DIY Electric Car Forums banner
41 - 41 of 41 Posts

· Registered
42 Posts
There has been a lot of discussion here...
The following is from experience with my EV conversion.
A standard proper DC-DC converter normally has a maximum current output of 30-40Amps.
Do not feed this into a small AGM battery as it will cook it. A small SLA/AGM battery will only accept a few amps.
I got around this by inserting a power diode in between the DC-DC converter (putting out around14Volts) and a 30Amp/Hr SLA/AGM battery (with a maximum charge current of around 9Amps).
This works because the DC-DC converter thinks the battery is fully charged when it sees the "battery" voltage reach the 14V, while the actual battery voltage is 14V less the 0.6V drop across the diode.
This worked for me for over 10 years when I recently replaced the 30Amp/Hr SLA/AGM with a lithium (LiFePo4) 20Amp/Hr battery.
This also works very well and I have only seen a maximum charge current of around 10Amps which is the recommended for this battery.
When I say "proper DC-DC converter", I am suggesting NOT to use a power supply that has an AC input (like Meanwell).
These do not last long in an EV conversion (I had one for a while before is was dead), because the input circuitry can not handle the current surges that are around when the car is accelerating. There is a work around for that, but that is another story.
If you don't want to mess around with diodes etc, keep the original lead acid battery, that came with the car, that can handle the high currents that these DC-DC converters are capable of.
41 - 41 of 41 Posts