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[EVDL] Using 12V batteries with 8V BMS

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There are two ways to upgrade a Ford Ranger EV from the
original 8V batteries to use standard 12V batteries:
1. Fake the 8V points using resistor dividers as shown on
2. Drill a hole into the 12V battery to contact the
inter-cell connection between the 4th and 5th cell
so you can actually regulate the voltage for every
set of 4 cells.
The drawback of 1. is that cou can't regulate the voltage,
just monitor it and if a cell gets out of balance, then
there is very little that can be done
The drawback of 2. is that you will need to drill a small
hole in the batteries, which will likely void their warranty
but you can accurately measure the voltage of each set of
4 cells and the BMS can equalize these cells.

I have an AGM that has an issue, so I could experiment with
it and did drill this hole, now I know for sure that this
technique is feasible.
I now also know how to spot the interconnects when just
looking at the top cover of this battery, as the compartments
will show as slight depressions in the top cover, but the
inter-cell connects are again a flat area.
I marked an 'x' in below picture where to drill, exactly
between the indents from the inter-cell walls:

| o |
|----- -|
| |
|- x -----|
| |
|----- -|
| |
|- -----|
| |
|----- -|
| o |
The above shows a rough drawing of a typical lead-acid battery,
I have my knowledge from the Universal Power Group UB121100 of
which I received some pictures when a battery was sawed open
to show the internal interconnects:

Cor van de Water
Systems Architect
Proxim Wireless Corporation
Email: [email protected] Private:
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Tel: +1 408 542 5225 VoIP: +31 20 3987567 FWD# 25925
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