Inverter/Charge Combo or separate devices?

[krby]

I'm building a portable power box with LFE cells. It's sort of like a PowerWall, but not tied into the grid or the house permanently. It'll charge from a standard AC plug, stay charged most of the time and then I'll use it during blackouts, camping, etc. I'm sizing it for about 3-4kWh of usable capacity and 2000W of power output. I could probably get away with 1500W, but I'd like a little headroom. Given the size, I figured 24V would be easier to work with.

My question is whether to buy an inverter charger combo or separate devices?

I don't need the auto-transfer or AC pass-thru of the combo, but having a single thing would simplify wiring and (I think) would take up less space overall. On the other hand, If I buy them separately it looks like I have more choices for sizing the charge current and the output in a 24V system. Of course, there's always the idea that a single failure of a combo unit takes out both my charger and inverter, but this isn't for anything I absolutely HAVE to rely on, and my reading about the current products indicates reliability is really good.

It seems like to combo units are generally more expensive than what I can find if I look for deals on separate units. Also, it looks like their charging profiles are designed for various lead acid types instead of LFE, but I'm not sure how configurable that is.

 

[Newenough]

Separate would be simple. Pure Sine inverters come in all shapes and sizes. So find one that best suits your arrangement. Then use a Progressive Dynamics charger. They're small for what they do and priced right (they have different ones for the various battery chems and charge amps). The good news is you can probably get both cheaper than an all in one unit, and as a bonus if you want to upgrade one or the other later you can. When I went to Lifepo4 from lead acid, rather than replace my inverter/charger completly, as it could not charge lifepo4's, I just install a 25a PD charger designed for lifepo4's to charge from generator when needed.

 

[HighTechLab]

If you are running a 24V system, I think you would be better with an inverter/charger combo. They use the same circuitry for charging and inverting, so in a portable power box you would have less weight. The inverter/chargers are also typically more robust, hence the cost increase, and typically have a greater output on their charging system since they are using the circuitry designed for inverting at a few thousand watts. They are also a cleaner power output because they typically have a transformer in them and are low-frequency, and the transformer filters out most of the high frequency interference. 24v has less losses since you are starting at a higher voltage - the bigger the difference between primary and secondary of a transformer the more heat it's going to make (losses).

If you are running a 12v system, then you are better to go with individual inverter and charger, because there is a lot of selection in the 12v world that all have their own shining features. If you go seperate you can add the pass through transfer switch type of stuff later on if you really need to.

 

[Ped]

I really like what I see in the victrons with current limiting capabilities. I wish I knew about them earlier and theyre priced well.

 

[krby]

Ok, I'm pretty convinced that I'm going to go with a combo, so now I'm going to ask the type of question you should never ask on the Internet: Which brand? I'm looking for 24V ~2000W , I want charging current no more than about 25A, and everything I'm considering seems to offer that. I'm looking at
- Samlex 2224
- Magnum Eng ms2024
- AIMS picoglf20w24v120vr
- Xantrex SW2024
- Victron (UPDATED: @Ped gave me a link for this) CMP242020100

Cost is a bit of an issue, for all or most of these I'm probably going to end up buying the remote control just so I can configure the charging profile for LFE batts and turn down the charge current. AIMS is the least expensive of the lot, but I'm not sure what I'm actually giving up by going with AIMS vs the Samlex or Victron (Both around $1100-$1200 which seems to be the sweet spot for me w.r.t to price vs quality) .

Will all of these work equally well with LFE batts?

 

[Ped]

Multi-plus. Theres a ton the one linked isnt exactly the right one. What youre wanting a bit pricey though.

Victron Energy PMP121800000 - Inverter Supply

Shop for Victron Energy PMP121800000 at Inverter Supply for best prices online. Victron Energy PMP121800000, Victron Energy, PMP121800000, MultiPlus 12/800/35-16, Victron Inverter Chargers

www.invertersupply.com

 

[krby]

Victron Energy PMP121800000 - Inverter Supply

Shop for Victron Energy PMP121800000 at Inverter Supply for best prices online. Victron Energy PMP121800000, Victron Energy, PMP121800000, MultiPlus 12/800/35-16, Victron Inverter Chargers

www.invertersupply.com

thanks! Updated my post.

 

[Steve_S]

AIms is very basic functionaily, download the manual and you will see. They do what they are supposed to do but not much more. There are a few versions / models but these are basic entry level. Victron, Magnum are Tier-1 products. Xantrex, Samlex is Tier-2 (Mid upper levels), AIms like most other Chinese "Value" inverters are Tier-3 basic.

Some may want to argue the Tier's but it is what it is. The saying of "You get wat you pay for" applies.
I went down the road to Chinese Value with a Yiyen SPC3024 Combi, it works, it's good but lacking in essential features (for me anyways) and having to play with dip switched and pots is just not fun. (Aims are virtually identical, likely that AIMS is a VAR using Yiyen actually, {the docs are the same text})

 

[Ped]

Heres the one I think youre looking for

Victron Energy CMP242200100 - Inverter Supply

Shop for Victron Energy CMP242200100 at Inverter Supply for best prices online. Victron Energy CMP242200100, Victron Energy, CMP242200100, Victron MultiPlus Compact 24/2000/50-50 120V VE.Bus, Victron Inverter Chargers

www.invertersupply.com

Nice current limiting adjustment

 

[Steve_S]

Will all of these work equally well with LFE batts?

My Yiyen (2015 vintage) could by setting a switch to AGM (similar profile). The Samlex yes, otherwise I would NOT have bought a 24V/400AH LifePO pack.

 

[krby]

Right, so then stepping up from the AIMS in price it looks like the Victron and Samlex are next. As @Steve_S those are either Tier 1 or Tier 2. I guess I need to read the manual on the Victron to see what I'm getting. One thing I spotted...is the Victron really only 25lbs vs 50lbs for the Samlex? How is that possible?

 

[Steve_S]

A Picture is worth a 1000 words. This is my EVO-4024

These are LOW FREQUENCY Inverter / Chargers, hence huge copper coils.
Inversion Methods Explained: High Frequency vs Low Frequency



This is the Yiyen 3024 below

 

[Ped]

I assume all the top ones are power factor corrected. Can be a concern if youre generator is smaller.