DC to DC Charger 25A

Work from the battery bank, not from the charger. For lead acid types, charge at 5 to 20 percent of the bank's amp hour capacity, so a 200Ah bank wants somewhere between 10 and 40 amps. For lead carbon you can go harder, 5 to 33 percent.

On top of that, every battery model has a maximum charge current, use it as a hard ceiling rather than a guideline. Those are listed model by model on the battery charging page.

Too small and the bank never finishes. Too big and you cook it. Tell us the bank and we will match a charger to it.

See the battery charging page

Somewhat but not properly with just a cable, no. A plain alternator puts out roughly 14.0 to 14.1V, and that cannot complete the staged charge a deep cycle battery needs, so the bank starts every day already low and sulphates over months.

What does the job is a DC-DC charger. It takes whatever the alternator gives it and produces a real multi-stage charge at the right voltage for your battery chemistry, and it isolates the house bank from the starter so you cannot flatten the one you need to get home.

Yes, and it saves you a box. Our 20A DC-DC charger has an MPPT solar controller built in, so the vehicle charges the bank while you drive and the panel takes over when you stop, with one set of battery settings instead of two devices arguing about the voltage.

Some will and some will not, and it matters more than with lead acid. Lithium wants a different voltage profile, no float stage, and it must not be charged below freezing.

We stock chargers with a proper lithium setting from 3A up to 50A, in 12V, 24V and 48V. Check the product page for the model you are looking at, because a lead acid charger on a lithium bank either will not fill it or will sit there holding a float voltage it should not.

Yes, from 1A up to 40A, including lithium and lead carbon models.

48V is where most people run out of options locally, so if you cannot see the size you want, ask. We do not list everything we can supply.

Three stage is bulk, absorption, float: fill it fast, hold it at the absorption voltage until it is actually full, then drop back to a holding voltage. That is the part that matters and a good three stage charger will look after a battery for years.

The extra stages on a seven stage charger are things like a soft start on a very flat battery, a desulphation pulse, an analysis step and a periodic top up. They are useful on a bank that gets abused or left standing, and they are not what decides whether your battery survives. Getting the voltage and the current right is.

It puts a brief discharge pulse into the charge cycle, which helps break down the sulphate crystals that build up on a plate when a battery spends time part charged. On a tired bank it can recover capacity. On a healthy one it is maintenance rather than magic.

It is not a substitute for charging properly. A battery that never reaches its absorption voltage will sulphate faster than any pulse can clear.

Roughly the amp hours you need to put back, divided by the charger's amps, plus about a third again for the absorption stage, which slows down on purpose as the battery fills.

So a 200Ah bank down to 50 percent needs about 100Ah back. At 20A that is five hours of bulk and closer to seven all up. The last 20 percent always takes longer than people expect, and skipping it is what kills banks prematurely.

It depends on the battery, not the charger. Every model line has its own absorption range, treat it as a hard ceiling you must never pass, and also its own float voltage, and they are set out line by line on the battery spec sheet and on our charging page.

Get it wrong on the low side and the battery simply never fills, which is the most common way a good deep cycle battery gets killed. Put a multimeter on the terminals and check the charger is actually delivering what it claims.

See the battery charging page

Yes, on anything with a proper float stage, which is everything we sell. That is what float is for: it holds the battery full without boiling it.

Worth knowing what it does not do. A battery on float is not being exercised, and a bank that never cycles will still age. If it is a standby bank that is fine and expected. If it is a house bank, use it.