So it will charge the battery whilst it has a load on it. (12v lights ,fridge is on )
Battery Ah size recommendations
- Thread starter tolbot boulton
- Start date
I’ve now read about @Dellmassive’s issue with the ctek & lithium batteries which is making me think about a new charger and rewire so much for a straight swap n drop.
I’m looking to do more off grid stays, festivals etc, I have a dometic fridge, TV, light, usb and a cpap machine so i’m deciding between:
Stick with lead acid, get a new battery and get a 140w solar panel fitted - total cost and install £860
Switch to lithium 105ah, stick with ctek charger add a victron charger - total cost £580
Switch to lithium 105ah, stick with ctek, add victron charger and 140w solar panel - total cost £1325
Switch to lithium 230ah, stick with ctek, add victron charger - total cost £930
Is it wise to get a solar panel for off grid regardless off lithium battery total ah?
I’m looking to do more off grid stays, festivals etc, I have a dometic fridge, TV, light, usb and a cpap machine so i’m deciding between:
Stick with lead acid, get a new battery and get a 140w solar panel fitted - total cost and install £860
Switch to lithium 105ah, stick with ctek charger add a victron charger - total cost £580
Switch to lithium 105ah, stick with ctek, add victron charger and 140w solar panel - total cost £1325
Switch to lithium 230ah, stick with ctek, add victron charger - total cost £930
Is it wise to get a solar panel for off grid regardless off lithium battery total ah?
I have the ctek 250 with a Renogy 100ah LiFePo and a 100w solar panel.
The ctek issue is more of a minor pita rather than a major problem.
eg I’ve just been away to Ripon and put the fridge on in the van in the morning before setting off - LB 100%
By the time we set off the LB was down to about 96%.
Drive to Studley Royal Deer park - no output from CTEK during journey. Leave parked in sun - no output from solar via CTEK.
Park up for night in Ripon and LB down to 90% and by following lunchtime it’s about 82%.
Drive to Harrogate and CTEK kicks in and gets LB to 90% by time of arrival and carries on charging via solar while we are in Harrogate.
So basically the CTEK doesn’t kick in until the LiFePo is about 85%, so you can get to site having us a full day driving and already have a depleted LB when you park up which is annoying. So if you are having a week on a site off grid then your solar will have to have enough juice to cover your daily useage and a little extra if you want to push the battery back to 100%
The ctek issue is more of a minor pita rather than a major problem.
eg I’ve just been away to Ripon and put the fridge on in the van in the morning before setting off - LB 100%
By the time we set off the LB was down to about 96%.
Drive to Studley Royal Deer park - no output from CTEK during journey. Leave parked in sun - no output from solar via CTEK.
Park up for night in Ripon and LB down to 90% and by following lunchtime it’s about 82%.
Drive to Harrogate and CTEK kicks in and gets LB to 90% by time of arrival and carries on charging via solar while we are in Harrogate.
So basically the CTEK doesn’t kick in until the LiFePo is about 85%, so you can get to site having us a full day driving and already have a depleted LB when you park up which is annoying. So if you are having a week on a site off grid then your solar will have to have enough juice to cover your daily useage and a little extra if you want to push the battery back to 100%
Going to lithium will give you more usable capacity
Investing in solar will give you more off grid charging
The gold standard would be to do both - reasoning being that more capacity allows you to accept more charge on a "good" day and cover you for the next "bad" day
As @Oceanis says above think about what you want to do and look at your power budget:
With specific regard to @Dellmassive experience with the CTEK chargers I believe he has stated its mostly a preference. You might not choose that charger if fitting new but if you have one in place I don't think it would be worth the effort to throw it away (or eBay it) and fit something else.
Investing in solar will give you more off grid charging
The gold standard would be to do both - reasoning being that more capacity allows you to accept more charge on a "good" day and cover you for the next "bad" day
As @Oceanis says above think about what you want to do and look at your power budget:
- For a couple of nights you may find that a high capacity lithium system allows you to just run on the stored charge so long as you make sure the battery is topped off on a decent drive/EHU at home.
- If you want longer term than that then you may want to look at solar - but only if solar will keep up with your power use. If you want to capture the most then a roof fitted panel (with no shading) will collect all day, but is limited in size. You can increase the size with additional fold out panels but you might only be comfortable with leaving those out when you are near the van.
With specific regard to @Dellmassive experience with the CTEK chargers I believe he has stated its mostly a preference. You might not choose that charger if fitting new but if you have one in place I don't think it would be worth the effort to throw it away (or eBay it) and fit something else.
Yes. The charger will adjust from bulk,absorb,float charge stages automatically as your loads increase and decrease.
Provided your charger is strong enough to counter your loads..... say 15A - 25A for example.
If you loads on full are 5A, then I would fit a 10A charger, leaving 5A to charge the battery.
If your loads were 10A then I'd fit a 15A or 20A charger, etc.
Thanks so much everyone for your help with this it’s much aporeciated.
Couple more questions and i promise i’ll stop
If I stick with the ctek charger with lithium and I turn up somewhere and the battery is not fully charged, due to having the fridge on or something during the drive, can i still use the battery or does it need topping up via solar panel or a hook up?
I forgot what question 2 was…
Couple more questions and i promise i’ll stop
If I stick with the ctek charger with lithium and I turn up somewhere and the battery is not fully charged, due to having the fridge on or something during the drive, can i still use the battery or does it need topping up via solar panel or a hook up?
I forgot what question 2 was…
Why wouldn't the battery be fully charged after a long(ish) run? The charger should easily cope with running the fridge & charging the battery at the same time whilst the engine is running. If, however the battery isn't at 100%, it'll be fine to run the loads until the battery is empty & shuts down or you get more juice into it by whatever means.
Something to do with the ctek D2505SE charge profile that when the battery is fully charged it starts to discharge to the float stage while driving.
See the post above or link below, i’m still struggling to get my head round it but i assume it is ctek’s way of dealing with lithium batteries when lithium batteries don’t need it.
Or something
[Guide] DC-DC Charger (for leisure battery) -- How I Done It --
Thanks Lee. Or should I say Mr. Renogy! Been looking at your threads so will work out how to do it all now. Thanks bud.
The answer is yes. Just use things as you want and let the hook-up or solar do their thing.
You need to keep an eye on the battery level in case your power demands are high, but that is always the case.
There is no reason why you can’t use solar and hookup together.
Pete
Don’t know if this helps, but our system is 110ah AGM with 2x100W solar panels and a Renogy DC50S.
We run a compressor fridge, two phones, one camera, one small sound system, our lad’s handheld games console, 21 led light bulbs etc off it.
Battery level never drops below 85% of usable charge at night, and is fully charged before we wake up in the summer.
Am going to get round to adding a PC ventilation fan at some point and am confident it will hardly dent available power.
I have the wiring in for hookup but it’s just not necessary for us so never got a mains charger.
We run a compressor fridge, two phones, one camera, one small sound system, our lad’s handheld games console, 21 led light bulbs etc off it.
Battery level never drops below 85% of usable charge at night, and is fully charged before we wake up in the summer.
Am going to get round to adding a PC ventilation fan at some point and am confident it will hardly dent available power.
I have the wiring in for hookup but it’s just not necessary for us so never got a mains charger.
The CTEK has a lithium charge profile with a final float stage at a lower voltage to some others. What this means is that rather than hold the battery right at 100% it will let it drop back a bit and then kick in again, if you're unlucky you might end up parking up with 95% or 90% charge.Something to do with the ctek D2505SE charge profile that when the battery is fully charged it starts to discharge to the float stage while driving.
See the post above or link below, i’m still struggling to get my head round it but i assume it is ctek’s way of dealing with lithium batteries when lithium batteries don’t need it.
Or something
[Guide] DC-DC Charger (for leisure battery) -- How I Done It --
Thanks Lee. Or should I say Mr. Renogy! Been looking at your threads so will work out how to do it all now. Thanks bud.www.t6forum.com
But, importantly, if you are lithium based you will still have much more usable charge than an equivalent lead acid system.
Why is CTEK doing this a bit differently? It's not clear but if you look around it's a known thing that holding many types of lithium battery to 100% all the time is bad for lifetime. Ideally they should be stored at around a third charge and you'll find modern laptops, phones and EVs tend to try and charge to about 80% unless you ask for full charge. CTEKs main history is in long term battery maintenance so my suspicion is they are using a strategy that is a balance of good available charge and better lifetime.
If you use your van as a daily drive and only need the full capacity a few times a year that may actually be an advantage. Does it make enough of a difference to worry about? Personally I don't think so, I'd just take note of it and use the higher capacity per volume of LiFePo to fit a bit bigger battery. For me the gentler charge rate and the not holding to 100% I'd see as an advantage and it's nice to have options in the charger marketplace. Would be better if CTEK was a little more clear about their choices and why they might be a good thing though...
Read my previous comment/example of the shortcoming of the ctek.
Yeah, stick with the CTEK and the Lithium. It’s not an issue. It just bugs me sometimes. You can discharge your LiFePo to 20% with no effect on number of charge cycles, which is better than the depth of discharge for AGM. It has many more charge cycles than an AGM. And most importantly you can discharge it 100% and not kill it. Do it enough times and you reduce it’s maximum number of charge cycles but do that to an AGM a couple of times and it’s toast.
Ahh right, hadn’t noticed that. Very strange.
does the fogstar fit under the drivers seat or do you lay it on its side , how does the renogy compare to these options ,its a little bit more expensive but i think its exactly the same size as my efb battery i have just now that is on its way out.
LiFePo isn't a "wet" chemistry so they should be fine on their side (but always double check the vendor's advice)
The 100ah Renogy lays on its side too.
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