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Author Topic: Mokai battery  (Read 3921 times)

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Offline happul3

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Re: Mokai battery
« Reply #15 on: March 05, 2017, 09:00:15 AM »
Nicely packaged battery. Not clear if it incorporates a BMS and/or requires external balancing periodically. Probably can find out by calling the tall free number - if they put together the battery to be drop-in replacement for Pb, they supposed to give sufficient info about using it.

Offline 2mokaiman

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Re: Mokai battery
« Reply #16 on: March 05, 2017, 10:13:06 PM »
I have used this SHORAI LFX07L2-BS12 for the last 2 years in both of my mokais. I have the KX21 engines in my mokais and they have a higher compression ratio than the EX21 and much harder to turn over. These batteries crank it over with ease. I have had no problems with them. The best feature about them is they weigh just under 1 pound. That is the reason I bought them in the first place. Weight is a big factor with the mokai speed. You cut it where you can. But after having these batteries and experiencing their performance I would never go back to a lead acid type. You just can't beat the size, weight & performance of this battery. They are worth the extra price you pay for them.  \./8

Offline Painlesstom

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Re: Mokai battery
« Reply #17 on: March 06, 2017, 07:18:06 AM »
Nicely packaged battery. Not clear if it incorporates a BMS and/or requires external balancing periodically. Probably can find out by calling the tall free number - if they put together the battery to be drop-in replacement for Pb, they supposed to give sufficient info about using it.

There is no balance port, so there is no way to balance charge regardless. They were designed to directly replace a Pb battery and the only requirements given were charging voltage should be above 13.1v at idle and no more than 15.2v at full throttle. Like Tim said, they work great and he's been using them for years.
Tom

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Offline happul3

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Re: Mokai battery
« Reply #18 on: March 06, 2017, 08:10:09 AM »
Thanks 2Mokaiman! Good to know that my speculation about using 4s LFP turned out to be reality. Do you use an external charger or just a regular use of battery in Mokai is sufficient to maintain it?

There is no balance port, so there is no way to balance charge regardless.

I think there is a balance port actually. In fact, Shorai recommends using specially designed charger if usage is less than couple times a month and  "The Shorai BMS01 charger or the Hyperion EOS 720 chargers are the suggested balance type chargers". If you look at BMS01 pictures you can see 5 pin balancing connector. 

Offline Painlesstom

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Re: Mokai battery
« Reply #19 on: March 06, 2017, 08:51:31 AM »
Ahh You are right, I stand corrected then..  :-[
Tom

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Offline 2mokaiman

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Re: Mokai battery
« Reply #20 on: March 06, 2017, 08:56:10 PM »
When I bought these batteries I also bought the special charger that is specific to this battery. On the top front center is a small 5 pin charging port closed in by a plastic flap. I will try to upload photo to show it. However You really don't need this charger because the engine charges this battery in short order. I never used it. The battery comes with a sufficient charge that starts the engine just fine and then just let it run for a few minutes and your good to go. This battery really holds it's charge quite well. After letting it sit for 4 months it only dropped
3/10th of a volt. I will also try to upload a photo of the charger connected to the batter so you have a clearer understanding of this. Glad I could help


Offline happul3

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Re: Mokai battery
« Reply #21 on: March 07, 2017, 12:00:12 PM »
Thanks a lot for pics and for sharing your experience. Sounds like a good upgrade.

By the way, since you already have balancing charger it is not a bad idea to use it periodically. If your battery gets out of balance, charging it from engine does not guarantee that  all cells are charging properly. Let's say that the dumb charging circuit is producing 14.4V maximum. Normally, it is split between 4 cells equally, meaning that each cell is at ~3.6V each max, which is fine. But consider the following scenario, one cell somehow gets discharged more than three others. When charging at 14.4V total, the split is unequal, driving normal cells above target voltage and weak cell not getting there at all. In this scenario, charging results in a seemingly correct voltage, but one cell is undercharged and three are overcharged (already unhealthy situation). Suppose the battery is used again, taking equal current from every cell. This can possibly driving undercharged cell below its designated minimum voltage, which is now unhealthy for that cell. Subsequent charging/discharging cycles further increase disbalance without reflecting in charged battery voltage, and eventually produce enough damage to individual cells to render the whole battery useless. That's why people use balance chargers, which ensure that each cell gets exactly to the target voltage.

I want to stress that the progressive disbalance scenario I outlined above is not a certainty. It is also possible that, depending on charging circuit, cell capacities, and usage pattern, the disbalance is self-limiting and may never becomes a problem, like in lead batteries. But if balance charger is already available, I'd just use it once every month or two. 

Offline Painlesstom

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Re: Mokai battery
« Reply #22 on: March 07, 2017, 12:48:25 PM »
He's aware of that, but even after a couple years of using these, his balance charger shows nothing out of balance. Seem to be pretty good batteries, best bang for the buck. In my experience with Li batteries, it's the discharge and charge cycle that leads to eventual imbalance. Especially if there was a substantial discharge with a large load. Starting the Mokai a couple times during the day, and running full throttle otherwise, pretty much keeps it topped off all the time and there is never any deep discharge going on to affect balance. Good to check it once in a while, but not something I wouldn't worry about under normal conditions. Certainly can't hurt if one wants to keep tabs on it and plug it in when they feel the need.
Tom

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Offline strick

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Re: Mokai battery
« Reply #23 on: October 07, 2019, 09:30:34 PM »
Question about those terminals...slip on is this even legal to use in a boat or did you change them somehow to post and nut ?

Strick

Offline Painlesstom

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Re: Mokai battery
« Reply #24 on: October 07, 2019, 09:46:24 PM »
Manufacturer could be bound by rules about what they can and can't use, but what you do with your boat is up to you unless there is some inspection for registration that would dictate otherwise.
Tom

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Offline strick

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Re: Mokai battery
« Reply #25 on: October 08, 2019, 08:15:26 PM »
The reason I ask is because I recently bought one of those 10 amp batteries but the terminals are slip on maybe I can drill a hole in the middle and put a nut in them.

Strick

Offline Painlesstom

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Re: Mokai battery
« Reply #26 on: October 08, 2019, 08:18:03 PM »
Nothing wrong with slip connectors, I use them in all my conversions and have for years. Not problem. Current draw isn't an issue and I've seen no problem with them. Not something I'd worry about.
Tom

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