question

oliver-vt avatar image

Which DC-DC charger 18A or 30A

Dear All,

I am new to all this and busy trying to design a simple electric diagram for my camper-van conversion.

I will only be using a 100Ah leisure battery and I was wondering if the DC-DC smart charger 12 / 12 18A would be enough.

I am assuming charging with the 18A would take twice as much time than with the 30A. Correct?
What would be a rough estimation of how much I could charge with say an hour of driving?

Many thanks for your support.
Oliver

chargerdc systembattery charger
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1 Answer
JohnC avatar image
JohnC answered ·

Hi @Oliver-VT

If that 100Ah is a Pb battery, then a 'design' point could be 0.1C or 10A. Depends who you ask, and even the batt maker might say they'll take more. Adding loads at the same time will add to that 10A, But if little load, then the 18 should be more than adequate.

Consider your alternator too. They can get hot, even burn out at low engine revs if supplying a lot of power.

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Hey JohnC,


Thank you for your feedback. I'll be fitting a 100Ah AGM battery, so yes, Pb it is...
I don't quite get your point with 0.1C or 10A. Could you expand on that a little bit if you don't mind?


Cheers
Oliver

@Oliver-VT

Yeh, it mightn't actually be technically correct to express it like that, but C is the battery Ah. You may spot various ratings for a particular batt such as C5 or C20, which designates their discharge capacity over 5 or 20 hours.

The 0.1 in front of the C means (to me anyway) a charge of one tenth of the C (your 100Ah), so 10A..

Most Pb's would find 0.1C a cosy place, and 0.2C perhaps 'uncomfortable'. Beyond that wouldn't usually be recommended, and in practice it would probably take little time to reach Absorb level and then self-restrict anyway.


Ok, you got me totally confused. I must admit my limits. I guess the DC-DC 12 12 18A will do then.
But I'll still investigate all this (I am only getting my van tomorrow) before making a purchase.

Thanks a lot anyways.
Oliver