[tomofreno]

I used the dip switch settings in the manzanita manual: switches 1,3,4 on the rest off. I just realized I misspoke in an earlier post and said you want lower voltage on pin2 to cut back to a smaller current. It should be clear from my last post you want the opposite, higher voltage cuts the charger back to lower current. Over about 4.5V shuts the current output down to zero.

[jtgreeson]

I got my Manzanita PFC-30 and played around with dip switches while charging a 24 volt lead acid. Here's an update on what I discovered and my "Plan" for High Voltage protection. It might help others and I invite comments or any corrections you might have:



Dip Switch #1 turns on timer when peak voltage limit is reached. With it off the charger still goes into constant voltage (CV) mode but never turns off.

Dip Switch #3, when on, allows timer to start when regbus pin 1 connected to pin 2.

Dip Switch #4 is described in the manual as "Reg buss disable". If it is on the timer will be reset each time Pins 1 and 2 are disconnected. If pins remain connected for the time the timer is set then the charger turns off and remains off. The minimum time the timer can be set is about 15 min.

If Dip Switch #4 is on when pins 1 & 2 are shorted then the timer starts and turns off the charger when it's time runs out. If pins 1 & 2 are disconnected the charger goes back to max charge but the timer still runs.


I plan on a "simple bms" to protect my ThunderSky LiFePo's using the 48 VoltBlochers I already have. My plan is to set Dip Switches 1 and 3 on, the rest off. I measured 5 miliamps (mA) between pins 1 and 2 so I believe I can connect them directly to all the opto HVC outputs of the VoltBlochers. I have calibrated all VoltBlochers to 3.8 volts at which they will start shunting and send a signal to turn off the charger and start the timer set at 15 min. (I will modify the circuit if I get any charger on/off oscilation) I will have a switch to turn off this High Voltage protection circuit if I wish to allow the VoltBlochers to shunt and top balance. I will set charging voltage limit to 3.65 volts average cell voltage (175.2 v for my 48 cell pack) The Voltblochers should not ever send a HV signal or shunt if the cells stay in balance. They should protect a cell overvolt condition if it occurs. The charger should operate as designed with high amp charging until 175.2 volts then constant voltage for 15 min.



Also, I tested the amp draw of each VoltBlocher at 3 volts and they all measured 3.15 to 3.20 mA., so I feel they are all good and will not drain any cells.

I'm toying with the idea to add a timer circuit to the HV signal that would latch it on for 5 minutes and a resistor to limit charging current to 2 amps. Tom described his voltage tests in a post above.

Thanks for any comments.

[tomofreno]

I will set charging voltage limit to 3.65 volts average cell voltage (175.2 v for my 48 cell pack) The Voltblochers should not ever send a HV signal or shunt if the cells stay in balance.

With HVC set at 3.8V I think this will perform as you expect, with the charger just timing out and HVC never triggered, unless a cell significantly drifts. I have not balanced cells for over 20 charge/discharge cycles now, and have not seen significant change in balance. I plan to operate in a similar way using the minibms which should arrive this week. Currently, I have the charger set so it just times out at about 3.42V/cell (Sky Energy cells, so exponential voltage rise with charging time starts at about 3.45V).

My experience is the Manzanita doesn't have a true "constant voltage" mode. It very gradually cuts back current once the timer starts, and voltage continues to rise. How much seems to be determined by how long the timer is set for, what magnitude charge current is used, and possibly how much pack voltage rises with charging time once the timer is triggered. With the timer set for 45 minutes, current cuts back from 30A to about 23A, then shuts off. With the timer set for 2 hours, current remains above 20A most of that time, cutting back very gradually until near the end when it drops more rapidly to around 4A before timing out. But near the end in this case, some cells were on the exponential rise in voltage with time part of the curve, so that is why I say it may depend on voltage increase - that's approximately when the charge current started dropping more rapidly with time.

[jtgreeson]

Thanks, Tom. That's useful information. I will post my charging data/experience when I get to that point.