[RE-wrenches] Magnum MM1524AE rebuild?

[larry at starlightsolar.com]

FWIW, we installed Magnum Energy inverters with Li battery systems for 8 years. Magnum inverters create a very high inrush current when connecting to any battery. A Li battery reaction time is much faster than LA so I think higher current for shorter duration is the problem. However, we have never damaged any inverter just by connecting it.

A few years back I was working with Magnum to develop a solution for one of our Li-ion battery brands. They tested a 2kW inverter and Li battery and found that it produced more than 600A inrush, the limit of their test equipment. They could not say how high the current was and could not offer any solution.

The BMS in LiFeBlue Battery was consequently redesigned to include a bypass loop to specifically handle high inrush. That cured the issue of the battery going into Short Circuit Protection mode which happens at 800A for 500us. 

Prior to the fix, we used 2.7V, 10F super capacitors in series connected to the battery terminals (photo attached). It was a bandaid cure but worked. The caps responded much faster than the BMS so they would provided the energy needed before the short circuit protection kicked in.

You can solder 6 of them to a PC board (12V battery). Use 200C PTFE #10 or larger wire as short circuit can produce many hundreds of amps.


Larry Crutcher
Starlight Solar Power Systems




On Jun 9, 2021, at 9:13 AM, Jeff Clearwater <jeffc at villagepowerdesign.com> wrote:

Hey Dave and Wrenches,

This is why now I always install a pre-charge circuit for Magnum's and other inverters - especially on a Lithium pack with a BMS.  A momentary on-off switch and 50 watt 20 ohm resistor - $20 worth of parts = a lifetime of less stress on main breaker - inverter caps and battery BMS.  I recommend it for any inverter over 2 KW.  Many LiFePO4 BMS's will shut down when sensing that much inrush so it's a must on many systems.

Best,

Jeff Clearwater
Village Power Design


> palumbo131m at gmail.com <mailto:palumbo131m at gmail.com> June 8, 2021 at 6:01 AM
> Is a Magnum MM1524AE inverter/charger repairable and if so by whom? 
> It failed after being reconnected to a battery bank, the typical small spark at the battery terminal when being reconnected was accompanied by a popping sound in the Magnum. Killed the Magnum.
>  
> Dave Palumbo
> Hyde Park, VT 
> 
> 
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