Navitron Renewable Energy and Sustainability Forum

General Renewable Topics => General Discussion => Topic started by: bobbybaz on December 18, 2018, 01:12:30 PM



Title: charging LA batteries with a fork lift charger
Post by: bobbybaz on December 18, 2018, 01:12:30 PM
Thinking of getting a fork lift battery charger to top up a bank of batteries using a generator. The battery bank is 350 Ah (Nameplate capacity) at 48 volts, Flooded lead acid Trojans. The system has 4 kw of PV but recent very low light has resulted in low battery SOC. Charger I have found is 40 amps at 48v single phase. Is there any reason why this would be problematic ?  There is a dump load controller to dump excess when the batteries are full, in case the charger takes the voltage too high. This is not intended as a regular operation, just a means of getting the batteries back from their low SOC.


Title: Re: charging LA batteries with a fork lift charger
Post by: billi on December 18, 2018, 02:13:40 PM
sounds fine  with me ,  through the bulk phase anyway , but absorption charge voltage might be  higher in the fork lift charger , then the trojans recomendation

So i would not  charge them completely full perhaps , without watching the voltage and the water , best let the PV finish the charge ( if sun  coming  whistle )

Regards Billi


Title: Re: charging LA batteries with a fork lift charger
Post by: knighty on December 18, 2018, 05:42:44 PM
didn't frotter kill his lard generator by using it to power a forklift charger?

iirc something was posted along the lines of, generators don;t like powering the big transformers... or something like that?


Title: Re: charging LA batteries with a fork lift charger
Post by: camillitech on December 18, 2018, 07:52:23 PM
didn't frotter kill his lard generator by using it to power a forklift charger?

iirc something was posted along the lines of, generators don;t like powering the big transformers... or something like that?

Methinks there is something in this as I had problems with a charger that was supposed to be 3kW but the 3kW Lister would not look at it (not even close). The 6 and 7kW ones operated it OK but they seemed to be working much harder than 'what the charger said on the tin'. The charger seemed to put much more load on the generators than resistive loads of the same (or even higher) value. I guess it's just a case of making sure the generator has plenty of 'headroom'.


Title: Re: charging LA batteries with a fork lift charger
Post by: rogeriko on December 19, 2018, 12:21:27 AM
Old heavy transformer chargers are notoriously inefficient. A 3kw charger will probably draw 5kw when charging.


Title: Re: charging LA batteries with a fork lift charger
Post by: camillitech on December 19, 2018, 05:27:13 AM
Old heavy transformer chargers are notoriously inefficient. A 3kw charger will probably draw 5kw when charging.

 :o That would be about right I guess Rog, it sounded like around 5kW, I didn't realise anything was 'that' inefficient.


Title: Re: charging LA batteries with a fork lift charger
Post by: biff on December 19, 2018, 06:51:54 AM
A small diesel or electric driven 2kw x 48 volt pmg will work through a rectifier block and an ordinary  controller.
I charge a 120 volt pack just like that except  it is managed through an ordinary  wind turbine controller. Very simple.
           Biff


Title: Re: charging LA batteries with a fork lift charger
Post by: camillitech on December 19, 2018, 07:17:19 AM
A small diesel or electric driven 2kw x 48 volt pmg will work through a rectifier block and an ordinary  controller.
I charge a 120 volt pack just like that except  it is managed through an ordinary  wind turbine controller. Very simple.
           Biff

Perhaps even drive the PMG from the generator prime mover if you already have the genny.


Title: Re: charging LA batteries with a fork lift charger
Post by: biff on December 19, 2018, 07:38:37 AM
Yup.
     However a good W/T pmg delivers it's  2kw charge @ 56v x35amp approx. It can cruise at that but needs to turn below 400rpm.
So small 3.5hp yanmar clone can drive it with a 60mm pulley to the 500mm pulley on the PMG.
 I recon that this is about as efficient  as you can get.
 We have ours set on half throttle and 12 to 9 amps @ 145vdc.
        Biff


Title: Re: charging LA batteries with a fork lift charger
Post by: biff on December 19, 2018, 07:49:59 AM
My present endeavours  are all about getting a 6.5 horse single cylinder Lifan to drive a 180 watt alt. Then when it is set up properly  switch  it to bottle gas. I believe that this can be done quite simply.
The only reason that I am reading up and working with  car alt is because  there are some very interesting toys inside them these days.
        Biff