Which size DC-DC charger?

[johnporter11]

I'm about to install the B2B charger. I've got two 100AH EFB leisure batteries, a Renogy 175w flexible solar panel and I bought a 50A Renogy DC-DC charger a few weeks back. I had originally intended to buy the 30A version but it was out of stock. It's now back in stock and Renogy will refund the 50A for me (which was considerably more expensive). But I'm not sure what to do.
I'm converting a Mk8 minibus, but I'm not sure of the alternator capacity.
Any thoughts on the pros and cons of 30A versus 50A charging?

[dumper]

The Sterling 30 amp I use to change my two 110 amp leisure batteries have been ok for mine had no problem in the last 3 years but I’m not parked up without moving during the day .

[workbox]

I'm about to install the B2B charger. I've got two 100AH EFB leisure batteries, a Renogy 175w flexible solar panel and I bought a 50A Renogy DC-DC charger a few weeks back. I had originally intended to buy the 30A version but it was out of stock. It's now back in stock and Renogy will refund the 50A for me (which was considerably more expensive). But I'm not sure what to do.
I'm converting a Mk8 minibus, but I'm not sure of the alternator capacity.
Any thoughts on the pros and cons of 30A versus 50A charging?

I have 30amps victron b2b with bluethooth app. But I wouldn't mind to have 50 amps instead, faster charge especially for larger battery banks.

[johnporter11]

So Dumper and Workbox are saying they've found 30A adequate. I guess 200AH battery bank could use 50A. But I'm worried about my alternator.

[workbox]

So Dumper and Workbox are saying they've found 30A adequate. I guess 200AH battery bank could use 50A. But I'm worried about my alternator.

Check video below how to test alternator amps output with just basic multi meter.
https://youtu.be/Q849H1s-g1o

[workbox]

So Dumper and Workbox are saying they've found 30A adequate. I guess 200AH battery bank could use 50A. But I'm worried about my alternator.

My transit mk8 2L engine have 165amps alternator, if your engine 2.2 L probably you have even bigger one
Check this eBay listing for alternator

[Boltrounder]

On my transit I have a vsr and 2 110ah battery’s and if I run them all night with the night heater on the most I’ve seen them draw is about 40amps for the first couple of minutes then as the voltage starts to raise it tapers down quite a lot.

But I’m thinking of getting a dc charger and a lifepo4 setup but it’s ££££


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[dumper]

I use my van on car rallies worst case is daytime night heater and two two way radios running for 8 hours inverter running a 500w microwave for a maximum of 15 minutes usually I go to the event the night before and run the night heater and tv for between 6& 8 hours and the microwave again for 15 minutes I don’t run the heater overnight but the radio in the rear is on all night and during the day the van engine will be run no more then a hour I have never had any problems with the batteries getting to low .the only battery problem I’ve had is when the van aux battery was getting weak I had to start the van up as the van radio used to cut out after about 6 hours till I fitted new batteries.
I never had any problems with the mk6 it was the same setup but it had a low power split change relay in that .

[workbox]

But I’m thinking of getting a dc charger and a lifepo4 setup but it’s ££££

if keen for DIY, you could build 270amps, grade A, lifepo4 battery bank under 600 pounds

[Boltrounder]

Would I need a bms?


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[workbox]

Would I need a bms?

Yes you would need one. Have a look these videos below see what you think.


https://youtu.be/IsvBlQJr7b0?t=251

https://www.youtube.com/watch?v=3U4ZfQ_IToI

[Boltrounder]

I will look in the morning, have you got any experience with lifepo4s?


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[workbox]

I will look in the morning, have you got any experience with lifepo4s?

I just build one for my campervan that's pretty much where my experience ends.

If you need extensive knowledge solar/batteries/bms and everything in between check link below

https://diysolarforum.com/