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An affordable way to fit Lithium Batteries?


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I will stick to whats in the batteries everybody but valence says it works all the time, Valence say it has to be connected to a master BMS.

The issue is when I plug in with the puter  all I see is closely balanced cells, and the master BMSs are a fortune, plus they wont supply one for secondhand batteries anyway! The internal BMS is live because it has a flashing green light to say all is good and red if its not [ I like the flashing green lights ?]

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5 hours ago, Dr Bob said:

The bms looks interesting.

In my set up, I bought the Aussie cell monitoring for around £80 and the BEP motorised switch for £150 .........and then used my BMV battery monitor to activate the auto disconnect. This unit however as you say can activate bi-stable relays so that means for less than £200 you can autodisconnect at individual cell voltages. The aussie unit only disconnects on very high or very low voltages. Buy a relay from a car breakers yard and for £150, you have the basis for a workable BMS. For another £20 you can have a 4 cell voltage monitor display as well.

It would certainly be high on my list for a future install, along with a cheap bi-stable relay or 2 like this one.

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15 minutes ago, Mike the Boilerman said:

 

Dead curious now. Two questions I bet I'm not the only one interested in:

 

1) What is a bistable relay?

2) Why do they fit them in Ford Transits?

 

Thanks!

 

 

1) A relay which retains its state without external power. There are two coils, one closes the contacts and the other opens them. The coils need pulses around one tenth of s second long. The contacts are either open if the open coil was pulsed last, or closed if the close coild was pulsed last. No power is used except when the state changes.

 

2) Seems to be used as part of an optional two battery split charge system for camper vans and vans with domestic lighting and heating setups.

 

That one looks like a good deal. I paid £60 for new one from Tyco, who make them for Ford.

 

MP.

 

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8 minutes ago, MoominPapa said:

1) A relay which retains its state without external power. There are two coils, one closes the contacts and the other opens them. The coils need pulses around one tenth of s second long. The contacts are either open if the open coil was pulsed last, or closed if the close coild was pulsed last. No power is used except when the state changes.

 

 

Ok that seems simple enough the way you explained it, thanks. 

 

So there will be a pair of terminals for solenoid 1, and a pair for solenoid 2, and a big fat pair for the switch, yes? (Or big fat three for a two way switch?)

 

 

 

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2 minutes ago, Mike the Boilerman said:

So there will be a pair of terminals for solenoid 1, and a pair for solenoid 2, and a big fat pair for the switch, yes? (Or big fat three for a two way switch?)

Or there could be a common for the two coil inputs, so just 3 terminals for switching.  Any number of contact configurations depending on the relay but commonly just the one set. 

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3 minutes ago, Mike the Boilerman said:

So there will be a pair of terminals for solenoid 1, and a pair for solenoid 2, and a big fat pair for the switch, yes? (Or big fat three for a two way switch?)

Three terminals for the coils,  on,  off, and common ground terminal. The 'wings' you see in the picture are the power terminals for bolting the connections to. 

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18 minutes ago, MoominPapa said:

That one looks like a good deal. I paid £60 for new one from Tyco, who make them for Ford.

I think I paid about £35 on Ebay for the one I used on our setup. Seem to be available cheaper if you search for "Ford battery switch" instead of bi-stable relay or by part numbers.

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47 minutes ago, Mike the Boilerman said:

 

Ok that seems simple enough the way you explained it, thanks. 

 

So there will be a pair of terminals for solenoid 1, and a pair for solenoid 2, and a big fat pair for the switch, yes? (Or big fat three for a two way switch?)

 

 

 

Yep. Expand the picture on Ebay and you can see the diagram printed on the relay. Four terminals in the plug at the bottom (for which you really need the right shell and crimp-on terminals) two for each coil. Note built-in back-EMF suppression diodes which dictate polarity. The contacts are the two big lugs sticking out of the sides, and the current carrying capacity depends on what they are bolted to, if you read the datasheet - Google Tyco BDS-A.

 

MP.

 

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14 minutes ago, MoominPapa said:

Yep. Expand the picture on Ebay and you can see the diagram printed on the relay. Four terminals in the plug at the bottom (for which you really need the right shell and crimp-on terminals) two for each coil. Note built-in back-EMF suppression diodes which dictate polarity. The contacts are the two big lugs sticking out of the sides, and the current carrying capacity depends on what they are bolted to, if you read the datasheet - Google Tyco BDS-A.

 

MP.

 

I'm a muppet and couldn't work out how to set up to switch the bi-stable relay (instructions that MP gave me that needed a PhD in summit to work out) so I forked out for the BEP motorized switch at £150. 

Great to see cheaper ways to do it for those not electrically challenged.

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3 minutes ago, Mike the Boilerman said:

 

That sounds FAR more komperlicated than a bistble realy!

Nah, dead easy when Tom (ex T&B) told me how to wire it up. The BEP switch is muppet proof but expensive.

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14 minutes ago, Dr Bob said:

I'm a muppet and couldn't work out how to set up to switch the bi-stable relay (instructions that MP gave me that needed a PhD in summit to work out) so I forked out for the BEP motorized switch at £150. 

Great to see cheaper ways to do it for those not electrically challenged.

Which is another big advantage of the bms I linked to earlier - direct support for bi-stable relay switching.

 

Just to clarify for anyone reading who is unsure of the advantages, the current draw from a high power relay coil can easily be 0.5A or more. Use 3 (load bus, charge bus, and emergency disconnect), then you can easily be using up to 36AH daily just powering your bms relays! Compare that to zero power usage for bi-stable relays and you can see the advantages!

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7 minutes ago, Mike the Boilerman said:

 

That sounds FAR more komperlicated than a bistble realy!

Bi-stable relays can be surprisingly hard to control if your control source only puts out a simple on/off signal! BEP switch on the other hand only needs one control wire.

 

Another example of good planning/design being needed to ensure simplicity and all components working together. 

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10 hours ago, Mike the Boilerman said:

 

Yes I can see that, which is why I can't really see how to use them unless with electronics deigned to deliver pulsed on and off signals.

 

 

Which is why the bms I linked to would make it so much easier! I'm using a standalone circuit to convert a simple switched supply to a pulse on pulse off output, but it's added complication, expense, and more potential points of failure. I still consider the power saving worth the effort though. 

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13 hours ago, Tom and Bex said:

I think I paid about £35 on Ebay for the one I used on our setup. Seem to be available cheaper if you search for "Ford battery switch" instead of bi-stable relay or by part numbers.

Where did you source the connector for it?

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1 hour ago, MoominPapa said:

That's the ones, only mine came from Ebay (probably China!).

 

Relay seems expensive from there! Not sure what they usually cost new though, mine was 2nd hand. 

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44 minutes ago, Tom and Bex said:

 

That's the ones, only mine came from Ebay (probably China!).

 

Relay seems expensive from there! Not sure what they usually cost new though, mine was 2nd hand. 

When I was putting my system in, in the spring, the new 200A tyco relays were around £75 the cheapest I could find.

 

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59 minutes ago, Dr Bob said:

When I was putting my system in, in the spring, the new 200A tyco relays were around £75 the cheapest I could find.

Much cheaper from RS (unusually!)

https://uk.rs-online.com/web/p/non-latching-relays/6900808/

1 hour ago, Tom and Bex said:

Not sure what they usually cost new

Less from RS than from Farnel, which is most unusual. 

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  • 1 month later...

I've not been on the forum for years, but noticed the article in Canal Boat magazine this month on Lithium battery systems and LifePO4.

 

If you are looking for a DIY BMS - I've built/designed one thats proving to be quite popular.

 

There is another forum where the discussion takes place.

 

https://community.openenergymonitor.org/t/diybms-v4/11292

 

 

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5 hours ago, stuart said:

I've not been on the forum for years, but noticed the article in Canal Boat magazine this month on Lithium battery systems and LifePO4.

 

If you are looking for a DIY BMS - I've built/designed one thats proving to be quite popular.

 

There is another forum where the discussion takes place.

 

https://community.openenergymonitor.org/t/diybms-v4/11292

Looks good :)

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