Still struggling to understand how it all works! (3 Viewers)

[Purrfecttune]

Julie and I bought a Swift Escape 674 in 2020 and have been very happy with it. Still being novices after 4 years we are still finding things out about it that we previously didn’t know (including additional hidden sockets)!

The thing I really struggle with is understanding what we really need for off-gridding for days at a time, so here’s the (known) spec and our experiences:

We have a fully sealed, long life 80 amp-hour leisure battery and a 100 watt roof mounted solar panel.
When we travel, we watch a couple of hours TV a night and obviously use the lights. Heating, hot water, fridge and cooking are all gas.

Last year, April to June, we toured Scotland, the Western Isles and Orkney and only had a total of two days without sun (yes I know, I’m sure it was Scotland!) As we went round we became braver and braver testing the capability of no electric supply. Finally, we comfortably managed 10 consecutive days without ehu BUT each day was a different location, so driving in between each stop. The battery never went below 85%.

This year, we did France/Spain from mid-April to end of June and did quite a few stops for up to three days.
Most times, the lowest our battery dropped to was 75% BUT after a dust storm covered the ‘van’ and I unsuccessfully tried to clean the solar panel at a car wash that didn’t have a gantry, we drove to our next stop and without ehu the battery went down to 65% in two days. Luckily, ehu was available and I then managed to clean the solar panel properly by hanging out the cab sunroof with an extended mop and bucket

After that, it went back to three days in one place without ehu equating to the leisure battery dropping to approximately between 85% & 75%. (We have a Sargent controller that indicates that the solar charging switches automatically between both the vehicle and the leisure battery as required)

That’s the background, now here are my questions:

The battery obviously charges while we are driving, but using what system? I am confused by the terms ‘B2B’ and ‘MPPT’ for instance. What is ours likely to be and is there a more efficient way of doing it?

What is the lowest I should allow the battery to decrease to?

What do I need to change/add if we want to stop off grid for up to a week?

Would a ‘plug-in’ solar panel for back up be worth carrying?

It is in my mind to replace the battery with a lithium when the time comes, but at the moment there isn’t really anything wrong with the original.

Thank you in advance for all advice, I have been reading up on this matter for a long time and there is sooooo much information out there it is doing my head in

 

[Lenny HB]

Sounds like you are fairly low power users so changing to lithium would be an expensive option. I've just spent over £3k on a DIY Lithium install but I wouldn't recommend that for you.

For your use I would replace the battery with two new batteries (your one is 4 years old so past it's prime) if sticking with lead acid fit a couple of 100 ah or bigger.
Fit one or two more solar panels and forget about the Sargent solar controller and fit a Victron MPPT controller.
If you are moving around a lot if you don't have a B2B it would be worth fitting one.

Have a word with RogerIvy & nigelivy at Off Grid you will get excellant advice good prices and a Funster discount.

Offgrid Power Solutions

Offgrid Power Solutions We are specialists in LiFePO4 batteries & Victron Energy systems. We’re here to help build the best offgrid electrical systems so you can focus on your adventure without stressing about how much power you have left! Get in touch with us about how we can help

offgridpower.solutions

 

[Kannon Fodda]

Standard batteries (lead-acid, AGM, etc) 50% max discharge is regarded as the limit to avoid shortening life. Battery life reduces on these simply from any charge/discharge cycle so after 4 years as Lenny says will be past their prime.

12V charging from engine. Most systems of the 2020 era when built in to boxes such as that from Sargent remain little more than a basic relay link. Some are appalling being non smart and only charge at a flat voltage rate so don't even recognise needs of batteries to have bulk, absorption and float, which in turn means the battery never gets a decent charge cycle to keep it at it's optimum. A B2B (battery to battery) type charger is used to bypass these older systems. It generally can work better especially with most modern engines that have smart alternators as they can compensate the voltage wizardry tricking the alternator that otherwise would only see the full engine starter battery and turn power output down, whilst also having proper charging profiles. Bigger wires connecting B2B usually means more current flow to the leisure battery so it can recharge sooner on shorter driving time but beware that lead-acid type batteries will have a max charging rate that your B2B could actually be too big especially with one battery only.

Solar charging controllers are either PWM or MPPT. PWM is the more basic and cheaper type usually fitted by the main UK converters and if your van has Sargent wiring that is what you have. Great in good sunlight. MPPT is more efficient and will give you a bit more charging from your panel in more marginal lighting conditions so may well work for a bit longer through the day or when it's quite cloudy (albeit you still need good sun to max out your panels output).

 

[DBK]

What is the lowest I should allow the battery to decrease to?

Not less than 50% is the general rule for lead acid batteries but even running them down to this level regularly will reduce their life significantly.

I endorse everything Lenny has said, more solar and more batteries with the right gizmos to control them will be all you need without going down the expensive lithium route.

 

[Purrfecttune]

Thank you for your replies, which have inspired further questions!

Our motorhome is on a Fiat Ducato base and the leisure battery is under the drivers seat.
What two batteries would you suggest would be best that would fit in the space?

I have read that two batteries rely on each other to be faultless so one big battery is recommended in some cases?

Looking to the (unknown) future of our use of the ‘van’ for off gridding I would be happy to buy a single lithium, so what would be the approximate cost difference and recommendation? Especially as there appear to be so many offers out there at the moment.

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[DBK]

Thank you for your replies, which have inspired further questions!

Our motorhome is on a Fiat Ducato base and the leisure battery is under the drivers seat.
What two batteries would you suggest would be best that would fit in the space?

I have read that two batteries rely on each other to be faultless so one big battery is recommended in some cases?

Looking to the (unknown) future of our use of the ‘van’ for off gridding I would be happy to buy a single lithium, so what would be the approximate cost difference and recommendation? Especially as there appear to be so many offers out there at the moment.

The problem with changing to lithium is you may/will have to change or add other components. For example the mains charger, which works on EHU, may need replacing if it doesn't have a setting for lithium. Ditto the solar controller and you will really also need to add a B2B.

You can just ignore the problem and drop in a lithium battery but the life of the battery will be reduced and it may not get fully charged.

 

[Brains]

Simple solution.
I have one of these.

A telescopic truck screen squeegee with a swivel head.
Cost £10 in Germany a couple of years ago.

Every few days I stick my head out of the rear roof vent and wipe down the solar panel.
It can almost double our solar input!

 

[Purrfecttune]

Thanks DBK

My thinking is that it will be worthwhile to change the solar controller to MPPT anyway, so that would be one thing addressed if we go for lithium.

The other consideration is if we might invest in an inverter in the future which will rely on a good battery. We have two electric bikes and so far we have used aires and campsites with ehu when we have needed a charge for them.

 

[Purrfecttune]

Simple solution.
I have one of these.

A telescopic truck screen squeegee with a swivel head.
Cost £10 in Germany a couple of years ago.

Every few days I stick my head out of the rear roof vent and wipe down the solar panel.
It can almost double our solar input!


View attachment 934335

Thanks for this

I was really shocked at our loss of charging after the dust storm, I never realised that it was a common occurrence.

 

[dunnah01]

Simple solution.
I have one of these.

A telescopic truck screen squeegee with a swivel head.
Cost £10 in Germany a couple of years ago.

Every few days I stick my head out of the rear roof vent and wipe down the solar panel.
It can almost double our solar input!


View attachment 934335

That looks very posh - this is my H&S compliant semi pro version

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[PeterCarole29]

Thanks DBK

My thinking is that it will be worthwhile to change the solar controller to MPPT anyway, so that would be one thing addressed if we go for lithium.

The other consideration is if we might invest in an inverter in the future which will rely on a good battery. We have two electric bikes and so far we have used aires and campsites with ehu when we have needed a charge for them.

If you have the budget dont hesitate to get in touch with off grid solutions you will get a discount off what are already fair prices they will advise you and if you want give you a price to install it
I dont know anyone who hasnt been happy
They will be at Malvern as well as they have a stand there

 

[Jabstatt]

Bearin mind that 100 amp hours of lithium can be discharged to, say five percent.
Needs 200 amp hours of lead acid to match!

I’ve very successfully substituted 200 lithium, added 460w Solar and a 2kva inverter. Nothing else.

All goes really well.

We even use spare power for the morning shower!

Tony

 

[Purrfecttune]

Sounds like you are fairly low power users so changing to lithium would be an expensive option. I've just spent over £3k on a DIY Lithium install but I wouldn't recommend that for you.

For your use I would replace the battery with two new batteries (your one is 4 years old so past it's prime) if sticking with lead acid fit a couple of 100 ah or bigger.
Fit one or two more solar panels and forget about the Sargent solar controller and fit a Victron MPPT controller.
If you are moving around a lot if you don't have a B2B it would be worth fitting one.

Have a word with RogerIvy & nigelivy at Off Grid you will get excellant advice good prices and a Funster discount.

Offgrid Power Solutions

Offgrid Power Solutions We are specialists in LiFePO4 batteries & Victron Energy systems. We’re here to help build the best offgrid electrical systems so you can focus on your adventure without stressing about how much power you have left! Get in touch with us about how we can help

offgridpower.solutions

Thanks Lenny

I have sent a message to Off Grid with a link to this thread so that they have all the details.

I think that we must have a B2B because of our 10 days without ehu in Scotland last year. At the time I thought this is great, we can off-grid anywhere, anytime, especially if we can do it in Scotland. However, I didn’t take into account that we were not staying in one place more than one day at a time

 

[Purrfecttune]

Bearin mind that 100 amp hours of lithium can be discharged to, say five percent.
Needs 200 amp hours of lead acid to match!

I’ve very successfully substituted 200 lithium, added 460w Solar and a 2kva inverter. Nothing else.

All goes really well.

We even use spare power for the morning shower!

Tony

That’s very helpful, thank you Tony.
The way you have described makes it very easy for someone of my limited knowledge to understand.

 

[Purrfecttune]

This is my solar power controller, which I guess means that I have B2B?

On the Sargent controller the readings invariably show the vehicle battery always being fully charged first before switching to the leisure battery regardless of which is currently highest, is this standard or adjustable?

Also, a bright sunny day today and the solar amp charge rate constantly goes up and down and I have never seen it more than about 3.8 amps, which is not quite half way round the dial. Is this normal?

Thanks again for advice, I really struggle to understand what this aspect should be doing.

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[DBK]

which I guess means that I have B2B?

Sadly no, that's a solar controller which has a seperate set of terminals for topping up the vehicle battery.

A battery to battery charger (B2B) is a different device connected by heavy cables to the vehicle and leisure batteries. It works by putting a load on the vehicle alternator and then charging the leisure batteries with the ideal charging voltage profile. They cost a few hundred pounds and more again if you need someone to fit one. Great bits of kit though.

 

[Purrfecttune]

Sadly no, that's a solar controller which has a seperate set of terminals for topping up the vehicle battery.

A battery to battery charger (B2B) is a different device connected by heavy cables to the vehicle and leisure batteries. It works by putting a load on the vehicle alternator and then charging the leisure batteries with the ideal charging voltage profile. They cost a few hundred pounds and more again if you need someone to fit one. Great bits of kit though.

Referring to our trip in Scotland last year, with 10 consecutive days, in 10 different places without ehu, does that confirm that we must have B2B, or is there some other method that the battery was always topped up to 100%?

Compared to sunny Spain, where I was surprised that we rarely had 100% charge on days without travel.

Also, the log book says that the ‘van’ is a ‘Euro 6D-Temp EV’ (and it also uses Adblue).
Based on Lennys info, this suggests that it might have the ‘smart alternator’ with B2B, although I note from other threads that certain manufacturers still don’t fit it.

 

[Brains]

That looks very posh - this is my H&S compliant semi pro version

View attachment 934341

An excellent piece of bodgery!

May I suggest the addition of a reading lamp wired to the EHU so you can clean your solar panel at night!

 

[Brains]

That looks very posh - this is my H&S compliant semi pro version

View attachment 934341

Just make sure you don't clean the satellite dish by mistake!
No more dirty movies!

 

[1967bowesj]

An excellent piece of bodgery!

May I suggest the addition of a reading lamp wired to the EHU so you can clean your solar panel at night!

I take it that is supposed to be an attempt at funny?
dunnah01 looks to have made a jig to clean around a fixed item on roof, like our sat dome, or he uses it from the side of van and puts it up over the edge to clean panels

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[Brains]

I take it that is supposed to be an attempt at funny?
dunnah01 looks to have made a jig to clean around a fixed item on roof, like our sat dome, or he uses it from the side of van and puts it up over the edge to clean panels

A joke explained is never funny.

But...
An electrical item wired to the mains in the same area as water has the potential of a lot of comedic value.
Likewise, making your solar panel more efficient in the dark when it is well known the the solar input from the moon is usually fairly low.
Which means the electric light addition may not be a major requirement.

 

[Peavy]

This is my solar power controller, which I guess means that I have B2B?

On the Sargent controller the readings invariably show the vehicle battery always being fully charged first before switching to the leisure battery regardless of which is currently highest, is this standard or adjustable?

Also, a bright sunny day today and the solar amp charge rate constantly goes up and down and I have never seen it more than about 3.8 amps, which is not quite half way round the dial. Is this normal?

Thanks again for advice, I really struggle to understand what this aspect should be doing.



View attachment 934348

This picture seems to show you just charge one battery as there are two pair of wires (solar panel and one battery).

 

[1967bowesj]

A joke explained is never funny.

But...
An electrical item wired to the mains in the same area as water has the potential of a lot of comedic value.
Likewise, making your solar panel more efficient in the dark when it is well known the the solar input from the moon is usually fairly low.
Which means the electric light addition may not be a major requirement.

A joke that needs to be explained is not really a joke then.
Apart from your light was wired to the ehu so fail to see your humour.

 

[hja]

I guess you may not have a payload issue but for us swapping from one lead acid battery to a larger capacity lithium was a weight saving. It fitted under the passenger seat in place of the original.

 

[Sneds]

For what a new battery costs (lead acid) I’d buy the biggest (amp hours) and best quality manufacturer that will sit in the space
It really doesn’t sound like you have any issues with your current (!) set up and a new battery will only enhance it.
Unless you have a stash burning a hole in your pocket, that’s what i’d suggest.

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[scotzsue]

We had a 2009 swift, with 1 solar panel and 2 batteries, added a battery master. All sargent electrics apart from that, as well as normal everyday usage we ran a CPAP machine every night longest we did off grid was 7 days and batteries were still ok, Whitby folk festival and thick fog was surprised at how well it worked

 

[Purrfecttune]

This picture seems to show you just charge one battery as there are two pair of wires (solar panel and one battery).

I’m guessing that they are attached in series as one wire goes to the negative on the left, two wires to the solar panel in the middle and one wire to the positive on the right.
The Sargent controller shows which of the batteries is currently being charged by a ‘sun’ symbol under the relevant battery and this changes regularly.

 

[Purrfecttune]

For what a new battery costs (lead acid) I’d buy the biggest (amp hours) and best quality manufacturer that will sit in the space
It really doesn’t sound like you have any issues with your current (!) set up and a new battery will only enhance it.
Unless you have a stash burning a hole in your pocket, that’s what i’d suggest.

Thanks Sneds

 

[Kannon Fodda]

Referring to our trip in Scotland last year, with 10 consecutive days, in 10 different places without ehu, does that confirm that we must have B2B, or is there some other method that the battery was always topped up to 100%?

Compared to sunny Spain, where I was surprised that we rarely had 100% charge on days without travel.

Also, the log book says that the ‘van’ is a ‘Euro 6D-Temp EV’ (and it also uses Adblue).
Based on Lennys info, this suggests that it might have the ‘smart alternator’ with B2B, although I note from other threads that certain manufacturers still don’t fit it.

Your first post suggests the most you have ever used is 35% of your battery, so just under 30Ah. Most of the time it's a lot less. You are presently a fairly frugal user of power. Unless you are going to increase your use a lot, your present setup is adequate so keeping simple even just a marginally bigger capacity (100Ah) replacement lead-acid type battery, when the present one dies, would serve you well.

In summer, on reasonable day, the 100W panel charges at well over 5A for a few hours. Most days that is sufficient to refill your battery. That is regardless of whether the solar controller is PWM or MPPT. If you are moving about you would get both solar charging and also engine charging so even cloudier days you are most likely to have met your needs. Spain, plenty of sun so the panel kept up with you even if the engine wasn't being used.

Note the Truma solar controller in your image is only connected to one battery system, presumably the leisure. So however you think it may be charging the engine first is unlikely unless there is some weird alternate switching in another box somewhere. The solar controller is entirely separate to the system that charges from the engine. It is the charging from the engine that if modern would have some form of B2B or not.

You haven't identified the Sargent, or other boxes in your van that do the 12V fusing, 230V fusing and charger. This may be a combined box, or a few separate components. Most likely to be the former with a separate display control panel somewhere. If you can tell us that we can confirm if it is a basic system or includes a B2B. You would only need to be concerned of benefit of a B2B type charging if you are going to shell out on much higher battery capacity (and use that capacity). Whatever you presently have is working for your present usage levels.

 

[Purrfecttune]

Your first post suggests the most you have ever used is 35% of your battery, so just under 30Ah. Most of the time it's a lot less. You are presently a fairly frugal user of power. Unless you are going to increase your use a lot, your present setup is adequate so keeping simple even just a marginally bigger capacity (100Ah) replacement lead-acid type battery, when the present one dies, would serve you well.

In summer, on reasonable day, the 100W panel charges at well over 5A for a few hours. Most days that is sufficient to refill your battery. That is regardless of whether the solar controller is PWM or MPPT. If you are moving about you would get both solar charging and also engine charging so even cloudier days you are most likely to have met your needs. Spain, plenty of sun so the panel kept up with you even if the engine wasn't being used.

Note the Truma solar controller in your image is only connected to one battery system, presumably the leisure. So however you think it may be charging the engine first is unlikely unless there is some weird alternate switching in another box somewhere. The solar controller is entirely separate to the system that charges from the engine. It is the charging from the engine that if modern would have some form of B2B or not.

You haven't identified the Sargent, or other boxes in your van that do the 12V fusing, 230V fusing and charger. This may be a combined box, or a few separate components. Most likely to be the former with a separate display control panel somewhere. If you can tell us that we can confirm if it is a basic system or includes a B2B. You would only need to be concerned of benefit of a B2B type charging if you are going to shell out on much higher battery capacity (and use that capacity). Whatever you presently have is working for your present usage levels.

Thank you for such detailed info Kannon Fodda

I am still a little confused regarding my set up though as the Sargent controller definitely shows it switching between two batteries.

Earlier, it was showing that it was charging the vehicle, now it is showing charging to the leisure, as in the photo.
(When on ehu, one will have the ‘sun’ underneath and the other a ‘lightning bolt’).

We have been very conservative with our battery use as we did not know what to expect and have always been mindful where the nearest ehu might be obtained. We would like to consider this a lot less, and do a lot more off-gridding and exploration. Hence my consideration of upgrading.

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