Newbie - Leisure Battery Set Up
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It's doable, but it's a hell of an investment just for the convenience of the occasional off-EHU microwave use.
Also, I'd reiterate my earlier comments about being off-grid for longer periods, that then comes down to energy in vs energy out more than battery capacity. A huge lithium battery setup will let you run a load of powerful appliances for the weekend, but it's only sustainable for longer periods off-grid if your energy input is enough to overcome the drain of all the power-hungry appliances.
Batteries and invertors can be added/changed relatively easily whereas a stuck-down solar panel is a real pain to change so I'd focus on getting this bit right if you think you'll have any interest in off-grid use.
Also, I'd reiterate my earlier comments about being off-grid for longer periods, that then comes down to energy in vs energy out more than battery capacity. A huge lithium battery setup will let you run a load of powerful appliances for the weekend, but it's only sustainable for longer periods off-grid if your energy input is enough to overcome the drain of all the power-hungry appliances.
Batteries and invertors can be added/changed relatively easily whereas a stuck-down solar panel is a real pain to change so I'd focus on getting this bit right if you think you'll have any interest in off-grid use.
By the sound of it I think we're going to need a bigger solar panel! I agree completely with the consensus opinion on how important the batteries are but as t0mb0 says these can be changed later. My hand is being (not so subtly) forced on the microwave, which has caused more 'discussions' than I had anticipated, so I think I'm going to keep that in, change the panel to 200w minimum (any suggestions welcome) and maybe start off with a pure lead carbon battery for quick charging (thoughts on these?). I'll then look at swapping this out later for one or two lithium batteries. For now I think we need to start looking at future proofing with the solar panel and if that means EHU is going to be our initial option then I'll just have to accept that and put off grid camping on the (literal) back burner for now. I genuinely appreciate all the input and I readily accept that this is a lot of work for very little gain but if there's one thing I've learned on here it's that specs, requirements and priorities are very personal to everyone.
Absolutely, people have such different ways of using their campers that it takes some puzzling out and experience to work out whether other people's ideas or experiences are really relevant to you. Added to this, how you use your camper naturally evolves over time so prioritising the elements that are hard to change in the first instance makes sense.
I don't know much about pure lead carbon batteries. It looks like they have longer cycle life than a traditional AGM and higher potential charging current (only really relevant for EHU/DC-DC charging, solar generally isn't going to get to that level of current anyway) but I'm not so sure on the ability to drive high power devices - I suspect they're much closer to a traditional AGM than lithium in this regard but you'd have to study the spec sheets carefully.
Confirmed on the ability of pure lead carbon to drive high power devices I think, I've just taken a look at the discharge curves on the spec sheets for an example pure lead carbon against similar capacity traditional AGM and the discharge characteristics are very similar so I think for high power devices from batteries, lithium is really the only game in town.
As a random idea, if you think that you'll really only want the microwave sporadically off grid, I wonder if it's worth considering hooking the invertor directly up to the alternator? This way you can run the engine for when you really need the microwave for a few minutes off-EHU? I've never heard of anyone doing this, but I don't see why you couldn't as long as the load is below the capacity of the alternator and it's all wired and fused correctly? Might be worth asking your convertor?
That's an interesting idea. He's going to love having me as a customer with all my questions and suggestions
Although the recharge rate on pure lead carbon is only about an hour to 90% from what I've read.
Yes, but to run high power devices, it's the discharge characteristics that matter and an AGM-like battery just isn't designed to run an 800w load for 5-10 minutes.
Also, to actually achieve that recharge rate, on a 100Ah battery, you're going to need in the region of 100A charging current. This is way beyond a van solar install, and also beyond the usual specification of EHU/DC-DC chargers, you'd need something fairly specialist, or multiple chargers in parallel to actually deliver this.
Have you had the hairdryer 'discussion' yet?
Ha ha, don't even go there!
Understood. I'd forgotten to say that the inverter is in the mix somewhere...
My harebrained inspiration has come from this video. Not real world but it's what sowed the original seed.
Bodans Microwave Solution
That is interesting. I'm slightly terrified by the way he seems to think it's fine to completely flatten the battery and then recharge, your battery really isn't going to last very long if you treat it like that!
He's run his 800W microwave for 32min before the battery dies (do not try this at home kids!). So, very roughly, a five minute microwaving will take out about 17Ah out of your battery? Maybe this is ok occasionally? I don't have a good feel for the consequences of doing this regularly on your batteries life though.
for some scrambled egg and warming baby bottles and food ........... all you need is a kettle and a good non stick pan / wok ...... your away in your van away from the rat race....... you have time on a hands ...
There is no way ever you will get back to 90% in 1 hour. The UK sun will let you down even with a 250watt solar panel. I think you need to spend a lot of time reading about batteries and solar and how they work. Get your head around charging a battery and topping up a battery (this is where folk fail to understand)
I live here in Spain and on a good day a battery discharged to 50% ( I had 3x110watt AGM's) will take about 5/6 hours from solar on my old motorhome with 400watts of solar. Now with my campervan with 250 watts about 6/7/8. In the UK on an average day, you might get 4/5 hours as the solar panel is laying flat and not following the sun.
In your case forget AGM or pure lead carbon (just another AGM) and go for LifePo4 Lithium-ion battery and all the charging bits required for it.. They will last you the life of the van and can be discharged down to 90% without problems. Have a good read about them as most motorhomes and now being build with them fitted as standard.
If you cut corners now you will regret it forever.
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There is NO way you can run a battery down to 0% and recharge it in 90 minutes unless he is using a LifePo4 Lithium-ion battery and even then I would be very surprised it can be fully charged in 90 munites. The charger would need to be supplying 1000/2000 watts or more and that is going to get hot very hot.......
I cannot believe a company like them post a video like that. Anyone who has bought a van from them and destroyed a battery using it as he has can make a very good claim in court as on his video he states you can............
Meanwhile, back at the ranch. My opinion (and that's all it is fwiw) is ditch the microwave and inverter & put your money into a simple good quality lithium setup & decent solar panel. A couple of weekends ago we were running our van fridge & 2 National Luna fridges + lights, USB etc. yada yada. No EHU just the 160W solar. The lithium battery was down to around 70% each morning after running 3 fridges all night in warm weather. By lunchtime, the battery was up to 100%, so the solar had run the 3 fridges AND charged the battery. We have a 1600W inverter & hardly ever use it, I probably wouldn't bother next time around.
Just my 2 penneth.
Just my 2 penneth.
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