[RE-wrenches] offgrid system question

[mick abraham]

Max wrote about the "problem child" system which is "tripping off when the AC unit tries to start".

Mick says: you didn't mention what brand of inverter is on board the system, but in any case there's probably an error code that you can find to explain the shutdown. The error could be due to the low voltage disconnnect point being reached on the battery, or it could be due to excessive AC amperage demand from the air conditioner...the latter case seems quite likely because of the 3.5 ton thing, but even if you address that part of the problem there still may be nuisance shutdown problems if there are battery health issues going on.

You mentioned MPPT60-150 as the charge controller. From that, I assume Xantrex XW...and one might assume the inverter is from that same product line. They build two 48 volt units...I'll bet if there's an XW inverter in the system that it's probably model 6048...6 kW continuous with a 12 kW surge. Please confirm.

I have a client who tried running (two different) 5 ton air conditioners using XW 6048 based gear. He didn't even try with a "single" but he found that inverter doubles succeeded with one of his refrigerated air systems and not with the other one. The difference was due to a different SEER rating. He added a third inverter/charger and now has plenty of cranking power for either air conditioner.

My big concern now is the grinding effect that such an intense load has on his battery bank, but I digress...if there's XW gear involved in your "problem child" system, throw another inverter at the load but watch the battery for signs of puckering.

If you do stack a second XW machine, there is some setup involved in naming the two units and in setting one up as the slave.

Mick Abraham, Proprietor 
www.abrahamsolar.com 
Voice: 970-731-4675

 
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