Extra battery or Solar panel or both and which one first?

PaulC70

PaulC70

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So, we don't often use ehu, we don't often stay anywhere more than 2 nights and then get a good charge on the LB while touring between stops, BUT, we stayed at a steam fair for 4 nights recently and plan to do that a bit more often in the future and the battery got down to 40% mainly due to charging the wifes mobility scooter battery.

So, looking for more of a "comfort buffer" to give us one less thing to worry about for longer off grid stays. Remembering this is mainly UK sunshine we're thinking of either a solar panel to match the current Truma 120watt already on the roof to harvest more daylight and keep the current 300ah Fogstar topped up, OR get another 300ah Foggy for more reserve?

Or do we go both and be done with it?
 
So, after 4 days you still had 40%, or possibly another 2 days left? How much more do you think you will need?

If you still need more, possibly extra foldout panels for summer use, it battery for winter?
 
You can waste a lot of money over specking what you don’t need. Another battery will cost £500 /600 plus you then may have to upgrade your charger etc, to charge your added battery
Another solar panel or two will only cost £75 / 150 👍 you say you did 4 days and still have 40%charge that’s close on half your capacity. Extra solar is the way forward for now😉

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You already have a decent size battery bigger than most.
You are lacking means to charge for 300ah of Lithium. Ideally you could do with another 200 Watts of solar.
What size B2B do you have as its probably worth increasing that.
 
Solar.

If you could take a screenshot of your input from your 120 watts over the past few days it will show you how many watts you harvested. (Victron app)
If you got another 120 watt panels you just double your harvest of the past 3 or 4 days and work out where your ample 300 ah lithium would be with that extra solar
 
The Wino said:
If it's very occasional how about a fold out extra solar panel for the odd occasions?
Click to expand...
I had a Dokio 300w foldable panel ready to go at that same show but didn't need it as the weather was quite bright...
But if you did choose to go down the foldable panel route, then remember Amazon Prime Day - 8/9th October. I got mine, currently priced at £250 for £185 special offer price in July
 
Langtoftlad said:
I had a Dokio 300w foldable panel ready to go at that same show but didn't need it as the weather was quite bright...
But if you did choose to go down the foldable panel route, then remember Amazon Prime Day - 8/9th October. I got mine, currently priced at £250 for £185 special offer price in July
Click to expand...
I don't know if would even need to be that big if there was 40% left on the battery after 4 days an extra panel of say 100w over 4 days would have added a fair bit.

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Unpopular opinion but I would say battery only because you say you usually only stay a few nights then drive on. Therefore the drive will charge the batteries back up quicker than solar would in my opinion. I've found solar is like a slow charger on most days. On really sunny days it's great but I've found my 400W solar never replaces what's used in the day. It's more money; however, I think it takes away the power anxiety and you don't have to rely on the weather.
 
PaulC70 said:
So, we don't often use ehu, we don't often stay anywhere more than 2 nights and then get a good charge on the LB while touring between stops, BUT, we stayed at a steam fair for 4 nights recently and plan to do that a bit more often in the future and the battery got down to 40% mainly due to charging the wifes mobility scooter battery.

So, looking for more of a "comfort buffer" to give us one less thing to worry about for longer off grid stays. Remembering this is mainly UK sunshine we're thinking of either a solar panel to match the current Truma 120watt already on the roof to harvest more daylight and keep the current 300ah Fogstar topped up, OR get another 300ah Foggy for more reserve?

Or do we go both and be done with it?
Click to expand...
Just thinking about your pattern of use. If your longer stationary stays off grid are likely to be in what passes for the summer the solar would make more sense. If however you stay off grid for several days quite often in the winter it could make more sense to add the battery as well.
 
So, just popped out and here's the screenshots etc.
So, in the last 4 days it looks like that one panels harvested enough to get to 57% only, to be fair weather heres been crap with little sun and 2 days in particular nothing but rain and thunder, if you've seen the national news of the A421 being turned into a river, that's 4 miles from me :-(

Anyway, it does indeed point to the need for more solar when relying only on that for charging and Im guessing that the current victron would indeed need an upgrade?

For those that have suggested a fold out, I'm reticent about that to be honest, especially if i want to use it off grid, I figure if I need more solar it may as well be fitted and be done?

IMG_6704.jpg
IMG_6705.jpg

IMG_6706.jpg
 
I’m pretty sure your Victron charge controller can take about 350 watts of solar so another 200 should be no problem ( from memory ) 😉
 
So last 5 days would have given you 40 extra amps (if you had an extra 120 solar) or further 13% of battery.

Us the weather that bad or are you parked in the shade ?

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suavecarve said:
So last 5 days would have given you 40 extra amps (if you had an extra 120 solar) or further 13% of battery.

Us the weather that bad or are you parked in the shade ?
Click to expand...
Weathers been bad and completly overcast too for about a week, not seen any sun. Shade wise, i'd say its in shade from about 230pm where it's parked currently but i've little option on that.
 
PaulC70 said:
For those that have suggested a fold out, I'm reticent about that to be honest, especially if i want to use it off grid, I figure if I need more solar it may as well be fitted and be done?
Click to expand...
The advantage of a fold up panel is that you can move it about to keep in direct sun so havesting a lot more
 
TravellingSmurff said:
Unpopular opinion but I would say battery only because you say you usually only stay a few nights then drive on. Therefore the drive will charge the batteries back up quicker than solar would in my opinion. I've found solar is like a slow charger on most days. On really sunny days it's great but I've found my 400W solar never replaces what's used in the day. It's more money; however, I think it takes away the power anxiety and you don't have to rely on the weather.
Click to expand...

Are your batteries lead, or LiFePO4?

The latter charge up much more efficiently than lead. Lead self-regulates and doesn’t always use all that the solar can provide.

Ian
 
Fogstar lithium.
bigtwin said:
Are your batteries lead, or LiFePO4?

The latter charge up much more efficiently than lead. Lead self-regulates and doesn’t always use all that the solar can provide.

Ian
Click to expand...
 
If there's budget / space for both then do both.

If not then it's a swings and roundabouts sort of a question.

The pessimistic version goes as follows:

No point adding more solar if it's not going to give you the extra capacity you want in poor weather (which is when you're likely to be spending more time inside the van consuming more power).

On the flip side, no point adding extra battery if you've got no way to top it up due to lack of solar.

However, the answer lies with knowledge only the OP has. These decisions are always about being honest with yourself about your use case.

An extra panel would have given you a nudge more power. Would that have been enough? If so, then a panel is probably your answer. If not, then you need more battery capacity, but work out if that extra capacity would be enough on it's own to see you though the 'static' time (it will charge as soon as you're moving)

I'd also consider how your existing panels are currently wired. If wired in series then the voltages combine so you need to look at the open circuit voltage (or OCV). This will typically be higher than 12v which can catch you out if you're not aware of it.

Your Victron 100/20 will take up to 100 volts and up to 20 amps.

If your combined OCV for a series setup exceeds 100 volts then you might need to wire the panels in parallel (which keeps the volts the same but combines the amps) - but again be careful you're not exceeding 20 amps or you might be buying a new MPPT controller...

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Lee Fryer said:
The advantage of a fold up panel is that you can move it about to keep in direct sun so havesting a lot more
Click to expand...
Yep I get that and while it would be good when off grid at something like a steam fair / organised event, it would be useless for my usual off grid using some uk aires, pub car parks etc.
 
fishplug said:
If there's budget / space for both then do both.

If not then it's a swings and roundabouts sort of a question.

The pessimistic version goes as follows:

No point adding more solar if it's not going to give you the extra capacity you want in poor weather (which is when you're likely to be spending more time inside the van consuming more power).

On the flip side, no point adding extra battery if you've got no way to top it up due to lack of solar.

However, the answer lies with knowledge only the OP has. These decisions are always about being honest with yourself about your use case.

An extra panel would have given you a nudge more power. Would that have been enough? If so, then a panel is probably your answer. If not, then you need more battery capacity, but work out if that extra capacity would be enough on it's own to see you though the 'static' time (it will charge as soon as you're moving)

I'd also consider how your existing panels are currently wired. If wired in series then the voltages combine so you need to look at the open circuit voltage (or OCV). This will typically be higher than 12v which can catch you out if you're not aware of it.

Your Victron 100/20 will take up to 100 volts and up to 20 amps.

If your combined OCV for a series setup exceeds 100 volts then you might need to wire the panels in parallel (which keeps the volts the same but combines the amps) - but again be careful you're not exceeding 20 amps or you might be buying a new MPPT controller...
Click to expand...

To be honest if it wasn't for the (usually daily) charging of the mobility scooter battery I'd not even consider changing anything. We use very little otherwise other than the tv. Charging of mobiles etc is always done on the journeys and as I say we "usually" move every one or 2 days so it's not an issue.

In a way a battery would be easier in that there's already cabling and a box for it to go in though it's obviously more expensive.

Panel wise worries me a little from a fitting perspective as I don't know how feasible it is to diy to be honest, would i need to drill holes in the roof or could I splice a new panel on the roof to the current one negating the need to drill holes so they'd be in parallel?
 
You can buy cables to join the two panels together for about £6 / 10 a pair basically two into one so no more wiring- only thing you would have to do is stick another panel on the roof
 
PaulC70 said:
To be honest if it wasn't for the (usually daily) charging of the mobility scooter battery I'd not even consider changing anything. We use very little otherwise other than the tv. Charging of mobiles etc is always done on the journeys and as I say we "usually" move every one or 2 days so it's not an issue.

In a way a battery would be easier in that there's already cabling and a box for it to go in though it's obviously more expensive.

Panel wise worries me a little from a fitting perspective as I don't know how feasible it is to diy to be honest, would i need to drill holes in the roof or could I splice a new panel on the roof to the current one negating the need to drill holes so they'd be in parallel?
Click to expand...

Just to play devil's advocate then...

Is a higher capacity battery for the mobility scooter an option? If so, that would not only extend the range of the scooter but also put the extra power where it's actually required.

If not, then how about a power bank? Could potentially have other uses and is more flexible than adding a battery to the van and again could be carried on the mobility scooter in order to extend the range or to allow charging while not at the van.

Just thinking out loud really.

DIY of the panels is entirely possible, but I'd advise against it if you aren't confident. None of it is terribly complex but if you get it wrong you can damage your MPPT controller and worse still (IMO) end up with water leaking through your roof...

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If you add another battery it doesn't have to a 300ah as the existing.
Personally if your existing 300 has 40 % left after 4 days then you just need some additional solar to charge it up until you move on.40 % is still over 100 ah remaining. (y)
 
Jimbohorlicks said:
If you add another battery it doesn't have to a 300ah as the existing.
Personally if your existing 300 has 40 % left after 4 days then you just need some additional solar to charge it up until you move on.40 % is still over 100 ah remaining. (y)
Click to expand...
120 ish remains - almost all can be used
 
PaulC70 said:
Yep I get that and while it would be good when off grid at something like a steam fair / organised event, it would be useless for my usual off grid using some uk aires, pub car parks etc.
Click to expand...
But are you stationary on UK Aires or pub car parks for your existing set up to be inadequate? If not you wouldn't need to put the panel out!
 
Terry said:
You can buy cables to join the two panels together for about £6 / 10 a pair basically two into one so no more wiring- only thing you would have to do is stick another panel on the roof
Click to expand...

Which I believe needs to be the same ie 100w? I'm overthinking this I think but Im assuming any 100w will do, doesn't have to be same make? I've seen sunshine solar are doing an offer at the moment (ends tomorrow) https://www.sunshinesolar.co.uk/Item/SSP100MS so a panel would be less than £100

Jimbohorlicks said:
If you add another battery it doesn't have to a 300ah as the existing.
Personally if your existing 300 has 40 % left after 4 days then you just need some additional solar to charge it up until you move on.40 % is still over 100 ah remaining. (y)
Click to expand...

I thought if adding another battery it should be same capacity? I may have misread that somewhere though. And actually youre right, I think my brain was just seeing the 40% rather than looking at the ah that was actually left available
Terry said:
120 ish remains - almost all can be used
Click to expand...

Yep, don't think my brain was letting me see past the 40% figure.

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