you never know what use might come in handy in the future.

I definitely reccommend such an addition to your future pack.

 

[imorton]

I am.

Very convenient, so far, at the cost of a little additional burden when you set things up (and a few more wires lying around in your battery box). Once you have the taps, you never know what use might come in handy in the future.

I definitely reccommend such an addition to your future pack.

Glad to hear that others are using these. I can see how useful these can be, and looking forward to setting it all up…

 

[dogman dan]

Sucks that plugs for external monitoring and single cell charging aren't standard. For Ebike repairmen to use if nothing else.

 

[Matt Gruber]

Sucks that plugs for external monitoring and single cell charging aren't standard. For Ebike repairmen to use if nothing else.

thats true. when i saw the Dewalt packs have this, i was so impressed i bought 2 even tho i didnt need them! Actually they are higher amp contacts, so cell pairs can be paralled pack to pack if u do deep DOD and want to use it that way. Kudos to dewalt engineers!

 

[Pete1961]

Does a high voltage alarm exist, i.e. a buzzer that sounds with a voltage rise (adjustable to about 42V) I have to set a time limit once a charger enters CV mode, so a warning that this voltage had been reached would be useful - they did at one time exist I think

 

[dumbass]

On my 48v packs lifepo4 packs (actually 2 - 24v packs connected) I use a set of
Cellog 8s. Each with an on/off switch and a 90db alarm connected to each Cellog 8, The alarms are also on an on/off switch. The Cellog 8 can be programed for any high/low voltage to want for setting off the alarm based on each individual cell or pack. And you cn use standard 9 lead balancing plug and wires from Ebay for under $5 each.

Bob

Thanks for the reply. What is the difference between the "cell logs" and the Low Voltage Alarm ( that I linked to/ photo above)…?

PS: I guess I will order the cable/connector (#2 in Red) to connect to the Low Voltage Alarms.

I guess that depends on exactly when you want to view your cell voltage. The Cellog 8s read out is to small to view while actually riding. But the more expensive unit can record each cells voltage and other info and it can be downloaded to your PC. It's also very easy to program for differing needs and it comes in a contained case. But the onboard alarm is not very loud hence the need to add an 24v busser.

Bob

 

[dumbass]

Does a high voltage alarm exist, i.e. a buzzer that sounds with a voltage rise (adjustable to about 42V) I have to set a time limit once a charger enters CV mode, so a warning that this voltage had been reached would be useful - they did at one time exist I think

The Cellog 8 monitors both LV and HV for both individual cells and complete pack and is user settable.

Bob

 

[imorton]

Does a high voltage alarm exist, i.e. a buzzer that sounds with a voltage rise (adjustable to about 42V) I have to set a time limit once a charger enters CV mode, so a warning that this voltage had been reached would be useful - they did at one time exist I think

The Cellog 8 monitors both LV and HV for both individual cells and complete pack and is user settable.

Bob

I haven't been able to find these HV & LV alarm/buzzers that you talk about. The ones that I ordered in my original post are only LV alarm/buzzers …

Does anyone have a link?

 

[dogman dan]

Cellog 8 should be findable many places. Stuff at hobby king can be out of stock a long time, but HK usually has them.

 

[imorton]

Cellog 8 should be findable many places. Stuff at hobby king can be out of stock a long time, but HK usually has them.

Would the CellLog8 use the same cable/connector as in my first post (that I ordered for the Low Voltage Alarms)….?

Thanks for any info. IAN.

 

[dumbass]

Ebay for $17.99 + $2.32 shipping. Be careful of the wiring because if I remember correctly you need a 9 wire (1 red and 8 black). They are also available on Ebay but you will need to do some of your own hunting for them.

Bob

 

[TheBeastie]

So we going to see some pics of your mod? Would like to see it.