increasing voltage to 48v on MAC motor

slawsonxo · Sep 17, 2014

Hi all,

I apologize in advance if this seems question seems dumb...

I just put together my new MAC motor and took the test drive with a 36v configuration with SLA batteries. I was very impressed and was able to get 23.9 mph out of it. But ideally I would like to use (4) 12v 9ah SLA batteries wired to make a 48v battery pack. I hope to buy better batteries next year. I currently do not have a 48v charger and one is in the mail in route. So I am charging the 4 batteries with a 12v Schumacher charger individually. The digital readout on the charger reads that they are 100 percent charged when they reach about 14.5v. So the 4 together will be about 58v. I am using a 12 FET Infineon controller that says it can handle voltage from 36v-52v. Will i need to somehow find a way to set a cutoff voltage or can the controller handle these few extra volts over the 52v limit?

Thanks in advance.

Icewrench · Sep 17, 2014

most 36 / 48 volt infinieon controlers will have an upper limit of 63 volts.
To be sure of this open your controller and check the rating on the caps.

Russell · Sep 17, 2014

slawsonxo said:
Hi all,

I apologize in advance if this seems question seems dumb...

I just put together my new MAC motor and took the test drive with a 36v configuration with SLA batteries. I was very impressed and was able to get 23.9 mph out of it. But ideally I would like to use (4) 12v 9ah SLA batteries wired to make a 48v battery pack. I hope to buy better batteries next year. I currently do not have a 48v charger and one is in the mail in route. So I am charging the 4 batteries with a 12v Schumacher charger individually. The digital readout on the charger reads that they are 100 percent charged when they reach about 14.5v. So the 4 together will be about 58v. I am using a 12 FET Infineon controller that says it can handle voltage from 36v-52v. Will i need to somehow find a way to set a cutoff voltage or can the controller handle these few extra volts over the 52v limit?

Thanks in advance.

Due to their chemistry the charge voltage required to get SLA batteries to a full charge is well above their actual fully charged voltage. A good SLA charger will boost to around that 14.5V you are seeing, or even higher, then it will fall to 13.2-13.8V to maintain the charge. The actual fully charged voltage for an SLA is right about 13.2V and that's what they'll register if you put the tiniest bit of load on them or simply let them sit for a day or so. That still gives you 52.8V but my guess is the controller can handle it. If you want more confidence open the controller and check the capacitor and FET ratings. You should have 2-3 capacitors rated at 63V. Record the part number for the FETs and look up the data sheet on line to get their maximum voltage.

-R

bowlofsalad · Sep 19, 2014

http://em3ev.com/store/index.php?route=product/product&path=38&product_id=81
"63V Caps, Max input voltage is limited to 60V" " 36-50V operation, 60V max"
This is assuming this is indeed the controller you have.

Electric Junk · Sep 20, 2014

I charged my 48v battery on a 12v charger in parallel.

The connector was able to disconnect the continuity and allow a bunch of small alligator clips to be connected parallel directly on the contacts.

you can follow the connections clipped and unclipped and see how it works.

increasing voltage to 48v on MAC motor

slawsonxo

1 mW

Icewrench

10 kW

Russell

1 MW

bowlofsalad

100 kW

Electric Junk

10 W

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