Re: Battery Array for Off-Grid In the Big City

[elnav]

When wiring batteries in series the voltage adds up but current remains the same. When wiring batteries in parallel voltage remains the same but current are added together. Yes 24 an de 48 systems are possible but that requires different inverter. no you cannot use a 12V inverter on a higher voltage bank damage to the battery system is suer to result.

You are getting into some serious power system application from your description. I have been designing such systems for the last decade since 1996. Although the concept is fine you are likely to get into some real difficulty if you simply kluge stuff together based on random bits of “free advice” gleaned piecemeal from casual users. You need somebody with an engineering background and some real system experience.

You are not going to get good results using an automotive type taper charger regardless of its ampacity. 10 amps output is simply a big waste of gasoline. As soon as you pull more than 120 Watts from the inverter the charger is falling behind and the generator will be wasting fuel constantly. You need a 100 – 150 amp @12V charger for any sort of decent deep cycle battery bank. Optimally the charging rate for any given bank is between C/10 and C/4 for the wet cells. Some AGM can tolerate charging as high as C/3

Not only must the charger output be matched to battery bank ampacity but if you use an AC driven charger it must be power factor corrected and it should be matched so the generatos is running at close to optimum output.

For a system I designed for a yacht built in Turkey we had a custom built generator made in Oregon because none of the standard off the shelf generators in Europe or in North America was suitable. Another option is a DC generator. This is something you can build yourself. Several of my customers have used this appproach with excellent results. But I have to admit it is different enough that operator education is required. It is not necessarily intuitive.

Let me know if you need more help. You can send me direct email at this address 2elnav (at) netbistro.com remove the spaces and substitute the correct symbol.