• Have you tried out dark mode?! Scroll to the bottom of any page to find a sun or moon icon to turn dark mode on or off!

diy solar

diy solar

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

BrandonW

New Member
Joined
Aug 3, 2022
Messages
6
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.
 
Last edited:
The issue I see is how angry will the AIO get when you yank the plug to the battery?
 
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'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.
 
Just be aware colors only match with each other so keep them the same (grey, black or red).
 
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.
 
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...
 
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?
 
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.
 
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.
 
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?
 
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.
 
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.
 
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.
 
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.
 
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.
 
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.
If you parallel the batteries, the lithium BMS will indeed open the connection. But you are no longer connected in parallel.

The KISS method would have one plug at the AIO, and matching plugs on both vehicles. However you will have a momentary power loss to the house during changeover.
 
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.
Raurre has the exact type of system I was looking at, even better since it has stationary batteries to provide 24/7 backup. I updated my post because I did mention golf cart again accidentally, when I meant to write Polaris Ranger instead. All lithium, no FLA involved.
 
If you plug in a pack so it is paralleled with a stationary pack it will cause you issues in the end. You may get away with it for a while, but bad things will eventually happen. Bad == flames, shortend battery life, damaged equipment.

The issue is if the packs are very close to an identical SOC, the higher charged pack will dump into the lower charged pack. If the difference is small you will get away with it, but constantly doing this would probably shorten the life, especially if one pack has more capacity than the other.

If the difference is large, say 20% vs 100%, you will get a spark and possibly high enough current to melt wires if you are unlucky or just blow fuses if you are lucky.

If you choose to go forward with this bad idea, make sure the wires are all the size of your maximum possible current. Fuse inverter side of the anderson connector with a class T in a ignition safe holder. If you don't have one get a clamp meter, preferably one that will do DC inrush, then get the packs 10% apart when 70% charged. So 70 and 60. Then monitor current to see how much you see. Then reverse the soc and repeat. Then gradually increase the difference and test to see how high it goes.
 
The battery pack in the cart is connected directly to the buss bars that feed or that are fed from the inverters.....If the SOC is different after we drive the cart the battery banks will ballance after a very brief inrush.
How does your system handle the inrush? Is there a precharge resistor? I also want to do this with my SOK server rack cart adding stationary storage.
 
Last edited:

diy solar

diy solar
Back
Top