inverter and battery bank problems

patricksday

hi guys i live in a house i inherited from my father.so i dont have very much experience in this field. I have 6 panels hooked to a magnum inverter with 4 6 volt batteries i believe wired in series parallel, i have two questions, 

1. i have a bad battery, should i pull two of them out for now until i can afford another 1500 dollars ?

2. i bought a champion 4500w inverter . shoiudl i run it in parellel with the magnum ? or jjust use it as a generator for now ?  

3. ( i know i only said two ) how hard is it to hook a switch up that turns that generator on when the battery bank gets to a certain level?

im sorry if these questions have already been answered,. if you could point me in the right direction i would greatly appreciate it .  

BB.

1.... Probably will not help you. Batteries typically fail in two ways... One as a short circuit (bad battery discharges the other batteries). The second is high resistance. And the bad battery will not do much (charging or discharging) (and any battery(ies) in series will probably will slowly degrade (big issue is limited/no charging current). Taking a known battery battery out of the bank is usually a good idea--On occasion, a bad battery can fail in a bad way (overheat, discharge other batteries, catch fire, etc.).

2.... Another inverter will not do anything to help you if the battery bank is bad (more loads, faster battery bank discharge/failure). A few AC inverters can parallel their AC outputs--But that is usually limited to identical AC inverters (with AC paralleling function). It is 99.9% sure that you will not be able to parallel two random AC inverter's AC output. And if you tried it would probably let the "magic smoke" out of one or both inverters.

3.... To set up your system so that you can have the AC output manual, or automatically, transfer from AC inverter to AC genset is pretty easy. Either a manual transfer switch or automatic transfer switch (basically using a relay). There are lots of options and here are a couple of examples:

https://www.solar-electric.com/midnite-mntransfer-30a-discounted.html (manual)
https://www.solar-electric.com/pomaxpmautrs.html (automatic relay)

You can also get a standard AC Breaker panel and buy/make a bolt on interlock to only let one source of AC power turn on at a time:

https://interlockkit.com/product-faqs/

Newer/higher end AC inverters can have internal transfer switches, AC battery charger function, genset autostart functions. There are large number of options out their.

You can purchase auto start kits for a generator... But it does come with issues... You need to have a compatible genset to the "black box". And configuring/debugging can be a big problem. Also--Stuff fails. Short of a more expensive system (genset with safety shutdowns, black box with integration to charge controllers/AC inverters/etc.). Genset fires (electrical, fuel, oil, etc.) and other issues (failure to start, failure to shutdown) are not uncommon failures. First suggestion is to go with a manual genset and some sort of transfer switch.

-Bill

Graham Parkinson

That Champion 4500 W Inverter is presumably a 4500 W Inverter Generator.  In this case "inverter" just means that the generator has internal electronics to make clean 60 Hz power no matter how fast it is running.

To charge batteries you connect your inverter generator to the AC input of your Magnum inverter (which should both be able to charge batteries and to convert battery power to normal house 120 VAC).   Many inverters (sorry, don't know if the Magnum has this) have "AC Pass Through" which allows selectable use of either battery or generator power.  If your Magnum's manual doesn't show this function you need a transfer switch of some kind to power your houses panel with either inverter (battery) power from the Magnum or generator power.

You are correct in that iIf you have a series-parallel setup you can only take out a whole string of series batteries at once (i.e. each series string must add up to the bank voltage).  So it sounds like you'd have to take out two batteries if you have four 6 V batteries in series-parallel consisting of two strings, each with 12 Volts.