New Electrical System (Solar, Victron, DIY Winston LiFePo4)

[rolandka]

I’m designing a new electrical system however I’m pretty new to this and would like to ask your help guys. I’ve been reading the forum for a while and there are plenty of helpful advice which is why I’d like to thank everybody who contributed. This forum is great source of information.

Now, this system goes in a VAN and not a boat/yacht. Hopefully, this is not a problem as most of this can be also used in boat. I’ve chosen the DIY lithium battery route instead of pre-made batteries due to cost. There are not so much information out there (in English) for DIY lithium batteries so that is why I though that I’ve got more chance getting help here. I’ve included all the info in the diagram please let me know if something is not right.

Anyway, you can see the wiring diagram attached and I’ll just put the list of the main components.

• Victron MultiPlus 12/3000/120 16A
• Victron SmartSolar MPPT 100/50
• 4 x 100W 24V Mono Solar Panel
• Victron BatteryProtect BP-65
• Victron BatteryProtect BP-100
• Victron Lynx Distributor
• Victron BMV-712
• Victron Venus-GX
• 4 x Winston 3.2V 260Ah Cell
• BMS123 Smart

My questions:

1. Is there any advantages using Victron’s BatteryProtect product over a simple latching relay? This is for the BMS123 Smart to switch off the load and/or the charge bus/devices.
2. MPPT’s max charge current is 50A. Is the BP-65 a good choice?
3. Do I need to use a fuse or a circuit breaker between the PV array (solar panels) and the MPPT charger?
4. Can I make a connection to the Victron Battery Protects straight from 123BMS Smart?
5. The cables measured one way. Are the cable grades seems correct?
6. Can I connect a switch to the remote port of the BatteryProtect while it is connected to the BMS? This is to be able to manually switch on/off the BatteryProtect?
7. The total capacity of the batteries is 260Ah. Would be able to handle this high current the Current Sensor that comes with the BMS as standard?
8. What size fuse should I use in the Lynx Distributor for the Victron Multiplus?

 

[pvb]

Maybe I've misunderstood, but don't you have to have auxiliary high-current relays for the load and charge connections to the BMS123?

 

[rolandka]

Maybe I've misunderstood, but don't you have to have auxiliary high-current relays for the load and charge connections to the BMS123?

Yes, that is right. However the BatteryProtect would replace it. If my thinking is right and if it is possible? It has remote contacts that would switch the BP.

 

[pvb]

Yes, that is right. However the BatteryProtect would replace it. If my thinking is right and if it is possible? It has remote contacts that would switch the BP.

Wouldn't you need another on the charger?

 

[lw395]

.....
2. MPPT’s max charge current is 50Ah......
7. The total amperage of the batteries is 260Ah. .....

These are capacities, not currents.
Your picture shows the Li-Ion cells wired in some strange way?

This is dangerous stuff for people who don't get the basics right.

 

[rolandka]

These are capacities, not currents.
Your picture shows the Li-Ion cells wired in some strange way?

This is dangerous stuff for people who don't get the basics right.

Thanks for pointing those out.

Sorry, the cells are wired in series, although I’m missing the terminal connectors from the image.... I’ll update the image as soon as I get home.

These are the LiFeYPo4 cells I’ll be using
http://www.everspring.net/product-battery-LYP260AHA.htm

 

[yotter]

Apologies for thread drift of a sort, being a bit cheeky perhaps. But that is a fine looking diagram. I am attempting to document all the additions to my own charging system, so wonder what software you used for the diagram?
Angus

 

[rolandka]

Wouldn't you need another on the charger?

Yep, only if it would be just a charger. This is an inverter/charger hybrid unit. A relay there would switch the whole unit which is not really convenient. Eg it would cut off the load at a high voltage event.

The multi can be remotely controlled to cut the load or the charge independently so that is good. However I was thinking to put a secondary protection on the AC line. There could be a relay that could cut the shore power from the charger or cut the AC load off. Im not sure what relay I should use though.

 

[pvb]

Yep, only if it would be just a charger. This is an inverter/charger hybrid unit. A relay there would switch the whole unit which is not really convenient. Eg it would cut off the load at a high voltage event.

So how do you protect the batteries from overcharge?

 

[rolandka]

So how do you protect the batteries from overcharge?

Well, the multi can be controlled remotely as I said. So it could be controlled by the BMS’ charge and discharge relay contacts. This would prevent the multi to charge or discharge beyond the limit.
Also, as a secondary protection there could be a relay on the AC line, cutting the shore power or the load.
As a tertiary option,.., there is also a V-Sense connector on the multi and it can be programmed to switch off on a certain voltage. (This is however only a battery level protection, it cannot see the voltage of the individual cells)

 

[pvb]

Well, the multi can be controlled remotely as I said. So it could be controlled by the BMS’ charge and discharge relay contacts. This would prevent the multi to charge or discharge beyond the limit.
Also, as a secondary protection there could be a relay on the AC line, cutting the shore power or the load.
As a tertiary option,.., there is also a V-Sense connector on the multi and it can be programmed to switch off on a certain voltage. (This is however only a battery level protection, it cannot see the voltage of the individual cells)

Isn't this all unnecessarily complicated? Not to mention expensive - it looks like your battery bank alone might be around £1500 for 260Ah.

 

[rolandka]

Diagram is updated, it includes the terminal connectors.

 

[rolandka]

Isn't this all unnecessarily complicated? Not to mention expensive - it looks like your battery bank alone might be around £1500 for 260Ah.

Well, it could be. I agree that it is complicated and very expensive. The complication is only because of the batteries but you only have to get it right once. It's still cheaper than getting a pre-made battery (eg Victron's).

In the long however it is supposed to be cheaper than lead acid or any other type. Longer life, about 80% of the battery capacity is fully usable, lightweight (compared to lead acid), charging speed, steady voltage... etc.

LiFePo4 batteries can also better at handling high current loads (inverter). If you apply load larger than the 20 hour Ah rating to a lead acid battery, the capacity of the it gets smaller.

This is really just an experiment of me trying these cells. I've heard many good things about them and these are just not popular in the UK. I don't know why. It is more popular in Germany for example. Many people have it and there is also a good source of information online.

 

[zoidberg]

Apologies for thread drift of a sort, being a bit cheeky perhaps. But that is a fine looking diagram. I am attempting to document all the additions to my own charging system, so wonder what software you used for the diagram?
Angus

I, too, am interested..... and in the software you have used for your diagram.

You have an enthusiasm for Victron devices - and that's probably justified.

 

[lw395]

I'd have thought that in a van, some sort of charging from the alternator would be worthwhile.
I am not very familiar with the Victron products in question, but how do they co-operate to ensure the correct charging regime if e.g. both solar and mains power are present, or solar is active and the inverter is drawing?

You'd have to know how the vehicle is intended to be used to know whether the complication is worthwhile.

 

[pvb]

In the long however it is supposed to be cheaper than lead acid or any other type. Longer life, about 80% of the battery capacity is fully usable, lightweight (compared to lead acid), charging speed, steady voltage... etc.

Yes, the theoretical cycle life is much greater than most lead-acid batteries. However 80% of 260Ah only gives you a usable 208Ah. If you had 400-450Ah of decent lead-acid batteries, you'd have the same usable capacity at 50% DOD, at about a third of the cost. OK, the weight would be about twice as much, but not massively more.

 

[GHA]

Piece on Morgans Cloud site about LiFePo4 -
https://www.morganscloud.com/2018/05/05/battery-options-part-1-lithium/

Behind a firewall but there is a good amount of battery info on the site , with the amount of cash involved might be worth the sub for a year.

Spoiler alert! They decided against on a hard core cruising boat...

Rejected
In the end, rejecting lithium in favour of some sort of lead acid was easy for me— just too dammed hard to do and expensive.


And even done right, at least to my thinking, a lithium battery system is just too complicated, fragile and hard to service in remote places to be appropriate for an offshore voyaging boat.

 

[halcyon]

Thanks for pointing those out.

Sorry, the cells are wired in series, although I’m missing the terminal connectors from the image.... I’ll update the image as soon as I get home.

These are the LiFeYPo4 cells I’ll be using
http://www.everspring.net/product-battery-LYP260AHA.htm

Passing question why current sensor and shunt ?

Does look complicated unless you have a special need, can you explain aims.

Brian

 

[rolandka]

Apologies for thread drift of a sort, being a bit cheeky perhaps. But that is a fine looking diagram. I am attempting to document all the additions to my own charging system, so wonder what software you used for the diagram?
Angus

I, too, am interested..... and in the software you have used for your diagram.

You have an enthusiasm for Victron devices - and that's probably justified.

I used draw.io, it's not really a schematic making tool but for me it visualizes my system. I had a better understanding looking at it. You can upload any image (which is what I did) and connect lines to it. It does take some time though... but I really like the end result.

 

[rolandka]

I'd have thought that in a van, some sort of charging from the alternator would be worthwhile.
I am not very familiar with the Victron products in question, but how do they co-operate to ensure the correct charging regime if e.g. both solar and mains power are present, or solar is active and the inverter is drawing?

You'd have to know how the vehicle is intended to be used to know whether the complication is worthwhile.

To be honest I did not have much time to look into how that would work. However, this is something that I would love to do later. I was thinking to get like a DC-DC Converter for charging the battery in vehicles with an intelligent dynamo. Do you have any recommendation?

The charge voltage control is centralized, so both MPPT and Multi working with the same setting, they will work perfectly together.

I'll be using the van full time. Living and working in it for a year or two... +missus on board doing the same thing. Therefore, the main reasons are quick charging, useable power, long life also weight (though calculating all the extra stuff that I'll be needing it could be close to the weight of lead acid batteries).