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[Jepe]

Hello.

A question about a 2025 SR/S: I understood that the 12v battery is charged from the main battery when the bike is in use, but when I charge the main battery without turning the key on contact first, will the 12v battery also be charged at the same time, or only when you turn the key on (for example, to unplug the cord from the bike at the end of a charge)?

[MVetter]

Whenever the 12v lines are active this means the DC-DC converter is also active. That is the thing that charges the 12v battery.

[Jepe]

So, let’s say I charge the bike till 55 %, and when the charge is finished, I put it on contact, disconnect the plug, set the chargegoal to 60 % for the next charge, and turn of the key.
The next time I connect the plug, so, without turning on the key, the main battery is charged but the 12 v is not?

[princec]

I believe that is the case yes. Annoying because the 12V battery doesn't last all that long on its own - make sure to turn the key on for an hour every couple of weeks.

Cas

[Specter]

but wouldn't it also charge every time you rode the bike too, sipping off the main battery?

aaron

[karlh]

Yes.  As MVetter said, whenever the 12V lines are active, the DC-DC converter is converting main battery voltage to 12V and charging the 12V battery.  If the dash is on, the 12V lines are active.

[Jepe]

but wouldn't it also charge every time you rode the bike too, sipping off the main battery?

aaron

Yes, that’s right, but the reason I asked is my situation in winter, when there’s frost and salt on the road. I don’t ride the bike in these conditions, so my plan was to put in the garage after “the last ride” and charge it till 55%, and after 3 or 4 weeks till 60%, a few weeks later till 65%, etc, in that manner I can span two or three months. That’s why I wondered if the 12v was charged too in this way, but it doesn’t seem te be the case.
Strange that you have to leave the bike with the contact on for an hour or so to keep the 12v in good health, I guess I’m still in the “internal combustion”-mood, where you cannot leave the contact on for such a long time without damaging the circuit  .

[Specter]

So besides the bikes electronics periodically checking on the main batteries health, what else is sucking off the 12 volt bus when it is off?  unless it's got a bunch of parasitic loads, or just a cheap shit battery, probably the case with oem batteries, or very old, a normal 12v  sli/sla should handle that without too much of a pain.

 get yourself one of these 2amp battery tenders, plug it into the battery direct, you should have fairly decent access to it, and keep it topped off that way.   it's probably lead acid, they are cheap and fairly reliable, BUT don't like to sit partially charged. keeping them topped off on a trickle constantly, they love it, unlike lith, which hates it.  this way when spring rolls around, you top off your lith, which DOES like to sit around 80 percent, and your LA, which loves to float at 100 percent, are both good to go.

aaron

[MVetter]

Yeah, there's nothing wrong with getting yourself a separate battery tender, ideally one designed for lithium batteries that doesn't bring it up to full and keep it there. Also, something else to consider for winter, this is the time of year when people load up the accessory port lines with things like heated gear. The DC-DC is only a 300W unit, and the 12v battery is there to sort of bolster it. The point is if you're pulling 300+ Watts during winter riding the 12v battery is actually being discharged and can't refill itself until the load on the 12v lines is reduced.

I'm not saying you're doing that, I'm just pointing out additional complications during times of cold weather riding.

[Specter]

From what Morgan said, 300 watts,  that's running your lights, accessories, abs pumps, sensors, bikes brain, heated hand grips etc, those watts go fast, there really are not a hell of a lot left for you to go plugging in a lot of extra toys.  You may be saying, well my heated suit only takes 180 watts, gloves and all.. but if your bike is already pulling 200 watts just to run. you are already running a deficit on the battery.  Now lets throw in the cold weather that's making you have to wear all that stuff.  That can be killing your battery 30 percent of it's capacity, so now those loads are really taking their toll.

A lead acid battery sitting a day or two, at less than full charge, can start sulfating, (losing capacity permanently), so no matter how it's being used, having a trickle charger for a lead acid battery to keep it topped, is really a good idea.

Aaron

[MVetter]

It's also funny because Zero started out with a 300W unit but bumped it up to a 500W unit in 2015 when they added ABS which required extra power. Then, when the gen 3 bikes were designed with the 12v battery as an additional power bank they opted to save a couple bucks and drop back down to the more cost-effective but weaker 300W unit. The units are functionally identical, so I would consider seeing if you can find a scrapped gen 2 Zero and scavenging a 500W Sevcon DC-DC then putting that in your gen 3 bike.

[Jepe]

Thanks for all the answers regarding the 12 volts battery. Now that I’m reading reactions about lead acid batteries I’m prepared to read advices about changing the cooling fluid on my SR/S soon too  .

[Specter]

fluids should be changed at least annually imo.

brake fluids pick up moisture, which reduces it's effectiveness and can cause corrosion, pitting, and very undesirable results during a hard stop.  Changing it once a year is also a great time to check your brakes for leaks, cracked covers, seals leaking, how much pad is left etc etc.

your fork oil picks up dust and grime from the roads you ride on, can break down, it's viscosity changes and it does not perform well.  the ports can get plugged causing further loss of performance. a quick flush / inspection there can give you early warning of issues creeping up on you.

anti freeze / cooling fluids, likewise can pick up contamination that reduces their effectiveness.  changing it, and seeing it's condition can give you an indication of your engines health, do you have any leaks starting, head gasket issues etc. excessive corrosion and so on?  in our case, inverter motor wear but same principles.  also it lets you check for leaks, running out of that will cook your stuff in very short order.

oils in gear boxes can pick up moisture, metal shavings etc which can give you grief, cause foaming, reduce effectiveness.  inspecting this lets you check for abnormal wear, indicating potential misalignments or bearing wear.  this is something you absolutely want to catch early on before it gives up the ghost.  the type of metal you do find, if any is a very good indication of which component is having issues.

so yes, it's your life, your safety, i honestly can't recommend doing this once a year highly enough.  if you can't, don't know how, don't have the time, etc, then have someone else do it for you, but this is stuff you really shouldn't be neglecting.

just my thoughts.
Aaron

[TheRan]

For someone that assumes everything is AI that has to be one of the most AI responses I've seen from you  Talking about headgasket leaks and gearbox fluid when it comes to a Zero.

Come to think of it are there any fluids in the gen 3 bikes other than brake fluid? Of course the battery, motor, controller are all air cooled but I thought the chargers still were as well.

[Specter]

im giving him the general reason to change the fluids on any bike annually.  given he is asking if he should bother changing the fluids or not, it seems he is new to bikes, so i am explaining to him, yes you do need to change them, inspect them and why, not just saying yes and walking away.

the energca has gearbox oil that you change, it's not much but you change it, it also has fluid for the inverter, again not much, that's about a cup or two i think in there.  the brakes you should always check because the fluid gets shitty especially if you use them hard.  same goes for the forks.  my point being you should change your fluids annually because you also should be taking a good look at your bike at least annually too, don't just ride it until shit starts falling off, it's not a harley.  this is something that should be done with every bike, not just electrics.  some people have gas bikes too, and if you have problems it can show up when you start getting antifreeze / oil where they don't belong or mixed. just like with a car.

aaron