Frequently Asked Questions

Here's What Our Customers Frequently Ask Us:

  • Is it normal for the UltraMax Smart Charger (20 A) to be loud and always on?  
    When the battery is fully discharged and during constant current charging at 20A it is normal for the fan to come on. It should go off as the battery is charged. 
  • The "t Bar" on the LifePO4 battery (for the Motocaddy golf trolley) has a red/black connection but my trolley has a blue/black connection. Will the connection be black to black/red to Blue? Yes. However, you can only connect the T-bar in one direction. It is polarity based and you won't be able to connect incorrectly. 
  • Currently I run packs of 12-12 Lifepo4 batteries in parallel which gives me 24ah @12v. what is the maximum safe charge current I can safely use to charge the battery packs?  
    You can safely charge the parallel set at 14A . 
  • Hi, I need to buy a battery to run a 100-watt transceiver drawing 15 amps, the amp draw is not all the time only on voice peaks, could you tell how long the radio would last, i would not be talking all the time, the receiver draw is 1 amp.  
    It is very difficult for me to tell you how long it will last. 
    Can you tell me how often in a day you will draw 15Amps ?  For how long each time. Is your standby current is 1Amps when you are receiving? I need a better usage profile before I can tell you how long your battery will last. You have at full charge 288Wh of energy. 
  • Hi, I have one of your Ultramax Lithium batteries. It’s a LiFePO4 100Ah Li100-12. The bar code on it is 5036446802743. Other information on it is Nominal Voltage of 12.8v Max Charge Current of 80A Maximum Discharge Current of 100A. Nominal Capacity 102Ah. I use it as a leisure battery in a Camper Van, and it was fitted professionally with a Solar panel and Victron MPPT Controller. I’ve today fitted Victron Smart Shunt 500A to be able to monitor the battery more accurately. I’d like to be able to configure the settings as accurately as possible in the Victron App, so wonder if you could tell me about your recommended settings for the following please:- The charged voltage parameter ( default in the app for a 12v battery is 13.2 volts ) but I believe this is g got a lead acid? The charge efficiency (for lithium the app says 99%) The Peukert Exponent (for lithium the app says 1.05) The discharge floor (default in the app is 50% but I’m sure this is for Lead acid. Tail current (Default is 4.00 %) Current Threshold default is (0.10A) Any other recommended settings?  
    • Battery Capacity — 100AH * 
    • Charged Voltage 14.6v * 
    • Tail Current — 4.0% 
    • Charged Detection — 03 
    • Puekert Exponent — 1.05 * 
    • Charge Efficiency Factor — 99% * 
    • Current Threshold — 0.10A 
    • Time to Go Averaging Period — 03 
    • Zero Current Calibration — ZERO 
    • Synchronize — SYNC 
    • Relay Mode – DFLT 
  •  Should you leave a lithium battery on charge all the time? 
    No, it's not recommended to leave a lithium-ion battery on charge all the time, as it can potentially damage the battery and shorten its lifespan. 
  • Should I charge my lithium battery after every use? 
    It depends on how often you use your lithium-ion battery and how much you drain it during each use. Lithium-ion batteries perform best when they are kept at a partial charge between 20% and 80%, so recharging the battery once it reaches around 20-30% capacity is generally recommended. If you use your lithium-ion battery frequently and drain it significantly during each use, then it's a good idea to recharge it after every use. However, if you only use the battery occasionally and don't drain it much, you may get away with recharging it less frequently. 
  • Can a dead lithium battery be recharged? 
    A completely dead lithium-ion battery cannot be recharged. When a lithium-ion battery is fully discharged, the voltage drops to a level that is too low for the charger to recognize and begin the charging process. Attempting to recharge a dead lithium-ion battery can also cause damage to the battery and may be dangerous. 
  • I am looking to purchase 2 x SLAUMXLI22-12USB with a view to effectively making a 44AH battery to temporarily run radio equipment in the event of an emergency blackout situation. With that said, I am writing to ask (1) if these batteries are safe to be connected in parallel, (2) is there a better connection option than the t-bar, for example, a post fitting, and (3) I assume I will be able to use ONE charger to recharge both batteries whilst they are connected in parallel? 


  • What is the effect of Bluetooth on Lithium batteries? 
    With Bluetooth, you can monitor the battery capacity and the number of cycles that the battery has been charged to. However, you may find that your battery is self-discharging rapidly. The reason is during storage Bluetooth communication uses the battery power to stay on and communicate. Most lithium batteries cannot switch off Bluetooth during storage, however, some have a switch which allows switching off Bluetooth during storage. 
  • My battery is showing 0 capacity when I connect via Bluetooth, is it now damaged? 
    This means the battery has been self-discharged during storage. Your battery is not dead, and a simple charge should wake up the battery easily. Unlike lead acid batteries a zero voltage on the lithium battery terminal does not mean the battery is damaged. BMS tends to protect the battery and goes into high impedance mode, so the battery is not discharged further. The battery voltage is in fact well above zero in most cases, just connect your charger and charge your battery.  
  • "I have an UltraMax LiFeP04 battery (SLAUMXL122-12). I left it on charge for a week, by mistake. Have I damaged it and therefore notice a drop-off in performance?" 
    No, you have not, but we recommend you remove the mains plug from the wall after you finish charging your battery. That way, you save Electricity, and you keep your charger healthy so it last longer lasting. 

  • "Hello, I have just moved into a flat with an UltraMax photoelectric smoke alarm fitted in my bedroom. And for the second time this week, it has gone off in the middle of the night with a really loud alarm sounding continuous beeping as if there is a fire. I can confirm there is no fire, my window was slightly open as it’s been warm so ventilation isn’t the issue. How can I get it to stop or disable it entirely? Is it the battery or is it faulty? I would imagine a low battery wouldn’t be such an aggressive sound. Please help, thanks! "
    Please do not ignore the alarm as there is a reason for it. It does not need a fire to be present, just smoke is sufficient. You have a smoke detector, not a temperature or heat detector. There must be some sort of smoke coming into your room at night and I suggest you should be very vigilant. When the smoke disperses the alarm will go off by itself.

  • How to charge lithium phosphate batteries?
    Charge at constant current at 0.2C Amps to 14.6V and then do constant voltage at this level. As the battery charges, the current goes down and when it reaches 0.025C the battery is fully charged. 

    if we have a 50Ah battery. 
    C is 50. 
    Charge constant current at 10A, when the voltage reaches 14.6 V keep the voltage constant, observe the current going down to 1.5 Amps and stop charging.