Can I run my SURTD5000XLI with only SURT192XLBP external battery pack?

[Hellrack_apc]

This was originally posted on APC forums on 12/27/2011

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Hi folks. Rbc44 cartridges of my SURTD5000XLI are dead so i'm going to replace them. Can I run my ups with only external battery pack? Is that possible?

[BillP]

This reply was originally posted by Chris on APC forums on 12/27/2011

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Your best option would be to take the RBC44's out of the external and put them in your UPS. You can leave the others disconnected(the ups doesn't use as many batteries as the external battery pack does). To answer your question though, it will probably still work but just isn't a practical way to do it.

[BillP]

This reply was originally posted by Dakota on APC forums on 12/28/2011

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leave The Battreries IN The External Pack The Ups Connects All Battery Packs In Paralell (Both Internal and External)

[BillP]

This reply was originally posted by Chris on APC forums on 12/28/2011

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There is no really benefit either way other than the fact that it prevents you from lifting the batteries of the external frame to the main.

[PanMICRO_apc]

This was originally posted on APC forums on 2/28/2013

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Hi, yes indeed you can. I am somewhat of a hardware hacker and it took me a little while to figure out the 'goings on' with UPS's but I share these finding with you.

My own IBM10000XVH is connected in parallel to the two supplied external 150A Anderson connectors that are in turn fed by 24 x x2v 500Ah Supersafe VRLA cells.

Don't forget that 10000VA@48VDC will draw 200A DC and that momentary surge values are >= 240A+. Therefore you need to consider the size of the cable feeding the UPS inputs from the battery banks. Too small and they will get hot as the voltage drop will be too great at elevated loads.

I use 2 x 1 metre lengths of 35mm2 copper cable (150A per cable) to go from the batteries to the UPS and another two to return to the Batt(-). I decided to do this as I already had the 35mm2 cable but you could also use a single 70mm2 as the Andersons are paralleled at the UPS end anyway. You could also use a 6061T 125mm2 bussbar (25mmx6mm) to feed the UPS inputs, derated x 0.6 for the Alu.

You are correct about the duty cycle being 100% on a double conversion UPS and cooling is sufficient, though I would err on the side of caution when it came to elevated [loading:duty cycle] ratios. 50% is the usual rule of thumb when it comes to the compromise of design, cost and thermal shutdown. What I am saying is that I have not tested this, if you are able, stick 2 Temp probes on the unit and test. 1 on the bridge heatsink and the other on the step up transformer. Neither should go much beyond 70degC. Anyway, I digress.

Concerning battery charging? have a look at the MIB for your UPS. You note that there are SNMP traps for battery ampacity values settable from 1 - 2000Ah and the battery types are also settable. Naturally the default is for 'Gel' however, there are 5 other types of battery chemistry catered for including 'VRLA', which I am using.

Makes a wonderful upmarket DC-AC solar inverter.

Hope that this info helps you out...

[TerryKennedy_apc]

This was originally posted on APC forums on 12/19/2012

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I'm not really familiar with the newer models - mostly I deal with SU and SUA Smart-UPS and Matrix and older Symmetra units.

If the internal pack just uses a 2-pin battery connector, the UPS won't notice that it is missing. All of the battery packs are just bridged together in parallel (though the batteries inside each module are wired in series to create 48V, or 24V on some units). You'll probably want to keep the empty battery pack in the UPS as the design may depend on that space being occupied to provide proper airflow. You definitely want to remove the individual batteries as worn-out batteries tend to overheat and swell as the UPS keeps trying to charge them.

[Bicka_apc]

This was originally posted on APC forums on 12/19/2012

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Can I run my SURT8000XLI off External Batteries only? I have the 4 of the RBC44 cartridges but theres no batteries inside. I was planning on building a custom pack of Lead Acid batteries for an extended run application (using deep cycle batteries).

I know this probably voids warranties and isn't supported.

I would just like a simple answer as to if this UPS will cold start from external batteries only, or will I have to wire the external pack through the Internal mounting point? where the cartridge plugs in.

Thanks.

[TerryKennedy_apc]

This was originally posted on APC forums on 12/19/2012

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I'm just another end user, so this certainly isn't a statement from APC. Having said that...

You can do this sort of thing with APC UPS's that support external battery modules but do not use a communication cable, just the positive and negative battery connections. These are generally the units that you have to tell how many external battery modules are connected. Matrix and Symmetra units (and probably some other models) use a communication cable which tells the UPS how many modules are connected, the state of charge on each, and so on. On those, unless you fake the data the UPS is expecting on that cable, it won't cold start.

You'll want to install fuse(s) of an appropriate rating in whatever sort of external battery pack you use. Other cautions would be that the UPS doesn't have an unlimited amp capacity for charging batteries (for example, a car battery on a Smart-UPS 750 won't get charged as the UPS can't supply enough charging current if the battery is discharged). Also, the UPS may not have been designed for continuous (or extended) run on batteries as the inverter components inside may overheat and trip a thermal safety. As an example, I believe the XR versions of the SUA1000 have a fan inside the UPS to keep the electronics cool, while the non-XR ones don't. If you limit yourself to a total Amp-Hour battery capacity that's equal to or less than the UPS with the maximum number of official APC battery modules, you'll probably have better reliability as that will be within both the charging and cooling ratings of the UPS.

[Bicka_apc]

This was originally posted on APC forums on 12/19/2012

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Thanks alot for the quick response. The unit is Double Conversion online so I assume since its rectifying the AC Input to DC and the batteries would be supplying DC there would be no difference to the Inverter as it is constantly running on utility power anyway.
I suppose it will be if the unit can power on with the RBC44 cartridges missing... or "tricked" by supplying the external pack voltage in parallel. I was planning on getting batteries that are a multiple of the standard external packs (SURT192XLBP) these contain 4 RBC44 cartridges. 5Ah x 8 standard RBC44. The external pack can be made to contain 16 x 50Ah deep cycle batteries as it will be the same as connecting 5 SURT192XLBP external packs (4 x 8 x 5Ah). or 4 Externals and 1 Internal.

Thanks for your help. Hope you follow my logic.

This assumes that the unit will cold boot from an external pack only with no internal RBC44 cartridges installed or installed and not populated with batteries.

[David.Harris_apc · Accepted solution]

This was originally posted on APC forums on 2/26/2017

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So following @psyfy's great post above, I wonder if this could extend to running a Tesla Powerwall 2 - or are there too much 'smarts' needed to charge this - am guessing you'd have to hack the interface too.

And obviously you'd need to have a substantial sized UPS to cater for its output, say 5kva or greater, because I believe the PowerWall is 5kva rated, but it certainly would take things to a whole new level.

The BlueSea 7610 Automatic Charging Relay on Amazon is $75 and caters for most of what is required, plus BlueSea have a bunch of circuits p13 through p49 of their catalog catering to dual battery charging and switching (I have no affiliation with them either, and its way overkill but great stuff)

http://catalog.bluesea.com/files/assets/basic-html/page-40.html 

Am now very interested to try this out - I happen to have a large APC 'online' UPS with stuffed batteries from many years ago that I'll drag out of storage and begin adding the stage one circuitry and Anderson plugs and test out a couple of deep cycle batteries in series. Then if someone has Tesla feedback I might get really game and order one . . .

Will revert with feedback and pics.

@psyfy please PM me if you're still active online.