charging Nissan Leaf 10s with diode.

Have not wired a diode into a charging circuit since I built wind turbines for sailboats in 1980 -86 so please forgive what I fear is a dumb oversight on my part.

I have two garden Etractors and an almost finished freighter trike, each using a pack of 5 leaf modules for nominal 36V. I like to run them between 40 and 38 volts to ensure the longest life possible, seems to be good with range so would like to automate the charging.
Step 1: put two small 42V 1.7 amp chargers in parallel and charged a 36V SLA pack, no problem, with our hero being the charge controller.
So thanks to another poster on Endless Sphere I was reminded of diodes, which will eat about .75 volts. Great means that the 42V charger is now topping out at 41.2 perfect thinks I. Bought a bunch of 5 amp diodes (hexagonal body, stud & nut one end solder loop on other).

charging. My first try to take a bank of 4pcs 2 amp chargers in parallel, each with it's own diode resulted in a rather exciting battery discharge which destroyed a 30 amp inline fuse holder, when connected to the tractor battery pack.

Would one of you young charger mavens mind drawing a circuit diagram indicating which way round the diodes should go on pos or neg charger wires?

Will test the chargers I used yesterday if they are blown I still have 12 of them so do not want to waste any more, thanks in advance.

PS> Am only allowed to work on my own projects on Sundays, SWMBO has honey do the other 6 days.

ynot said:

So thanks to another poster on Endless Sphere I was reminded of diodes, which will eat about .75 volts.

Click to expand...

That depends on the specific kind of diode, and the current thru them at that moment. More current, greater voltage drop; less current, less drop. You'd need to check the specific datasheet for the diodes you actually have to find out what that drop will be at the "termination current" (the current draw of the pack on your chargers when at the "full" voltage you want them at). If you list the diode model and manufacturer, I can probably find the spec sheet and info.

Great means that the 42V charger is now topping out at 41.2 perfect thinks I. Bought a bunch of 5 amp diodes (hexagonal body, stud & nut one end solder loop on other).

charging. My first try to take a bank of 4pcs 2 amp chargers in parallel, each with it's own diode resulted in a rather exciting battery discharge which destroyed a 30 amp inline fuse holder, when connected to the tractor battery pack.

Would one of you young charger mavens mind drawing a circuit diagram indicating which way round the diodes should go on pos or neg charger wires?

Click to expand...

If you are only using one diode's worth of voltage drop, then just put one diode in series with the positive + wire of each charger, at that charger's output. The arrow on the diode indicates current flow, something like this shape:
-|>|-
So the wide part of the arrow goes toward the charger, and the point toward the battery's positive charge wire.

The chargers won't connect directly to each other at the positive wire, only at the negative wire where they meet up at the battery negative charging wire.

The diodes' pointy-arrow-ends do connect directly to each other at the battery positive wire.


If you need more than one diode's worth of voltage drop, then you connect that many diodes in series first (one diode's pointy-arrow-end to the next one's wide-arrow-end, etc), then put those diodes in the positive charger wires just like above.


(you could put the diodes in the negative line instead, but it's just easier to think of it with arrows pointing out of charger to battery, which happens on the positive line).

Once again Amberwolf, you offer aid, it is appreciated.
My post was a result of two problems, one I had been working on for about 12 days and a bunch of money & it was giving problems. the other was the charger. The charger is wired correctly and some idiot soldered the wires on the XT30 the wrong way round. The sky was falling and I was looking for the reason. Find that am not as nimble on my diagnostic feet as once was, please forgive.