Higher Voltage diodes won't hurt, since the price difference between a 100V and 1000V diode is only a few cents.
Although in defense of my diode selection, the 200V diodes are effectively in series, and since the 144V pack is isolated from ground, it makes the effective breakdown voltage 400V to get reverse breakdown. With the fuse it should be pretty safe.
Several people have asked me what connector to use.
I have been reluctant to say, as we all have different priorities.
Here is a list of what I see as the key issues to consider:
As Peter suggest, the fuse/diode assembly should be securely mounted near the battery.
To connect to the battery without this diode/fuse board, is tempting fate, and is not recommended.
The way that assembly is built will effect how and where it should be mounted.
The wiring to the connector and the battery needs to be supported and isolated from any possibility of vibrating and rubbing through the insulation.
The connector should be securely mounted in a place where nothing will stick into the sockets and short.
I like the passenger side storage place as the cargo insert protects the connector, but this makes it more difficult to use if you will charge nightly.
The trailer and AC receptacles that Jim suggested will work, as will hundreds of other connectors.
The key issues with the connector is that the thing can be securely mounted, has sufficient insulation for the 200V, and is something you can afford.
Remember that the charger end of the connector will kill you if you get across the pins with it turned on.
The pack temperature with the fan running stays at just about ambient, so it is tempting to say that the fan is not required.
Without the fan, the center of the pack will get much hotter than the extremities, the fan keeps it uniformly cool and temperature is no longer a factor.
For those that hate to run the fan full speed?, either turn down the voltage of the 12V supply, or possibily get one that outputs 6V instead.
This thread is where people that are building a charger can share how they have attached the charger, and their experience on how to use it.
For connecting the trickle charger to the outside world, I have selected a connector from Mouser Electronics.
Mouser #173-0603-E
Search for that number, click on the data sheet, and you will see a cable that has male/female ends on it that are a matched pair.
The female end has the normal protection, and the male end has a purposeful shroud around the pins, making it harder to accidentally touch them.
I ordered these two of these cables, along with some other parts.
1) One pair for disconnecting the battery from the panel mounted fuses in the car. The dual fuses are for both battery connections.
2) Another pair for connecting the trickle charger to the battery, through the fuses, through the first cable and to the tap points that Mike suggests on his website.
I do have a question about the diode use:
If I use a diode on the positive battery lead, and this prevents voltage from going outside the battery cabinet, then how do I monitor the battery voltage as the battery charges fully?
Or to put another way, how do I find out what the current battery voltage is, to adjust the trickle charger to this level, before attaching the charger to the battery, *if* the diode is present?
Remember that the charger end of the connector will kill you if you get across the pins with it turned on.
Can you not introduce a 12V interlock/pilotline so you only get a live connector if the charger is plugged in? Then no charger = no high voltage at the socket.
The diodes do mean that you cannot measure the pack on the connector, but will be able to measure the charger side which will be about 1.2V higher than the pack.
The pack voltage that represents full charge is when it no longer rises with the 350MA applied rather than a specific voltage. Part of the problem with using voltage to determine SOC on a hybrid car is that the widely varying current into and out of the pack with the associated lag in settling to a specific voltage, makes it nearly useless.
On a constant current charge with no thermal issues to add a variable, we will see a trend in the rate of rise in voltage that is pretty linear when the pack is in the under 90% SOC range, and almost stops rising when all cells are at 100%.
So the bottom line is that you dont need to measure the pack, only where the charger voltage is and the rate of change.
If you want to read the battery volts at start, the diodes present a problem.
Maybe put a 10K resistor across each diode? This would allow a 15meg DVM to measure the voltage but would limit max current back out of the pack to about 20ma?
Those computer cables look safe enough, except that they will dangle and could eventually break?
Were you planing to support them?
My plan was to support the male/female connector pair inside the battery compartment.
One plan was to use some zip ties and hold the pair to the inside wall of the cover during assembly when closing the battery compartment.
The zip ties can easily be cut to remove the cable and battery again, if more maintenance needs to be done.
The second plug will work it's way out of the battery box to the storage area, which is accessed by removing the 'basket'. I suppose the loose end of the cable could be attached with zip ties as well, to keep it from flopping around over bumps and such.
Obviously, the other mating end of this cable will be attached to the trickle charger.
I like this cable as well, as it does give an increased level of protection.
When working with this voltage level, I wear a rubberized pair of gloves for extra safety. You never know when you might need it. Usually accidents occur during some type of distraction.
One question I had on the use of *two* diodes to limit voltage from the battery compartment to outside world is as follows:
Picture the following scenario:
We have a normal 144 DC battery that needs charging
Current flows into the positive lead to the battery from the charger
Current flows out of the negative lead back to the charger
With this in mind, if we use two 'safety diodes' to protect the user from danger, the diode positioned on the positive lead keeps the current from coming back towards the operator. This is the normal flow of current when charging.
While the second diode *allows* the current to pass right through it back to the operator since this is the normal direction of current flow back to the charger.
So how does the second diode keep the negative battery lead from becoming a source of concern for the operator if utilized for this purpose?
The pack is floating related to the cars chassis ground, so as long as you only touch one pack lead, you would not get shocked.
If the pack got shorted to chassis ground in an accident, the diodes on both legs would stop current to chassis.
A single diode will prevent current from flowing out of the pack, and since current must flow to the other side of the pack, the diode blocks it.
The charger has more voltage than the pack, so it can run through the diode in the forward conduction direction and charge the pack, but a short or a person between the sides of the pack would be blocked by the diode.
The second diode just adds a second level of protection on the other lead.
The built in pack isolation is protector #1 ( no current from either lead to chassis, no protection if you get across the terminals)
The two diodes are protection # 2 and 3, (no current out of either lead for any reason.)
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