I was asked a similar thing recently, one organisation where I volunteer has a hydraulic lift that is needed when any works is needed to the walls or roof of the gym. Between uses it sits unused for months, so most of the time the 12V battery is dead. Since it is pretty much used with the charger plugged in, they asked if I could make a 12V power supply to replace the battery. I decided to first try and measure the current draw when the lift is operated, to get an idea what I needed for power supply. So, I dug my big 20V 100A lab supply out of my garage and hauled it to the lift, disconnected its battery, set the power supply to 12V 100A and started the lift... nothing. Lab supply immediately went into overcurrent shutdown so now I tried a different route: I could read the model number of the hydraulic motor and looked up its spec. Aha. 300 Amps starting current. No wonder the supply went into protection. But that also meant that a power supply would be required to deliver almost 4kW of starting power, that is not going to happen from a 110V 15A outlet. I am considering to take 3 Leaf modules, open one in the front to cut the interconnection between the two pairs of cells, so I can wire all 4 cells inside in parallel, then take the other two modules, put them in parallel and then add the modified module in series, so that it is now 4 parallel and 3 series, giving a nice 12V for the pump motor and having 400 Amps continuous rating. It will need a simple balancer that either throttles back the charger or has sufficient bypass capability to avoid the charger overvolting a cell and when all 3 series are at 4.1V it can shut off the charger completely
Cor van de Water Chief Scientist Proxim Wireless office +1 408 383 7626 Skype: cor_van_de_water XoIP +31 87 784 1130 private: cvandewater.info http://www.proxim.com This email message (including any attachments) contains confidential and proprietary information of Proxim Wireless Corporation. If you received this message in error, please delete it and notify the sender. Any unauthorized use, disclosure, distribution, or copying of any part of this message is prohibited. -----Original Message----- From: EV [mailto:[email protected]] On Behalf Of John Lussmyer via EV Sent: Friday, September 02, 2016 10:03 PM To: Electric Vehicle Discussion List Subject: [EVDL] Alternatives for Golf Cart and Forklift batteries I have a couple of old electric forklifts that I use occaisionally in my shop. One is a little walk behind unit that uses 2, 6V golf cart batteres. The other is a full size forklift that has a 36V, 750AH battery. The batteries in both are old, and have close to 0 capacity. (To use the bit forklift, we actually have the charger mounted up on the guard rack above the driver, and pretty much have to have the charger plugged in for 30 minutes before using the lift, and also plugged in WHILE using the lift. i.e. there is a 2nd person managing the extension cord when the lift is in use.) So, I need to replace these batteries. I don't like Lead-acid batteries for these machines, as they often sit unused for months. When I do need them, I generally only need them for 15-30 minutes to move something around the shop. I don't know the actual peak current draw on either lift. (kinda hard to measure, especially now with crappy batteries.) So I'm thinking of using some smaller LiIon cells to get approximately the correct voltage. For the 36V pack, a set of 5 Leaf Modules may work (35V-42v) at 60Ah. I hope they can handle the peack current demand. Not sure what to use on the smaller 12v unit though. Suggestions? (for either) Note: on the full size forklift, I'll probably replace the 2000 lb battery with a stack of steel plates to keep the weight - needed to balance heavy loads. -- Bobcats and Cougars, oh my! http://john.casadelgato.com/Pets _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
