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36v inverter for SAMSUNG 8S 28.8v 7.8ah 225wh w/ BMS

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dantheman2020

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Mar 9, 2020
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Hey guys,

Looking for some help with a system I am building using 8 36v battery packs.

Wondering what the best option is for a 1000-2000watt 36v inverter for off-grid setup? It seems that 36v inverters are hard to find and wondering if there are any other options using step down converter or another method. The recommendations say to use a 24 invertor that accepts up to 32v. But having trouble finding those as well.

I have 8 of the following battery packs from battery hook up
SAMSUNG 8S 28.8v 7.8ah 225wh w/ BMS
Pack fully charged voltage: 33.6v (4.2v/cell)
Fully discharged voltage: 22.4v (2.8v/cell)

batteryhookup.com

SAMSUNG 8S 28.8v 7.8ah 225wh w/ BMS

Here are fully tested and balanced 8s lithium ion medical batteries. These are absolutely beautiful packs with a legit BMS. The best part about medical grade batteries is they only use the best name brand cells with super high quality BMS units. (CHECK OUT THE VIDEOS IN THE BOTTOM OF THE...
batteryhookup.com

I am using this solar charge controller.
Victron SmartSolar 100|20 48V Solar Charge Controller SCC110020160R

And i have 4 Kolder kyocera 130watt 19v pannels.

Thanks for your help in advance.


 
You're way off the mark.

I'm very sorry you bought those. They are pretty much useless as configured.

Those aren't 36V packs. They're 28.8V. If you attempt to use those in a 36V system, you will experience intense regret. Most 36V inverters (if they exist) will cut off around 29-31.5V leaving you with no usable capacity.

MANY 24V inverters should support up to 32.4V as that's a common voltage for lead-acid equalization. You're probably just looking to carry on the tradition of buying cheap components that may or may not be useful in this regard. Cheap stuff often lacks features. You get what you pay for.

IMHO, you should break down the packs and take the 24 * 8 = 192 cells and build yourself a 27P7S 25.2V battery.

Using them in their existing configuration runs a significant risk of exceeding cell current limits.
 
I would like to use the packs as is in the current configuration as I like that they already have BMS, self-contained rugged and heavy-duty case and I don't have the skill to break them down and build a pack.

So any info on such as the 24V inverter suggestion to use the packs as is much appreciated.

Alternatively, any recommendations on something to step down the voltage from 32V to 12v to power 12v items.

Thanks!
 
I know you would, but it's a mistake unless you plan to only use very low loads or devise a meaningful way of paralleling them that distributes the load evenly (see "wiring" link in sig item #2).

I'd start with Will's recommendations and see if you find something that fits:

www.mobile-solarpower.com

Off Grid Solar Inverters

Building a vehicle mounted solar power system? Let me help.
www.mobile-solarpower.com

DC-DC converter:

Amazon.com: DC 24v to DC 12v Step Down 30A 360W Heavy Duty Truck Car Power Supply Adapter Converter Reducer Regulator for Auto Car Truck Vehicle Boat Solar System etc.(DC15-40V Inputs): Home Audio & Theater

Amazon.com: DC 24v to DC 12v Step Down 30A 360W Heavy Duty Truck Car Power Supply Adapter Converter Reducer Regulator for Auto Car Truck Vehicle Boat Solar System etc.(DC15-40V Inputs): Home Audio & Theater
www.amazon.com

Wide range, 15-40V input conversion to 12V output, 30A, 360W
 
Outback does market a 32V inverter. The specs state that is has an operating range of 28-45V.

OutBack FX2532MT Sealed Inverter - RES Supply

Free Shipping! OutBack FX2532MT Sealed Inverter, 2500W, 120VAC, 60Hz, 40A Transfer, 32VDC, Sinewave, Off Grid, 5 Year Warranty, 35A Charger, With BTS & Switched Ground
ressupply.com ressupply.com
Can't tell you if it would actually work well for you. I'd never buy randum low-budget items and try to figure out how to use them.
 
snoobler said:
If you attempt to use those in a 36V system, you will experience intense regret.
Click to expand...
Harsh toke, dude! ;)
dantheman2020 said:
So any info on such as the 24V inverter suggestion to use the packs as is much appreciated.
Click to expand...
Victron's 24V inverters (e.g. Victron Phoenix 3000VA|120V) supports from 19V - 33V so my guess is that others do. You might want to restrict your charge voltage to 4.12V per cell (8S = 33V) = to stay within specs.
 
Hello Dan,

dantheman2020 said:
Wondering what the best option is for a 1000-2000watt 36v inverter for off-grid setup? It seems that 36v inverters are hard to find and wondering if there are any other options using step down converter or another method. The recommendations say to use a 24 invertor that accepts up to 32v. But having trouble finding those as well.

I have 8 of the following battery packs from battery hook up
SAMSUNG 8S 28.8v 7.8ah 225wh w/ BMS
Pack fully charged voltage: 33.6v (4.2v/cell)
Fully discharged voltage: 22.4v (2.8v/cell)
Click to expand...
Samlex 24V inverters have a wide operating voltage, a 3 year warranty and won’t break the bank as some of the other inverters will That operate across a wider voltage range:

https://www.samlexamerica.com/products/ProductsList.aspx?cid=SS31

Wide operating DC input range:
10.7 - 16.5 VDC / 21.4 - 33.0 VDC

If you charge your pack to 32V (4Vper cell), you’ll be within the operating voltage. And they’ll last longer.

8 packs aren’t enough to power a 2000W inverter continuous! Each modules recommended peak current is 5A or 100W continuous so be careful!
 
You could also configure the 28v packs in 2S (2 in series) for 56v which fits nicely in the range of "48v" systems.

For instance a Growatt all in one will support configurable battery parameters with low voltage cuttoff from 40.0-48.0v and high voltage cut off (bulk/float charge) of 48.0-58.4v (the 24v growatt is exactly half those values)
 
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The whole point of those packs is that they have a working BMS. If you are not able to parallel them up in sufficient quantity to meet your load demands, why even bother? Snoobler is right.

The OP has 8 packs, so a couple hundred dollars total. Why spend much bigger money on an oddball inverter, especially with such a small battery? 225 watts? He can go on Battery Hookup right now and buy a more user friendly pack, and pair it up with any one of dozens of good inverters at 24v or even 48v. He states he doesn't have the knowledge to work on them, so unless the OP wants to learn all about BMS's, and pack construction it would likely be best to sell them and start over. First, define what it is you want to accomplish, then read and ask questions.
 
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