Split Chargers - B2B & Relays: Which one - or Both?

[SquirrellCook]

Rather than swapping over the plugs manually

This is the way I swap between mains and leisure inverter, except I found a relay with good isolation. If it detects external mains it switches to that. I also have some neon wally lights to show where the mains is coming from. The relay is a bit sensitive as it can get upset when the external mains is supplied by a generator.

Your travelvolts relay would be good if I were to develop Murky further. Once Anita has finished the bodywork it will be up for sale. Betty is getting a Multiplus.

 

[wildebus]

The Multiplus is the way to go for a van which is even slightly electrics-centric I think

The only Multiplus I don't think I would bother to go for is the 12/500 version as that doesn't have the Power Assist feature.

 

[SquirrellCook]

The Multiplus is the way to go for a van which is even slightly electrics-centric I think

The only Multiplus I don't think I would bother to go for is the 12/500 version as that doesn't have the Power Assist feature.

I'm being bullied into going bigger than I'd like as I haven't found a 500w element for my calorifier yet I was hoping that a 800 would do the job.

 

[wildebus]

I mentioned to Robert about Victron naming ... just a reminder just in case on that subject - the outputs of the inverters are in VAs, not in Watts. so the 12/500 is a 400W inverter; the 12/800 is either 650 or 700W Inverter, and the 12/3000 is a 2400W inverter (can't recall the ones between )

 

[RAW]

Works very well, but it is pricer than a SSR solution for sure. I am not using it anymore, as the Victron Multiplus covers that function, so available for sale (used of course) for £20 plus postage (£3.10) and including an ABS box to stick it in.

Had a look at Spec, think it would work in my situation when I have saved up for a decent inverter so will take it off your hands, thanks @wildebus

 

[Nabsim]

@wildebus heres a question going back to your CTec 250/smartpass comparison. Did I not read somewhere when Del was looking at this that it also takes a feed from solar into one of them?

 

[wildebus]

Hi Neil,
The CTEK 250SA does indeed have an MPPT controller integrated into it. lt is fairly limited at being a 20A unit and only supports 12V panels (and multiple panels in parallel only).
Oh, something to be aware of as well... the CTEK is not recommended for Lithium Batteries (this is a Manufactuer statement).

 

[Nabsim]

Yes I know they are no good for Lithium, no good for me but I am okay with what I have now. I just need to do something with mains charging for the back end of the year

Did the solar actually power the B2B side when engine not running to give more boost or was it not that clever (CTej)?

 

[wildebus]

...Did the solar actually power the B2B side when engine not running to give more boost or was it not that clever (CTej)?

Not sure what you are meaning/asking here?
The CTEK 250SA is a B2B/MPPT Combo unit. So engine running, the B2B side is active; engine not running the Solar MPPT side is active.
I don't think they work at the same time on the CTEK. (some Combo units, such as the Redarc BCDC Dual do have the B2B and MPPT both active, with Solar providing all it can always, and the B2B when engine running is active topping up to the chargers limit.)

 

[RAW]

Just wondering on the engine and Solar Side that on the Merc I have there is Solar always on via the MPPT and then also the engine alternator via the Cyrix-CT when the engine is running, will this potentially damage anything ? I would have thought not as the currents involved are not that high. Though on the Solar Side I do have a plan to increase the yield.
Bearing that in mind I was running same MPPT 100-30 in Sylvia the Talbot with a higher PV yield and using another VSR and seemed to do no harm.

 

[wildebus]

I don't think there will be an issue. It is the same as if you were on a campsite on EHU and your solar will still be operational then as well, so no difference there really. The battery will be the limiting factor on what it will accept (I had the Mains Charger and the Engine Running at the same time a couple of weeks ago to see what I could get up to ... maxed out at 145A (120A from the mains, 25A from the Alternator))

 

[wildebus]

Just wondering on the engine and Solar Side that on the Merc I have there is Solar always on via the MPPT and then also the engine alternator via the Cyrix-CT when the engine is running, will this potentially damage anything ? I would have thought not as the currents involved are not that high. Though on the Solar Side I do have a plan to increase the yield.
Bearing that in mind I was running same MPPT 100-30 in Sylvia the Talbot with a higher PV yield and using another VSR and seemed to do no harm.

I went out in the van yesterday, and the new Victron B2B was used for the first time "in anger". It was also a reatively sunny day so the Solar was doing its thing as well.

I tried my best to plot the charging from the MPPT and from the B2B against what the overall system was doing and this is shown below.
I also turned on the water heater (a 2000W load) to get some demand going - you can see that load with the big negative spikes in the graph, and how the B2B and MPPT respond to that demand on the battery system.
I've also added the vehicle speed to the chart (you can then see the period when the engine would have been stopped as in the shops so the B2B would be inactive)

 

[Nabsim]

Not sure if I posted at the time but one day last week I thought my controller had died. Since fitting the battery monitor I tend to look at my phone rather than checking the solar display. Anyway the display was showing 0.0 amps (I usually work by amps) at around 11 in the morning with wall to wall sun.

of course there was nothing wrong it just stopped harvesting as the battery’s were full but it made the heart beat a little faster and blood pressure rise for a few minutes

 

[wildebus]

That is what people tend to forget when they want to check their system. When there is no room in the battery, nowhere for the power from the solar to go
(why I stuck my heater on to get some load going on without that the B2B would have done nothing)

 

[xsilvergs]

I went out in the van yesterday, and the new Victron B2B was used for the first time "in anger". It was also a reatively sunny day so the Solar was doing its thing as well.

I tried my best to plot the charging from the MPPT and from the B2B against what the overall system was doing and this is shown below.
I also turned on the water heater (a 2000W load) to get some demand going - you can see that load with the big negative spikes in the graph, and how the B2B and MPPT respond to that demand on the battery system.
I've also added the vehicle speed to the chart (you can then see the period when the engine would have been stopped as in the shops so the B2B would be inactive)
View attachment 2549

Nice to see some data David. Solar peaking at a little over 25 Amps?

Do you think there was any gain in State Of Charge? Just wondering if you can heat your water and at the end of the days drive and have a 100% SOC and a tank of hot water. That one of my ambitions (while doing only about 150 miles/day).

Time to buy shunt, put in the B2B +ve line and log even more data

 

[wildebus]

Nice to see some data David. Solar peaking at a little over 25 Amps?

Do you think there was any gain in State Of Charge? Just wondering if you can heat your water and at the end of the days drive and have a 100% SOC and a tank of hot water. That one of my ambitions (while doing only about 150 miles/day).

Time to buy shunt, put in the B2B +ve line and log even more data

I started the drive (after 15:00) at full 100% SOC, and by 17:30 was back to 100% with a full hot tank of water (my tank is only 10 Litres, mind).
Total distance driven? maybe 40 miles
Solar yesterday peaked at 401W and 29.4 Amps. I am curious what the current will actually max out to on the 100/30A Controller. If I am setting 29.4A at a peak of 401W, and the controller is rated at 440W, 30A max current means a very high voltage 14.66V to achieve that power rating (My controller is set to 14.2V Absorption).
Definately getting some good combination charging - hitting over 40A with the pair when the heater was on (if the Cyrix ct was live rather than the B2B it would likely have been better. Could have maybe set it up so when the heater is actually running, the Cyrix kicks in (that is a potential option in the Venus OS setup - relay can be set to go on if the current load exceeds a certain level)

 

[xsilvergs]

I started the drive (after 15:00) at full 100% SOC, and by 17:30 was back to 100% with a full hot tank of water (my tank is only 10 Litres, mind).
Total distance driven? maybe 40 miles
Solar yesterday peaked at 401W and 29.4 Amps. I am curious what the current will actually max out to on the 100/30A Controller. If I am setting 29.4A at a peak of 401W, and the controller is rated at 440W, 30A max current means a very high voltage 14.66V to achieve that power rating (My controller is set to 14.2V Absorption).

I've a Varta AGM, my Victron 100/30 is set to Absorption 14.8 volts (as data sheet). This would have been a bit high for the Starter Battery but that's now sorted with the Ablemail AMT.

 

[wildebus]

Just looked at the settings and made the tweaking .....

First a "heads up" on naming .... I am using the "Generator" selection in the Venus configuration, where the Generator in my case will actually be the Cyrix ct-230A Battery Combiner (aka VSR in essence).

Went into the settings for Battery Current and set it up for the VSR to be enabled when the current goes over 30A for over 3s (set it for 3 seconds as I can hit that for upto 2 seconds when the Fridge kicks on).

The VSR will turn off once the current goes below 10A for 2 minutes (I have the water heater set to cycle on and off. The off cycle is less than 2 minutes (I think?) so this means when using the heater, the VSR will stay on while the water heater is in its general heating mode.


The Battery State of Charge control I did tweak a bit after initially doing the test

I setup "Quiet Hours". Usually used to avoid the generator coming on in the middle of night, but I have it set up for a very high 99% SOC Start, and a quiet time of 7AM to 8AM.
The Fridge will have come on a few times overnight and by 7AM, the Battery SOC will have dropped below 99%. This means the VSR will turn on if the solar is providing charge, and the result will actually be some Starter Battery maintenance for upto 1 hour a day.

And finally, you can chose multiple causes of activation of the relay, so not stuck with a one or other only

Quite pleased with this setup The system will use the VSR when the battery needs bulk charging; switches to B2B when the charging needs to be at a higher voltage and more controlled at a higher battery SOC level; but when there is a high demand (water heater in this case), the VSR will kick in automatically to help deliver the high current demand

 

[wildebus]

I've a Varta AGM, my Victron 100/30 is set to Absorption 14.8 volts (as data sheet). This would have been a bit high for the Starter Battery but that's now sorted with the Ablemail AMT.

My lead-carbon batteries are a little unusual in that the recommended voltage in the data sheet tends to recommend 14.2V as the preferred charging voltage, which does seem low, but I trust they know their product better than I do

 

[wildebus]

Following on from post about adding settings for more control and flexibility on the B2B - VSR switching, I looked at the options and did a bit more tweaking and thought might be interesting to post the results for this morning...

WARNING: GEEK ALERT. If this kind of thing doesn't interest you, bypass this post


The Water Heater, once initially run, tends to come on again automatically every 6 hours or so (depending on thermostat setting) to maintain the hot water. How does that affect how the B2B-VSR relay?
As well as the settings for Current Load level, I also added a AC Power Demand setting. TBH, for my use, it will serve the same purpose so will probably turn one of them off (if you had a high DC-only load, you would chose the Current Load option). I also decided to turn off the "Quiet Hours" setting and enable a Daily "test" setting, where you can set a start time and duration of when to turn on the relay.
This gives more flexibility in fact than relying on the SOC as if I was plugged into EHU, the SOC would stay at 100% and the relay would never turn on. As I am using this aspect to provide a Starter Battery Maintenance function, it would not allow that to happen - using the "Test" option is SOC independant.

So the graphing. I've done this as four images so it should be visible on a smaller screen still, but is best viewed as each directly under the one above to line up the timeline.
You see the dips where the heater comes on (Graph #1 - Battery Current). Graph #2 - Relay State shows the relay closes at those times, as well as for a longer period between 10:00 and 11:00.
Graph #3 - Generator State shows the reason for the relay being closed and Graph #4 - Starter Battery Voltage shows the effect on the Relay Closing (so enabling the Cyrix VSR) on the Starter Battery

In the example above, the relay closing due to the heater going on and thus enabling the VSR actually made no difference. This is important as the vehicle was stationary and the engine not running. This means the voltage levels are too low for the Cyrix/VSR to actually turn on and so no power taken from the Starter Battery. If however the engine WAS running, the vehicle side (battery& alternator) would contribute to the demand.
At 10:00, the Relay turns on (the reasoon is show in Graph #3 is "Test Run"), and this enables the Cyrix/VSR, allowing it to work IF the voltage levels are high enough. Because the solar was working at that time and putting in a charge, the battery voltage had risen enough to turn on the Cyrix/VSR and so the the Starter Battery gets connected to the Leisure Battery and a charge starts to go in - but just for an hour until the relay in the Venus GX times out, disabling the Cyrix/VSR unit and forcing a disconnect despite the Leisure Battery Voltage being still at a high level.
Having kit like the Victron Venus GX really does add a level of flexibility that is often not exploited