CTEK 25000 -vs- D250S Dual + SmartPass

5455 Views 9 Replies 6 Participants Last post by Hein, Oct 19, 2017

Ramsel Ruiz

Discussion Starter · May 14, 2016

I'm been reading the electrical threads here and have decided to go with a CTEK charger for battery to battery charging. There seem to be two main setups that people go with.

1. CTEK25000 - about $230
2. CTEK D250S Dual + Smartpass - about $440 together

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I'm going to have a 200w solar setup and 250ah Lifeline AGM battery. I'll be moving around a lot, so want to take advantage of charging from car battery.

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- The CTEK "D250S Dual has a built-in Maximum Power Point Tracker (MPPT)". That sounds great, so I can save money on the MPPT. Is that correct? Are there any major tradeoffs with going with the Dual instead of a separate MPPT?

- So if I go with the CTEK25000 I'll not only have to get a separate MPPT, but what exactly am I missing out on from not having the Smartpass in the system? What else would I have to buy if I go with the CTEK25000 setup?

I half understand these setups and any help clarifying would be much appreciated.

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RandomJoe

· #5 · May 15, 2016

The CTek's MPPT works okay, in full sun it's not too far off the Morningstar. It just won't produce quite as much overall, and it may be considerably lower during partly-cloudy conditions. If you aren't completely dependent on the solar it isn't a problem.

If I were buying everything new I might just use the CTek but I happened to already have the Morningstar so what the heck...

One comment I'd have about the Smartpass, though - can your battery bank handle / does it need 80A charging capacity? I'm using two 6V AGMs for a bank of 200AH at 12V. According to the manufacturer max charge rate is supposed to be around 60A (30% of rated capacity). Some brands recommend a lower percentage than that. IIRC Lifeline's a bit different from most, but can't remember their specs.

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RandomJoe

· #8 · May 15, 2016

My impression from the manual is it's just the Smartpass (80A total) until the current drops low enough for the CTek's 20A to cover it. Just a guess, though, from a quick read.

It would be nice if there was a way to configure the Smartpass to limit max current. For that matter, some adjustments on the D250S would be nice as well. It just occurred to me that the D250S manual specifies it's usable with basically all lead-acid battery types - but there's nothing to tell it what you're charging. Each type of battery has slightly different absorb and float voltages. The Morningstar has a DIP switch to select flooded or AGM, or you can even get fancy and set custom parameters using software to talk to it with a computer.

I do tend to run a bit light on charge current. My radio bench has a 100AH 12V AGM and a single 140W panel, about 10% charge rate. That's all it's had for - wow, 7-8 years now, time flies - and is still going so far. My big home system is 320AH 48V, 2.2kW in panels. Still only about 14%! It also has an AC powered charger in the inverter, I occasionally run it to give the batteries a stout charge current. They're flooded tall-case batteries so need some heavy amps occasionally to mix the electrolyte and prevent stratification.

In the van, I'll have 15A from the Morningstar and 20A from the CTek. If I run both together on a sunny day 35A is pretty reasonable - about 18%.

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