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Using a generator to charge batteries


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Hello everyone 

I am currently on day 3 of very cloudy conditions and it is not forecast to change. I am fully offgrid with no utility power.

I would like to charge my batteries with my generator (5kva), but I am unsure if I can just wire a lead from the generator into the AC input on the inverter and start up the generator, I have a axpert mecer 5kva inverter and plan to set charging limit to 20A for utility. 

Can anyone advise if I can just wire it up and go? 

Thank you, Alessandro 

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Have a look at this discussion: https://www.4x4community.co.za/forum/showthread.php/323657-Can-we-connect-a-6kVA-Online-UPS-on-a-5kVA-Diesel-Power-Generator

I am personally not at ease with this way of doing things..

If your genset doesn't have a DC output I would connect it to a battery charger and charge the batts that way..


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@Richard Mackay - Most Gensets only have a 12VDC output, so not going to help on a 24VDC or 48VDC that Axpert uses.

@Sandro - Gensets are all different, so difficult to say if the output will be accepted by the Axpert. You can most often safely try putting the output of the Genset to the Input of the Axpert, if the Axpert doesn't like the supply then it will stay "offline". Be aware of something I like to call "hunting" - This is when the Axpert will switch from one mode to another on/off - This could damage the Axpert if done over long periods and will NOT actually charge the batteries. So , the simple answer is to try. Unless your genset is majorly faulty, you can't damage the Axperts inputs while testing for short periods (10 min, unless "hunting"). Think of an Axpert like a large PC UPS, it might or might not like the stepped 220VAC that the genset provides. I have 3 UPS's that are happy with my genset stepped output and 1 that doesn't - As they say: "Milage may vary".😄

Addendum - If the Axpert "hunts" you wont have damaged it if it is for a short period (like 10 min) and then you just disconnect and know it wont work:(

Edited by KLEVA
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If you install a normal changeover mains / generator switch this will be easy. I use this method whenever I need to charge the batteries. Any gen will supply only what it can output. It may be necessary to limit its output to prevent it from running at max output. Their output tends to go haywire at max. My inverter is set to charge the batteries at 49a and my gennie runs flat out to get it right. 

Edited by Johandup
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