120VDC battery bank charger controller

[(unknown)]

Is there any battery charge controller out there that will charge a 120VDC battery string. I am working on a project that uses a PV array to charge a 120VDC battery string which then uses a heavy duty Inverter to change the 120Vdc into 120Vac. but i cant find a charge controller that will control the charge for the 120VDC battery string. The largest charge controller I can find (outback MX80) is only design to work with battery voltages up to 60VDC. is there any combination of multiple charger controllers or any other industrial sized charged controller that can handle this. HELP!!!

Moved to the proper section since it is about a controller.

[dbcollen]

You can use 2 MX-60s in series for 72-120v battery banks, it is docomented in the manual

Page 36

"Charging a 120 volt battery is possible by inter-connecting 2 MX60 charge controller in series with 2 banks of 60 volt

batteries in series. A 72 volt nominal array is recommended for this particular setup. Accordingly, charging a 72 volt

battery bank can be accomplished using the same method by using 2 series banks of 36v batteries."

[boB]

>>You can use 2 MX-60s in series for 72-120v battery banks, it is docomented in the manual

Yep, that works.  Been there...  You have to clip out one of the MOVs on the 64 to 120V MX60 though.  That's about it.  The top PV array is floating with respect to the bottom one.  i.e. you don't ground it.

boB

[simonbrookes]

If it works on a 120V system would it work on my 240V battery string connected to a 10Kw wind turbine.

[Flux]

In theory yes you could use 4 independent strings of 60v.

I don't know enough detail of the MX60 to know how far you can push your luck. I suspect that 240v dc is pushing your luck. You need to be worried about creepage distances and the effect of spikes and other things. If you can synchronise switching it may help but if switching is individual to each unit you may get a lot of spikes.

At 240v you are in the realms of Igbts and high voltage motor drives and it is not simply possible to keep adding low volt units in series for any voltage.

It may be reliable and I suspect boB may be the only one to tell you how far you can push your luck. 240v dc is something not to be messed with especially in this day and age when high voltage circuit breakers are no longer readily available. Fine when it works but the mess after a fry is often spectacular.

Flux

[simonbrookes]

Thanks for that. At the moment I only use a voltage switch with hysteresis which brings in some DC contactors with a large air gap. This then puts the dump load heaters on.  Yes it is impressive when an arc does start.