Feeling cute today, may build a 480V battery later. .

[TheDan]

This is completely a result of happen-stance more than anything and I really hope that curiosity DOES NOT kill the cat in this story. As part of my job duties I was tasked with disposing of brand-newish UPS modules that were ordered, forgotten, and then re-discovered only to find out that the install-by date had passed. Instead of paying a recycling service to take this equipment I volunteered to remove it myself so now I am the proud owner of 5 Eaton Blade UPS EBMs. I am sure that you guys will be giving great advice on how to keep that from happening and aside from "don't do it" I will do my best to heed your warnings.

To give a little back-story, over the past few months I have been installing my solar system (weekend warrior) and taking my time. System consists of:
2 X SolarCity Delta H6 hybrid grid tie inverters (high PV input voltage and high DC battery voltage)
32 X Jinko 405W / 49.7Voc panels / 4 strings and 8 in series

Eaton EBMs consist of:
20 x 12v 9ah lead acid batteries in series giving us a total of 240V per pack and what's more is that each pack has a built in cross connect for daisy chaining packs.

Since starting my solar project I wanted to figure out how to add a battery BUT it seemed unfeasible as the inverters had a proprietary CAN port and there was no way to tell whether it would work on a non-Tesla battery. Why spend thousands on batteries I may not even be able to use, right?

So my first few questions are:
1. Do I need a pre-charge resistor to connect to the inverter for the first time?
2. Is the total watts per pack 2160? (9ah x 240v = 2160W)
3. What gloves would you recommend using when working on this? Gloves seem really stiff and impractical
4. Can I test this without a BMS just to see if the inverter will charge/draw down the batteries at all.

Here are some pictures of what this looks like.

 

[brandnewb]

I still have a burning question.
Is there a use case for high voltage battery packs other than economics of wiring.

If you have one or more then I am all ears. I for one am already way past the danger line. So why not go all the way

 

[rin67630]

with disposing of brand-newish UPS modules that were ordered, forgotten, and then re-discovered only to find out that the install-by date had passed.

So these lead-acid batteries were never charged during that long time?
Which voltage did they show up when you got them?

 

[TheDan]

So these lead-acid batteries were never charged during that long time?
Which voltage did they show up when you got them?

They were all between 12.5 to 12.7v, with one exception at 12.3. I have put a 12v charger on then and they all are charging and holding the charge for at least a few days so far.

My goal is to test the inverters to make sure they will actually charge and discharge the batteries reliably. Currently I have about 8kw of battery that I'll use until they stop working and at that time I can maybe get a better battery.

 

[Supervstech]

I have a tripplight 240V 5kW ups, ant is came with 19 9Ah batteries.
I feel your pain.
You are in better shape than I am.
In your case I would tie all the batteries in parallel and let them bulk charge up to 14V and float at 13.6 for a week.

Then once they are all connected see how well it works.

 

[Delmar]

Soooo jealous, I too have a UPS fetish. Seriously I am considering changing careers to be a sales manager for a UPS distributor in the Houston area. Will give me access to older equipment removed from customer sites.

My golf cart FLA batteries provide the 48V power for my APC 3000XL's and Reliable inverter.

For a precharge resistor I use a 60W incandescent bulb. When it stops glowing the caps are charged. Amazing how long the bulb will light.

 

[TheDan]

I still have a burning question.
Is there a use case for high voltage battery packs other than economics of wiring.

If you have one or more then I am all ears. I for one am already way past the danger line. So why not go all the way

I know that it's a lot easier and cheaper to run panels in series. No combiner boxes, cheaper wire, less material. Same would go for batteries so your right about that.

As far as higher voltage vs higher amps the analogy that comes to mind is a water pipe. You can run a bigger pipe (amperage) or just increase the pressure (voltage). In plumbing I don't know that ANY plumber would oversize a line vs running higher PSI up to the pipe rating.

 

[Supervstech]

I know that it's a lot easier and cheaper to run panels in series. No combiner boxes, cheaper wire, less material. Same would go for batteries so your right about that.

As far as higher voltage vs higher amps the analogy that comes to mind is a water pipe. You can run a bigger pipe (amperage) or just increase the pressure (voltage). In plumbing I don't know that ANY plumber would oversize a line vs running higher PSI up to the pipe rating.

Actually… in plumbing, water pressure is a near constant, so additional volume requires larger pipe… and since plumbing materials are fairly limited, higher pressure would lead to rapid failure in short order… it’s why homes have pressure reducers in them to get a stable pressure and protect the pipes.

 

[Ampster]

Actually… in plumbing, water pressure is a near constant,

It is constant until you open a spigot or have a leak, then the pressure drops.

 

[Ampster]

I don't know that ANY plumber would oversize a line vs running higher PSI up to the pipe rating

It depends on what you call oversizing? My home starts with 1¼ inch and ends up with ½ inch pipe.

 

[Hedges]

2 X SolarCity Delta H6 hybrid grid tie inverters (high PV input voltage and high DC battery voltage)

So my first few questions are:
1. Do I need a pre-charge resistor to connect to the inverter for the first time?

3. What gloves would you recommend using when working on this? Gloves seem really stiff and impractical

4. Can I test this without a BMS just to see if the inverter will charge/draw down the batteries at all.

I think precharge would be a good idea.
It may be the "high voltage" battery intended for that inverter was actually a low-voltage battery and boost converter. Some work that way.

Lead-acid doesn't use a BMS, but probably some communications needed, maybe just to make it work. Then you'll need to get the desired charge profile and low-voltage cutout.

That would only be half the gloves you need.
According to our training, rubber high voltage gloves are to be retested 1 year after package is opened, or 18 months after last date of retest.
Assuming they were used with leather outer gloves.
If no leather gloves used to protect them, retest after 1 shift.

https://www.amazon.com/Magid-PowerMaster-Protector-Glove-Insulating/dp/B004OEIRUI/ref=pd_bxgy_img_sccl_1/146-0736482-5629319?th=1

It may be possible to assemble with touch-safe connectors, so you never put a wrench on a high-voltage terminal. e.g. Anderson or MC.

 

[TheDan]

Actually… in plumbing, water pressure is a near constant, so additional volume requires larger pipe… and since plumbing materials are fairly limited, higher pressure would lead to rapid failure in short order… it’s why homes have pressure reducers in them to get a stable pressure and protect the pipes.

I guess it would depend on where you are. Most rural areas are typically on well and we adjust the pressure switch to get the "right" water pressure. AMPster is also right as far as dynamic and static pressures but in the end the safe operating PSI is what everyone typically looks at.

Not an expert by any means and I went the high voltage route purely because of cost. The inverters were dirt cheap, good quality, and it also meant I could run lighter wire.

 

[Ampster]

It may be the "high voltage" battery intended for that inverter was actually a low-voltage battery and boost converter. Some work that way.

If I recall the heritage of these inverters they were Solar City before the merger with Tesla but Tesla CEO was on the Board of Solar City and Tesla already had experience with high voltage batteries. I think they then evolved to the Powerwall which contained an Inverter that could AC couple to any previously installed GT system I went to the original presentatation for the Powerwall in Hawthorne in 2015 and the merger was maybe six months later. Shortly after the merger they redesigned the Power but I do not recall the details. That fundemental design has not changed much since then.

 

[JoeHam]

Hyundai and Kia are already using 800V systems in their new cars and V2L or V2H is definitely a desired feature.

I would bet that in 5 years or so we will be using 800V AIO units in our homes and charging cars directly at 800V.

Time will tell ?.

 

[TheDan]

Hyundai and Kia are already using 800V systems in their new cars and V2L or V2H is definitely a desired feature.

I would bet that in 5 years or so we will be using 800V AIO units in our homes and charging cars directly at 800V.

Time will tell ?.

Less material, less cost, less weight seems especially practical in EVs.

 

[Supervstech]

Less material, less cost, less weight seems especially practical in EVs.

Also, the higher battery voltage means fast charging can be done with smaller cable at the pump.

 

[rin67630]

Also, the higher battery voltage means fast charging can be done with smaller cable at the pump.

Yes, but it means also another league in regulations.
Above 48V, you shouldn't fiddle yourself, if you expect your Insurance to take over fire damages.
And you may be badly injured as well. DC is much more harmful than AC.

 

[Ampster]

DC is much more harmful than AC.

I seem to recall that Edison proved that AC could kill more than DC since Edison was a proponent of DC versus the Westinghouse/Tesla AC proponents.

 

[Supervstech]

Yes, but it means also another league in regulations.
Above 48V, you shouldn't fiddle yourself, if you expect your Insurance to take over fire damages.
And you may be badly injured as well. DC is much more harmful than AC.

I seem to recall that Edison proved that AC could kill more than DC since Edison was a proponent of DC versus the Westinghouse/Tesla AC proponents.

Both statements are true…

DC high voltage causes massive plasma arcs at far lower voltages than ac does destroying normal switches, relays etc…

DC is much less dangerous to humans at voltages under 200V, but only under normal dry conditions. A wet salty sweaty body in contact with voltages above 30V will get anywhere from a tingle to locking paralysis depending on the conditions…

 

[stienman]

1. Do I need a pre-charge resistor to connect to the inverter for the first time?

No, the Solarcity Delta H6 inverters have a DC battery switch. Use that and you should be fine.

2. Is the total watts per pack 2160? (9ah x 240v = 2160W)

Even if they are deep discharge rated, you will get significantly more life out of them if you never discharge below 40-50%, so in practice I recommend assuming they are 1kwH each.

3. What gloves would you recommend using when working on this? Gloves seem really stiff and impractical

Proper high voltage gloves rate to 600VDC, with leather overgloves. Replace the inner gloves yearly or by their expiration date.

In general, don't work with the high voltage. I don't know what attachment points the batteries have, hopefully they have DC safe connectors that prevent you from ever touching the contacts, but if not add some. Once your system is set up with proper connectors and breakers/switches you should never need to touch live 240VDC.

4. Can I test this without a BMS just to see if the inverter will charge/draw down the batteries at all.

Absolutely! Lead acid batteries will not need a BMS, although a simple battery shutoff if the cells go below voltage would save you from small amounts of damage, lead acid cells typically don't need or use BMS.

One thing to consider in your specific case is that you can set the inverter to never charge the batteries, and use external MPPT chargers meant for lead acid with proper float, bulk, etc cycle.