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Battery to Battery Charger / Maintainer 24V to 12V / 1A, Pro Batt M
Battery to Battery Charger / Maintainer 24V to 12V / 1A, Pro Batt M
Battery to Battery Charger / Maintainer 24V to 12V / 1A, Pro Batt M
Battery to Battery Charger / Maintainer 24V to 12V / 1A, Pro Batt M

Battery to Battery Charger / Maintainer 24V to 12V / 1A, Pro Batt M

Article No.: BM24121 Shipping weight: kg per piece, Shipping as parcel Availability: stock Lieferfrist: 1 to max. 5 working days *
110,00 EUR incl. statutory VAT 19%
plus Shipping costs

Battery - to - Battery Charger / Maintainer Pro Batt M

24V to 12V, max. 1A, IP68

for Expedition trucks, Car, Boat, Camper, Solar, Motor home, Solar

Save money on batteries and stop them from being destroyed by discharging. A flat battery means you need an expensive replacement.
The auxiliary battery charger maintainer is simple to install and is a low cost product. It is designed to enable extra battery banks on a boat or a camper van to be kept topped up from a separate battery bank which has, for example, a battery charger / wind generator / solar cell connected to it.

Input V DC Output V DC Amps Out Size L x W x D mm Weight Kg Part Number
12 12 3 140 x 45 x 40 0.25 BM12123
12 24 1 140 x 45 x 40 0.25 BM12241
24 24 1 140 x 45 x 40 0.25 BM24241
24 12 3 140 x 45 x 40 0.25 BM24121


Why use this product instead of a voltage sensitive relay?
A voltage sensitive relay takes a relatively large amount of charge to hold in a relay. This is power you cannot afford if you are only producing low current (e.g. from solar / wind input). The Battery Maintainer uses FETs instead of relays and as such uses very little power itself (less than 1 mA) thus solar input can be more efficiently used. The Maintainer is also current limiting so the high load on starting would not affect it. Relays also have a limited life cycle and on low power generation a relay could be clicking ‘on’ and ‘off’ all day. However, with a FET control system there is no physical contacts to wear out and no noise produced. This Maintainer should not be used on a battery with a sustained heavy discharge/drain as it can’t pass high currents. See Voltage Sensitive Relays or the Battery to Battery Chargers section.
A 100Ah battery at 50% discharge would take about 24-36 hours.

How does it work?
This unit is activated when the main battery has reached about 13.3V and allows excess power to be transferred from the primary charging system to charge / maintain an auxiliary battery bank.
Please note that this product has no fast charge / boost ability but simply mirrors the input voltage with a small voltage drop (depending on the current flow), the final charge voltage would be around 0.2V lower than the primary charge voltage. This is more than enough to keep a battery topped up and supply any small loads, such as: the battery internal discharge and the engine management system discharge (up to about 1A continuous). This product should not be used on a battery with a sustained heavy discharge or drain as it does not have the ability to pass high currents, for higher currents see the Voltage Sensitive Relays or the Battery to Battery Chargers sections of the catalogue.
This maintainer has the ability to charge and maintain the charge, even if the battery is low (in a long time frame for example a 100A battery at 50% discharge could take about 1-2 days) it would never do this if the current discharge from that battery is in excess of 2A.

Delivery contains:

  • Battery to Battery Charger 24V/12V 1A, BM24121

Further helpfull informations you will find here: FAQ

Technical Details:

  • Nominal Input voltage: 24V DC
  • Nominal Output voltage: 12V
  • activating voltage: Primary Battery >26,6V
  • deactivating voltage: Primary Battery <25,6V
  • Charging voltage: primary battery voltage : 2 minus 0,2V
  • Standby current: <2mA
  • charging current: max. 1A
  • Protection: IP68
  • Fan: no Fan
  • Connection wires: 1 meter, AWG12 / 4mm²
  • Dimensions (LxWxH): 140 x 45 x 40mm
  • Weight: 0,5kg

Attention: If you should not have the Adobe AcrobatReader installed on your system, you may download it for free from Adobe Inc. using the link

You have questions regarding the order process or the item?

Just contact an employee of our customer service team.

You can reach us by phone from Monday to Friday between 8:00 and 18:00 clock.
Tel: +49 6024 6341 560 or by fax +49 6024 6341 569
Of course we are also available via e-mail: kontakt@fraron.de


You would like to see the product before you purchase it, or you need personal conversation?

In case you like you can see all items in our show room in Mömbris.
We are also available from Monday to Friday between 8:30-12:30 and 13:30.18:30


What payment methods are available?

  • Cash / EC card payment for pick-up in the office branch in Schöllkrippen
  • Transfer / Payment by bank transfer
  • COD ( cash on delivery is only available for parcel shipments within Germany ) You pay the shipment at the deliverer.
  • PayPal including Buyer Protection (for EU countries plus Liechtenstein, Norway, Iceland)
  • Credit Card (Visa / Mastercard)


How long is the delivery-time / transportation-time

The stock status is indicated on the product page. In stock items will be shipped according to the method of payment or immediately after payment.
Transportations within Germany handed by DHL, abroad by DHL or DPD.
The transportation-time in Germany will be 1-2 business days. DHL deliver also on Saturday in Germany.
Forwarding goods like batteries we ship via the forwarder Emons, the terms range from 2-3 business days within Germany and abroad can not be stated flat rate, please contact us.

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