Suggestion - dc / dc converter 500 - 1000W

I'd probably try hacking the undervoltage lockout on the inverter, but don't set it too low or you might start a fire.

Cheers

Phil Hobbs

Why not add an extra cell?

I can not add extra cell because its sealed truck car battery.

----------------------- I was thinking on hacking the DC/AC converter but i don't have enough knowledge to do that. Beside, there is no schematics on the converter. It's some Chinese stuff (1500W / 3000W peak ).

--------------- If i would go with dc/dc converter ( let's say some 500W ), how can i limit the battery current ? As far as i know, such converters have some max input current value and it's most always under 20A.

P = U * I So I = P / U

This means that at 12.5 volt a 500 Watt converter is going to draw 40A or more.

No way you are going to limit that to 20A, unless the converter has an output power of 500 Chinese Watts. Chinese Watts are a lot less power than SI Watts. That is how they spec the 1500W/3000W Peak things.

Running one SMPS off another isn't necessarily easy, especially if the second one (your inverter) expects a super-low-resistance source, i.e. a big lead-acid battery.

They can interact in strange ways, including oscillating. At your power level, oscillating switchers would be seriously bad news, like maybe burning your house down or spraying you with boiling acid. (I'm not a high power SMPS guy myself, but believe me, they're no joke.)

Perhaps you could find a better quality used unit on eBay that has schematics available?

Cheers

Phil Hobbs