Leisure Battery Size

[cocky9]

Hi Guys,

Looking into the world of electrics!

I’m planning on running a 12V system for fridge which would be on a low setting (for cold beers), a diesel heater (which I’d like the option of having running throughout the night if required) and some lights/reading lights and phone charging.

What size battery should be sufficient? And looking to have it under drivers seat.

My set up would be dc to dc charging, and also solar charging too. I’m looking at a power station to use also as I like the idea of this being versatile. I would be doing approximately 3 days off grid max.

Thanks folks

 

[Salty Spuds]

As much lithium as you can physically fit & afford. No one has ever complained about having too much battery capacity.

 

[ginkster]

From the details you’ve given a 105ah lifepo4 would easily do. Much more is wasted money and space unless you have future plans (e.g. an inverter) that require more power. Have a look at Nohma.com, they have some good articles about system design and sizing including a power audit chart.

 

[icn05]

Hi Guys,

Looking into the world of electrics!

I’m planning on running a 12V system for fridge which would be on a low setting (for cold beers), a diesel heater (which I’d like the option of having running throughout the night if required) and some lights/reading lights and phone charging.

What size battery should be sufficient? And looking to have it under drivers seat.

My set up would be dc to dc charging, and also solar charging too. I’m looking at a power station to use also as I like the idea of this being versatile. I would be doing approximately 3 days off grid max.

Thanks folks

My use requirements are similar to yours, I fitted a Roamer 160ah and although I’ve not gone completely off grid camping yet I have done trial runs in the drive by leaving the fridge running, leaving lights on for probably longer than I would when camping and using the diesel heater for 30 minutes a day. I did run to the shops a couple of times (short runs), the battery was still showing over 80% on the Roamer app after 3 days..

TBH I would have gone for the for 230ah for the reasons @Salty Spuds mentions but it wouldn’t have fitted without major alterations. If I was starting from scratch and fitting it under the seat I’d go for the 230Ah

 

[Drive Wayne]

I'm with @Salty Spuds on this one, when we do our outings we are rather power hungry. A coffee machine for me, wifeys various hair products, an induction hob for kettle boils, we started taking out an air fryer last year too. The list goes on.
However we aren't constrained by underseat space, the battery and 2000 watt inverter is behind the wheel arch in the back under the tambour door wardrobe.
Only a modest 180 watt solar panel on top which is fine when the weather is kind, this past year has been a bit of a solar shocker though!
I'm now waiting for father Christmas to deliver my upgrades for next year's travels.
I'll be swapping out a 200Ah LB for a new 230Ah 'upright' Roamer, upgrading the Victron Orion TR smart 30 to the new 'run cool' Victron XS-50, and even throwing in the Cerbo GX system for good measure!
If it has to be underseat, have a look at @TallPaul_S for his system using a 230Ah seatbase lithium battery. Fantastic install.
No one has ever complained about having too much battery capacity, especially my wife! Those GHD's don't run themselves!

 

[TallPaul_S]

3 days off grid, with worst case scenario of zero solar (under trees, or just normal British weather!) with a fridge (25Ah per day), diesel heater, phone charging etc, a typical 105Ah LiFePO4 might be cutting it fine - you're looking at 75Ah for just the fridge for 3 days of use. Generally you don't want to plan on going below 20% regularly on a LiFePO4 battery - you can, but it's best not to.

I'd agree with @Drive Wayne - go big or go home!!

A 230Ah will fit under the driver's or passenger seat with enough space for your DC-DC charger, MPPT etc. it also gives you the option of fitting up to a 2000w (or 3000w I think if you get the Roamer battery) inverter and have the capacity to use it for charging laptops, induction cooking, coffee machines, and keeping your main starter battery topped up.

I've gone big with a 230Ah seat base battery, 300w solar with 20a MPPT, 50a DC-DC, 2000w inverter, and Victron Cerbo GX for loads of monitoring. All fitted inside (or attached to) the passenger seat base. Did me well for 3 weeks off grid in Europe earlier this year, zero hookup required even with a fair amount of induction cooking.

 

[cocky9]

Cheers guys, appreciated the input! The last thing I want is to be worrying that we will run out of power. Or being cold in the nights but not putting the heater on for fear of depleting the battery!
I’ve just ordered “the van conversion guide” to hopefully get my head around things. It’s a headache.
If I had the money I would be all over the Clayton units they seem so simple.
However we won’t be using massive amounts of power off grid, I like to be “simplistic” when we get away. The less the better. But cold beers are non negotiable and a warm nights sleep!

 

[kipperman]

I'm going 560Ah in our new build..
No doubt someone will out do me

 

[cocky9]

Haven’t got the money for that

 

[Salty Spuds]

Just to add perspective. We have a 100ah lithium & managed 3 days off grid in -20C, but we had to manage the power consumption. Obviously the fridge wasn’t doing much, but we used the Webasto for 5-6 hours/day. We had to be careful with the lights, only switching on what was absolutely necessary, as & when. After 3 days we were down to 20% remaining on the battery. We have solar & because we were in a sunny spot, we actually got a good yield from the panel for 4-5 hours a day, but it was no way keeping up with our consumption. I think without the solar, we would be struggling after a couple of nights. We didn’t run the heater overnight.
So, 100Ah is good for a couple of days imho, but that’s still with strict management. My next van will have at least 200Ah.

 

[cocky9]

Thanks @Salty Spuds puts it into perspective nicely. How long do you these batteries take to recharge when charging dc to dc when I’d be driving?
For example if we were going NC500 and stopping in lay bys would the battery have time to recharge between stops?

 

[TallPaul_S]

Thanks @Salty Spuds puts it into perspective nicely. How long do you these batteries take to recharge when charging dc to dc when I’d be driving?
For example if we were going NC500 and stopping in lay bys would the battery have time to recharge between stops?

It's simple maths:

50a for an hour is 50Ah (Amp hours). If the battery is 230Ah it'd take 4 and a bit hours to fill, maybe a bit more as 50a being pulled from the SB with only be about 48a at the LB. So just under 5hrs from fully empty.

50Ah (20% roughly) from an hour's drive is basically enough to see you through a day or so of use, maybe 36hrs worth.

You'll want a big DC-DC with a big battery or it'll take ages to charge.

If you don't understand the maths it's worth learning it - it's pretty basic. For instance a device pulls 1a. 1a for an hour is 1Ah. Times 24 is 24Ah. That's your daily usage for the fridge. Also, amps, watts and volts are all related to each other, if you know 2 you can work out the other one. Watts divided by volts = amps, for instance. So an 800w appliance uses 66 amps.

 

[Salty Spuds]

Thanks @Salty Spuds puts it into perspective nicely. How long do you these batteries take to recharge when charging dc to dc when I’d be driving?
For example if we were going NC500 and stopping in lay bys would the battery have time to recharge between stops?

All depends on your DC-DC charger. Lithium will absorb anything you throw at it upto & including the point where it becomes dangerous. The recommended charging rate for lithium for maximum battery life is C/3, where C is the battery capacity. So a 100Ah battery would be 100/3=33.333A or 30A charger in real money. You can go to C/1 on certain high end batteries, but this will significantly reduce the battery life.
So if you ran a 30A charger for 3 hours, it would charge a 100Ah battery from flat, give or take. But if you’re moving on every day, you’re unlikely to be running down the battery completely overnight.
I suggest you have a read of @Dellmassive’s How to guides for more information.

 

[Stay Frosty]

I wouldn't go down the power station route as you really do pay top dollar for pretty packaging and amped up power output claims, most have 100 Ah batteries inside.

 

[ginkster]

However we won’t be using massive amounts of power off grid, I like to be “simplistic” when we get away. The less the better. But cold beers are non negotiable and a warm nights sleep!

Sounds like how we go. As I mentioned above, your use case doesn’t need a massive setup. I have a 105ah lifepo4 and do not feel the need for any more. I don’t use an inverter and the fridge is the most power hungry thing I have. With a 200w solar panel I have yet to ever get close to running out of power or needing to run the engine or hook up (I’ve not even bothered fitting my mains charger).

Real world experience was this year at the British Grand Prix. It rained a lot and was overcast for all bar a few hours on the Sunday afternoon. We parked up on Thursday evening (full battery) and left late Monday morning and the battery never dropped below 85% and was fully topped up everyday by the solar. The fridge was on permanently, lights used every evening, 3 x phones, an iPad and 3 battery packs charged each night and the heater run on at least 3 evenings. The system was also keeping my ailing starter battery alive via an Ablemail AMT12-2.

I’ve had similar experiences in hotter conditions with the fridge running harder but no heating. And in freezing, overcast conditions with lots of heater and lights. In anything other than the depths of winter my system, with my use, is self sustaining without starting the engine. Even with no solar I comfortably get 4 days off-grid. Clearly if you have any thought of using power hungry kit like induction hobs, coffee machines or curlers then go bigger now while you are at it. If not, save money and space and spec the system appropriately.

 

[cocky9]

It's simple maths:

50a for an hour is 50Ah (Amp hours). If the battery is 230Ah it'd take 4 and a bit hours to fill, maybe a bit more as 50a being pulled from the SB with only be about 48a at the LB. So just under 5hrs from fully empty.

50Ah (20% roughly) from an hour's drive is basically enough to see you through a day or so of use, maybe 36hrs worth.

You'll want a big DC-DC with a big battery or it'll take ages to charge.

If you don't understand the maths it's worth learning it - it's pretty basic. For instance a device pulls 1a. 1a for an hour is 1Ah. Times 24 is 24Ah. That's your daily usage for the fridge. Also, amps, watts and volts are all related to each other, if you know 2 you can work out the other one. Watts divided by volts = amps, for instance. So an 800w appliance uses 66 amps.

Thanks for this. I get all other aspects but the electrics is a head scratcher for me. Going to go away and do some research but that has helped me a lot so thank you.

 

[cocky9]

Sounds like how we go. As I mentioned above, your use case doesn’t need a massive setup. I have a 105ah lifepo4 and do not feel the need for any more. I don’t use an inverter and the fridge is the most power hungry thing I have. With a 200w solar panel I have yet to ever get close to running out of power or needing to run the engine or hook up (I’ve not even bothered fitting my mains charger).

Real world experience was this year at the British Grand Prix. It rained a lot and was overcast for all bar a few hours on the Sunday afternoon. We parked up on Thursday evening (full battery) and left late Monday morning and the battery never dropped below 85% and was fully topped up everyday by the solar. The fridge was on permanently, lights used every evening, 3 x phones, an iPad and 3 battery packs charged each night and the heater run on at least 3 evenings. The system was also keeping my ailing starter battery alive via an Ablemail AMT12-2.

I’ve had similar experiences in hotter conditions with the fridge running harder but no heating. And in freezing, overcast conditions with lots of heater and lights. In anything other than the depths of winter my system, with my use, is self sustaining without starting the engine. Even with no solar I comfortably get 4 days off-grid. Clearly if you have any thought of using power hungry kit like induction hobs, coffee machines or curlers then go bigger now while you are at it. If not, save money and space and spec the system appropriately.

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Thanks for this, nice to see a real life example!
I’m more inclined to go this way, im on a budget and I don’t think I’ll need more than this realistically, especially with not staying in one place too long.
We won’t be using power hungry things really, jet boil for the coffee, cadac to cook and we’ll be tucked up in a country pub stinking of wet dog so she won’t be needing her curlers
Cheers guys

 

[cocky9]

I wouldn't go down the power station route as you really do pay top dollar for pretty packaging and amped up power output claims, most have 100 Ah batteries inside.

I think you pay the premium though for what the product is, a portable power station. It’s so versatile. Agreed it doesn’t suit everyone but on the other hand it’s the perfect fit for some people

 

[Stay Frosty]

In the case of the larger Clayton units the price tag is nearly double the cost of my diy seat base battery, 2 KW inverter and twin solar panel set up.
I'll admit the Clayton is prettier and can be used away from the van but by the time you've got one in the van charging from the vans alternator and rooftop solar it's just a more expensive way of adding 230 volt AC to the van.
Versatility is if you want to use the power station for other uses too and fair enough it's hard to take a Transporter everywhere.

 

[TallPaul_S]

In the case of the larger Clayton units the price tag is nearly double the cost of my diy seat base battery, 2 KW inverter and twin solar panel set up.
I'll admit the Clayton is prettier and can be used away from the van but by the time you've got one in the van charging from the vans alternator and rooftop solar it's just a more expensive way of adding 230 volt AC to the van.
Versatility is if you want to use the power station for other uses too and fair enough it's hard to take a Transporter everywhere.

Yeah, your paying for convenience and portability.

But, £4k for the 2kwh version is a lot of money, and it's still not as much battery capacity as a 230Ah 12v system! And you'd need to add solar and alternator charging on top. You can build a 230Ah (2.7Kwh), 3000w with 50a of alternator charging and as much as you can fit on your roof for about £1500 or less...