What batteries do you recommend

[YellowBuzzaroundEX]

BTW - I've heard good things about MK Gel, Vmaxtanks AGM, and Odyssey AGM. However, I've never tried any of those. So I can't comment on them, except to say that I don't think Odyssey makes a U1 size AGM.

[Burgerman]

Odyssey best for low impedance, high current delivery, good but not the best cycle life and charge speed. And sport powerchairs etc.
MK gel best for cycle life reasonable impedance, and average powerchairs etc. IF CHARGED CORRECTLY otherwise they last no better than the rest.
Tanks, not spectacular at all.

But they must fit so that limits what you can use. And always max out capacity in the space you have. And non of them get anywhere close to the cycle life and internal resistance or range (up to 5x better) of lithium done properly. That doesent mean ready to go drop in lithium lead brick replacements with built in BMS as they are mostly unusable and far too low capacity and so C rate too.

[rover220]

the victron super cycle seem to be performing very well in chairs i have used them in.

[Burgerman]

https://www.batterymegastore.co.uk/prod ... 412110081/

These? Optimised for cycle life and capacity. Much like a gel battery. But pretty high impedance if the 500A max current is anything to go by. So OK for average user or someone with lighter chairs or no hills or someone with typical programming. Bit like MK gel in performance. And price.

[rover220]

https://www.batterymegastore.co.uk/product/victron-energy-agm-super-cycle-battery-12v-100ah-m6-bat412110081/

These? Optimised for cycle life and capacity. Much like a gel battery. But pretty high impedance if the 500A max current is anything to go by. So OK for average user or someone with lighter chairs or no hills or someone with typical programming. Bit like MK gel in performance. And price.

Yes exactly, I can’t find an actual figure anywhere for internal resistance mind.

[Burgerman]

No but that max 500 Amps tells me that its way higher impedance than say the 5000A capabiliy of the Odyssey or its 5 second 1500A capability! And thats a low 2.5mOhm. The MK is max 400A. Mostly because its a gel and bubbles in the gel are permanant. Thats not the case with AGM its limited only by its voltage drop to a low level under load.

If you have a fixed grp24 volume then one of the three competing sides of the triangle is higher then the other two drop. So if its got great cycle life then it will lose capacity or will increase impedance. If great capacity then it loses out on the other two. So if cycle life AND capacity are good, then impedance must suffer.

Increased cycle capability for e.g is unsually achieved by weaker acid. So less damage in deep cycle use. But that means hat the battery has weaker high current capabiity due to higher resistance esp towards charge end. You cant get all 3 of the competing requirements all at once. The Odyssey for e.g has less cycle life. But better in internal resistance. Which to ME matters more due to programming and perforance. (torque, fast charge, etc)

[rover220]

No but that max 500 Amps tells me that its way higher impedance than say the 5000A capabiliy of the Odyssey or its 5 second 1500A capability! And thats a low 2.5mOhm. The MK is max 400A. Mostly because its a gel and bubbles in the gel are permanant. Thats not the case with AGM its limited only by its voltage drop to a low level under load.

If you have a fixed grp24 volume then one of the three competing sides of the triangle is higher then the other two drop. So if its got great cycle life then it will lose capacity or will increase impedance. If great capacity then it loses out on the other two. So if cycle life AND capacity are good, then impedance must suffer.

Increased cycle capability for e.g is unsually achieved by weaker acid. So less damage in deep cycle use. But that means hat the battery has weaker high current capabiity due to higher resistance esp towards charge end. You cant get all 3 of the competing requirements all at once. The Odyssey for e.g has less cycle life. But better in internal resistance. Which to ME matters more due to programming and perforance. (torque, fast charge, etc)

Good info, should mean they are great for most users. I've got several sets out there now and had mo problems or complaints yet.

[Burgerman]

Yes.

Some more useless info for you...

As well as using a weaker water acid electrolyte in a deep cycle capable battery, and so called starved electrolyte to prevent overly deep discharge (runs short of acid before completely discharged) which all increases internal resistance and so current capability and increases peukert too. They also use thicker plates to make them less prone to warping and damage due to deep cycle use. Which happens because of the sulfates that coat the plates both externally and internally as the battery discharges.

But while the plates are a grid, with lead paste in the centres (like a strawberry cream chocolate at xmas) much of the capacity is less accesible to the electrolyte, and not on the face of the plates but inside the plate. In the lead past interior. In a deep cycle battery these plates are fewer and thicker. But since theres less of them (with the overall same capacity) more of this capacity is inside the plates. Because theres less outside surface area in direct contact with the electrolyte. So impedance is increased yet again. And peukert too. And so accessng this stored power is slower. Sacrificed to make the plates able to withstand deep discharge sulfation/distortion.

A starter battery offers much higher current to start an engine. Lower impedance. It uses many thin plates. Higher strength acid/water electrolyte. So deep cycling it destroys it. But a lot of thin plates means you can take a lot of power out fast! A battery with very thick, fewer plates, and the same capacity as seen in a typical battery designed for deep cycle use and high cycle count will not start your car. Well it will if you double the case/Ah size...

The odsyssey is different here. It uses many pure lead thin plates to avoid corrosion from dissimilat metals, and distortion and unwanted reactions because of impurities, and added metals like calcium zinc, tin, etc. And avoids distortion by having the whole thing like a tightly compressed thin plate sandwhich with very thin seperators. It allows 450 cycles, and the lowest impedance per Ah in the industry. So charges fast, can be discharged fast, due to super low impedance compared to normal batteries. But they dont always fit in wheelchairs...