Need help with batteries/Inverter.......

[Dagwood_73]

I've got a 5er with 4 Trojan T-105 wired to 12v with 2ga. cables. My inverter is a Magnum ME Series 2200 or something close. I think everything works correctly but:

After charging to 13.2+ (float charge), hopefully fully charged. I then unplug from shorepower, then put controler on invert. Then turning on 2 lights, controler says I'm drawing 6amps, which sounds correct... The problem is after only a few mins., my batteries are already down to 12.1 to 12.0v. And on top of that confusion, sometimes, after a few mins. of inverting, the controller will start showing: using 24Amps, with nothing on, until i flip off that breaker....

Anyone offer help???

Thanks,
Vic

[Dagwood_73]

I've got a 5er with 4 Trojan T-105 wired to 12v with 2ga. cables. My inverter is a Magnum ME Series 2200 or something close. I think everything works correctly but:

After charging to 13.2+ (float charge), hopefully fully charged. I then unplug from shorepower, then put controler on invert. Then turning on 2 lights, controler says I'm drawing 6amps, which sounds correct... The problem is after only a few mins., my batteries are already down to 12.1 to 12.0v. And on top of that confusion, sometimes, after a few mins. of inverting, the controller will start showing: using 24Amps, with nothing on, until i flip off that breaker....

Anyone offer help???

Thanks,
Vic

[Dagwood_73]

Nevermind on the second problem. I found out when the fridge is on Auto and you start inverting, the fridge thinks it is on shore power and switches for gas to elect-hence the big amp draw. Got to keep the fridge switch on 'gas' when inverting...

Checked all 4 batteries with a hydometer and they all showed 'fair/1250', so......

[KU9L]

In a small cabin home power PV system the batteries are wired together with 2 ga. wiring, infact my medium sized system used 2/0 ga interbattery wiring while my 2400 watt inverter has 4/0 wiring. Voltage drop is the key troublemaker and there is not a lot of power in only 4 golf cart batteries so the most has to be made from it. RV manufacturers typically shamefully undersize PV wiring from the panels all of the way to the batteries & inverters from what I've seen so far ... the main motivation factor seems to be cost over performance 10 to 1. -Dave

[Dagwood_73]

Sorry to sound ignorant, Are you saying I should use 2/0 wiring??

[KU9L]

Each time you go up a size in wiring you essentially double the amount of copper in the wiring, so 10 ga is twice as much copper as 12 ga and 0/0 is twice as much copper as 2 ga. To see a picture of this idea go to Backwoods Solar and then click on the Wire Sizing Tables drop down menu under the Reference Material section on the lower left. 4/0 wiring is about as big as my thumb and is the biggest practical size I've seen used in a home power situation, which gets harder to work with or bend the larger it gets. I can safely and efficiently run a 1/2 hp 120 volt AC well pump on my 2400 watt inverter (130 amp draw from my battery bank), which is possible because I have ten 350 amp-hour L-16 batteries. If I used smaller sized wiring I would have to reduce my loads accordingly and is why my 100 watt car inverter has 12 ga wiring. I could still power a microwave from a 2000 watt inverter, but I'd be doing it from at least 2/0 wiring from the 4-batteries in the RV to the inverter (under 10 feet in length maximum) for example.

Hope this helps visualize the general idea. Dave

[Dagwood_73]

Got it fixed. I had to go to 2/0 cables. I had to go to a welding shop for these and make them up myself.

Life is good again!!

[KU9L]

Cool, now more watts stored in your batteries will be more efficiently used towards the loads you power. That gauge of wire is harder to work with but the batteries and inverter will love it!

Dave