Charger for 48v battery bank

[Can'tWeld]

As a bit of a side hustle I do a bit of off-grid/RV electrics, trucks, vans, boats, that sorta thing.

Most recent system I did was a static system at a campsite, it runs off a 48v battery bank.

Obviously we're in summer right now and the panels are keeping up just fine but I've promised them I will get a solution in place for mains trickle charging so they can keep the batteries topped up in winter.

Anyone got any suggestions for a good charger for a 48v battery bank, 4x 12v leisure batteries? Seems pretty hard to find them off the shelf, I think Victron do one but obviously it's silly money.

It will be something they keep plugged in all the time in winter just to keep the batteries charged when there isn't enough solar.

Thanks.

 

[chunkolini]

Can'tWeld
do you have any idea of what size solar panel and battery id need to run a small fridge in my Doblo camper?
What info is needed to calculate the needs?
I'm not after running 240v cookers etc really just fridge and maybe lights
Its fitted with a 5w solar panel and a 10ah battery which is ok for charging phones and thats about it

 

[Chippie]

As a bit of a side hustle I do a bit of off-grid/RV electrics, trucks, vans, boats, that sorta thing.

Anyone got any suggestions for a good charger for a 48v battery bank, 4x 12v leisure batteries? Seems pretty hard to find them off the shelf, I think Victron do one but obviously it's silly money.

It will be something they keep plugged in all the time in winter just to keep the batteries charged when there isn't enough solar.

Thanks.

How about a s/h stick welder transformer with a suitably rated bridge rectifier and a couple of smoothing caps? If the tax outputs not much more than around 50v it should suffice?

 

[Chippie]

Can'tWeld
do you have any idea of what size solar panel and battery id need to run a small fridge in my Doblo camper?
What info is needed to calculate the needs?

More details of the fridge are needed to make a suggestion on size…
How long does the fridge need to run for?

 

[Matrixx]

What about 4 x 12 V chargers , one connected to each battery , batt + and Batt - to each battery so no cross charging? or 2 x 24V DC?

 

[chunkolini]

Is this becoming a thread hijack?
Linky to the fridge https://www.amazon.co.uk/dp/B07FY2MFFC?psc=1&ref=ppx_yo2ov_dt_b_product_details basically a small fridge that runs off mains or 12v it says 50watts.
Id like to keep it running at least over night and be charging during the day and also have it connected to a battery charged from the alternator.
Id be lookingot get someone to do it for me electrickery is definitely not my bag.
I guess gel battery as they seem a lot cheaper than Lithium

 

[sako243]

I've got a 3 phase -> 48V forklift battery charger going spare if that's any use? Old fashioned, massive transformer and all completely analogue controls. Lump of a thing though.

 

[fizzy]

I've got a 3 phase -> 48V forklift battery charger going spare if that's any use? Old fashioned, massive transformer and all completely analogue controls. Lump of a thing though.

I was going to suggest a forklift charger BUT mine puts out up to 120A - wouldn't do silly little car batteries much good
Rule of thumb is to charge at 10% of capacity so I am guessing he will need about 10 amps.

This can charge at 4amps

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Then you have various electric scooter ones for lead acids

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48v 20amp/h for only £22

 

[fizzy]

Is this becoming a thread hijack?
Linky to the fridge https://www.amazon.co.uk/dp/B07FY2MFFC?psc=1&ref=ppx_yo2ov_dt_b_product_details basically a small fridge that runs off mains or 12v it says 50watts.
Id like to keep it running at least over night and be charging during the day and also have it connected to a battery charged from the alternator.
Id be lookingot get someone to do it for me electrickery is definitely not my bag.
I guess gel battery as they seem a lot cheaper than Lithium

I am in Swansea most evenings and weekends - would happily give a hand.

 

[chunkolini]

Mr Fizzy I'd happily pay to have it done, is that up your street?
Id be happy holding tools and supplying coffee
We can switch to DM if you like

 

[Chippie]

If that fridge is 50w then a standard 100w panel and a controller would suffice.

 

[fizzy]

Mr Fizzy I'd happily pay to have it done, is that up your street?
Id be happy holding tools and supplying coffee
We can switch to DM if you like

Pay?
Don't be silly!

 

[voipio]

Did some quick calculations for a 60W fridge, a while back. Assumed fridge was compressor type, with duty cycle 50% during hot weather, requires 720Wh per day. Battery capacity 120Ah. Solar panel capacity 200W, should work reasonably well in the summer. For winter, increase the panel capacity to 800W or more, since cloudy skies can give less than 5% of full output, even 800W worth of panels will barely keep up.

 

[Chippie]

Did some quick calculations for a 60W fridge, a while back. Assumed fridge was compressor type, with duty cycle 50% during hot weather, requires 720Wh per day. Battery capacity 120Ah. Solar panel capacity 200W, should work reasonably well in the summer. For winter, increase the panel capacity to 800W or more, since cloudy skies can give less than 5% of full output., even 800W worth of panels will barely keep up.

I based mine on the fridge having a heating element (adsorption type or similar ) rather than a compressor….
I think the fridge in my van has a 100 watt element..

 

[chunkolini]

Sounds doable
Fizzy feel free to pop over sometime for a look-see.
That's a very generous offer.
You have pm

 

[CompoSimmonite]

I've actually got a 48v charger. It was used in my G-Wiz electric car when the original onboard charger failed. I'll have a look tomorrow and let you know more details of make, output etc. It automatically switches to float mode when batteries fully charged

 

[Can'tWeld]

Chunkolini - As above, I'd need to know the specs of the fridge to advise.
Inlaws live in a DAF 45 which I wired, I think the fridge draws a couple of amps with the compressor running but has higher inrush current on startup.
You'd need to know the approximate duty cycle and how much current it draws. Do you already have the fridge?

CompoSimmonite - that would be amazing, thank you. Doesn't need to be anything huge, just a trickle charger.

 

[Can'tWeld]

Didn't think of making one but it would be possible, but I need something that would switch to trickle charging. I suspect it would be fairly simple, maybe just make a current limiting circuit with a voltage cutoff?

 

[willie.macleod]

It will be something they keep plugged in all the time in winter just to keep the batteries charged when there isn't enough solar.

Is there any need for batteries in that case? I can understand if you have an off-grid system, but if there is already provision for mains I'm not sure what benefit in the batteries being involved rather than just solar PV straight into the grid.

 

[CompoSimmonite]

Mine is a no name Chinese. Data tag states 58.8v and 30A. It is exactly the same as mine -

http://www.aliexpress.com/item/1005...949279241!sea!UK!0&curPageLogUid=9hkM5PpOhdJU