As great as the 24V system of the Pinz is for the winter - easier to start - and thin wires as the current requirement for a given load is just half of what it would be at 12V it’s a headache to find 24V accessories in the US (the only real sources are marine places as large boats are usually 24V too).
Even if you can find 24V “appliances” they usually cost a lot more then their 12V counterparts.......

This problem can be solved with in two ways:
- a converter which converts the nominal 24V into a fixed output voltage of 12V (or 13.2V)
- a battery equalizer (see later)

Voltage converter or “DC transformer”
There are several 24V to 12V converters on the market with max output currents from 1A to more then 100A. You simply hook them up to the 24V supply (battery) and connect all your 12V equipment to the 12V output (which is usually 13.2V as that’s the voltage of a regular 12V battery). Easy to install but has a drawback.... Let’s assume you have 12V equipment which is rated to a total of 20A power consumption. Naturally you will think that a 20A converter is what you will need. Wrong! All your 12V equipment will need a much higher current if you turn them on to charge internal capacitances. As the converters are all current protected (at least they should be) they will shut down and all your 12V stuff is off. For this reason the surge current of the converter has to be much higher then the continuous current. Depending on what equipment you have the surge current requirement may be up to twice the continuous current. As the efficiency of the power conversion is lower at lower power levels the system may become quite hot or inefficient.

Example of a typical 20A/23A voltage converter:
and it’s installation:

Battery Equalizer
Battery equalizers (BEs), like the voltage converters, are nothing but switchmode power supplies. BE’s are designed in a way that they are connected to the 24V battery and the center tab of the battery (12V). Whenever the 2 batteries have unequal voltages they draw current from the higher voltage battery and charge the lower voltage battery with it until both batteries have the same voltage level. This works fine with batteries which are similar but not with different or worn out batteries! BEs are available with output currents from 2A to 100+A too but there is a major difference to the voltage converter. As the BE is connected to the center (12V point) of the battery the system has an almost unlimited surge current capability! Until you exceed the max rated current of the BE the load is equally supplied from both batteries. If you exceed the rating the power comes from the lower battery but as soon as the load is removed (or lowered below the BE current rating) the BE will continue to equalize the batteries again. Good BE’s have up and down converters which even allow you to charge your 24V battery from a 12V charger, just hook it up to any battery. There are BEs which have an input for the ignition which makes them much easier to install as the relays are not required.

Example of a typical 20A battery equalizer (this one shows it’s good efficiency by the missing heat sink!):
Typical wiring diagram for an equalizer w/o ignition switch input. Wire gauge, relay current capability and fuses according to power handling capability of the equalizer: Caution! Contact K2 has to be able to handle the max current of the 12V section of the equalizer, K1 the 24V max input current of the equalizer which is slighly more then 0.5 * the 12V output current. Regular automotive 12V relays usually should be sufficient.

Summary
Voltage converters are a fast and simple method to power 12V equipment in the Pinz but a good battery equalizer is only slightly more expensive then a voltage converter and provides a lot of advantages. If you think long term a BE may be the better solution.
One word of caution for both types of converters: they all draw some quiescent current (usually in the order of 10mA to 50mA) which will drain your battery over time. They should be installed after the main power switch (voltage converter) or with relays powered from after the main power switch (battery equalizer, relay(s) have to switch of both, the 24V and 12V connection).

Contributed by: Juergen Schoepf

Click here to see Jay Reichs installation of two Optimas, a battery equalizer and the relays.