How to create quick disconnect for parallel 48V batteries in golf cart straight to AIO inverter as battery storage?

[BrandonW]

I've been a longtime lurker, but I can't find the answer to this. If you can redirect me I apologize for this post.

I'm thinking of putting an AIO inverter with grid pass through to sub panel in garage. I would like to upgrade my golf cart to a Polaris Ranger EV and put at least 2 100aH 48V batteries in it (Probably the $999 EG4 ones). I was thinking this would also serve as the battery back up for that sub panel through the AIO. I could use the 30% tax credit off the new panels, AIO, and batteries for this small system, and get a nice lithium upgrade to a Ranger. I would park the Ranger near the sub panel and plug it into the AIO to charge, and then while the Ranger is not being drove around, use the battery storage (maybe set it's threshold to 50% so it could always been driven) to power the subpanel after dark. The AIO would obviously have grid pass through/assist, for when battery is low and when it's disconnected.

So my question is, is there an easy way to create a 1awg plug system to easily connect and disconnect the 48V? Or is there a major flaw in my idea that will keep it from working in the first place?

Thank you for any help.

 

[SparkyJJO]

The issue I see is how angry will the AIO get when you yank the plug to the battery?

 

[Rednecktek]

Would the AIO have its own battery on top of the golf cart? If so, just tie in a breaker off the battery, run a fat cable out of it to a hefty Anderson connector, and install the same size Anderson's on the golf cart. That's how forklifts do it all the time, unplug from the machine and plug into the charger. In your case it would be unplug from golf cart, plug into AIO and turn on breaker.

 

[Brucey]

I've been a longtime lurker, but I can't find the answer to this. If you can redirect me I apologize for this post.

I'm thinking of putting an AIO inverter with grid pass through to sub panel in garage. I would like to upgrade my golf cart to a Polaris Ranger EV and put at least 2 100aH 48V batteries in it (Probably the $999 EG4 ones). I was thinking this would also serve as the battery back up for that sub panel through the AIO. I could use the 30% tax credit off the new panels, AIO, and batteries for this small system, and get a nice lithium upgrade to a ranger. I would park the golf cart near the sub panel and plug it into the AIO to charge, and then while the Polaris is not being drove around, use the battery storage (maybe set it's threshold to 50% so it could always been driven) to power the subpanel after dark. The AIO would obviously have grid pass through/assist, for when battery is low and when it's disconnected.

So my question is, is there an easy way to create a 1awg plug system to easily connect and disconnect the 48V? Or is there a major flaw in my idea that will keep it from working in the first place?

Thank you for any help.

Anderson SB175 Copper Battery Cable Assembly 1 Gauge AWG w lug/terminal/clamp

www.batterycablesusa.com

 

[Brucey]

Just be aware colors only match with each other so keep them the same (grey, black or red).

 

[BrandonW]

Would the AIO have its own battery on top of the golf cart? If so, just tie in a breaker off the battery, run a fat cable out of it to a hefty Anderson connector, and install the same size Anderson's on the golf cart. That's how forklifts do it all the time, unplug from the machine and plug into the charger. In your case it would be unplug from golf cart, plug into AIO and turn on breaker.

I thought about having a battery constantly connected to the AIO, and then have the disconnect/connection to the bus bar. But haven't I read that is not ideal for overall battery health with they are all being discharged/recharged not in unison? Since the golf cart batteries could come in at 25% while the permanent battery could be at 100%, do the modern bms/serial connectors handle these scenarios?

Thank you for your response.

 

[seeyalater]

I just ordered that $999 ($1200 shipped) EG4 48v / 100ah battery for my golf cart and was thinking of doing the exact same thing using my Victron Multiplus and Ruixu server rack battery system. The golf cart is usually parked in the garage just a few feet away from the Victron system, so it would be nice to have them all working together.

Now, I just have to figure out how to get it done...

 

[BrandonW]

The issue I see is how angry will the AIO get when you yank the plug to the battery?

This is an answer I need! Could you put a DC disconnect switch, plug in with an Anderson connector, and then switch the DC connector back on? Is it hot swappable and the AIO will recognize the battery and keep on humming along?

 

[wpns]

This is an answer I need! Could you put a DC disconnect switch, plug in with an Anderson connector, and then switch the DC connector back on? Is it hot swappable and the AIO will recognize the battery and keep on humming along?

I’ve asked this a few times lately and there doesn’t seem to be any way to limit the charge current.

 

[raurre]

I have mine connected with Anderson plug and 4awg battery cable. This is the battery bank for the inverters and the golf cart.

 

[BrandonW]

I have mine connected with Anderson plug and 4awg battery cable. This is the battery bank for the inverters and the golf cart.View attachment 217840View attachment 217839View attachment 217838

This is looking like what I was asking. Does your golf cart batteries act as backup when they are connected? How does the system recognize your golf cart batteries and charge them with the Anderson cable?

 

[raurre]

The battery pack in the cart is connected directly to the buss bars that feed or that are fed from the inverters. As far as the system is concerned it's just another bank of batteries just like the permanent ones in the cabinet. If the SOC is different after we drive the cart the battery banks will ballance after a very brief inrush.

 

[BrandonW]

The battery pack in the cart is connected directly to the buss bars that feed or that are fed from the inverters. As far as the system is concerned it's just another bank of batteries just like the permanent ones in the cabinet. If the SOC is different after we drive the cart the battery banks will ballance after a very brief inrush.

This is great. Did you set your inverter settings to recognize the whole capacity(total aH) of the batteries together? Or does that not really matter, just for statistics for usage?

Also, the inverter doesn’t care when there is a voltage drop when you plug in the Anderson?

 

[raurre]

The inverters only care about overall voltage. They the the buss voltage not the individual packs. Each bms protects and balances it's battery. The inverters are set to keep the overall high and low voltage from damaging the batteries. The different battery banks will naturally balances themselves when connected at the common point of the buss bars.

 

[raurre]

Just for reference my system consists of 304ah eve banks in the cabinet and 230ah in the cart.

 

[raurre]

Here's a link to the cart build hope it helps. Thread 'DIY 230Ah EVE Mobile Battery (aka) EZGO Golf Cart' https://diysolarforum.com/threads/diy-230ah-eve-mobile-battery-aka-ezgo-golf-cart.40927/

 

[Delmar]

Maybe I am missing something here. Please type slowly so I can follow along.

I believe the OP wants to parallel the FLA in the golf cart and the lithium in the Polaris. Once the connection is made they are going to equalize in an angry hurry.

Otherwise could you use a DC rated transfer switch to eliminate the two batteries from joining? Not sure how the inverter will handle the sudden change in voltage.

 

[zanydroid]

Doesn’t this approach rely on the BMS as primary protection of the battery while connecting? And the voltage difference and wire resistance as another protection.

I’m surprised there’s not more people giving this criticism.

 

[zanydroid]

Using the golf cart battery as the only battery would avoid the equalizing current issue. The orthodox recommendation would be to include precharge circuit eg use a 55-60V rated 3 position switch, set up for OFF, precharge resistor, On. There are threads for this.

 

[raurre]

I can only really speak to my own experience and measurements for my system. I originally had some doubts about it working as well as it does. This video made me try my idea.

I'm sure that there is a better method to design a way to connect the two systems. I can only say that I haven't had any arcing, blown fuses or bms protection to occur when connecting or disconnecting the two battery banks.