Altronix power supply battery backup

[kurtmccaslin]

I am looking at the manual for an Altronix Eflow6N16D.    It says that you can only install one battery in the enclosure if the voltage is set to 12 volts.   I cannot understand why you cannot install two batteries in parallel.   The manual shows that the charger can take up to 40AH of batteries.   Two 7AH batteries in parallel gives you 14AH.   
 
My very basic understanding of batteries is that a 40AH battery just has more cells connected in parallel than a 7AH battery.   Therefore, connecting two 7AH batteries is the same thing as a 14AH battery (except the parallel connections are external to the battery)
 
Am I missing something here?
 
The manual can be found at http://www.altronix.com/products/installation_instructions/eFlow6N_Series.pdf
 
 

 

[Del91574]

UL listing.
 
The battery primaries are unfused and the supply was not tested for the UL listing with dual battery leads. The problem, however, with multiple batteries in parallel is a failure can result in the batteries becoming a push-pull arrangement and can lead to supply failure.

 

[RAL]

DEL - out of curiosity, do you never put SLA batteries in parallel in the installations you do to avoid the UL issue?

 

[Del91574]

As it's always said...application, application, application.
 
If you need to meet UL and maintain the listing, you don't modify from what is shipped, even to the point of replacing boards, IE: Altronix cans are universal based on "style" as to what boards can fit in them, but say I need to swap a AL1024 for an AL1012 because the voltage ordered was wrong...well, I can't just replace the board 1:1 because the listing for the enclosure would be voided, even though the only difference is literally the sticker on the enclosure.
 
In the specific case of the supply vs. battery size, if they intended on supporting a larger standby battery, there would be a fused Y-harness included or available as an option like most panel manufacturers offer, otherwise you install a battery enclosure to support the needed standby time. 26 aH batteries are a commodity and price point is not any different than 2 or 3 7aH units, without the issues of a push-pull developing and as a per-aH installed, cheaper than installing multiples. The problem of multiple batteries in parallel is if one goes flat, the push-pull starts and it'll drag the whole supply down or in the specific case of 2 unmatched loads to the charger, it'll fight trying to make them "even".
 
As far as the specifics go as to whether or not to install multiple batteries in parallel in this case...it's cut and dry, all the documentation tells you flat out to NOT do it and install a separate battery enclosure and suitably sized battery inside of it (and follow class 1 wiring methods).

 

[mikefamig]

I just got off the phone with altronix tech support and they tell me that my al400ulpd4 is UL tested with two 12 volt batteries in paralell up to 40ah total. The reason that the installation manual states to use only one battery when set to 12 volt output is because some people were wiring two 12 volt batteries in series instead of paralell. The tech rep was very clear that it is perfectly fine to use two batteires in paralell.
 
Mike.

 

[RAL]

I just got off the phone with altronix tech support and they tell me that my al400ulpd4 is UL tested with two 12 volt batteries in paralell up to 40ah total.

 
That's really reassuring to know. Thanks for chasing that down!

 

[Del91574]

The Eflow6N16D is an entirely different supply.

I just got off the phone with altronix tech support and they tell me that my al400ulpd4 is UL tested with two 12 volt batteries in paralell up to 40ah total. The reason that the installation manual states to use only one battery when set to 12 volt output is because some people were wiring two 12 volt batteries in series instead of paralell. The tech rep was very clear that it is perfectly fine to use two batteires in paralell.
 
Mike.